Earth Government for Earth Community
A grassroots process
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Earth Government for Earth Community A grassroots process |
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Earth Government Newsletter Newsletter Volume 1 Issue 8, November 2003 |
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Theme Protection of the global life-support systems Table of Contents
1.0 President's Message 2.0 Letter to the Prime Minister of Canada, Jean Chretien, concerning the Kyoto Protocol 3.0 Reports 3.1 Impact of human activity on global climate, agriculture, wealth, health, security and all life on Earth This report was developed by the global ministry on Climate Change in response to the unavoidable climate change. A.1 Climate change overview 3.2 World overpopulation and its global problems by year 2024: a threat to humanity 1.0 Overview of the problem4.0 Research and development papers The Oxygen we breathe is finite 5.0 General articles A) The Oxygen we breathe OverviewB) The Ozone layer C) Photosysnthesis 1.0 OverviewD) Respiration, the opposite of photosynthesis E) The biosphere F) Earth's atmosphere 1.0 Composition, chemical and physical properties
Losses of biomass through deforestation and the cutting down of tropical forests put our supply of oxygen (O2) gas at risk.
The Earth's forests did not use to play a dominant role in maintaining O2 reserves because they consume
just as much of this gas as they produce. Today forests are being destroy at an astronomical rate. No O2 is created after a forest is put down, and more CO2 is produced in the process.
In the tropics, ants, termites, bacteria, and fungi eat nearly the entire photosynthetic O2 product.
Only a tiny fraction of the organic matter they produce accumulates in swamps and soils or is carried down the rivers
for burial on the sea floor.
The O2 content of our atmosphere is slowly declining. The content of the atmosphere decreased at an average
annual rate of 2 parts per million. The atmosphere contains 210,000 parts per million.
Combustion of fossil fuels destroys O2. For each 100 atoms of fossil-fuel carbon burned, about 140 molecules of
O2 are consumed.
Scientists will need to become more involved in assessing the viability of response options aimed at storing excess carbon in terrestrial or ocean systems. Land use changes from agricultural to forest ecosystems can help to remove carbon from the atmosphere at rates of 2 to 20 tonnes of carbon per hectare per year for periods of 50 years or more, until a new ecosystem equilibrium is reached. Similarly, soil conservation practices can help build up carbon reservoirs in forest and agricultural soils. Proposals to extract CO2 from smoke stacks and dispose of it in liquid form in underground reservoirs or deep oceans also need careful evaluation in terms of long-term feedbacks, effectiveness and environmental acceptability. However, much remains to be learned about the biological and physical processes by which terrestial and ocean systems can act as sinks and permanent reservoirs for carbon. The Global Community can contribute in evaluating options and strategies for adapting to climate change as it occurs, and in identifying human activities that are even now maladapted to climate. There are two fundamental types of response to the risks of climate change: 1. reducing the rate and magnitudes of change through mitigating the causes, and Mitigating the causes of global warming implies limiting the rates and magnitudes of increase in atmospheric concentrations of greenhouse gases, either by reducing emissions or by increasing sinks for atmospheric CO2. Reducing the harmful consequences can be achieved by co-operating together with the global ministries on climate change and emergencies. The Global Community has created the global ministries to help humanity be prepared to fight the harmful consequences of a global warming through anticipatory adaptation. The global ministries on climate change and emergencies are now operating. The ministries have developed: 1. policy response to the consequences of the global warming, andThe Global Community also proposes that all nations of the world promote the Scale of Human and Earth Rights and the criteria to obtain the Global Community Citizenship. Every global community citizen lives a life with the higher values described in the Scale and the criteria. Global community citizens are good members of the human family. Most global problems, including global warming and world overpopulation, can be managed through acceptance of the Scale and the criteria. We need to improve on our ability to: * predict future anthropogenic emissions of greenhouse gases. While demographic, technological and economic factors are in many respects inherently speculative, better observations and understanding of the processes by which human activities directly or indirectly contribute to emissions are clearly required. These in particular include emissions from deforestation and agricultural activities; Comprehensive population policies are an essential element in a world development strategy that combines access to reproductive health services, to education and economic opportunities, to improved energy and natural resource technologies, and to healthyer models of consumption and the "good life." Policies to decrease world population:
The vast disparities in reproductive health worldwide and the greater vulnerability of the poor to reproductive risk point to several steps all governments can take, with the support of other sectors, to improve the health of women and their families:
More and more young people on every continent want to start bearing children later in life and to have smaller families than at any time in history. Likewise, in greater proportions than ever, women and girls in particular want to go to school and to college, and they want to find fulfilling and well-paid employment. Helping people in every country obtain the information and services they need to put these ambitions into effect is all that can be done, and all that needs to be done, to bring world population growth to a stable landing in the new century.
Dear Prime Minister:
Greenhouse gases are accumulating in the Earth's atmosphere as a result of human activities, and temperatures are rising globally due to these activities. There are plenty of observable effects of the global warming. And certainly this ridiculous and false solution of buying environmental credits from each other should not be considered as a way out of resolving the problem. The ratification the Kyoto Protocol is only a beginning to protect the global life-support systems. There is much more to do! It is OK to be more energy efficient for the purpose of reducing greenhouse gas emissions. It is OK to follow the best energy efficient machines such as the use of natural gas-fired co-generation power plants to provide steam and power requirements to oil sands development in Canada or elsewhere for other purposes. It is also OK to build new cars with engines that do not emit greenhouse gases. Earth Government has seen oil companies improving a lot on many important aspects of their business. And that is OK! A lot of new solutions to resolve the problem of global warming are welcome and certainly are OK. But none of them tackle the problem head-on! None of the solutions make a dent in resolving the problem. None are significant solutions! None of the solutions truly show any significant cut in greenhouse gas emissions. None of the solutions tell us that producers of the deadly gases are the problems and so are consumers. Producers of the deadly gases are fooling themselves first and then they fool the consumers of their products of mass destruction, the greenhouse gases. Global warming is the highest threat to Earth security and is everyone's business. Terrorism was, and still is, a problem humanity needed to tackle head-on and resolve the best we could, but global warming is by far the greatest threat to the security of all people on Earth and to life itself. We have never tackle the problem head-on. We played around the problem and its solution. We know the solution to the problem of global warming, we know what we need to do to make this generation and future generations safe and secure, but we just never do what we really have to do to resolve the problem. Why? What will it take to make us act on the problem of global warming? What will it take to make the North American Way of Life safe and secure to humanity? What will it take to make Canadians and Americans understand that it does not matter how many guns we have, how many weapons of mass destruction we have hidden everywhere, or how good a 'Star War System' could be, and how many nations we invade, and how big is our GDP and how good is our economy. None of that matters! None! The biggest problem to security is smaller than anything we can see, smaller than the smallest particle we can breathe, and it is a trace element in the air we breathe. A deadly gas, the greenhouse gas! We all know the problem, and we also know the solution. We can stop creating greenhouse gases. So now what is the problem? The biggest problem is the North American continent Way of Life, consuming too much of the wrong things. The biggest problem is too much freedom of doing the wrong things. The biggest problem is our own weaknesses and helplessness in tackling the problem head-on and solve it. The biggest problem is that Canadians and Americans are getting too proud about things that are completely unimportant and missing out on the things that are truly important, and we have been left behind by most other nations on those things that are truly important for the generations to come and to life itself. Earth Government is asking North Americans and everyone else on Earth to tackle the problem head-on. We must solve the problem we have with global warming. Producers of the greenhouse gases tell us "we are energy efficient" but the truth of the matter is that they are producing the deadly gases of mass destruction, and those deadly gases are killing us all, and all life on Earth. It does not matter how smart you may be in fooling yourselves in accepting a slow death, a suicide in a way, you are still killing yourselves and the people of the next generations. That is a crime against humanity. You are criminals. An oil company is proudly telling us with all sorts of gifts, grants and awards to the community that every year they have 'given' to their customers trillions of litres of the deadly gases. And, their customers, very proudly and carefully burned all of those litres. That is the biggest problem. We are told that we should be proud of burning the deadly gases. Americans invaded the Middle East to take over OPEC and their oil and burn trillions of barrels of oil. That means trillions of litres of the deadly gases entering the atmosphere of the Earth. The best and cheapest oil in the world being taken over by the worst consumers of the world. Just how mad are we? How insane are we getting to be? How can anyone be proud of thenselves about such an invasion? What is it? We enjoy driving with freedom on the highway?! We enjoy driving and to forget completely that we are actually killing ourselves and taking away the lives of people of the next generations. We want to forget we are destroying all life on Earth. And please dont even mention the 'carbon emission trading permits' (a mechanism by which oil companies could buy and sell greenhouse gas emissions trading permits) as a possible solution. You are just extending the death of all lives by a few years, and you are not tackling the problem head-on. Over its long past history trade has never evolved to require from the trading partners to become legally and morally responsible and accountable for their products from beginning to end. At the end the product becomes a waste and it needs to be properly dispose of. Now trade must be given a new impetus to be in line with the global concepts of The Global Community. You manufacture, produce, mine, farm or create a product, you become legally and morally responsible and accountable of your product from beginning to end (to the point where it actually becomes a waste; you are also responsible for the proper disposable of the waste). This product may be anything and everything from oil & gas, weapons, war products, to genetically engineered food products. All consumer products. All medicinal products! All pharmaceutical products! In order words, a person becomes responsible and accountable for anything and everything in his or her life. As a business you may be using standards of operating and managing that are similar to the ISO 14001 environmental management plan (internationally recognized standards that provide guidelines to reduce environmental impacts). ISO 14001 provides a framework for continual improvement to mitigate potential environmental impacts from operations and businesses dealing with your company. The problem is not so much how good is your environmental management plan. The problem is the product you produce and put on the market to consumers. The problem is your product, a deadly product of mass destruction. It is worst than all known weapons of mass destruction as it kills by making consumers believe it is good for them. Like smoking cigarettes! Companies making cigarettes have for long told their consumers that a longer filter would not affect them so much and they would not get cancer and die of it. Whether or not you use the most energy-efficient machines and the best management team, and ISO 14001 for that matter, at the end it does not matter. You are still producing the deadly gases and consumers are still burning them. Consider the long filter for cigarettes as an illusionary solution to the problem and so are carbon emission trading permits. Oil companies are responsible and accountable of their products from beginning to end. The 'end' for an oil company does not end at the gas pump where a consumer buy your refine products. No! The end for you goes all the way to global warming, to pollution of the environment, to the destruction of the global life-support systems, to taking away lives of future generations, to the destruction of life on Earth. Very much so! Earth Government proposes to ask you to pay a global tax on your products. The tax would be high enough to discourage consumers from buying your products and force you to use viable alternatives. The Governments of the United States and Canada should put a high tax on all oil based products and their derivatives and certainly gasoline should have the highest tax possible. The tax would be a carbon tax allocated for the protection of the environment and the global life-support systems. A workable type of Tobin tax should also be in place as it is a powerful instrument to promote sustainable development and force shareholders in moving away from producing oil. Earth Government also proposes to develope a method of raising global taxes, of redistributing incomes to the poorest communities, of providing debt-free technical assistance to non-industrial and developing countries to help them out of poverty and to meet environmental and social standards. The WTO, the World Bank, the IMF, the EU and the UN are worldwide organizations that can and should be used to raise global taxes to redistribute to the poorest and developing nations. The Global Community can contribute in evaluating options and strategies for adapting to climate change as it occurs, and in identifying human activities that are even now maladapted to climate. There are two fundamental types of response to the risks of climate change: 1. reducing the rate and magnitudes of change through mitigating the causes, and Mitigating the causes of global warming implies limiting the rates and magnitudes of increase in atmospheric concentrations of greenhouse gases, either by reducing emissions or by increasing sinks for atmospheric CO2. Reducing the harmful consequences can be achieved by co-operating together with the global ministries on climate change and emergencies. The Global Community has created the global ministries to help humanity be prepared to fight the harmful consequences of a global warming through anticipatory adaptation. The global ministries on climate change and emergencies are now operating. The ministries have developed: 1. policy response to the consequences of the global warming, andThe Global Community also proposes that all nations of the world promote the Scale of Human and Earth Rights and the criteria to obtain the Global Community Citizenship. Every global community citizen lives a life with the higher values described in the Scale and the criteria. Global community citizens are good members of the human family. Most global problems, including global warming and world overpopulation, can be managed through acceptance of the Scale and the criteria. Germain Dufour President Earth Community Organization
A.1 Climate change overviewThe term climate change is used to refer to changes in the Earth's climate. Generally, this is taken to mean changes in the temperature, though 'climate' encompasses many other variables (precipitation, clouds, etc). 'Climate change' includes natural and anthropogenic forcing; 'global warming' is usually used to mean changes with predominantly anthropogenic forcing. Carbon dioxide (CO2 ) is one of the most important greenhouse gases (second only to water vapor), and is one of the gases of most concern with global warming. Due to human activities, the concentration of CO2 in the atmosphere has increased greatly over recent decades, owing to human activities. Understanding the natural cycling of carbon on Earth will help us understand ways by which human activities can affect concentrations of CO2 in the atmosphere,. One important component of carbon cycling is the biological carbon cycle. It basically involves: * CO2 uptake by plants in the process of photosynthesis, with conversion of a fraction of that CO2 into organic material (sugars, initially) and * Release of CO2 by respiration of plants, animals, and microbes. The biological carbon cycle involves an enormous amount of carbon; more than 20 times the quantity that is released each year by fossil fuel combustion! Until recently, the biological carbon cycle was usually balanced; as much was taken up by plants in photosynthesis as was given off in respiration and decomposition. That is, uptake of CO2 from the atmosphere was balanced by its release back to the atmosphere. Thus, there was no net gain or loss of atmospheric CO2, and the biomass (the organic non-fossil material of biological origin which includes all plants and animals as are the materials they produce, such as animal droppings and wood) on earth was roughly constant. There have been times, historically, when biomass accumulated. One notable example is the Carboniferous era when much of the biomass that later became our fossil fuels was deposited. This was a warm and damp period during which uptake and storage of carbon from the atmosphere must have been greater than its release via decomposition and respiration. That is, there was a net increase in biomass (carbon storage) during this time. Currently, the biological carbon cycle in the broadest sense may not be balanced because of human influences on it. CO2 released via respiration, decomposition, and burning may not all be taken up by plants. That is, we may be experiencing a net loss of biomass on Earth at present. However, this is not certain. A few years ago, scientists believed that anthropogenic land conversion (basically, deforestation, and largely in the tropics) constituted a large net input of CO2 to the atmosphere. A.2 Solar radiation variabilityThe main natural external factor is the variability in the amount, and geographic and temporal distribution of solar radiation that reaches Earth. The solar radiation can change on short (yearly to century) timescales because of solar cycles and on century to millennial timescales because of cyclic changes in Earth's orbit.It was observed that there exists a strong correlation between the length of the solar cycle and temperature changes throughout the northern hemisphere. Scientists have looked at both natural forcing agents (solar variations and volcanic emissions) as well as anthropogenic forcing (greenhouse gases and sulphate aerosols). They found that the natural factors accounted for gradual warming to about 1960 followed by a return to late 19th-century temperatures, consistent with the gradual change in solar forcing throughout the 20th century and volcanic activity during the past few decades. These factors alone, however, could not account for the warming in recent decades. Similarly, anthropogenic forcing alone was insufficient to explain the 1910-1945 warming, but was necessary to simulate the warming since 1976. It was found that combining all of these factors enabled them to closely simulate global temperature changes throughout the 20th century. Continued greenhouse gas emissions can cause additional future temperature increases at a rate similar to that observed in recent decades. A.3 Causes of Global WarmingCauses of global warming are:
Some of these causes are human in origin, such as deforestation. Others are natural, such as solar variation. The greenhouse effect includes both human causes, such as the burning of fossil fuel, and natural causes, such as volcanic emissions. A.4 The "greenhouse effect"Greenhouse gases are transparent to certain wavelengths of the sun's radiant energy, allowing them to penetrate deep into the atmosphere or all the way to the Earth's surface, where they are re-emitted as longer wavelength radiation, mostly in the infrared region. Greenhouse gases and clouds prevent some of this radiation from escaping, trapping the heat near the Earth's surface where it warms the lower atmosphere. Alteration of this natural barrier of atmospheric gases can raise or lower the mean global temperature of the Earth. The concentrations of several greenhouse gases have increased over time due to human activities, such as:
The greenhouse effect is the trapping of some solar radiation by the planet's atmosphere, specifically by water vapour and greenhouse gases, increasing the temperature on and near the surface. The amount of greenhouse gases in the atmosphere has increased in recent years, and many scientists believe that the greenhouse effect is the major cause of recent global warming.
Greenhouse gases are responsible for changes in global climate. They trap excess heat from the sun's
infrared radiation that would otherwise escape into space, somewhat like a greenhouse is used to trap heat. When we drive our cars,
and light, heat, and cool our homes, we generate greenhouse gases. And we also burn the Oxygen of the air. Drivers affect three global
life-support systems by: * creating the global warming of the planet In 1998, global data were available for both population and heat-trapping carbon dioxide emissions and it was found that per capita emissions of CO2 continued the upward trend that dominated the middle 1990s. When combined with growing world population these increased per capita emissions accelerated the accumulation of greenhouse gases in the global atmosphere and, thus, increased further the global warming. With 4.6 percent of the world's population, the United States accounted for 24 percent of all emissions from fossil fuel combustion and cement manufacture, by far the largest CO2 contributor among nations. Emissions remained grossly inequitable, with one fifth of the world's population accounting for 62 percent of all emissions in 1996 while another-and much poorer-fifth accounted for less than 2 percent. Based on the position of Earth relative to the sun and characteristics of Earth's surface, the average temperature of Earth's surface should be -18°C. However, the mean temperature is closer to +15°C. What makes these results so different? Earth and its atmosphere receive radiant energy from the sun in various wavelenths:
About 1/3 of this incoming radiation is reflected from Earth's surface or from clouds and particles in atmosphere, without being absorbed. The remaining 70% is absorbed by the atmosphere or by Earth's surface. This absorbed energy is then ultimately re-emitted at longer, lower energy wavelengths, such as infrared wavelengths (longer wavelengths are less energetic), by the atmosphere and Earth's surface and organisms. Some of the energy radiated from the atmosphere goes out to space, while some travels to Earth, where it is absorbed and, ultimately, radiated out again. Energy that is radiated out from Earth either: (1) passes through the atmosphere and out to space (approximately 10% of the energy radiated from Earth), or (2) is absorbed by clouds, gases, and particles in the atmosphere, after which much is then returned to Earth as slightly longer wavelength (heat) radiation (approximately 90% of the energy radiated from Earth). This energy then warms the atmosphere of the Earth. Without an atmosphere capable of trapping and re-radiating energy, the earth's surface would be below freezing (about - 18°C) rather than the current +15°C (59°F). Thus, Earth is warmed largely from trapping and re-radiation of heat -- infrared radiation -- by gases and particles in the atmosphere. This trapping and re-radiation of heat by gases in the atmosphere is called the "greenhouse effect." The gases that are most active at trapping this radiant heat energy are referred to as "greenhouse gases" or "radiatively active gases." Therefore, Earth's temperature is not simply a function of our distance from the sun, but also of gases in our atmosphere. If the greenhouse effect is a natural phenomenon, why be concerned about it? The concern is about an acceleration
of the greenhouse effect, caused by human-influenced emissions of radiatively important gases, including CO2. We often hear about
it as though the greenhouse effect itself is a product of humans polluting the atmosphere, but that's not true; there was a greenhouse
effect long before there were humans. The real concern is human activities have caused an increase in atmospheric concentrations of radiatively active gases. Carbon dioxide is a colorless gas with a weak odor. Its density at 298K is 1.98 kg m-3, about 1.5 times that of air. The carbon dioxide molecule
Carbon dioxide can be reduced to a liquid and solid form by intense pressure.
At standard pressure, it is never liquid: it directly passes between the gaseous and solid phase at -78°C in a process called sublimation.
Water will absorb its own volume of carbon dioxide, and more than this under pressure. About 1% of the dissolved carbon dioxide turns into carbonic acid, resulting in a slightly acidic taste. The carbonic acid in turn dissociates partly to form bicarbonate and carbonate ions.
Carbon dioxide in its solid frozen form it is also known as dry ice. It is used
Carbon dioxide is a waste product in organisms that obtain energy from breaking down sugars or fats with oxygen as part of their metabolism, in a process known as cellular respiration. This includes all animals, many fungi and some bacteria. In higher animals, the carbon dioxide travels in the blood (where most of it is held in solution) from the body's tissues to the lungs where it is exhaled.
Carbon dioxide, when breathed in high concentrations (about 5% by volume), is toxic to humans and other animals. Hemoglobin, the main molecule in red blood cells, can bind both to oxygen and to carbon dioxide. If the CO2 concentration is too high, then all hemoglobin is saturated with carbon dioxide and no oxygen transport takes place (even if plenty of oxygen is in the air). Carbon dioxide and dry ice should therefore only be handled in well ventilated areas.
Plants remove carbon dioxide from the atmosphere by photosynthesis, which uses light energy to produce organic plant materials by combining carbon dioxide and water. This releases free oxygen gas. Sometimes carbon dioxide gas is pumped into greenhouses to promote plant growth.
The earth's atmosphere contains about 0.037% or 370 ppm CO2 by volume. Due to the greater land area, and therefore greater plant life, in the northern hemisphere as compared to the southern hemisphere, there is an annual fluctuation of about 5 ppm, peaking in May and reaching a minimum in October at the end of the northern hemisphere growing season, when the quantity of biomass on the planet is greatest.
Despite its small concentration, CO2 is a very important component of Earth's atmosphere, because it traps infrared radiation and enhances the greenhouse effect of water vapor, thus keeping the Earth from cooling down. The initial carbon dioxide in the atmosphere of the young Earth was produced by volcanic activity; this was necessary for a warm and stable climate conducive to life. Volcanic activity now releases about 130-230 million tonnes (145-255 million tons) of carbon dioxide each year. Volcanic releases are about 1% the amount which is released by human activities.
Atmospheric CO2 has increased about 30 percent since the early 1800s, with an estimated increase of 17 percent since 1958 (burning fossil fuels such as coal and petroleum is the leading cause of increased man-made CO2, deforestation the second major cause).
The global warming hypothesis was recorded in scientific literature near the end of the 19th century. It predicts that increased amounts of CO2 tend to increase the greenhouse effect and thus cause a man-made global warming. The widespread opinion that there is currently a warming phase and that the increased carbon dioxide amounts are a major contributor to it has led to widespread support for international agreements such as the Kyoto Protocol which aim to regulate the release of CO2 into the atmosphere.
The Earth's oceans dissolve a major amount of carbon dioxide. The resulting carbonate anions bind to cations present in sea water such as Ca2+ and Mg2+ to form deposits of limestone and dolomite. Most carbon dioxide in the atmosphere eventually undergoes this fate: if all the carbonate rocks in the earth's crust were to be converted back in to carbon dioxide, the resulting carbon dioxide would weigh 40 times as much as the rest of the atmosphere.
Deforestation is the removal of trees, often as a result of human activities. It is often cited as one of the major causes of the enhanced greenhouse effect. Trees remove carbon (in the form of carbon dioxide) from the atmosphere during the process of photosynthesis. Both the rotting and burning of wood releases this stored carbon carbon dioxide back in to the atmosphere. Pressure has been exerted on forests by the worldwide demand for wood and by local people who clear forests in their quests to establish an agrarian land base. Clearing of forests for the development of pasture for cattle has also resulted in deforestation as has the encroachment upon forests due to increasing human populations. Deforestation promotes erosion of soil. Under normal circumstances trees and bushes and the forest floor act as a 'sponge' for rainfall, slowing its' overland and underground flow and releasing it back into the atmosphere through transpiration. Without the buffering effect of forest cover, rain impacting bare soil runs off, often causing flooding. In this environment, nutrients in the soil are leached off and the microorganisms which can replenish these nutrients are disturbed. Forests are rich in biological diversity. Deforestation causes the destruction of the habitats that support biological diversity. Some societies are making efforts to stop or slow deforestation. In China, where large scale destruction of forests has occurred, each citizen must plant at least 11 trees every year. In western countries, increasing consumer demand for wood products that have been produced and harvested in a sustainable manner are causing forest landowners and forest industries to become increasingly accountable for their forest management and timber harvesting practices.
A rainforest is a biome, a forested area where the annual rainfall is high. Some mention 1000 mm of rain each year as a limit of what is a rainforest, but that definition is far from complete. Rainforests are primarily found in tropical climates, although there are a few examples of rainforests in temperate regions as well. As well as prodigious rainfall, many rainforests are characterized by a high number of resident species, and a great biodiversity. It is also estimated that rainforests provide up to 40% of the oxygen currently found in the atmosphere. Dense tropical forests also have a great effect on the hydrological cycle through evapotranspiration and the reduction of surface runoff. With dense foliage, about a third of the rain falling on the forest never reached the ground, being re-evaporated off the leaves. Locally, deforestation results in:
Computer models have analized the Amazonian deforestation and indicated that the deforestation of a typical rainforest (air temperature 27oC, mean monthly rainfall of 220 mm) and subsequent degradation to savanna would result in:
B.2 Impact of human activity on the carbon cycleConcern about the potential effects of human (anthropogenic) activities on the atmosphere is growing. The two major results of human activity resulting in global changes in the Earth's climate are:
B.3 Human activities that add CO2 to the atmosphere(1) Burning of fossil fuels, contributing about 5 billion metric tons C/year. The combustion of fossil fuels oxidizes organic carbon, with carbon and oxygen combining to yield CO2. Historically, CO2 taken up in the biological carbon was approximately equal to the CO2 released in the biological cycle. The global production of carbon fixed by plants was then equal to
the global ecosystem respiration that comprised respiration by plants plus respiration by all other living things on land.
On a global basis, there was no net flux of carbon to or from the atmosphere, and there was no net change in carbon storage in terrestrial ecosystems (globally).
Unfortunately, humans have recently been converting forested landscapes to grazed, cultivated, or urban landscapes.
The impacts of such activities have been to:
(1) Remove a large sink for atmospheric carbon (because forests take up and store larger amounts of carbon than do other terrestrial ecosystems). Tropical and temperate rainforests have been subjected to heavy logging during the 20th century, and the area covered by rainforest around the world is shrinking rapidly. Estimates range from 1 1/2 acres to 2 acres of rainforest disappear each second. Rainforests used to cover 14% of the Earth's surface. This percentage is now down to 6% and it is estimated that the remaining rainforests could disappear within 40 years at this present rate of logging. Further estimates suggest that large numbers of species are being driven extinct, possibly 50,000 species a year due to the removal of their habitat. The largest rainforests can be found today in the Amazon basin (the Amazon Rainforest), the inner parts of Democratic Republic of Congo and on Borneo. A mature forest stores a large amount of carbon. When cut, it is often replaced by an ecosystem that stores less carbon, (pasture or crops) with the difference in carbon content of the ecosystems being balanced by a flux of CO2 to the atmosphere. Thus, there is an increased flux of carbon from terrestrial ecosystems to the atmosphere, resulting from this land conversion. It was estimated that the net input of CO2 to the atmosphere from ALC was about 1/4 as much as from fossil fuel burning (1.3 billion metric tons of carbon per year compared to 5 billion metric tons of carbon per year from fossil fuel combustion). Most of this increased flux now comes from tropical Africa and Asia, but until about 1920, North America actually provided the largest ALC flux to the atmosphere. There is much uncertainty concerning the magnitude of fluxes associated with tropical deforestation, and whether it does in fact represent a net flux. The current range of estimates for fluxes from tropical deforestation is from 1.1 - 3.6 billion metric tons of C/year, which would be between 20-65% as much as from fossil fuel emissions. Quite a huge spread in estimates! Most estimates agree that between 1/5 -1/3 of the increased flux of CO2 to the atmosphere results from deforestation.Why is there so much variation in estimates of the size of fluxes resulting from deforestation in the tropics? Several reasons, all relating to uncertainty in estimating the factors that contribute to the fluxes: (1) What are actual rates of deforestation (and what counts as deforestation -- e.g., does selective logging count, or must it be clearcutting?) (2) What is the fate of deforested land? Is it cleared permanently or temporarily, and what proportion is treated in each way? (3) How big are the stocks of carbon stored in these forests? Estimates of the standing stock differ by a factor of two! In terms of sources and sinks, then, tropical deforestation does constitute a source of carbon to the atmosphere.
Why might biomass (and carbon storage) of some areas be increasing? There are several potential reasons,
including changing land use (e.g., afforestation of areas that were formerly fields, pastures; drainage and conversion to forest
of wetlands; and fire suppression, which allows woody vegetation to encroach on areas that weren't formerly occupied by woody vegetation),
and possible effects of CO2 fertilization and/or nitrogen fertilization from atmospheric deposition. Currently, changes in land use are believed to be the dominant force behind increased carbon storage in forests,
with contributions from CO2 fertilization or nitrogen fertilization believed to be relatively minor. Soils represent an important component of the terrestrial compartment.
In fact, more carbon is stored in soils (including peat) than in all of the vegetation of the world! Note, however, that carbon
storage in soils has also shrunk since preindustrial times. Respiration and decomposition increase with ALC, and under most kinds of agricultural systems, such that carbon
storage in soils is decreasing. Oceans represent a major sink for carbon. Oceans take CO2 up through chemical and biological means. Chemically, ocean waters absorb CO2 by the formation of carbonic acid: CO2 + H2O <-----> H2CO3 The double-headed arrow on this equation indicates that this is an equilibrium reaction. Hence, as CO2
in the atmosphere increases, more is taken up by the oceans, "pushing" the reaction towards formation of H2CO3 (carbonic acid). Oceans also take up CO2 biologically, largely through photosynthesis of plankton and other algae. This "fixed"
carbon is eventually removed from the water by biochemical processes (for example, the algae are eaten by shell fish, which die and
sink to the ocean floor, eventually forming carbonates and entering the long term geochemical cycle. Oceans hold 50-60 time more carbon in various forms than does the atmosphere, which holds it mostly as CO2. Some parts of the ocean are major
sinks; such as the North Atlantic during the spring planton bloom (population explosion). On the other hand, some areas of the oceans
are net sources, such as the equatorial Pacific. On balance, however, oceans are net sinks for carbon. The oceans are currently taking up more carbon than they are releasing, but we don't know how rapidly they can take it up in response to increases in atmospheric
CO2 concentration.
There is much uncertainty in estimates of what fraction of extra CO2 emissions the oceans are really
taking up. Oceans were estimated to be taking up about half of the excess CO2 put into the atmosphere by human activities.
That is: 6.3 billion tons C/year input to the atmosphere from ALC + fossil fuel burning 2.4 billion tons C/year as net ocean net uptake That is, the oceans were estimated to be taking up about 38% of the human-influenced flux into the atmosphere. More recent estimates put the net input to the atmosphere at 7 billion tons (from ALC and fossil fuel burning). Of that, about half (3.4 billion
tons) are estimated to stay in the atmosphere, with a net influx into the oceans of 2 bill tons. (Net influx means ocean uptake
in excess of its giving off of CO2 back to the atmosphere). Notice anything wrong here? Seven billion tons into the atmosphere and only a total of 5.4 billion of those
tons accounted for! The remaining 1.6 billion tons represents the "missing carbon mystery!" If 40-50% of the
carbon emissions stay in the atmosphere and 15-30 % go into the oceans, what happens to the remaining 20 - 35%? See sections J3 and J5
for possible explanation. The process of destroying unwanted materials by burning is known as incineration. Incineration is done on a small scale by individuals, and on a large scale by industry.
Examples:
These uncertainties aside, it is clear that humans are putting tremendous quantities of CO2 into the atmosphere,
and that fossil fuel combustion is currently the most important contributor to that flux. While this is true at present, over
the period 1860-1980, the global emission of CO2 from landscape changes has about equaled that from fossil fuel burning. At present,
however, fossil fuel burning is a more important source of CO2 to the atmosphere than is anthropogenic land conversion (ALC).
Let us evaluate the impact of burning fossil fuels. Crude oil is certainly a major fossil fuel in use today. About 77% of crude oil has already been discovered, and 30% of it has been used so far. From 1859-1968 200 billion barels of oil have been used, and since then oil production has stabilized to 22 billion barels per year. It is estimated that oil reserves will become scarce by 2050s.
Most of oil is concentrated in the Near East - around 41%. North America, Russia, and Antartic are also rich in crude oil.
According to the U.S. Department of Energy/Energy Information Administration (U.S. DOE/EIA) and the American Petroleum Institute (API)
oil production will increase far into the future. These organizations project a significant expansion of world oil production in the future due to the application of advanced oil production technology.
The North Sea has been a major oil production province since its first significant production in the middle 1970s. In 1998, North Sea oil production represented nearly 9% of world oil production.
Norway and the United Kingdom (U.K.) are the main oil producing countries in the North Sea and major oil fields within these two countries will be analyzed. In this paper, a major field is considered one with an estimated ultimate recovery (EUR) of greater than 100 million barrels oil (mbo). There are approximately 35 major Norwegian oil fields and 55 major U.K. oil fields in the North Sea. Masters et al. (1994) assessed the total EUR (all fields) for Norway at approximately 30 billion barrels oil (bbo) and the U. K. at approximately 36 bbo. U.K. field data from 1976 through 1997 were obtained from Oil & Gas Journal. Field data for Norway from 1978 through 1997 are from Oil & Gas Journal and 1998 field data from the Norwegian Petroleum Directorate (NPD). In practice, almost all parts of the high voltage system are designed to be replaced in the field. A classic car has a set of
"points," usually in the distributor housing. These open and close once for each cylinder. The points drive battery current
through the primary winding of a step-up transformer, the "spark coil." The output of the spark coil is then distributed
through a set of rotating mechanical contacts called the "distributor." Constant arcing in the points and distributor
eventually cause them to wear, and need replacement. In more modern engines, the points or the entire distributor are often
replaced by an electronic circuit. More rarely, in a few European engines, the distributor is sometimes replaced by a spark
coil for each cylinder.
One crucial component in older and smaller engines is the carburetor, which mixes the gasoline with air. Carburetors are
fluidic and mechanical computors that meter the fuel and mix it with the air in precise proportions. Classic carburetors
measure spark advance by measuring the difference in pressure between the outside and inside of the carburetor. The degree of
throttle advance is also measured. The air temperature is measured to make the measure richer in the cold, because the air
is denser, and contains more oxygen per unit of volume. It would be nice to measure the engine's exhaust for carbon monoxide
or unburned hydrocarbons to see how well the carburetor is working.
In more modern engines, a small electronic computer measures these parameters, and controls one or two small electric injectors ,
which can be in the carburetor throat. Premium systems have two injectors so that the system will not have a single point of
mechanical failure. This is called throttle-body injection. It has many of the advantages of electronic fuel injection, but
costs much less. Electronic fuel injectors perform similar feats, but inject the fuel directly into the cylinder, where it is
more violently mixed with air in a higher-temperature environment. Almost all new cars now use electronic fuel injection
because it allows the engine computer to precisely regulate the fuel air mixture which increases energy efficiency and
reduces pollution.
More exotic mixing, with heaters and ultrasonic mixers, is known to further improve efficiency.
Most manufacturers don't bother.
The mass or volume of air required to provide sufficient oxygen to achieve this complete combustion is the "stoichiometric" mass or volume of air.
Insufficient air = "rich", and excess air = "lean", and the stoichiometric mass of air is related to the carbon:hydrogen ratio of the fuel. The
procedures for calculation of stoichiometric air-fuel ratios are fully documented in an SAE standard. The US contributes about 23% of total world CO2 emissions (and their emissions increased more than 8% between 1990 and 1996). China is second (14%; 1997
data) and their emissions are increasing fast (increased 27% between 1990-1995). Brazil, India and Indonesia all had large increases
during the 1990 - 1995 period as well (20, 28, and 40% increases respectively).
Per capita, the US is still the largest polluter as indicated by the following data for 1992 (tons of carbon per person per year): Now that we know who is adding CO2 in the atmosphere and how much reserves of oil are still available
in the world, what can we say about CO2 concentration? The increase since the mid-nineteenth century (or preindustrial time) has, of course, been greater than this
and is over 30% (from about 280 ppmv to the current 368 ppmv). CO2 persists for quite a long time in the atmosphere; its atmospheric residence time is on the order of decades to a century or so. This increase in atmospheric CO2 concentration is predicted to cause an increase in global temperatures and in global precipitation;
how much, how fast, and how distributed globally are the important questions.
There are greenhouse gases other than CO2 whose concentrations are also increasing. What evidence do we have that concentrations of CO2 in the atmosphere are really related to global temperatures?
Evidence comes from a variety of sources, and reflects relationships between gas concentrations and temperatures over a wide range of time scales. Evidence from the ancient past links timing of plate tectonic activity (which is associated with abundant
volcanic activity and degassing of CO2) with climate changes, and evidence from the more recent past links atmospheric CO2
with climatic fluctuations during the ice ages in the Pleistocene. How do we know what CO2 concentrations in the atmosphere were present thousands of years ago? One source of information
is polar ice, which forms from snowfall accumulating over centuries. Annual layers are formed in this ice, and air bubbles in the ice
trap gases from the time when the ice was formed. Concentrations of gases in these ancient air bubbles can be measured. How about ancient temperatures? The ratio of various isotopes of oxygen (16 and 18, based on the number
of neutrons per atom) and of various isotopes of hydrogen in the water comprising the ice is dependent on the temperatures prevailing
at the time of its formation, hence analysis of these isotopic ratios gives insights into temperatures. There were fluctuations in CO2 and temperature over the past 160,000 years.
This data set comes from a 2 km long (2000 m) ice cores from Antarctica (the Vostoc ice core). This 160,000 years encompasses our current
interglacial period, the last 100,000 yr ice age, a previous interglacial, and an even earlier ice age. It shows clearly that atmospheric
CO2 varied in parallel with temperatures; when temperatures were up, so was CO2. Concentrations of another trace gas,
methane, also varied in parallel with CO2. For example, temperatures fell in synch
with CO2 at the onset of the last glacial period and then these rose together as the ice retreated about 10,000 yr ago. Globally, temperatures were about 5 °C cooler during glacials than during interglacials, while concentrations
of CO2 were about 25% lower during glacials than during interglacials.
There was a post-glacial climate optimum about 6800 years ago, and a general cooling has been in place since then. Temperature increases may have caused CO2 concentrations to increase. This is because of effects of temperature increases
on biological processes and changes in ocean circulation (or vice versa).
Ocean uptake of gases such as CO2 increases as cooling occurs (remember gases have higher
solubility in colder water). This pulls CO2 out of the atmosphere, and would serve to amplify the orbitally-induced cooling. As another
example, the volume of oceans decreases with cooling (as more water is frozen), which results in nutrients in the water becoming
more concentrated, and fostering algal blooms, which pull CO2 out of solution, again amplifying cooling. These algal blooms
also resulted in the production of sulfate. Changes in gas concentrations, as indicated above, are considered essential to cause changes of the magnitude actually observed. Data representing fluctuations in temperature and CO2 concentrations over the past 100 years are derived from a variety of sources, including: During the last 100 years, atmospheric CO2 increased another 25% above its interglacial level. (Concentrations of methane
doubled again too.) Data on temperatures from a variety of recording stations and instruments give us reasonable surface air temperature
data for the past 100 years or so. After applying corrections for urban heat, and other factors, we can see that recent decades
have been unusually warm. El Nino was parly responsible for some of the recent extra-warm years, such as 1998, but even after correcting
for the influence of these events (El Nino's) the 90's remain the warmest decade since instrumental monitoring of temperatures began. What is the EL NINO phenomena? Years 1992 and 1993 were cooler than adjacent years (after correcting for 1992 being an El Nino year), probably because of Mt. Pinatubo's eruption in June of
1991. What should a volcano have to do with global temperatures? A volcano injects large quantities of SO2 into the atmosphere, much of which is converted to SO4 (sulfate) in the stratosphere. Much of the sulfate is present as very small,
aerosol-sized particles, which cause cooling by reflecting incoming radiation. The sulfate particles also serve as condensation nuclei
for high thin clouds, which also increase the albedo (reflectance, essentially) of the stratosphere. The aerosol sizes are so small
that they are more effective at reflecting shortwave solar radiation than they are at attenuating longer wavelengths of radiation emitted
from Earth. Climate modelers predicted that the eruption of Mt. Pinatubo would decrease global mean temperatures by about 0.5 degrees C -- enough to temporarily
mask warming -- and this did occur between the summers of 1991 and 1992 (briefly impeded by an El Nino early in 1992). Most of
the particles resulting from the eruption then precipitated out of the atmosphere, so by 1993, global temperatures were back on
an upswing. Climate modelers were pleased that global temperatures responded as predicted to the eruption of this volcano, as the
correspondence between model predictions and actual events serves to validate the models; they accurately predicted these climate consequences. The warming over recent decades is uneven over the globe. It tends to be greatest over mid- latitude continents
(40 - 70 degrees N). For example, summer temperatures in N Siberia have recently been hotter than any time in the past millenium.
Antarctica has warmed at more than twice the global rate in the last 50 years, perhaps causing several of its ice shelves to disintegrate. Automobile exhausts, coal-burning power plants, factory smokestacks, and other waste vents of the industrial age now pump five billion metric tons of carbon dioxide greenhouse gases into the earth's atmosphere each year from fossil fuel combustion. In addition to CO2, there are other trace greenhouse gases that are causing the greenhouse effect. These other greenhouses gases (not including CO2 and water vapour) contribute collectively about the same amount of warming as does CO2! Recently, the concentration of
many of them has been increasing as rapidly or more rapidly than that of CO2 (which has been increasing at about 0.4%/yr). Water vapour is an important greenhouse gas whose contribution to global warming is the greatest -- actually
greater than CO2. Water vapor absorbs radiation of about the same wave length as CO2.
It is not clear if human activities are having any net global effect on the concentration of water vapor
in the atmosphere, hence controls on water vapor aren't being discussed at present in negotiations about controlling emissions
of greenhouse gases. A significant warming would imply more evaporation and hence more water vapor in the atmosphere.
Whether this will amplify or dampen warming is unclear, as the effects of water vapor in
the atmosphere depend on the droplet sizes and their height in the atmosphere. It is difficult to assess its concentration globally, and it is different from hemisphere to hemisphere.
Best estimates are that radiative forcing from it is about 15% of that contributed by the longer-lived radiative gases. In contrast to most other greenhouse gases, Ozone has a short (60 hr) atmospheric residence time, which means
that it doesn't accumulate in the atmosphere to the same extent than other greenhouse gases. Methane as a trace greenhouse gas Methane (CH4) is another very important greenhouse gas. While it is present in lower concentrations in
the atmosphere than CO2 (about 1.7 ppmv vs about 368 ppmv for CO2), it is very effective at causing warming because it absorbs
radiation of a different wavelength than CO2. Mole for mole, methane is about 25 - 30 times more effective at causing warming than is CO2. Methane currently contributes
about 1/4 the warming effect that CO2 does. The atmospheric concentration of methane has been increasing for about 300 years, and, over geological
time, its concentration has changed in parallel with CO2's (and therefore with temperature). Its recent
increase began before the recent rapid increase in CO2, beginning about 300 years ago, as compared to about 100 years ago for CO2.
Its concentration has increased more than 100% in the last 100 years that is, has more than doubled. In contrast, concentrations of CO2 "only" increased a bit more than 25% since preindustrial
times. The average rate of increase in methane over the 1984-1994 decade has been about 0.6% per year or 10 ppbv. About 80% of atmospheric methane has originated from biological sources. Biological doesn't necessarily mean
"natural," as humans have affected many of the biological sources. In fact, anthropogenically-related sources contribute
about twice as much as natural sources (340 vs 160 tg/yr). Methane is produced by: The largest single source is wetlands; followed by mining, processing and use of coal; extraction and use of oil
and natural gas; "enteric fermentation" (mainly cattle); and rice paddies (120, 100, 80, 50 tg/yr respectively) Note that all of these sources are linked to the rising human population and to agriculture! How? Methane has direct warming effects on its own, and it also contributes to the production of CO2, ozone,
and water vapor in the atmosphere, which contribute about as much warming as the methane itself.
Methane has approximately a 12 year atmospheric residence time, which is shorter than that of CO2 (which is about
100 years) or halocarbons, which are also about 100 years.
The increase in methane concentrations in the atmosphere began slowing in the 1980's and in mid-1992, the
rate of increase dropped sharply in the Southern hemisphere and actually went to zero in the Northern hemisphere. By now, the
rate of increase than held during most of the 1980's has been resumed. Why these changes in the rate at which its atmospheric
concentration has been changing? Particularly, why did the increase slow or even stop for a while? Two possibilities: No one really knows, but in 1999, it was back to "normal" in terms of concentration increases. Nitrous oxide originates mostly from "natural" sources, which contribute about twice the anthropogenic sources.
It is produced by bacterial action as part of the nitrogen cycle. It is produced by aerobic nitrification, in which NH4
is oxidized to NO2, releasing N2O along the way, and also by anaerobic denitrification, in which NO3 and NO2 are reduced to molecular
nitrogen, and by other bacterial transformations. However, anthropogenically related emissions are increasing, and, as for methane, many are connected to human
population and agriculture: It is hard to measure its concentration in the atmosphere, but concentrations appear to have increased
about 0.25% per year over last decade. (Its increase, like that of methane, slowed temporarily in 1991-1992.) Its concentration
in the atmosphere has increased about 12% since preindustrial times (275 up to 312 ppbv). The only source of these compounds is anthropogenic, as they are not naturally occurring. They are synthetic chemicals. They are halogenated carbon compounds, such as CFC11 (CFCl3 or Freon) They all contain
carbon and halogens, such as Cl (chlorine), F (fluorine), or Br (bromine), and, in the case of the HCFC's, they also contain H
(hydrogen). They are (or were until recently, in some cases) used in refrigeration, aerosols, for puffing foams, as solvents for
cleaning in the electronics industry, and in automobile air conditioners. In addition to their effects on stratospheric ozone, these are important greenhouse gases. They are tremendously
effective at producing warming because, even though they are present in low concentrations in the atmosphere, they absorb heat radiation
of different wavelength than CO2. Mole for mole, Halocarbons are 12,000 - 15,000 times more effective at causing global warming than is CO2. Their concentrations in the atmosphere have been monitored since the late 1970's and they increased steadily
and rapidly over most of that time at rates of 3-5% per year.
Both production and emissions fell precipitously from 1989 on, as result of international
treaties intended to halt destruction of stratospheric ozone, and now their concentrations in the atmosphere are actually beginning
to decline as well. Because these
compounds are very long-lived (atmospheric residence times on the order of 75 - 120 years), the decline in atmospheric concentrations lagged greatly behind the decline in emissions. Replacements for CFC's (largely hydrochlorofluorocarbons (HCFC's) and hydrofluorocarbons – (HFC's)) are also greenhouse
gases, but are expected to make a relatively small contribution to the global warming potential contributed by other greenhouse
gases. Current models suggest that warming due to all halocarbons (CHC's , halons, and their replacements) will be at most 4-10%
of the total expected greenhouse warming by 2100. The depleting stratospheric O3 has a negative radiative forcing e.g., tends towards cooling. The cooling results from
indirect effects of Cl and Br, and also of reactions involving other constituents that are speeded in the presence of increased
ultraviolet radiation (as results from loss of stratospheric ozone); constituents that have negative radiative forcing effects.
Climate change models must take all greenhouse gases into account. This is a great challenge
as they have complex atmospheric chemistry. It is challenging to predict trends in their production, and there are complex feedbacks
and interactions among them. Policy decisions must also take this variety of gases into account. Therefore, it is a mistake to think
that the prospect of global climate change is reducible to CO2 alone. Automobile exhausts, coal-burning power plants, factory smokestacks, and other waste vents of the industrial age now pump six billion tons of carbon dioxide and other greenhouse gases into the earth's atmosphere each year.
Industrial greenhouse gases include the heavy halocarbons (chlorinated fluorocarbons), CFC, HCFC-22 molecules such as freon and perfluoromethane, and sulphur hexafluoride.
They are called greenhouse gases because they trap radiant energy from the sun that would otherwise be re-radiated back into space. The fact that a natural greenhouse effect occurs is well-known and is not at issue in the debate over global warming. Without it, temperatures would drop by approximately 30°C,
the oceans would freeze and life as we know it would be impossible. Rather, what we are concerned about is that increased levels of greenhouse gases in the atmosphere
might cause more heat to be trapped. Concentrations of greenhouse gases in the atmosphere are currently at approximately 25% above
pre-industrial values. This is considerably higher than at any time during the last 420,000 years, the period for which reliable
data exists from ice cores. From less direct geological evidence it is believed that values this high were last attained 40 million years ago.
Since the beginning of the Industrial Revolution the concentrations of many of the greenhouse gases have increased.
The lifetime of an individual molecule of gas in the atmosphere is frequently much shorter than the lifetime of a concentration anomaly of that gas. Thus, because of large (balanced) natural fluxes to and from the biosphere and ocean surface layer, an individual CO2 molecule may last only a few years in the air, on average; however, the calculated lifetime of an increase in atmospheric CO2 level is hundreds of years.
Aside from water vapour near the surface, which has a residence time of few days, the other greenhouse gases take a very long time to leave the atmosphere. It is not easy to know with precision how long is necessary, because the atmosphere is a very complex system. However, there are estimates of the duration of stay, i.e. the time which is necessary so that the gas disappears from the atmosphere, for the principal ones.
Duration of stay and warming capability of the different greenhouse gases can be compared:
Since global warming is such an important issue, governments need predictions of future trends in global change so they can take political decisions to avoid undesired impacts.
Global warming is being studied by the Intergovernmental Panel on Climate Change(IPCC). In its last report, the IPCC made some predictions about future climate change.
These predictions are the basis for current political and scientific discussion.
IPCC predictions are based on the same models used to establish the importance of the different factors in global warming.
These models need data about anthropogenic emissions of greenhouse gases and aerosols. These data are predicted from economic models based on 35 different scenarios.
Scenarios go from pessimistic to optimistic, and predictions of global warming depend on the kind of scenario considered.
None of these scenarios consider any kind of measures to avoid global warming.
In any case, proponents of the IPCC assessment say that the current climate models are good in predicting surface temperatures.
They furthermore argue that it is surface temperatures that will have the greatest and most direct effect on the environment, agriculture and the stability of polar ice.
The IPCC says that it has corrected the land station data to account for the urban heat island effect.
In its last report, IPCC stated that average surface temperature is projected to increase by 1.4 to 5.8 °C over the period 1990 to 2100, and the sea level is projected to rise by 0.1 to 0.9 metres over the same period.
IPCC uses the best available predictions and their reports are under strong scientific scrutiny.
The IPCC concedes that there is a need for better models and better scientific understanding of some climate phenomena, as well as the uncertainties involved.
Critics point out that the available data is not sufficient to determine the real importance of greenhouse gases in climate change.
Sensitivity of climate to greenhouse gases may be over-estimated or under-estimated estimated because of some flaws in the models and because the importance of some external factors may be misestimated.
It is important to recognize that in each of its five year reports, the IPCC has increased its certainty
that humans are now influencing the global climate. Its 1990 report was quite uncertain, concluding cautiously that, "Observed
warming is broadly consistent with predictions of climate models, but it is also of the same magnitude as natural climate variability.....the
observed increase could be largely due to this natural variability. Alternatively, this variability and other human factors could
have offset a still larger human-induced greenhouse warming." This cautious message came in part because of the following problems: (1) We would expect a steady warming from the fairly steady increase in greenhouse gases, but have seen instead: However, as understanding of factors regulating climate has improved, so have models, and so has the correspondence
between model predictions and reality. In particular, modelers:
Thus, the general consensus in the scientific community has changed since 1990 to the view global warming is already
being detected, and it is sure to increase in the future as emissions continue to increase. The IPCC's 2001 report stated, " "There is stonger evidence" yet on human influences on climate;
human-made greenhouse gases, "have contributed substantially to the observed warming over the last 50 years." No equivocation
in that language! Similarly, the American Geophysical Union (comprised of over 35,000 international earth and planetary scientists)
issued a statement in 1999: "There is no known geologic precedent for the transfer of carbon from the Earth's crust to the atmoshpere
in amounts comparable to fossil fuel burning withour simultaneous change in the climate system." "There is a compelling
basis for legitimate public concern." and "The present level of scientific uncertainty does not justify inaction in the
mitigation of human-induced climate change." Even for those who are reluctant to agree that we are already experiencing the predicted warming, there
is little doubt that eventually warming would occur. The open question is still how much and how fast, and how drastically will
emissions of radiatively active trace gases need to be reduced to prevent further change. Global warming can trigger a sudden change (a shut down, basically) in an ocean current that warms
Northern latitudes. If that happened, we'd have sudden and dramatic cooling, as this ocean "conveyor belt" that warms Northern
Europe stopped. This change has happened in the past in response to dramatic climate changes. There are records
of as much as 10°C temperature swings in just a few years in regions affected by this ocean current. This shut down is apparently
caused by pulses of fresh water coming into the N Atlantic from melting glaciers and ice caps, and from the increased precipitation
associated with the previous warming. Whether this kind of abrupt change may be on the horizon is hotly debated at present. Nevertheless, phenomena such this serve to remind us that the global climate system is probably full of surprises! Climate scientists generally agree that Earth has undergone several cycles of global warming and global cooling in the last 20,000 years. The IPCC estimates that surface temperatures have risen by around 0.6°C since the late 19th century.
The UN's Intergovernmental Panel on Climate Change (IPCC) predicts 1.5 to 7 °C warming is likely within the 21st century, unless severe measures are taken.
Many researchers predict disastrous consequences for a warming of 1.5 to 7 °C. Government officials are concerned that the current warming has the potential for harm to the environment and agriculture.
If warming continues at the present rate, it will cause changes in ocean circulation, catastrophic global climate change, loss of biodiversity and irreversible damage to agriculture in those ecoregions most affected. In some regions, e.g. Western Europe, Bangladesh, damage is projected to be extreme, due to loss of Gulf Stream warming and global sea level rise respectively. More frequent bouts of destructive weather are also anticipated, and risk experts in the insurance industry have expressed very strong concerns, advocating a proactive approach based on the precautionary principle. Estimates accepted by the IPCC and by some insurance industry bodies estimate up to 3.5 billion people could be affected by rising disease, loss of fresh water supply, and other impacts.
The examples of secondary evidence cited above (lessened snow cover, rising sea levels, weather changes) are examples of consequences of global warming that may influence not only human activities but also the ecosystems. Increasing global temperature means that ecosystems may change; many species will be forced out of their habitats and to extinction because of changing conditions, while others may spread. Few of the terrestrial ecoregions on Earth could expect to be unaffected.
Another cause of great concern is sea level rise. Sea levels are rising 1 to 2 centimetres per decade and some small countries in the Pacific Ocean are expressing concerns that if this rise in sea level continues they soon will be entirely under water.
Global warming causes the sea level to rise mainly because sea water expands as it warms. Scientists are concerned that the polar ice caps and glaciers have started to melt.
As a consequence, the sea level could rise by several metres.
Due to potential effects on human health, the economy and on the environment, global warming is a cause of great concern. Already some important environmental changes have been observed and linked to global warming.
In opposition to action stand the fossil fuel industry and skeptics, who oppose immediate action to mitigate Global Warming. They argue that crippling industry and infrastructure to prevent an unconfirmed ecological catastrophe does not make economic sense and that healthy economies are required to fund technologically innovative solutions, as required by the UNFCCC. President G. W. Bush, made this argument in rejecting the Kyoto Protocol. Bush did not reject the science outright, and argued that the greenhouse gas control was a matter of voluntary restraint by industry.
The Kyoto Protocol to the UNFCCC proposes binding greenhouse gas limits for developed countries. The United Nations Framework Convention on Climate Change (UNFCCC) establishes a process for developing an international response to the perceived global warming problem. 181 countries have ratified the UNFCCC, including all industrial nations.
The UNFCCC, however, does not provide any binding emission targets.
The Kyoto Protocol to the UNFCCC proposes binding greenhouse gas limits for developed countries. It has been ratified by 104 countries, representing 43.9% of emissions. Developed countries are required to limit their emissions to, on average, 5.2% below 1990 levels: 29% below pre-Kyoto estimates for 2010. The precise amounts vary from an 8% reduction for the European Union to a permitted increase of 10% for Iceland. Controversially, developing countries, including India and China, are exempted from reductions until they become sufficiently industrialised.
Because global warming is a " tragedy of the commons" problem, the Kyoto Protocol will not take effect until 90 days after countries responsible for over 55% of emissions ratify it. This will occur when Russia ratifies it. The United States, responsible for one-third of emissions of greenhouse, has signed the Kyoto Protocol, but does not intend to ratify it.
The formal name of the proposed agreement is the Kyoto Protocol to the United Nations Framework Convention on Climate Change.
It was negotiated in Kyoto, Japan in December 1997, opened for signature on March 16, 1998, and closed on March 15, 1999. The treaty is expected to come into force when it is ratified by Russia.
U.N. and European backers of the Kyoto Protocol who had hoped Russia would commit to ratification were disappointed in September 2003 when Putin indicated his reluctance to sign at a Moscow conference.
According to a press release from the United Nations Environment Programme:
Demographic studies indicate that world population growth is expected to slow markedly in the next century, increasing of nearly 3 billion people by 2050. Hence, in the coming years, unless population size is stabilized, agriculture will have to face an increasing challenge in feeding the growing population of the world. Assessment of the impacts of global climatic changes on agriculture might help to properly anticipate and adapt farming to limit potential food shortage.
Many scientists position is that agricultural shifts are likely.
Several types of changing parameters can have an impact on agriculture
The assessment of these effects is different whether one considers annuals crops (cereals, leguminous) or herbaceous perennial cultures (fodder, meadows) or other cultures such as vine or fruit trees...
The effects are also different depending on the latitude: in temperate countries, effects are found less negative or even rather beneficial, while in tropical and desertic countries they tend to be adverse.
Finally, effects depend on altitude, mid and high altitude places rather benefiting from a warmer temperature.
Climate change induced by increasing greenhouse gases is likely to affect crops differently from region to region. For example, average crop yield is expected to drop down to 50% in Pakistan according to the UKMO scenario whereas corn production in Europe is expected to grow up to 25% in optimum hydric conditions.
However, the more favourable effects on yield depend to a large extent on realization of the potentially benefiting effects of CO2 on crop growth and increase of efficiency in water use. Decrease in potential yields is likely to be caused by shortening of the growing period, decrease in water availability and poor vernalization.
Duration of crop growth cycles are above all related to temperature.
An increase in temperature will speed up development. In the case of an annual crop, the duration between sowing and harvesting will shorten (for example, corn duration cycle could shorten between 1 to 4 weeks). The shortening of the cycle would rather has adverse effect on productivity because of senescence occuring sooner.
Temperature changes could also have serious implications for crops and trees that need vernalisation(to shorten the growth period
before the blossoming and fruit or seed bearing of a plant by chilling its seed or bulb).
Carbon dioxide is a perfect example of a change that could have both positive and negative consequences.
CO2 is believed by many scientists to be potentially responsible of productivity increase: 10-15 % for wheat and soybean, 8% for corn and rice for a +2°C scenario on average. However, these results mask great differences among countries.
Water is a major limiting factor in the growth and production of crops worldwide.
In spite of better water efficiency use, higher summer temperature and lower summer rainfall is likely to have adverse impact. The intensification of the hydrological global cycle will have consequences such as more frequent drought in northern sub-tropical areas or desertification extension in arid areas.
Soil degradation is more likely to occur, and soil fertility would probably be modified.
A very important point to consider is that weeds would undergo the same acceleration of cycle than cultivated crops, and would also benefit of carbonaceous fertilization.
Most weeds being C3 plants, they are likely to compete even more than now against crops such as corn. However some results make it possible to think that weedkillers could gain in effectiveness with the temperature increase.
The increase in rainfall is likely to lead to an increase of atmospheric humidity and maybe to the duration of moisturing. Combined with higher temperatures, these could favor the development of fungal diseases.
Similarly, because of higher temperatures and humidity, there could be an increased pressure from insects and disease vectors.
Climate change is likely to increase agricultural land surface near the poles by reduction of frozen lands. Sea levels are expected to get up to one meter higher by 2100, though this projection is disputed. Rise in sea level should result in agricultural land loss in particular in South East Asia. Erosion, submergence of shorelines, salinity of water table, could mainly affect agriculture through inundation of low-lying lands.
Some scientists think agriculture could be affected by any decrease in stratospheric ozone, which could increase biologically dangerous ultraviolet radiation.
Many believe the general foreseeability of the climate will decrease, making it more difficult to plan agricultural practices. They also think likely that extrem climatic conditions become more frequent, particularly in terms of intense rainfall, droughts and heat spells.
They are large uncertainties to uncover, particularly the lack of information on the local scale, the uncertainties on magnitude of climate change, the effects of technological changes on productivity, global food demands, and the numerous possibilities of adaptation.
Most agronomists believe that agricultural production will be mostly affected by the severity and pace of climate change, not so much by gradual trends in climate.
If change is gradual, there will be enough time forbiota adjustement. Rapid climate change, however, could harm agriculture in many countries, especially those that are already suffering from rather poor soil and climate conditions.
The adoption of efficient new techiques (varieties, planting date, irrigation...) is far from obvious. Some believe developed nations are too well-adapted to nowadays climate. As for developing nations, there may be social or technical constraints that could prevent them from achieving sustainable production.
The idea is that a central authority will grant an allowance to entities based upon a measure of their need. For example an allowance to a country might be based upon total population. An industrial facility might be granted a license for its current actual emissions. If a given facility does not need all of its allowance, it may offer it for sale to another organization that has insufficient allowances for its emission production.
The United States began emissions trading after passage of the 1990 Clean Air Act, which authorized the Environmental Protection Agency to put a cap on how muchSulfur dioxide (which causes acid rain) the operator of a fossil-fueled plant was allowed to emit.
In New York State's proposed cap and trade program, the state would set an industry-wide "cap" on carbon dioxide emissions, lower than the current amount, and then give each power plant a target and a deadline. Companies that reduce emissions further than required could then "trade" emission credits with companies who cannot meet their goals. The concept, used with some success in the national Clean Air Act to reduce smog and acid rain emissions, is designed to reduce costs for the regulated businesses.
The Kyoto Protocol will bind ratifying nations to a similar system, with the UNFCCC setting caps for each nation. Under the proposed treaty, nations that emit less than their quota of greenhouse gases will be able to sell emissions credits to polluting nations.
Critics of the Kyoto Protocol see it as a means of forcibly redistributing wealth from the United States to the Third World. This is because the U.S., which produces 25% of the world's greenhouse gas emissions, would likely exceed its quota and would have to buy emissions credits from nations such as China, India, and Russia.
Critics also argue that emissions trading does little to solve pollution problems as groups that do not pollute are granted emissions credits which they then sell. Some environmental groups are attempting to solve this problem by buying credits and refusing to use or sell them.
In private enterprise, emissions trading is very attractive because it does not harm industrial concerns, or require government subsidies. When the price per ton of emissions becomes high-enough, well-managed polluting enterprises can make a rational decision to invest in pollution control equipment, and sell part of their emissions licenses.
In some proposed systems, the government grants tax credits to enterprises. However, these are more expensive for governments, and far less popular for that reason.
Emissions trading is attractive to public-interest environmental organizations, because in an open market, they can purchase, and retire emissions licenses. This permanently reduces the total amount of pollution produced.
The effect on the environment is that if the total permitted amounts are fixed or decreasing, public interest groups can decrease them further by purchasing licenses. The net effect is to drive total emissions toward zero with no economic harm to industry.
A critical part of emissions trading is that the amount of emissions must be fixed, or controlled in some socially-agreed fashion. Many people favor starting at the current level of emissions. It clearly can form no emergency for existing industrial concerns, and at the same time promises no new pollution.
The total of all allowances issued may be adjusted to an agreed reduction rate for the particular emission or pollutant. Thus, the central authority may control the emissions, and allow market forces to encourage countries to produce less of the emissions.
For example, less developed countries with relatively high populations, and lower pollution per head than western countries may sell their allowances to the industrialised west. However, as the supply is finite, the more that the west produces, the more that the additional allowances will cost them, until it becomes uneconomic to pollute, and more economic to convert to less environmentally harmful technologies.
Another critical part of the bargain is enforcement. Without effective enforcement, the licenses have no value. Two basic scheme exist.
In one, the regulators measure facilities, and fine or sanctions those that lack the licenses for their emissions. This scheme is quite expensive to enforce, and the burden falls on the agency, which then may need to collect special taxes. Another risk is that facilities may find it far less expensive to corrupt the inspectors than purchase emissions licenses. The net effect of a poorly financed or corrupt regulatory agency is a discount on the emissions licenses, and greater pollution.
In another, some other agency, usually a commercial agency licensed by the government, verifies that polluting facilities have licenses equal or greater than their emissions. Inspection of the certificates is performed in some automated fashion by the regulators, perhaps over the internet, or as part of tax collection. The regulators then audit licensed facilities chosen at random to verify that certifying agencies are acting correctly. This scheme is far less expensive, placing most regulation in the private sector. In addition, auditing can be performed on well-paid contracts by persons (such as university professors or antipollution activists) whose reputation is more valuable to them than any practical amount of graft.
The protocol operates in an interesting fashion. Each Annex I country has agreed to limit emissions to the levels described in the protocol, but many countries have limits that are set above their current production. These "extra amounts" can be purchased by other countries on the open market. So, for instance, Russia currently easily meets its targets, and can sell off its credits for millions of dollars to countries that don't yet meet their targets, Canada for instance. This rewards countries that meet their targets, and provides financial incentives to others to do so as soon as possible.
Countries also receive credits through various shared "clean energy" programs and " carbon sinks" in the form of forests and other systems that remove carbon from the atmosphere.
Washington D.C.-based NGO, in their report "Getting It Right: Emerging Markets for Storing Carbon in Forests", assumes values of $30-40/ton in the US and $70-80/ton in Europe. On April 18, 2001, The Netherlands purchased credits for 4 megatons of carbon dioxide emissions from Poland, Romania, and the Czech Republic.
As of February 2002, the agreement had been ratified by 104 countries, representing 43.9% of emissions. Countries do not need to sign the treaty in order to ratify it—signing is a symbolic act only. A total of 19 countries had signed the protocol but not ratified it. The remaining 58 parties to the UNFCCC had neither signed nor ratified the protocol.
According to the terms of the protocol, it enters into force "on the ninetieth day after the date on which not less than 55 Parties to the Convention, incorporating Parties included in Annex I which accounted in total for at least 55 per cent of the total carbon dioxide emissions for 1990 of the Parties included in Annex I, have deposited their instruments of ratification, acceptance, approval or accession."
The protocol left several issues open, to be decided later by the COP. COP6 attempted to resolve these issues at its meeting in the Hague in late 2000, but was unable to reach an agreement due to disputes between the European Union on the one hand (which favoured a tougher agreement) and the United States, Canada, Japan and Australia on the other (which wanted the agreement to be less demanding and more flexible).
In 2001, a continuation of the previous meeting was held in Bonn where the required decisions were adopted. After some concessions, the supporters of the protocol (led by the European Union) managed to get Japan and Russia in as well by allowing more use of carbon dioxide sinks.
As of 2002, 104 countries have ratified the protocol, including Canada, People's Republic of China, India, Japan, New Zealand, and the fifteen countries of the European Union.
19 countries have signed the protocol but not ratified it. Of those eight are Annex I countries:
The eleven Annex II countries that have signed but not yet ratified are: Egypt, Indonesia, Israel, Kazakhstan, Marshall Islands, Niger, Philippines,
Saint Lucia, Saint Vincent and the Grenadines, and the Solomon Islands.
On May 31, 2002, all fifteen members of the European Union deposited the relevant ratification paperwork at the UN. The EU produces around 21% of global greenhouse gas emissions, and has agreed to a cut, on average, to 8% of 1990 emission levels. The EU has consistently been one of the major supporters of the Kyoto Protocol, negotiating hard to get wavering countries on board.
In December, 2002, the EU created a system of emissions trading in an effort to meet these tough targets. Quotas were introduced in six key industries: energy, steel, cement, glass, brick making, and paper/cardboard. There are also fines for member nations that fail to meet their obligations, starting at €40/ton of carbon dioxide in 2005, and rising to €100/ton in 2008. Current EU projections suggest that by 2008 the EU will be at 4.7% below 1990 levels.
Summary: The United States, although a signatory to the protocol, has neither ratified nor withdrawn from the protocol. The protocol is non-binding over the United States until such time that the United States ratifies it.
On June 25,1997, before the Kyoto Protocol was to be negotiated, the U.S. Senate passed by a 95-0 vote the Byrd-Hagel Resolution (S. Res. 98), which stated the sense of the Senate was that the United States should not be a signatory to any protocol that that did not include binding targets and timetables for developing as well as industrialized nations or "would result in serious harm to the economy of the United States". Disregarding the Senate Resolution, on November 12, 1998, Vice President Al Gore symbolically signed the protocol. Aware of the Senate's view of the protocol, the Clinton Administration never submitted the protocol for ratification.
The current President, George W. Bush, has indicated that he does not intend to submit the treaty for ratification, not because he doesn't support the general idea, but because he is not happy with the details of the treaty.
China is an Annex II country under the protocol, and emits 2,893 million metric tons of CO2 per year (2.3 tons per capita). This compares to 5,410 million from the USA (20.1 tons per capita), and 3,171 million from the EU (8.5 million per capita). China has ratified the Kyoto Protocol, and is expected to become an Annex I country within the next decade. The US Natural Resources Defense Council, stated in June 2001 that: "By switching from coal to cleaner energy sources, initiating energy efficiency programs, and restructuring its economy, China has reduced its carbon dioxide emissions 17 percent since 1997".
In June 2002, the American Environmental Protection Agency (EPA) released the "Climate Action Report 2002". Some observers have interpreted this report as being supportive of the protocol, although the report itself does not explicitly endorse the protocol.
The prospect of the US staying outside the agreement influenced a number of other countries including Australia, Japan, and Canada to discuss whether they should ratify the agreement, putting themselves at a competitive disadvantage with the USA. While Japan and Canada ultimately decided to ratify the protocol, Australia's current government has said it will not ratify. This may change at the next change of government, as the major opposition parties have committed to ratification if in a position to do so.
However an additional twist is involved. The US is Canada's major trading partner (and vice versa), so with Canadian companies having to pay for emissions, and US companies not, the fear is that Canadian companies will not be able to compete on a fair trading ground. In one example a company can sell natural gas to the US to be burned in an electrical plant to produce electricity. That gas, burned in the US, is not subject to "Kyoto tax". However if that same plant were operated in Canada, the gas would be taxed as it was burned. That would result in the same electricity costing more if produced locally.
The result is an ongoing "war of words", primarily between the government of Alberta (a major oil and gas producer) and the federal government. It also appears that the federal government will ask for additional credits for "clean" fuels sold to the United States, most notably natural gas.
Currently, the biological carbon cycle in the broadest sense may not be balanced because of human influences on it.
CO2 released via respiration, decomposition, and burning may not all be taken up by plants. That is, we may
be experiencing a net loss of biomass on Earth at present. However, this is not certain. A few years ago, scientists believed that
anthropogenic land conversion (basically, deforestation, and largely in the tropics) constituted a large net input of CO2
to the atmosphere. The concentrations of several greenhouse gases have increased over time due to human activities, such as:
The earth's atmosphere contains about 0.037% or 370 ppm CO2 by volume. Due to the greater land area, and therefore greater plant life, in the northern hemisphere as compared to the southern hemisphere, there is an annual fluctuation of about 5 ppm, peaking in May and reaching a minimum in October at the end of the northern hemisphere growing season, when the quantity of biomass on the planet is greatest.
Despite its small concentration, CO2 is a very important component of Earth's atmosphere, because it traps infrared radiation and enhances the greenhouse effect of water vapor, thus keeping the Earth from cooling down. The initial carbon dioxide in the atmosphere of the young Earth was produced by volcanic activity; this was necessary for a warm and stable climate conducive to life. Volcanic activity now releases about 130-230 million tonnes (145-255 million tons) of carbon dioxide each year. Volcanic releases are about 1% the amount which is released by human activities.
Atmospheric CO2 has increased about 30 percent since the early 1800s, with an estimated increase of 17 percent since 1958 (burning fossil fuels such as coal and petroleum is the leading cause of increased man-made CO2, deforestation the second major cause).
Thus, there is an increased flux of carbon from terrestrial ecosystems to the atmosphere, resulting from this land conversion.
It was estimated that the net input of CO2 to the atmosphere from ALC was about 1/4 as much as from fossil fuel burning (1.3 billion metric tons of
carbon per year compared to 5 billion metric tons of carbon per year from fossil fuel combustion).
Most of this increased flux now comes from tropical Africa and Asia, but until about 1920, North America actually provided the largest ALC flux to the atmosphere. Notice anything wrong here? Seven billion tons into the atmosphere and only a total of 5.4 billion of those
tons accounted for! The remaining 1.6 billion tons represents the "missing carbon mystery!" If 40-50% of the
carbon emissions stay in the atmosphere and 15-30 % go into the oceans, what happens to the remaining 20 - 35%? See sections J3 and J5
for possible explanation. About 77% of crude oil has already been discovered, and 30% of it has been used so far. From 1859-1968 200 billion barels of oil have been used, and since then oil production has stabilized to 22 billion barels per year. It is estimated that oil reserves will become scarce by 2050s.
Per capita, the US is still the largest polluter as indicated by the following data for 1992 (tons of carbon per person per year): In its last report, IPCC stated that average surface temperature is projected to increase by 1.4 to 5.8 °C over the period 1990 to 2100, and the sea level is projected to rise by 0.1 to 0.9 metres over the same period.
At standard temperature and pressure, oxygen is found as a gas consisting of two oxygen atoms, chemical formula O2. This oxygen is an important component of air, produced by plants during photosynthesis and is necessary for animals' respiration. The word oxygen derives from two words in Greek, the Greek oxus (acid) and gennan (generate).
Liquid oxygen and solid oxygen have a light blue color and both are highly paramagnetic. Liquid oxygen is usually obtained by the fractional distillation of liquid air.
Oxygen finds considerable use as an oxidizer, with only fluorine having a higher electronegativity. Liquid oxygen finds use as an oxidizer in rocket propulsion. Oxygen is essential to respiration, so oxygen supplementation has found use in medicine. People who climb mountains or fly in airplanes generally have supplemental oxygen supplies. Oxygen is used in welding, and in the making of steel and methanol.
Oxygen, as a mild euphoric, has a history of recreational use that extends into modern times. Oxygen bars can be seen at parties to this day. In the 19th century, oxygen was often mixed with nitrous oxide to promote a kind of analgesic effect.
Oxygen was discovered by the Swedish pharmacist Karl Wilhelm Scheele in 1771, but this discovery was not immediately recognized, and the independent discovery by Joseph Priestley was more widely known. It was named by Antoine Laurent Lavoisier in 1774.
Oxygen is the most abundant element in the Earth's crust, estimated to comprise 46.7% of the crust. Oxygen comprises about 87% of the oceans (as H2O, water) and 20% of the atmosphere of Earth (as O2, molecular oxygen, or O3, ozone). Oxygen compounds, particularly metal oxides, silicates (SiO44-) and carbonates (CO32-), are commonly found in rocks and soil. Frozen water is a common solid on the outer planets and comets. The ice caps of Mars are made of frozen carbon dioxide. Oxygen compounds are found throughout the universe and the spectrum of oxygen is often seen in stars. In fact stars wouldn't produce light without oxygen.
Due to its electronegativity, oxygen forms chemical bonds with almost all other elements (which is the origin of the original definition of oxidation). The only elements to escape the possibility of oxidation are a few inert gases. The most famous of these oxides is of course hydrogen oxide, or water (H2O). Other well known examples include compounds of carbon and oxygen, such as carbon dioxide (CO2), alcohols (R-OH), aldehydes, (R-CHO), and carboxylic acids (R-COOH). Oxygenated radicals such aschlorates (ClO3-),perchlorates (ClO4-), chromates (CrO42-),dichromates (Cr2O72-), permanganates (MnO4-), and nitrates (NO3-)are strong oxidizing agents in and of themselves. Many metals such as Iron bond with oxygen atoms, Ferric Oxide (Fe2O3). Ozone (O3) is formed by electrostatic discharge in the presence of molecular oxygen. A double oxygen molecule (O2)2 is known, found as a minor component of liquid oxygen.
Oxygen has three stable isotopes and ten radioactive isotopes. The radioisotopes all have half lives of less than three minutes.
Prolonged exposure to pure oxygen at higher pressures can be toxic, having both pulmonary and neurological effects. Pulmonary effects include edema, loss of lung capacity and damage to lung tissues. Neurological effects can include loss of vision, convulsions and coma.
Compounds of oxygen, such as ozone (O3), peroxide, and superoxide, are also highly toxic. Highly concentrated sources of oxygen promote rapid combustion and therefore are fire and explosion hazards in the presence of fuels. This is true as well of compounds of oxygen such as chlorates, perchlorates, dichromates, etc. Compounds with a high oxidative potential can often cause chemical burns.
The fire that killed the Apollo 1 crew on a test lauchpad spread so rapidly because the pure oxygen atmosphere was at normal atmospheric pressure instead of the one third pressure that would be used during an actual launch. (see partial pressure)
Plant respiration is limited by the process of diffusion.
Insects use a system of tracheae, thin channels, through their exoskeleton, to improve on simple diffusion and let air flow more freely throughout the organism.
Cellular respiration is, in its broadest definition, the process in which the chemical bonds of energy-rich molecules such as glucose are converted into energy usable for life processes. All forms of life except viruses carry out respiration. Oxidation of organic material — in a bonfire, for example — releases a large amount of energy rather quickly. The overall equation for the oxidation of glucose is:
In respiration, the process of oxidation is broken down into a large number of steps. These steps are catalysed by enzymes and coenzymes; each step releases a small amount of energy in the form of ATP. This process consists of two main steps: glycolysis, and pyruvate breakdown.
Ozone in the earth's atmosphere is generally created by ultraviolet light striking oxygen molecules containing two oxygen atoms (O2), splitting them into individual oxygen atoms (atomic oxygen); the atomic oxygen then combines with unbroken O2 to create ozone, O3.
The ozone molecule is also unstable and when ultraviolet light hits ozone it splits into a molecule of O2 and an atom of atomic oxygen, a continuing process called the
ozone-oxygen cycle, thus creating an ozone layer in the stratosphere.
The ozone layer can be destroyed by the presence of atomic chlorine, fluorine or bromine in the atmosphere leading to the so-called
ozone hole in the polar stratosphere during winter months; these elements are found in certain stable compounds, especially chlorofluorocarbons (CFCs)
which may find their way to the stratosphere and there be liberated by the action of ultraviolet light on them.
The concentration of atmospheric ozone in the ozone layer varies by a large factor worldwide, being thicker near the equator and
thinner at the poles. Ozone levels, over the northern hemisphere, are dropping by ~4% per year. Approximately ~4.6% of the Earth's
surface is not covered by the ozone layer; these are the ozone holes.
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Plants, unlike animals, do not get food by eating other organisms (as always in nature, there are exceptions: carnivorous plants such the Venus fly trap). They make their own food, usually in the form of glucose, from the inorganic compounds carbon dioxide and water. Carbon dioxide is taken in through the leaves, and water is taken in mainly through the roots. Sunlight acts as the energy needed to run the reaction that yields glucose as the product the plant needs and oxygen as a waste product that is released into the environment.
In green plants and algae, the pigment molecules that initially absorb the light energy are chlorophyll and various carotenoids. Bacteria contain various other pigments. It may be noted that the typical colors of photosynthetic organisms (green, brown, golden, or red) result from the light that is not absorbed by the pigment molecules, but instead is reflected before meeting the eye.
The typical overall chemical reaction of photosynthesis is:
In simple English, this is carbon dioxide plus water plus light (energy) yields oxygen plus sugar. In animals, this is exactly reversed in the process of respiration (which plants also use, to release the energy stored in photosynthesis): oxygen plus sugar yields carbon dioxide plus water plus energy. However, it is important to note that this chemical equation is highly simplified; in reality photosynthesis employs a very complex mechanism for the adsorbption and conversion of light into chemical energy, using chemical pathways with many important intermediates. Photosynthesis has two distinct stages, called the light reaction and carbon fixation (often called the dark reaction as it is not dependent on light, but the term is confusing as it has nothing to with the dark), which typically occurs via the Calvin cycle.
Primary production is the amount of carbon fixed by plants per unit area over time via photosynthesis.
It is interesting to note that the oxygen released during photosynthesis is not in fact derived from the carbon dioxide, but rather from the water molecules which are consumed in the reaction. This was first proposed in the 1930s by C. B. van Neil of Stanford University, while investigating photosynthetic bacteria, many of which do not release oxygen. One significant group of such organism are bacteria which use hydrogen sulfide instead of water in their photosynthetic pathway:
Some of these produce globules of sulfur as a waste product instead of oygen, while others further oxidize it, producing sulfates. In general, photosynthesis requires a source of hydrogen with which to reduce carbon dioxide into carbohydrates. Van Neil's proposal was confirmed 20 years later by using the O18 isotope of oxygen as a tracer label to follow the fate of oxygen atoms during photosynthesis.
Oxygen is not only a waste product of photosynthesis, it can even harm the photosynthetic process. This is because RubisCO, the primary CO2-fixing enzyme in most plants, also "fixes" oxygen, but this does not lead to useful sugar production. Rather, it results in the loss of both CO2 and nitrogen (in the form of ammonia, NH3) from the plant, in a process known as photorespiration. While some evidence indicates that photorespiration can help protect plants from damage due to very high light intensities, it is generally considered a wasteful process, in which as much as 50% of the plant's fixed carbon can be lost to the atmosphere. Some plants have evolved strategies to minimize photorespiration; these plants are grouped into C4 plants and CAM plants.
The "light reactions" are the first processes of photosynthesis. In them, light is absorbed by molecules of the green pigment chlorophyll. The light is used to "charge" an electron, which is transported via an electron transport system to a molecule of NADP+, which turns into the hydrogen carrier NADPH (used later on in the Calvin cycle).
In the meantime, a molecule of water is split. The oxygen is released into the atmosphere, while the hydrogen ions (which are merely protons after being split from oxygen) diffuse through Transmembrane ATPase. This energy is harnessed to synthesize a molecule of ATP.
The Calvin cycle is similar to the Krebs cycle in some regards. Carbon enters the Calvin cycle in the form of CO2 and leaves in the form of a carbohydrate such as sugar, with the reaction being driven by ATP and NADPH. This ATP and NADPH is usually produced by the light reaction described above, but there is nothing inherent in the process which requires this to be the case; other sources of ATP and NADPH can be used, and in some cases are.
Despite humanity's success in feeding a growing world population, the natural resources on which life depends-fresh water,
cropland, fisheries and forests-are increasingly depleted or strained. One hopeful sign for the new millennium is that population growth is
slowing at a much faster rate than was previously predicted. While slowing, however, significant growth continues, meaning that more people will
be sharing such finite resources as fresh water and cropland. Having reached 6.3 billion in 2003, human population continues to grow.
UN population projections for the year 2050 range from 7.9 billion to 10.9 billion, suggesting the extent to which we can influence our
future. More people and higher incomes worldwide are multiplying humanity 's impact on the environment and on natural resources essential to life.
Based on these trends, it is clear that the 21st century will witness even greater pressures on natural resources. Current demographic trends
offer hope, however. Over the past 40 years the average number of children born to each woman has fallen from five to less than three. Young
people increasingly want to wait to have children and to have smaller families. Policymakers have a choice. They can do nothing, or they can help
ensure that in the 21st century the world 's population peaks with fewer than 8 billion people, simply by committing the financial resources to
meet the needs of couples who want to have smaller families, later in life. It is difficult to achieve zero growth of population and even more difficult to reverse the trend to a negative growth in population. An examination of the
simple numbers makes the difficulty clear. In particular, population growth has "momentum" which means that if one makes a sudden change in the fertility
rate in a society, the full effect of the change will not be realized until every person has died who was living when the change was made.
Thus it takes approximately 70 years to see the full effect of a change in the fertility rate.
There are many encouraging signs from communities around the industrialized world that indicate a growing awareness of the local problems of continued
unrestrained growth of populations, because population growth in our communities never pays for itself. Taxes and utility costs must
escalate in order to pay for the growth. In addition, growth brings increased levels of congestion, frustration, and air pollution.
In recent years, several industrialized nations have seen taxpayer revolts in the form of ballot questions that were adopted to limit the allowed tax increases.
These revolts were not in decaying rust-belt nations; the revolts have been in the nations that claimed to be the most prosperous because they had
the largest rates of population growth. These limits on taxes were felt to be necessary to stop the tax increases that were required to pay for the
growth. Unfortunately the growth has managed to continue, while the schools and other public agencies have suffered from the shortage of funds.
Communities can slow their population growth by removing the many visible and hidden public subsidies that support and encourage growth.
It clear that there will always be large opposition to programs of making population growth
pay for itself. Those who profit from growth will use their considerable resources to convince the community that the community should pay the costs of
growth. In our communities, making growth pay for itself could be a major tool to use in stopping the population growth.
The terms "growth management" and "smart growth" are used interchangeably to describe urban developments that are functionally and esthetically
efficient and pleasing. Sometimes these planning processes are advocated by those who believe that we can't stop population growth, therefore
we must accomodate it as best we can. Other times they are advocated by those who are actively advancing population growth. The claim is made
that growth management and smart growth "will save the environment." They don't save the environment. Whether the growth is smart or dumb, the
growth destroys the environment. "Growth management" is a favorite term used by planners and politicians. With planning, smart growth will destroy
the environment, but it will do it in a sensitive way. It's like buying a ticket on the Titanic. You can be smart and go first class, or
you can be dumb and go steerage. In both cases, the result is the same. But given the choice, most people would go first class.
It is frequently said that we can reduce congestion and air pollution by building high-speed super highways. This can be proven false
by noting that if this were true, the air would be the cleanest, and there would be no global warming.
The falacy arises because of the fact that the construction of the new highways generates new traffic, not previously present, to fill
the new highways to capacity.
As populations of nearby cities grow, the call is made for "regional solutions" to the many problems created by growth. This has two
negative effects: What happens to the idea of the dignity of the human species if this population growth continues at its present rate?
It will be completely destroyed. Democracy cannot survive overpopulation. Human dignity cannot survive overpopulation. Convenience and decency cannot
survive overpopulation. As you put more and more people onto the world, the value of life not only declines, it disappears. It doesn't matter
if someone dies, the more people there are, the less one person matters. Demography relies on the use of large amounts of data, including census returns and records of births, marriages and deaths. The earliest modern census was carried out in Great Britain in 1801. See also Demographic statistics.
In many countries, particularly in the third world, reliable demographic data are still difficult to obtain. For example, during the 1980s the population of Nigeria was widely estimated to be around 110 million, before it was established to be as little as 89 million (without adjustment for undercounting) in a census carried out in 1991.
Important concepts in demography include:
Note that the crude death rate as defined above and applied to a whole population can give a misleading impression. For example, the number of deaths per 1000 people can be higher for developed nations than in less-developed countries, despite standards of health being better in developed countries. This is because developed countries have relatively more older people, who are more likely to die in a given year, so that the overall mortality rate can be higher even if the mortality rate at any given age is lower. A more complete picture of mortality is given by a life table which summarises mortality separately at each age. A life table is necessary to give a good estimate of life expectancy.
Many of the nations with high and relatively unchanging TFR's have several features in common: As of 2003, there is a permanent human presence in space, specifically the three-man crew of the International Space Station.
The northernmost settlement in the world is Alert, Ellesmere Island, Canada.
Age structure:
Birthrate: 22 births/1,000 population (2000 est.)
Death rate: 9 deaths/1,000 population (2000 est.)
Sex ratio:
Life expectancy at birth:
Motivation, rather than differential access to modern contraception is a major determinant of fertility. Individuals frequently respond
to scarcity by having fewer children, and to perceived improved economic opportunity by having more children.
Economic development does not cause family size to shrink; rather, at every point where serious economic opportunity beckons, family size preferences expand.
A) Foreign aid conveys to the recipients the perception of improving economic wellbeing, which is followed by an increase in the fertility
of the recipients of the aid.
B) Migrations from regions of low economic opportunity to places of higher economic opportunity result in an increase in the fertility of the
migrants that persists for a generation or two.
Future historians may see the 20th century as a demographic anomaly – seven decades of accelerating population growth,
unlike any previously experienced, followed by three of subsiding growth as use of contraception spread around the world.There is
no certainty about future trends, however. And barring catastrophe, human population will continue expanding for decades to come.
The planet’s water and land resources will provide less amply for each person, and environmental problems will become more challenging
to resolve. At what level and in what decade population growth halts, and what kind of societies will witness this peak, will
depend very much on how seriously governments and other social institutions take the commitments agreed to at the International
Conference on Population and Development (ICPD) in Cairo in 1994. In Cairo, the governments of the world agreed on a set of policies that could lead to a stabilized world population but which also
make sense on other grounds. The relatively inexpensive strategies endorsed at this meeting are worth supporting regardless of population’s
role in environmental or human well-being. The strategies are grounded not in demographic objectives but in fostering the development
of each person’s capacity to make major life decisions for herself or himself, decisions such as how long to stay in school
or when to have a child. In Cairo, the governments of 179 nations agreed that an estimated $17 billion annually by the year 2000
(rising to $21.7 billion by 2015) would be required to assure universal access to basic reproductive health services within
20 years. Five years later, in 1999, the same governments reiterated the importance of reaching these financial goals. Unfortunately,
except for a handful of donor- and developing-country governments, most have failed to provide their share of this total. In the
United States, ideological divisions within Congress have resulted in this country falling far short of its needed contribution.
Unless such trends reverse, reproductive health services will remain unavailable to many of the world’s poorest people.
And the projected declines in fertility and population growth that many experts point to as the likely future simply will not
occur. The density of population has an impact on a broad range of social and economic issues, such as land prices and housing costs. For example, relatively
densely populated countries such as Japan have higher land prices than less densely populated countries such as Australia, and even in that country, land
prices have doubled and redoubled as the population has increased. It is sometimes argued that reducing the populations of some areas, such as large
cities, would have positive benefits for these reasons.
The world’s human population currently numbers about 6.1 billion people, and the figure grows by nearly 90 million people
each year, or around 240,000 each day. This annual addition to population is greater than ever before in history prior to
the 1980s. It stems in large part from the unprecedented size of current population. The growth rate itself has actually declined
since 1970, from about 2 percent to about 1.5 percent today. However, because this rate is applied to a much larger population
than in 1970—when world population stood at 3.7 billion people—the added yearly increments are larger. If the population
growth rate is not reduced further, world population will double by the year 2040. This growing global population affects the
welfare of communities and ecosystems around the world. In our lifetimes, humanity has become a force on the planet that rivals nature. The reasons for this are complex and linked
to changes not only in human population but in technology, consumption patterns, unequal distribution of wealth and the choices made
by people, businesses and governments. Research on these issues is far from complete. At some point, however, the cumulative
weight of the evidence argues for prudent efforts that will contribute to a stable world population within at least the
lifetimes or our children. The need is not to control population growth. Governments cannot control childbearing and attempts
to do so have sometimes led to coercive approaches to reproduction that violate human rights. The need is rather to expand the
power individuals have over their own lives, especially by enabling them to choose how many children to have and when to have them.
Population is a complex issue, closely tied to a wide range of other issues such as: Clearly the environmental challenges facing humanity in the 21st century and beyond would be less difficult in a world with slower population
growth or none at all. Population is a critical variable influencing the availability of each of the natural resources considered here. And
access to family planning services is a critical variable influencing population. Use of family planning contributes powerfully to lower fertility,
later childbearing, and slower population growth. Yet policymakers, environmentalists and the general public remain largely unaware of the
growing interest of young people throughout the world in delaying pregnancies and planning their families. In greater proportions than ever, girls
want to go to school and to college, and women want to find fulfilling and well-paid employment. Helping people in every country to obtain
the information and services they need to put these ambitions into effect is all that can be done, and all that needs to be done, to end world
population growth in the new century. Comprehensive population policies are an essential element in a world development strategy that combines access to reproductive health services,
to education and economic opportunities, to improved energy and natural resource technologies, and to healthyer models of consumption and the "good
life." Together these can bring humanity into enduring balance with the environment and the natural resources upon which we will always depend. Today more than 1.1 billion people live in the areas richest in species diversity and the most threatened by human activities.
While these areas comprise about 12 percent of the planet's land surface, they hold nearly 20 percent of its human population.
The population in these biodiversity hotspots is growing at a collective rate of 1.8 percent annually, compared to the world's
population's annual growth rate of 1.3 percent. The planet's major renewable natural resources — its fresh water, fisheries and forests — are already strained. Our
atmosphere has been dramatically altered. Based on these trends, it is clear that the 21st century will witness even greater pressures
on natural resources. Current demographic trends offer hope, however. Over the past 40 years the average number of children born to each woman has
fallen from five to less than three. Young people increasingly want to wait to have children and to have smaller families. Policymakers
have a choice. They can do nothing, or they can help ensure that in the 21st century the world's population peaks with fewer than
8 billion people, simply by committing the financial resources to meet the needs of couples who want to have smaller families
and delay childbearing. Population control is the practice of curtailing population increase, usually by reducing the birth rate. The practice has sometimes been voluntary, as a response to poverty, or out of religious ideology, but in some times and places it has been government-mandated. This is generally done to try to prevent a believed threat of Malthusian catastrophe, or overpopulation in general.
Given the nature of human reproductive biology, controlling the birth rate generally implies one of the following practices:
An important example of mandated population control is China's one child policy, in which having more than one child is made extremely unattractive. This has led to allegations that practices like infanticide, forced abortions and forced sterilization are used as a result of the policy.
The policies that contribute to the slowing of population growth are tested and cost-effective. Improving
access to a range of high-quality contraceptive services remains a central strategy for closing the
gap between reproductive intentions and outcomes. Lack of such access is a primary reason that today nearly two out of every
five pregnancies are unintended, and that more than 150 million women do not want to become pregnant but are not using any form
of contraception. Similarly, making sure that all girls and boys everywhere complete secondary school
not only improves human development and health outcomes, but also discourages early and frequent pregnancy and thus contributes
powerfully to slower population growth. The same is true of improving opportunities for women to find paying jobs or start their own
businesses. International agreements provide benchmarks for performance in these areas. In particular, governments
should support and fund the social investments called for by the Programme of Action of the ICPD, which both focus on
women’s well-being and promise to contribute to slower population growth and the conservation of critical natural resources. When
projecting future changes in environmental conditions, environmental and policy analysts should take into account scenarios suggested
by the full range of population projections published by the United Nations Population Division and others, rather than
merely those based on middle projections. Both governments and non-governmental organizations should consider
integrated, global community-based approaches that improve both natural-resource conservation and access to reproductive health services. Family planning and reproductive health services can affect the lives of women, men, and children. There are vast disparities in sexual and reproductive health and risks between rich and poor
countries of the world. The past century witnessed dramatic improvements in what we now call “reproductive health,” especially
in the more developed countries. There, near-universal access to high quality care in pregnancy and childbirth, to life-saving
drugs and safe surgical procedures—including safe abortion—coupled with high levels of contraceptive use and low fertility, all contribute
to good reproductive health overall. The situation is quite different in the developing world. In the year 2000, fully 98
percent of the 3.43 million adult deaths from causes related to poor reproductive health occurred in the developing world. In
developed countries, a woman has only a 1 in 2,125 risk of dying in pregnancy or childbirth over the course of her lifetime. That
risk is 33 times higher, at 1 in 65, for women in developing countries. Sexual activity and childbearing early in life carry significant risks for young
people all around the world. Teen mothers face twice the risk of dying from childbirth than do women in their twenties, and
their children are more vulnerable to health risks as well. Every year, almost half of all new HIV infections and at least one-third
of all new sexually transmitted infections occur to people younger than 25. Every year nearly 80 million unintended pregnancies occur worldwide. More than
half of these pregnancies end in abortion. An estimated 150 million women in developing countries say they would prefer to plan their
families but are not using contraception, and another 350 million women lack access to effective family planning methods. Reproductive health services can help. Voluntary family planning and other reproductive
health services can help couples avert high-risk pregnancies, prevent unwanted childbearing and abortion, and avoid diseases
such as HIV/AIDS and other sexually transmitted infections, that can lead to death, disability, and infertility. Worldwide, more than one-fifth of all pregnancies—nearly 46 million—are
terminated each year. An estimated 36 million procedures take place in the developing world and 10 million in the developed
world. Twenty million of these abortions are carried out under illegal and often Restrictive abortion policies mainly affect the poor who rely on the public sector for all their Iron-deficiency anemia is the most prevalent micronutrient deficiency in the world
today. It is especially common in women of reproductive age and particularly during pregnancy. The prevalence of anemia varies
greatly among and within countries and is often related to poverty. By some estimates, levels among pregnant women reach 70 percent in South Asia. In
sub-Saharan Africa outside of South Africa, levels exceed 40 percent. Yet anemia can easily be treated with oral iron supplements. Approximately one-quarter of pregnant women develop complications. More than one pregnancy
in 350 is fatal. Adequate care during pregnancy and especially at labor and delivery are the most cost-effective interventions
for improving maternal and newborn health, according to the World Bank. Yet in the developing world some 45 million women do not
receive prenatal care and 60 million births take place in the absence of skilled attendants. AIDS is one of the leading killers of our time. In 2000, 4.7 million adults around
the world became infected with the human immuno-deficiency virus (HIV) and another 2.5 million died of AIDS. Over 95 percent of
these deaths and new infections occurred in the developing world. Sub-Saharan Africa is the epicenter of the pandemic, with more
than 70 percent of all new infections and 80 percent of deaths in 2000. AIDS kills people at the height of their reproductive and productive years.
Dying young often leaves women enough time to bear children, but not enough to raise them. Where the epidemic is well advanced,
it adversely affects the well-being of families and precarious economies. Where HIV infection rates are the highest in the world, condom use is lowest.
With growing numbers of infections among women due to the increase in heterosexual transmission of HIV, the need for female-controlled
methods has taken on greater urgency. Every pregnancy
entails risk, especially where health care is poor.
Each year, more than 500,000 women worldwide die from pregnancy or childbirth-related causes, almost all of them in the developing world. Most maternal deaths could be prevented with inexpensive measures. The World Bank and World Over the past three decades, the world has made substantial progress towards improving reproductive health and slowing population growth, but many challenges remain: Comprehensive reproductive health services, especially care in pregnancy and childbirth and for sexually transmitted infections,
are key to preventing disability and death and improving women's health. Better access to emergency care during childbirth and
safe abortion services would also contribute significantly to lower maternal death rates. Family planning diminishes risks associated
with frequent childbearing and helps reduce reliance on abortion. An important obstacle to couple negotiation of contraceptive use and protection from STDs including HIV is that most women
have unequal access to resources and decision-making. Yet women are more vulnerable to the consequences of unplanned pregnancies
and often HIV/STI's. For these reasons, countering the prevailing gender stereotypes that increase risky behaviors and decrease
couple communication is a key strategy for promoting good reproductive health. Many developing countries lack the funds to provide universal
access to good quality reproductive health care. Most women and couples, therefore, rely for their reproductive health services
on government programs funded through international population assistance. Declining and irregular contributions form donor nations
to the United Nations Population Fund, however, threaten continuation of these crucial services. Concurrently, the last few decades
have seen an enormous increase in the use of such services and rising demand could easily drain the dwindling resources the world
provides. Increased financial support from donor countries remains essential to improving reproductive health and slowing population growth. The risks associated with sexual activity and childbearing vary tremendously from country to country, reflecting differences in
public health policies, income levels, and social and cultural practices affecting sexual relationships and access to healthcare.
In developed countries, one woman in 2,100 dies during pregnancy or childbirth over the course of her lifetime. The situation is
quite different in the developing world where a woman's risk of death from maternal causes is 1 in 60, fully 35 times that of
her developed country counterpart. More than a quarter of pregnant women in developing countries still receive no prenatal care and
nearly half give birth with no help from skilled health personnel.
Improving the social and economic status of women, which greatly affect and are affected by poor reproductive health, is a vital
concern. Increasing a woman's educational level and control over financial resources can improve her status within the household,
thereby increasing not only her role in decision-making, knowledge about health and services available to her, and access to food and other resources that contribute to good health. Ultimately,
good sexual and reproductive health benefits everyone and
its consequences extend from the family to the entire planet. The vast disparities
in reproductive health worldwide and the greater vulnerability
of the poor to reproductive risk point to several steps all governments
can take, with the support of other sectors, to improve the health
of women and their families: More and more young people on every continent want to start bearing children later in life and to have smaller families than at any
time in history. Likewise, in greater proportions than ever, women and girls in particular want to go to school and to college, and
they want to find fulfilling and well-paid employment. Helping people in every country obtain the information and services they
need to put these ambitions into effect is all that can be done, and all that needs to be done, to bring world population growth
to a stable landing in the new century. Recent studies conclude that the underlying causes of biodiversity loss include population
growth, migration to ecologically sensitive areas, poverty and inequity, policies that promote unsustainable resource consumption, and a lack
of environmental awareness. Growth in demand for food and housing, each rooted in population growth, has contributed greatly to the loss
of biodiversity. Both conversion of species-rich forests and wetlands to cropland and the increasing intensity of fertilizer and pesticide
use are major factors in the extinction of species, and they are direct responses to increases in food demand. More than 1.1 billion people now live in the world's 25 biodiversity-rich hotspots. The hotspots
are home to around 20 percent of the world's population, although the original boundaries of these regions enclose only about 12 percent of the planet's land surface. The forest-to-people ratio-a simple division of a country's forest cover by its population -helps
quantify the number of people living with low levels of forest resources both now and in the future. Many are vulnerable to scarcities of key
forest products such as timber and paper and risk the collapse of vital forest services such as control of erosion and flooding in populated
areas. In some countries the forest-to-people ratio declines even though forests expand, simply because their populations grow more rapidly than their forests. The well-being of the world's natural resources is closely linked to the health and well-being of
women. Investing in education for girls helps them to contribute to their national economies-and to postpone childbearing until they are
ready for a family. Providing credit and other economic opportunities for women creates alternatives to early and frequent childbearing.
Finally, better access to quality reproductive health services directly benefits women and their families. These approaches increase human
capacity, providing the greatest long-term return to societies, individuals and the environment. Moreover, they are likely to lead to an early
peak in world population in the coming century-quite possibly at levels that can co-exist with forests that teem with human and non-human
life for centuries to come. Clearly the environmental challenges humanity faces in the 21st century and beyond would be less
difficult in a world with slower population growth or none at all. Population is a critical variable influencing the availability of each of the natural
resources considered here. Access to family planning contributes powerfully to lower fertility, later childbearing, and slower population growth.
Yet policymakers, environmentalists and the general public remain largely unaware of the growing interest of young people throughout the world
in delaying pregnancies and planning their families. In greater proportions than ever, girls want to go to school and to college, and women want
to find fulfilling and well-paid employment. Helping people in every country to obtain the information and services they need to put these
ambitions into effect is a critical step towards ending world population growth in this century. Comprehensive population policies are an essential element in a world development strategy that
combines access to reproductive health services, to education and economic opportunity, to improved energy and natural resource technologies, and
to saner models of consumption and the "good life." Together these can bring humanity into enduring balance with the environment
and the natural resources upon which we will always depend. When pregnancy is not desired, either at least one of the participants must be sterile, sexual intercourse must be avoided, or contraception must be used prior to conception.
Contraception (even vasectomy) is not always 100% effective. More generally, in sexual behavior contact of semen with the vagina should be avoided. For example, partners can restrict themselves to masturbation, oral sex, etc., but they should not forget to keep not only the penis but also the sperm away from the vagina. Abstinence is sometimes called the only 'sure' way to avoid pregnancy. If perfectly adhered to, it is. However, some who habitually rely on it as their primary protection may cease to abstain and thereby incur the risk of pregnancy.
Condoms and herbal birthcontrol methods existed before the modern era. The herbal methods were of various effectiveness, and were available in China and Europe.
The official position of the Catholic Church regarding birth control is expressed very clearly in Pope Pius XI's encyclical entitled Casti Connubii. It was written in response to the Episcopalian approval of artificial means of contraception when used in cases of grave necessity.
In 1968 Pope Paul VI released a document called Humanae Vitae, which again forbade chemical and barrier methods but suggested natural methods such as the rhythm method or natural family planning might be considered in cases of necessity. The public response to this suggestion was immediate and overwhelming. There is dissent however. Some priests and theologians accept only abstinence as moral and there are also those who assert abstinence within a marriage can be immoral.
Couples seeking marriage in the Catholic Church are required to undergo counseling by a Catholic priest. In the past priests led couples seeking to delay children to rhythm, today they are instructed to point new couples toward the more effective natural family planning.
Individuals, too, can help bring about a world that is more secure and more supportive of life, health and happiness. They
can educate themselves on population dynamics, consumption patterns
and the impact of these forces on natural resources and the environment. They can be socially, politically and culturally active to elevate
the issues they care about. They can become more environmentally responsible in their purchasing
decisions and their use of energy and natural resources. And individuals and couples can consider the impacts
of their reproductive decisions on their communities and the world as a whole. What is needed is for government and the private sector to make reproductive health services available to all who seek them, to
make sure that girls and boys can go to and stay in school, and to make economic opportunities as accessible to women as to men.
Combined with improved energy and natural-resource technologies and saner models of consumption and the “good life,”
these strategies can bring humanity into enduring balance with the environment and the natural resources that people will always need. The world's ocean fisheries are already being fished to their maximum capacities or are in
decline. Global fish production climbed modestly in 1997, the last year for which global data were available, almost
entirely because the farming of fish expanded in the world's most populous country, China. While the number of fishermen continues
to increase, the amount of fish each fisherman catches is falling steadily. The poor have long depended on fish for complete protein but
population growth has caused this important food source to be out of their reach. Today about 1.8 billion people live in 36 countries with less than 0.1 hectare of forested land per
capita, an indicator of critically low levels of forest cover. Based on the medium population projection and current deforestation
trends, by 2025 the number of people living in forest-scarce countries could nearly double to 3 billion. Most of the world's original
forests have been lost to the expansion of human activities. In many parts of the developing world, the future availability of
forest resources for food, fuel and shelter looks quite discouraging. Future declines in the per capita availability of forests, especially
in developing countries, are likely to pose major challenges for both conservation and human well-being. The world's forests provide goods and services essential to human and planetary well-being. But forests are disappearing faster
today than ever before. Due both to deforestation and human population growth, the current ratio of forests to human beings is less thn half
what it was in 1960. Yet we not only need more forests, we need forests more than ever before–to protect the world's remaining plant and
animal life, to prevent flooding, to slow human-induced climate change, and to provide the paper on which education and communication still
depend. More efficient consumption of forest products and eventual stabilization of human population–a prospect that appears more promising today as birthrates decline–will be needed to conserve the world's forests
in the coming millennium. Half of the world's original forest cover is gone, a loss that reflects humanity's intensive use of land since the invention of farming.
Of the forest that remains, less than one-fourth could be considered relatively undisturbed by human activity. The vast primeval forests
of Europe and Asia survive today only as patchwork remnants of secondary growth, much of it vulnerable to logging, encroachment by development,
pollution, fire and disease. Forests are currently expanding in much of the industrialized world, while shrinking in most of the developing world. In just the first
five years of the 1990s, 65 million hectares of forest–an area the size of Afghanistan– were converted to other uses in developing
countries. By contrast, the industrialized countries gained 9 million hectares of forested land, an area about the size of Hungary. The pattern
of forest loss in developing countries today differs from past losses in Europe and elsewhere in two key respects: human populations are much
larger than before, and the pace of deforestation is more rapid. In the last four decades, an area half the size of the United States has
been cleared of tropical forests, while population in developing countries has doubled to 4.7 billion. Among the most encouraging trends for the
future of forests is the fact that fertility and birthrates are now declining in developing countries, leading demographers to revise downward
their projections of future population growth. Population dynamics are among the primary underlying causes of forest decline. Poverty, corruption, inequitable access to land and wasteful
consumption practices also influence the decisions of governments, corporations and individuals to cut and clear forests. The interaction of these forces
is most evident in areas such as South Asia, Central America and sub-Saharan Africa, where poverty, rapid population growth and weak institutions
contribute to forest loss and severe environmental degradation. The dominant force in forest loss is growth in the demand for farmland. Subsistence agriculture is the principal cause of forest loss in Africa,
Asia and much of Latin America. Slash-and-burn farming and other traditional techniques were sustainable for centuries when population densities
were lower. Today they are a major factor, along with the expansion of commercial farms and livestock grazing areas, in the permanent conversion
of wooded land to agriculture. The need to increase food production is expected to accelerate the forest-to-farmland cycle, especially in
countries where alternatives for meeting this demand are limited. A typical American uses 15 times as much lumber and paper as a resident of a developing country. Total wood consumption has tripled during the 20th century. Per capita consumption has changed little on a global basis–actually
decreasing slightly–but consumption patterns vary widely between countries. A typical American uses 15 times as much lumber and paper
as a resident of a developing country. Reducing wood consumption in the industrialized world is unlikely to stop forest loss in developing
countries however, since most of the wood consumed comes from trees in the industrialized countries themselves. Nevertheless, the consumption
model offered to the rest of the world threatens accelerated forest loss as both populations and economies grow in developing countries. Commercial logging of tropical forests has doubled since 1960, accounting for 5 million to 6 million hectares of forest loss each year,
an area nearly the size of Sri Lanka. This is about one third the forest area lost each year in the developing world. Illegal logging causes
a significant, though unquantified, amount of additional forest loss. Logging's biggest role in deforestation, however, is more indirect.
Logging roads provide pathways deep into forests that farmers and other settlers then follow, permanently clearing the land for crops and pasture. Nearly 3 billion people depend on wood as their main source of energy. The production of fuelwood and charcoal accounts for over
90 percent of the wood harvested in Africa, 80 percent in Asia and 70 percent in Latin America. Population growth is closely linked to rising
woodfuel demand. The effects of woodfuel scarcity are most severe in impoverished areas, where more modern fuels are inaccessible or unaffordable. Women and children are the victims of woodfuel scarcity. The search for fuel consumes the time, energy and health of women and their
children. As local wood supplies grow scarce, women risk spinal column damage and uterine prolapse from carrying heavier loads over longer
distances. Girls are often kept home from school to help their mothers gather wood, depriving them of educational opportunities. Where wood
is unavailable, women cook with inefficient fuels such as animal dung or crop wastes, depriving livestock of fodder and soils of natural fertilizer.
This endangers both the nutritional and respiratory health of women and their families. Forest scarcity threatens the use of paper for education, the activity most likely to improve health and economic well-being. 80 percent
of the world's population lack access to enough affordable paper and reading materials to meet basic standards for literacy and communication.
Reducing paper consumption could help ensure enough paper for all. These efforts are undermined, however, by broader inequalities in access to
education and economic opportunity. Closing the "paper gap" between rich and poor nations ultimately depends on government action
to increase spending on education, health and social services in developing countries. Future population growth and forest loss will largely determine
whether and when this gap can be closed. Population policies based on human development and the Scale of Human and Earth Rights offer the greatest hope for the future of forests. This is not an
argument for population "control" but for the social investments that allow couples to choose when to have children and how many to have.
Programs linking conservation activities with family planning services show promise for achieving both the sustainable use of forests and greater
acceptance of reproductive health services. Sustainable wood consumption is essential for the future of forests. Individuals and institutions alike should promote the ecologically sound
and socially responsible use of forest products. Eco-labeling, or the environmental certification of wood products, could speed the adoption
of more sustainable forestry practices. Consumer demand for green-certified paper and other wood products is an important complement to recycling
and other efforts to reduce wood consumption. The well-being of the world's forests is closely linked to the health and well-being of women. Investing in education for girls
helps them to contribute to their national economies–and to postpone childbearing until they are ready for a family. Providing credit and
other economic opportunities for women creates alternatives to early and frequent childbearing. Finally, better access to quality reproductive
health services directly benefits women and their families. These approaches increase human capacity, providing the greatest long-term return to
societies, individuals and the environment. Moreover, they are likely to lead to an early peak in world population in the coming century–quite
possibly at levels that can co-exist with forests that teem with human and non-human life for centuries to come. The number of people living in countries where cultivated land is critically scarce is projected to increase
to between 600 million and 986 million in 2025. Despite the Green Revolution and other technological advances, agriculture
experts continue to debate how long crop yields will keep up with population growth. The food that feeds the future will be raised
mostly on today's cropland. The soil on this land must remain fertile to keep food production secure. The minimum amount of
land needed to supply a vegetarian diet for one person without any use of artificial chemical inputs or loss of soil and soil
nutrients is .07 hectares, or slightly less than a quarter of an acre. An estimated 415 million people already live today in
countries that have less than that per person. Easing world hunger could become unimaginably difficult if population growth resembles
demographers' higher projections. The United Nations Food and Agriculture Organization defines adequate nourishment as consumption of at least 2,100 kilocalories
(often called calories informally) per day. Countries are shaded to illustrate the proportion of the population which does not
have access to enough food to satisfy this requirement. Having reached nearly 6.1 billion in 2000, human population continues to grow. UN population
projections for the year 2050 range from 7.9 billion to 10.9 billion, suggesting the extent to which we can influence our future. More
people and higher incomes worldwide are multiplying humanity's impacts on the environment and on the natural resources that are
essential to life. The planet's fresh water, fisheries, forests and atmosphere are already strained. Based on these trends, it is clear that the 21st century will witness even greater pressures on natural resources. Current demographic
trends offer hope, however. Over the past 40 years the average number of children born to each woman has fallen from five to
less than three. Young people increasingly want to wait to have children and to have smaller families. Policymakers have a choice.
They can do nothing, or they can help ensure that in the 21st century the world's population peaks with fewer than 8 billion
people, simply by committing the financial resources to meet the needs of couples who want to have smaller families, later in life. The problem is worse than it often appears on the ground, because
much of the fresh water now used in water-scarce regions comes from deep aquifers that are not being refreshed by the natural
water cycle. In most of the countries where water shortage is severe and worsening, high rates of population growth exacerbate
the declining availability of renewable fresh water. While 25 countries currently experience either water stress or scarcity,
39 to 41 countries are projected to face similar conditions by 2025. In biology, the carrying capacity of an environment for a particular species
is a measure of the steady-state density that the species can have for a particular habitat to support sustainably.
When populations exceed the carrying capacity, famine and disease tend to reduce the size the population.
Humans are the only species known to possess the ability to increase their carrying capacity. In the case of humans, or theoretically, any other specie that is able to extend its carrying capacity through agricultural and technological means, it means harnessing a natural system to sustainably support it with or without causing environmental damage, and the continuous ability to do so. Overpopulation is regarded by many as a critical issue concerning the growth, and future size of the earth's population.
There is a growing awareness that the unrestrained growth of populations should pay for itself. Taxes and utility costs must
escalate in order to pay for the growth. In addition, growth brings increased levels of congestion, frustration, and air pollution.
In recent years, several industrialized nations have seen taxpayer revolts in the form of ballot questions that were adopted to limit the allowed tax increases.
The revolts have been in the nations that claimed to be the most prosperous because they had
the largest rates of population growth. These limits on taxes were felt to be necessary to stop the tax increases that were required to pay for the
growth. Unfortunately the growth has managed to continue, while the schools and other public agencies have suffered from the shortage of funds.
Communities can slow their population growth by removing the many visible and hidden public subsidies that support and encourage growth.
It clear that there will always be large opposition to programs of making population growth
pay for itself. Those who profit from growth will use their considerable resources to convince the community that the community should pay the costs of
growth. In our communities, making growth pay for itself could be a major tool to use in stopping the population growth.
What happens to the idea of the dignity of the human species if this population growth continues at its present rate?
It will be completely destroyed. Democracy cannot survive overpopulation. Human dignity cannot survive overpopulation. Convenience and decency cannot
survive overpopulation. As you put more and more people onto the world, the value of life not only declines, it disappears. It doesn't matter
if someone dies, the more people there are, the less one person matters. Many of the nations with high and relatively unchanging TFR's have several features in common: Clearly the environmental challenges facing humanity in the 21st century and beyond would be less difficult in a world with slower population
growth or none at all. Population is a critical variable influencing the availability of each of the natural resources considered here. And
access to family planning services is a critical variable influencing population. Use of family planning contributes powerfully to lower fertility,
later childbearing, and slower population growth. Yet policymakers, environmentalists and the general public remain largely unaware of the
growing interest of young people throughout the world in delaying pregnancies and planning their families. In greater proportions than ever, girls
want to go to school and to college, and women want to find fulfilling and well-paid employment. Helping people in every country to obtain
the information and services they need to put these ambitions into effect is all that can be done, and all that needs to be done, to end world
population growth in the new century. Reproductive health services can help. Voluntary family planning and other reproductive
health services can help couples avert high-risk pregnancies, prevent unwanted childbearing and abortion, and avoid diseases
such as HIV/AIDS and other sexually transmitted infections, that can lead to death, disability, and infertility. Comprehensive reproductive health services, especially care in pregnancy and childbirth and for sexually transmitted infections,
are key to preventing disability and death and improving women's health. Better access to emergency care during childbirth and
safe abortion services would also contribute significantly to lower maternal death rates. Family planning diminishes risks associated
with frequent childbearing and helps reduce reliance on abortion. An important obstacle to couple negotiation of contraceptive use and protection from STDs including HIV is that most women
have unequal access to resources and decision-making. Yet women are more vulnerable to the consequences of unplanned pregnancies
and often HIV/STI's. For these reasons, countering the prevailing gender stereotypes that increase risky behaviors and decrease
couple communication is a key strategy for promoting good reproductive health. Individuals, too, can help bring about a world that is more secure and more supportive of life, health and happiness. They
can educate themselves on population dynamics, consumption patterns
and the impact of these forces on natural resources and the environment. They can be socially, politically and culturally active to elevate
the issues they care about. They can become more environmentally responsible in their purchasing
decisions and their use of energy and natural resources. And individuals and couples can consider the impacts
of their reproductive decisions on their communities and the world as a whole. The world's forests provide goods and services essential to human and planetary well-being. But forests are disappearing faster
today than ever before. Due both to deforestation and human population growth, the current ratio of forests to human beings is less than half
what it was in 1960. Yet we not only need more forests, we need forests more than ever before–to protect the world's remaining plant and
animal life, to prevent flooding, to slow human-induced climate change, and to provide the paper on which education and communication still
depend. More efficient consumption of forest products and eventual stabilization of human population–a prospect that appears more promising today as birthrates decline–will be needed to conserve the world's forests
in the coming millennium. Population dynamics are among the primary underlying causes of forest decline. Poverty, corruption, inequitable access to land and wasteful
consumption practices also influence the decisions of governments, corporations and individuals to cut and clear forests. The interaction of these forces
is most evident in areas such as South Asia, Central America and sub-Saharan Africa, where poverty, rapid population growth and weak institutions
contribute to forest loss and severe environmental degradation. The dominant force in forest loss is growth in the demand for farmland. Subsistence agriculture is the principal cause of forest loss in Africa,
Asia and much of Latin America. Slash-and-burn farming and other traditional techniques were sustainable for centuries when population densities
were lower. Today they are a major factor, along with the expansion of commercial farms and livestock grazing areas, in the permanent conversion
of wooded land to agriculture. The need to increase food production is expected to accelerate the forest-to-farmland cycle, especially in
countries where alternatives for meeting this demand are limited. Population policies based on human development and the Scale of Human and Earth Rights offer the greatest hope for the future of forests. This is not an
argument for population "control" but for the social investments that allow couples to choose when to have children and how many to have.
Programs linking conservation activities with family planning services show promise for achieving both the sustainable use of forests and greater
acceptance of reproductive health services. Sustainable wood consumption is essential for the future of forests. Individuals and institutions alike should promote the ecologically sound
and socially responsible use of forest products. Eco-labeling, or the environmental certification of wood products, could speed the adoption
of more sustainable forestry practices. Consumer demand for green-certified paper and other wood products is an important complement to recycling
and other efforts to reduce wood consumption. Motivation, rather than differential access to modern contraception is a major determinant of fertility. Individuals frequently respond
to scarcity by having fewer children, and to perceived improved economic opportunity by having more children.
Economic development does not cause family size to shrink; rather, at every point where serious economic opportunity beckons, family size preferences expand.
A) Foreign aid conveys to the recipients the perception of improving economic wellbeing, which is followed by an increase in the fertility
of the recipients of the aid.
B) Migrations from regions of low economic opportunity to places of higher economic opportunity result in an increase in the fertility of the
migrants that persists for a generation or two. The well-being of the world's forests is closely linked to the health and well-being of women. Investing in education for girls
helps them to contribute to their national economies–and to postpone childbearing until they are ready for a family. Providing credit and
other economic opportunities for women creates alternatives to early and frequent childbearing. Finally, better access to quality reproductive
health services directly benefits women and their families. These approaches increase human capacity, providing the greatest long-term return to
societies, individuals and the environment. Moreover, they are likely to lead to an early peak in world population in the coming century–quite
possibly at levels that can co-exist with forests that teem with human and non-human life for centuries to come. The vast disparities
in reproductive health worldwide and the greater vulnerability
of the poor to reproductive risk point to several steps all governments
can take, with the support of other sectors, to improve the health
of women and their families: More and more young people on every continent want to start bearing children later in life and to have smaller families than at any
time in history. Likewise, in greater proportions than ever, women and girls in particular want to go to school and to college, and
they want to find fulfilling and well-paid employment. Helping people in every country obtain the information and services they
need to put these ambitions into effect is all that can be done, and all that needs to be done, to bring world population growth
to a stable landing in the new century. The biosphere is divided into a number of biomes, or areas inhabited by a broadly similar flora and fauna.
Terrestrial organisms in temperate and arctic places have relatively small amounts of total biomass, smaller energy budgets, and display prominent
adaptations to cold, including world-spanning migrations, social adaptations, homeothermy, estivation and multiple layers of insulation. Some theorists therefore believe that
the Earth is poorly suited to life. However, every part of the planet supports life, from the polar ice caps to the Equator.
Recent advances in microbiology have proven that microscopic life lives inside rocks under the Earth's surface, and that the total mass of microbial life in so-called "uninhabitable
zones" may, in terms of sheer biomass, outweigh all animal and plant life combined on the surface of the Earth.
Oceans mediate the cold and distribute nutrients. The Antarctic krill, Euphausia superba, for example, is generally considered to be the most successful
animal of the planet, with a biomass probably over 500 million tonnes (c.f. human biomass of about 250 million tonnes).
In reality, however, the atmosphere contains a large amount of water vapour, resulting from evaporation from surface water and transpiration by plants. Near the surface,
this is typically about 4% (by volume) but only 3-6 parts per million (ppm) above 10 km.
Air is a mixture, the composition of which varies with the altitude at which the sample is taken, its composition begins to change materially above 62 miles. Since air is a mixture, there are two vapor pressure curves, one for the saturated liquid and the other for the saturated vapor. The average composition of dry air at surface altitudes is shown here: Source: Definition of the U.S. Standard Atmosphere (1976) The present atmosphere of the Earth is probably not its original atmosphere. Our current atmosphere is what chemists would call an oxidizing
atmosphere, while the original atmosphere was what chemists would call a reducing atmosphere. In particular, it probably did not contain oxygen.
The original atmosphere may have been similar to the composition of the solar nebula and close to the present composition of the
Gas Giant planets, though this depends on the details of how the planets condensed from the solar nebula. That atmosphere was lost to space, and replaced by compounds outgassed from the crust or (in some more recent theories)
much of the atmosphere may have come instead from the impacts of comets and other planetesimals rich in volatile materials.
The oxygen so characteristic of our atmosphere was almost all produced by plants
cyanobacteria or, more colloquially, blue-green algae). Thus, the present composition of the atmosphere is 79% nitrogen, 20% oxygen, and 1% other gases.
The Earth is surrounded by a blanket of air, which we call the atmosphere. It reaches over 560 kilometers (348 miles) from the surface of the Earth, so we are only able to see
what occurs fairly close to the ground. Early attempts at studying the nature of the atmosphere used clues from the weather, the beautiful multi-colored sunsets and sunrises,
and the twinkling of stars. With the use of sensitive instruments from space, we are able to get a better view of the functioning of our atmosphere. Life on Earth is supported by the atmosphere, solar energy, and our planet's magnetic fields. The atmosphere absorbs the energy from the Sun, recycles water and other
chemicals, and works with the electrical and magnetic forces to provide a moderate climate. The atmosphere also protects us from high-energy radiation and the frigid vacuum of space. The envelope of gas surrounding the Earth changes from the ground up. Four distinct layers have been identified using thermal characteristics (temperature changes), chemical composition, movement, and density. Oxygen is a highly reactive element and is capable of combining with most other elements. It is required by most living organisms and for most forms of combustion.
Impurities in molten pig iron are burned away with streams of high pressure oxygen to produce steel. Oxygen can also be combined with acetylene (C2H2)
to produce an extremely hot flame used for welding. Liquid oxygen, when combined with liquid hydrogen, makes an excellent rocket fuel. Ozone (O3)
forms a thin, protective layer around the earth that shields the surface from the sun's ultraviolet radiation. Oxygen is also a component of hundreds of thousands of organic compounds.
The boundaries between these regions are named the tropopause, stratopause and mesopause.
The average temperature of the atmosphere at the surface of earth is 14 °C.
The modern atmosphere is sometimes referred to as its "third atmosphere"; in order to distinguish the current chemical composition from two notably different compositions. The original atmosphere was primarily helium and hydrogen; heat (from the still molten crust, and the sun) dissipated this atmopshere.
About 3.5 billion years ago, the surface had cooled enough to form a crust, still heavily populated with volcanoes releasing steam, carbon dioxide, and ammonia. This led to the "second atmosphere"; which was, primarily, carbon dioxide and water vapor, with some nitrogen but virtually no oxygen. This second atmosphere had ~100 times as much gas as the current atmosphere. It is generally believed that the greenhouse effect, caused by high levels of carbon dioxide, kept the Earth from freezing.
During the next couple billion years, water vapor condensed to form rain and oceans, which started to dissolve carbon dioxide. Approximately 50% of the carbon dioxide would be absorbed into the oceans. Photosynthesizing plants would evolve and convert carbon dioxide into oxygen. Over time, excess carbon became locked in fossil fuels, sedimentary rocks (notably limestone), and animal shells. As oxygen was released, it reacted with ammonia to create nitrogen; in addition, bacteria would also convert ammonia into nitrogen.
As more plants appeared, the levels of oxygen increased significantly (while carbon dioxide levels dropped). At first it combined with various elements (such as iron), but eventually oxygen accumulated in the atmosphere — resulting in mass extinctions and further evolution. With the appearance of an ozone layer (a compound of oxygen atoms) lifeforms were better protected from ultraviolet radiation. This oxygen-nitrogen atmosphere is the "third atmosphere".
The troposphere is the lowermost portion of Earth's atmosphere and the one in which most weather phenomena occur; this layer extends to an altitude of 7-17 km, depending on latitude. Generally, jets fly near the top of this layer. The troposphere is directly below the stratosphere.
The tropopause marks the limit of the troposphere and the beginning of the stratosphere. The temperature above the tropopause increases slowly with height up to about 50 km.
The troposphere starts at the Earth's surface and extends 8 to 14.5 kilometers high (5 to 9 miles). This part of the atmosphere is the most dense. As you climb higher in this
layer, the temperature drops from about 17 to -52 degrees Celsius. Almost all weather is in this region. The tropopause separates the troposphere from the next layer. The
tropopause and the troposphere are known as the lower atmosphere. Temperature and water vapour content in the troposphere decrease rapidly with altitude. Water vapour plays a major role in regulating air
temperature because it absorbs solar energy and thermal radiation from the planet's surface. The troposphere contains 99 % of the water
vapour in the atmosphere. Water vapour concentrations vary with latitudinal position(i.e. North to South). They are greatest above the tropics, where they
may be as high as 3 %, and decrease toward the polar regions.
The troposphere is where all weather takes place; it is the region of rising and falling packets of air.
The air pressure at the top of the troposphere is only 10% of that at sea level (0.1 atmospheres). There is a thin buffer zone between the troposphere and the next layer called the tropopause.
All weather phenomena occur within the troposphere, although turbulence may extend into the lower portion of the troposphere means
"region of mixing" and is so named because of vigorous convective air currents within the layer.
The boundary between the troposphere, and the stratosphere is called the tropopause. The height of the tropopause from the ground ranges from 8
km in high latitudes, to 18 km above the equator. Its height also varies with the seasons; highest in the summer and lowest
in the winter. Air temperature within the tropopause remains constant with increasing altitude. The tropopause is a boundary layer defined by a
sudden change in lapse rate.
In telecommunication, the term troposphere has the following meanings: 1. The lower layers of atmosphere, in which the change of temperature with height is relatively large. It is the region where clouds form, convection is active, and mixing is continuous and more or less complete.
2. The layer of the Earth's atmosphere, between the surface and the stratosphere, in which temperature decreases with altitude and which contains approximately 80% of the total air mass.
Note: The thickness of the troposphere varies with season and latitude. It is usually 16 km to 18 km thick over tropical regions, and less than 10 km thick over the poles.
The stratosphere starts just above the troposphere and extends to 50 kilometers (31 miles) high. Compared to the troposphere, this part of the atmosphere is dry and less
dense. The temperature in this region increases gradually to -3 degrees Celsius, due to the absorbtion of ultraviolet radiation. The
ozone layer, which absorbs and scatters the solar ultraviolet radiation, is in this layer. Ninety-nine percent of "air" is located in the troposphere and stratosphere. The
stratopause separates the stratosphere from the next layer. The mesosphere starts just above the stratosphere and extends to 85 kilometers (53 miles) high. In this region, the temperatures again fall as low as -93 degrees Celsius as
you increase in altitude. The chemicals are in an excited state, as they absorb energy from the Sun. The mesopause separates the mesophere from the thermosphere. The regions of the stratosphere and the mesosphere, along with the stratopause and mesopause, are called the middle atmosphere by scientists. This area has been closely studied on the ATLAS Spacelab mission series. The structure of the ionosphere is strongly influenced by the charged particle wind from the Sun
(solar wind), which is in turn governed by the level of Solar activity. One measure of the structure of the ionosphere is the free electron density, which
is an indicator of the degree of ionization. The thermosphere starts just above the mesosphere and extends to 600 kilometers (372 miles) high. The temperatures go up as you increase in altitude due to the Sun's energy.
Temperatures in this region can go as high as 1,727 degrees Celsius. Chemical reactions occur much faster here than on the surface of the Earth. This layer is known as the upper atmosphere. The upper and lower of the thermosphere will be studied more closely during the Tethered Satellite Mission (TSS-1R). Earth is actually beyond the outer edge of the orbits which would be warm enough to form liquid water. Without some form of a greenhouse
effect, the Earth's water would freeze. Paleontological evidence indicates that at one point after blue-green bacteria (Archaea) had colonized the
oceans, the greenhouse effect failed, and the Earth froze solid for 10 to 100 million years.
On other planets, such as Venus, gaseous water is cracked by solar ultraviolet, and the Hydrogen is ionized and blown away by the solar
wind. This effect is slow, but inexorable. It is believed that this is the reason why Venus has no water. Without hydrogen, the oxygen interacts
with the surface and is bound up in solid minerals.
On Earth, a shield of Ozone absorbs most of this energetic ultraviolet high in the atmosphere, reducing the cracking effect. The magnetosphere
also shields the ionosphere from direct scouring by the solar wind.
Finally, vulcanism, aided by the moon's tidal effects, continuously emits water vapor from the interior. Earth's plate tectonics recycle Carbon
and water as limestone fields are subducted into magma and volcanically emitted as gaseous carbon dioxide and steam.
An ecosystem is a community of organisms (plant, animal and other living organisms - also referred as biocenose) together with their environment (or biotope), functioning as a unit. Ecosystems are studied in Ecology. An ecosystem is a dynamic and complex whole, interacting as an ecological unit. Some consider it is a basic unit in ecology, only a structured functional unit in equilibrium, caracterized by energy and matter flows between the different elements that compose it. But others consider this vision or a self-standing unit with coherent and stable flows only to be a bit restrictive.
An ecosystem may be of very different size. It may be a whole forest, as well as a small pond. Different ecosystems are often separated by geographical barriers, like deserts, mountains or oceans, or are isolated otherwise, like lakes or rivers. As these borders are never rigid, ecosystems tend to blend into each other. As a result, the whole earth can be seen as a single ecosystem, or a lake can be divided into several ecosystems, depending on the used scale.
The organisms in an ecosystem are usually well balanced with each other and with their environment. Introduction of new environmental factors or new species can have disastrous results, eventually leading to the collapse of an ecosystem and the death of many of its native species.
Ecosystem and ecoregion terms are often confused (large ecosystems being called ecoregions), but there is a large consensus to define ecoregions as being geographical defined units, relatively large, land or water, with distinctive features. Ecoregions are a way to codify the different regions within which are observed particular patterns or similarities in ecosystems.
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