Global Warming and the Greenhouse Effect
The greenhouse effect occurs when certain gasses in the atmosphere trap infrared radiation. This effect makes the planet warmer than it would be without a greenhouse effect.
The greenhouse effect is caused by greenhouse gasses; the most important greenhouse gasses in Earth's atmosphere are: water vapor, carbon dioxide, and methane.
Recently, the greenhouse effect has gotten stronger. Scientists believe this is because humans have been using large amounts of fossil fuels, which release carbon dioxide when they are burned. Since carbon dioxide is a greenhouse gas, it has caused the planet to warm over the past 150 years. Scientists believe that this greehouse effect is responsible for global warming.
The greenhouse effect was first discovered by Joseph Fourier in 1824. Mars, Venus and other planets with atmospheres also have greenhouse effects.
Global warming is a term having to do with the slow increase of the earth's temperature. Global warming may become a problem for the world and has already been linked to floods and other types of storms.
Today, the atmosphere of the world is about a half a degree Celsius warmer than it was two hundred years ago. Many people want to know why the earth's climate is changing. Most say that the changes are caused by people (by cars and factories, for example). Some say the change is not the fault of humans.
The average temperature at the surface of the Earth has gone up by 0.6 Celsius since the late 19th century. There are several theories (ways) which try to explain this increase. Some scientists think that the warming of the last 50 years is believed to be a result of increases in the greenhouse effect caused by human-generated carbon dioxide (CO2). Others think that variations in the amount of heat from the sun and other natural causes.
A "theory" in science is not just an idea. It is a proposed answer which has been tested and confirmed. Climate theories are hard to test because they usually depend on computer models, which are themselves theories. Today, most climatologists agree that the theory of anthropogenic global warming has survived challenges and testing against data from many sources. Anthropogenic global warming is a better "fit" to what is being observed in all the data than answers such as warming from the sun, or normal, periodic warming the Earth has experienced before. Those theories don't fit the data as well as does anthropogenic global warming.
Climate models show that temperatures will probably increase by 1.4°C - 5.8°C between 1990 and 2100. Much of the uncertainty in this increase results from not knowing future CO2 emissions, but there is also uncertainty about the accuracy of climate models. Climate commitment studies predict that even if levels of greenhouse gases and solar activity were to remain constant, the global temperature will increase by 0.5°C over the next one hundred years due to the lag in warming caused by the oceans.
Although the discussion of global warming often focuses on temperature, global warming or any climate change may cause changes in other things as well, including the sea level, precipitation, weather patterns, etc. These may affect human activity via floods, droughts, heat waves, changes to farm productivity, etc.
A recent UN report indicates livestock generate more greenhouse gases on a global scale than the entire transportation sector. A senior UN official and co-author of the report Henning Steinfeld said "Livestock are one of the most significant contributors to today's most serious environmental problems."
Coal-burning power plants, car exhausts, factory smokestacks, and other waste vents of the human environment give off about 23 billion tons of carbon dioxide and other greenhouse gases into the Earth's atmosphere each year. The atmospheric concentration of CO2 has increased by 31% above pre-industrial levels since 1750. This is quite higher than at any time during the last 420,000 years, the period for which reliable data has been extracted from ice cores. From less direct geological evidence, it is believed that CO2 values this high were last attained 40 million years ago. About three-quarters of the antropogenic emissions of CO2 to the atmosphere during the past 20 years are due to fossil fuel burning. The rest is predominantly due to land-use change, especially deforestation.
There may be other causes of global warming. A few scientists believe that atmospheric carbon dioxide is actually determined by global temperatures, and that increased solar (sun) activity has caused the temperature rise.
So, if the theory is correct, then it is possible to predict future climate, based on assumptions of future emissions. Climate models project a warming of 1.4°C to 5.8°C between 1990 and 2100.
The possible effects of global warming are frightening. The United Nations' Environmental Program recently announced that severe weather around the world has made 2005 the most costly year on record.
It would cost a lot of money to cut off human-caused greenhouse gases completely. And, that would not stop the warming that must come from the gases already in the atmosphere. Money spent now to reduce greenhouse gas increases could be significantly less money than the financial losses that will come later from climate warming. The sea level will rise, causing huge population movements from places like Bangladesh. There will be more rain, which will cause floods. Storms will be stronger, which will cause damage. There will be more diseases such as malaria and dengue fever, and it is possible that more people will die in disasters. It is also possible that winters will be colder in some climates. And, obviously, droughts will last longer and will be hotter in some areas.
Some scientists believe that if we don't take effort in reducing global warming in the next decade or two, we will lose our chance. This is because of a "tipping point." There is a point at which enough greenhouse gases have accumulated that humans cannot remove them from the atmosphere and the warming will proceed regardless of efforts to stop it. There is a "lag time" between the date on which a quantity of greenhouse gas is put into the atmosphere and a much later date when that quantity of gas causes warming. When humans begin to experience the very harmful consequences of warming, it may be too late to stop the warming--the tipping point will have been passed.
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Source: Wikipedia (All text is available under the terms of the Creative Commons Attribution-ShareAlike License)