The Greenhouse effect refers to the change in the thermal equilibrium temperature of a planet or moon by the presence of an atmosphere containing gas that absorbs infrared radiation. Greenhouse gases warm the atmosphere by efficiently absorbing thermal infrared radiation emitted by the Earth's surface, by the atmosphere itself, and by clouds. As a result of its warmth, the atmosphere also radiates thermal infrared in all directions, including downward to the Earth's surface. Thus, greenhouse gases trap heat within the surface-troposphere system. This mechanism is fundamentally different from the mechanism of an actual greenhouse, which instead isolates air inside the structure so that heat is not lost by convection and conduction. The greenhouse effect was discovered by Joseph Fourier in 1824 and first investigated quantitatively by Svante Arrhenius in 1896.
In the absence of the greenhouse effect, the Earth's average surface temperature of 14 °C (57 °F) would be about -18 °C (–0.4 °F) (Black body temperature of the Earth). Anthropogenic Global warming (AGW), a recent warming of the Earth's lower atmosphere as evidenced by the global mean temperature anomaly trend , is believed to be the result of an "enhanced greenhouse effect" mainly due to human-produced increased concentrations of greenhouse gases in the atmosphere and changes in the use of land.
In our solar system, Mars, Venus, and the moon Titan also exhibit significant greenhouse effect.
GREEN HOUSE GASES
Greenhouse gases naturally blanket the Earth and keep it about 33 degrees Celsius warmer than it would be without these gases in the atmosphere. This is called the Greenhouse Effect. Over the past century, the Earth has increased in temperature by about .5 degrees Celsius and many scientists believe this is because of an increase in concentration of the main greenhouse gases: carbon dioxide, methane, nitrous oxide, and fluorocarbons. People are now calling this climate change over the past century the beginning of Global Warming. Fears are that if people keep producing such gases at increasing rates, the results will be negative in nature, such as more severe floods and droughts, increasing prevalence of insects, sea levels rising, and Earth's precipitation may be redistributed. These changes to the environment will most likely cause negative effects on society, such as lower health and decreasing economic development. However, some scientists argue that the global warming we are experiencing now is a natural phenomenon, and is part of Earth's natural cycle. Presently, nobody can prove if either theory is correct, but one thing is certain; the world has been emitting greenhouse gases at extremely high rates and has shown only small signs of reducing emissions until the last few years. After the 1997 Kyoto Protocol, the world has finally taken the first step in reducing emissions.
(1) Carbon Dioxide : Carbon Dioxide (CO2) is a colorless, odorless non-flammable gas and is the most prominent Greenhouse gas in Earth's atmosphere. It is recycled through the atmosphere by the process photosynthesis, which makes human life possible. Photosynthesis is the process of green plants and other organisms transforming light energy into chemical energy. Light Energy is trapped and used to convert carbon dioxide, water, and other minerals into oxygen and energy rich organic compounds. Carbon Dioxide is emitted into the air as humans exhale, burn fossil fuels for energy, and deforest the planet. Every year humans add over 30 billion tons of carbon dioxide in the atmosphere by these processes, and it is up thirty percent since 1750 .
Fossil Fuels were created chiefly by the decay of plants from millions of years ago. We use coal, oil and natural gas to generate electricity, heat our homes, power our factories and run our cars. These fossil fuels contain carbon, and when they are burned, they combine with oxygen, forming carbon dioxide. The two atoms of oxygen add to the total weight. The increase from developing countries was three times that from developed countries.
Deforestation is another main producer of carbon dioxide. The causes of deforestation are logging for lumber, pulpwood, and fuel wood. Also contributing to deforestation are clearing new land for farming and pastures used for animals such as cows. Forests and wooded areas are natural carbon sinks. This means that as trees absorb carbon dioxide, and release oxygen, carbon is being put into trees. This process occurs naturally by photosynthesis, which occurs less and less as we cut and burn down trees. As the abundance of trees declines, less carbon dioxide can be recycled. As we burn them down, carbon is released into the air and the carbon bonds with oxygen to form carbon dioxide, adding to the greenhouse effect.
(2) Methane :Methane is a colorless, odorless, flammable gas. It is formed when plants decay and where there is very little air. It is often called swamp gas because it is abundant around water and swamps. Bacteria that breakdown organic matter in wetlands and bacteria that are found in cows, sheep, goats, buffalo, termites, and camels produce methane naturally. Since 1750, methane has doubled, and could double again by 2050. Each year we add 350-500 million tons of methane to the air by raising livestock, coal mining, drilling for oil and natural gas, rice cultivation, and garbage sitting in landfills. It stays in the atmosphere for only 10 years, but traps 20 times more heat than carbon dioxide.
(3) Nitrous Oxide : Nitrous oxide is another colorless greenhouse gas, however, it has a sweet odor . It is primarily used as an anesthetic because it deadens pain and for this characteristic is called laughing gas. This gas is released naturally from oceans and by bacteria in soils. Nitrous oxide gas risen by more than 15% since 1750. Each year we add 7-13 million tons into the atmosphere by using nitrogen based fertilizers, disposing of human and animal waste in sewage treatment plants, automobile exhaust, and other sources not yet identified. It is important to reduce emissions because the nitrous oxide we release today will still be trapped in the atmosphere 100 years from now.
Nitrogen based fertilizer use has doubled in the past 15 years. These fertilizers provide nutrients for crops; however, when they breakdown in the soil, nitrous oxide is released into the atmosphere. In automobiles, nitrous oxide is released at a much lower rate than carbon dioxide, because there is more carbon in gasoline than nitrogen.
(4) Fluorocarbons : Fluorocarbons is a general term for any group of synthetic organic compounds that contain fluorine and carbon. Many of these compounds, such as chlorofluorocarbons(CFCs), can be easily converted from gas to liquid or liquid to gas. Because of these properties, CFC`s can be used in aerosol cans, refrigerators, and air conditioners. Studies in the 1970`s showed that when CFC`s are emitted into the atmosphere, they break down molecules in the Earth's ozone layer . Since then, the use of CFC`s has significantly decreased and they are banned from production in the United States. The substitute for CFC`s are hydrofluorocarbons (HFC's). HFC`s do not harm or breakdown the ozone molecule, but they do trap heat in the atmosphere, making it a greenhouse gas, aiding in global warming. HFC`s are used in air conditioners and refrigerators. The way to reduce emissions of this gas is to be sure that in both devices the coolant is recycled and all leaks are properly fixed . Also, before throwing the appliances away, be sure to recover the coolant in each.
(5) Water Vapour : Water vapor is a naturally occurring greenhouse gas and accounts for the largest percentage of the greenhouse effect, between 36% and 66%.Water vapor concentrations fluctuate regionally, but human activity does not directly affect water vapor concentrations except at local scales (for example, near irrigated fields).
The Clausius-Clapeyron relation establishes that warmer air can hold more water vapor per unit volume. Current state-of-the-art climate models predict that increasing water vapor concentrations in warmer air will amplify the greenhouse effect created by anthropogenic greenhouse gases while maintaining nearly constant relative humidity. Thus water vapor acts as a positive feedback to the forcing provided by greenhouse gases such as CO2.
IMPACT OF GREENHOUSE EFFECT ON VEGETATION AND CLIMATE
We use the fully coupled atmosphere-ocean-land model, FOAM-LPJ, to predict future changes in global vegetation and climate due to continued rising levels of carbon dioxide (CO2). In these simulations, we allow CO2 to transiently increase 1% per year until reaching 4xCO2. We perform separate simulations to investigate the radiative (increased CO2 in the atmosphere leads to higher temperatures) and physiological (increased CO2 in plants leads to greater photosynthesis) effects of rising CO2 and to compare simulations with interactive and fixed vegetation cover. The model predicts that in the future, tropical rainforests will suffer due to higher temperatures and reduced rainfall while the boreal forests will continue to shift poleward. The model simulates a substantial heat stress on the boreal forest, which causes a vast loss of trees along the southern portions of the modern boreal forest, although the likelihood of this vegetation response remains uncertain. Vegetation feedbacks on the atmosphere are not substantial on a global average but produce important regional effects, such as a reduced warming trend over the areas of boreal tree loss in Eurasia.
FUTURE AND THE GREENHOUSE EFFECT
Over the last two centuries, the composition of the Earth's atmosphere has been altered substantially by human activities, including fossil fuel burning, agriculture,deforestation and industrial emissions. In addition to regional problems, such as higher levels of tropospheric ozone and other forms of air pollution, there is growing evidence that these changes will have a significant, long-term impact on the planet's climate and biota. Considerable research effort is now underway to unravel the often complex interactions and feedbacks among climate, atmospheric chemistry, biogeochemistry and ecosystem dynamics under past, present and potential future conditions. Accurate projections of future climate change and its impact on society and the natural environment hinge on two key questions: how will radiatively active trace gas and aerosol concentrations in the atmosphere evolve in the future, and how sensitive is the climate system to these changes in forcing? The questions are, of course, not independent because many of the chemical species of interest have natural biological sources and sinks that respond to climate variations. A third issue, the effect of the expected climate perturbations on society and on natural and managed ecosystems, is crucial to the problem but beyond the scope of this review. In recent years, researchers also have become much more aware of how variable the 'natural' climate can be from studies of historical phenomena such as El Niño and longer-term palaeorecords. The past several centuries appear to have been unusually stable, but dramatic oscillations in climate and atmospheric composition have been observed in the palaeorecord with time scales as short as a few decades to centuries (e.g. Petit et al., 1999). Thus future, human-induced changes must be understood against this background of an inherently variable natural system.
MEANING AND CAUSES OF GLOBAL WARMING
Global warming is the increase in the average measured temperature of the Earth's near-surface air and oceans since the mid-20th century, and its projected continuation.
Global surface temperature increased 0.74 ± 0.18 °C (1.33 ± 0.32 °F) during the 100 years ending in 2005. The Intergovernmental Panel on Climate Change (IPCC) concludes "most of the observed increase in globally averaged temperatures since the mid-twentieth century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations" via an enhanced greenhouse effect. Natural phenomena such as solar variation combined with volcanoes probably had a small warming effect from pre-industrial times to 1950 and a small cooling effect from 1950 onward. These basic conclusions have been endorsed by at least 30 scientific societies and academies of science, including all of the national academies of science of the major industrialized countries. While individual scientists have voiced disagreement with these findings, the overwhelming majority of scientists working on climate change agree with the IPCC's main conclusions.
EFFECTS OF GLOBAL WARMING
(1) Environmental Effects : The effects of global warming on the environment and human life are numerous, varied, accelerating and taking scientists studying global warming by surprise.
Scenarios studied by the Intergovernmental Panel on Climate Change (IPCC) predict that global warming will continue and get worse much faster than was expected even in their last report. The IPCC reports attribute many specific natural phenomena to human causes. The expected long range effects of recent climate change may already be observed. Rising sea levels, glacier retreat, Arctic shrinkage, and altered patterns of agriculture are cited as direct consequences of human activities. Predictions for secondary and regional effects include extreme weather events, an expansion of tropical diseases, changes in the timing of seasonal patterns in ecosystems, and drastic economic impact. Concerns have led to political activism advocating proposals to mitigate, eliminate, or adapt to it.
The 2007 Fourth Assessment Report by the IPCC includes a summary of the expected effects.
(2) Social Effects : Agriculturally, Dr. Sylvan H. Wittwer believes that global warming is good for the human race, because it helps increase food production. "The most determinant factor in agriculture production is climate. History reveals that for food production, warming is better than cooling." Dr. Wittwer says that carbon dioxide is an essential nutrient for the production of food, and food is one of the most important things in our lives. As the temperature rises, more farmland will be open towards the poles and the length of the growing season will also lengthen. With all the people who go hungry each day, Dr. Wittwer believes food production should be one of our main concerns. Dr. Wittwer is the scientific pioneer who conducted the original studies on atmospheric CO2 enhancement of the production of food crops.
Increasing amounts of greenhouse gases in the atmosphere and global warming could also lead to more health concerns. A statement released from the Intergovernmental Panel on Climate Change (IPCC) said, "Climate change is likely to have wide-ranging and mostly adverse impacts on human health, with significant loss of life." As temperatures increase towards the poles, similar to farmland, insects and other pests migrate towards Earth's poles. These insects and pests could be allowed to migrate up to 550 Km or 550 miles. Some insects carry diseases such as malaria and dengue fever. Thus, an increase in these particular insects and pests closer to the poles results in an increase in these diseases. This could lead to 50 to 80 million additional cases of Malaria annually, a 10-15% increase.The most obvious health effect is directly from the heat itself. With an increase in heat waves, there will be more people who will suffer from heatstroke, heart attacks and other ailments aggravated by the heat. According to the EPA, "In July 1995, a heat wave killed more than 700 people in the Chicago area alone." If this is happening already from heat, imagine what would occur in the future with global warming. Hot conditions could also cause smoke particles and noxious gases to linger in the air and accelerate chemical reactions that generate other pollutants. This leads to an increase in risk of respiratory diseases like bronchitis and asthma.
Global warming causes the oceans to warm and expand, inducing a rise in sea level. Eventually, the rising waters could take away land inhabited by people, forcing them to move. Dr. Robert Buddemieir, of the Kansas Geological Survey said, "Bangladesh is massively populated, achingly poor, and something like a sixth of the country is going to go away". Bangladesh cannot afford to build barriers to hold back the sea, so people would have to move inland, increasing the populations density and leading to an increase in hunger and disease. The Maldive Islands in the Indian Ocean have the same problem They are a nation of 1190 islands with an average height of about 1.5 meters above sea level. If the sea level rises, more than 200,000 people will have to abandon their homes. Warming of the oceans could also promote toxic algae which can lead to cholera.
NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION
The National Oceanic and Atmospheric Administration (NOAA) is a scientific agency within the United States Department of Commerce focused on the conditions of the oceans and the atmosphere. NOAA warns of dangerous weather, charts seas and skies, guides the use and protection of ocean and coastal resources, and conducts research to improve understanding and stewardship of the environment. In addition to its civilian employees, NOAA research and operations are supported by 300 uniformed service members who make up the NOAA Corps. The Under Secretary of Commerce for Oceans and Atmosphere at the Department of Commerce, retired Navy Vice Admiral Conrad C. Lautenbacher, serves as the administrator for NOAA and will resign on October 31, 2008.
Contribution : NOAA efforts represent one of the most comprehensive campaigns in the world to understand the greenhouse effect and climate change. NOAA also focuses on monitoring, understanding, and predict in seasonal and inter annual climate changes, like El Nino, and on monitoring the global buildup of carbon dioxide and other trace gases in the atmosphere. NOAA's research includes:
- Developing coupled atmosphere-ocean models to better simulate global climate and predict its future evolution
- Continuously monitoring carbon dioxide and other greenhouse gases to determine trends necessary to identify climate change
- Conducting field and laboratory research on critical chemicals relevant to climate change
- Estimating ocean-atmosphere fluxes of crucial chemicals
- Managing the U.S. Program Office for the Tropical Ocean Global Atmosphere (TOGA) program and studying how the interaction between the atmosphere and ocean influences inter annual climate variability.
NOAA has implemented a comprehensive approach to climate issues in its Climate and Global Change Program. NOAA seeks to establish anew national information service based on the achievement of reliable assessments and quantitative predictions of changing global climate. This program organizes activities to monitor climate, conduct climate process studies, predict future climate, and provide climate information services as the NOAA contribution to the U.S. Global Change Research Program.
The greenhouse effect is changing the climate of the Earth. Rapidly rising levels of greenhouse gases due to the burning of coal, gas and oil are one the contributing causes of global warming.
Unless we reduce greenhouse gas emissions, we can expect the effects of global warming to have catastrophic consequences for wildlife around the world.
From plankton to penguins to polar bears, the greenhouse effect is harming our animals by forever changing their natural habitats. A recent sobering study says that scientists are now predicting that a quarter of the world's animal and plant life would face extinction by 2050 due to climate change.
In the Arctic, global warming is already responsible for the loss of sea ice, which scientists believe to be affecting the health of polar bears and reducing their population. The polar bears' hunting season is being cut short due to warmer temperatures, melting their sea-ice hunting ground at a faster rate. As a result, polar bears now have less food to eat and to raise their young. It is doubtful that polar bears could ever survive if there is a complete loss of the Arctic's summer sea-ice cover, according to the International Arctic Science Committee.
In Antarctica, the Adelie penguin's numbers have also diminished because of rising temperatures and loss of sea ice. The delicate domino effect is played out in this way: Melting sea ice reduces the amount of algae... If the algae doesn't thrive neither does the krill shrimp, which feeds on the algae, and neither does the Adelie penguins since the krill shrimp is their primary food source.
Whales, caribou, trout, coral reefs, monarch butterflies, the artic fox and songbirds are just some of the species in danger from the effects of greenhouse gases. And if our wildlife is threatened by global warming, then it goes to reason that so are we.
Thankfully, there are simple things that we can do right now to reduce the effects of global warming and help save our wildlife.