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What Is Global Warming?

|What is Global Warming? |
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|Global warming is the increase in the average temperature of the Earth's near-surface air and the oceans since the mid-twentieth 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 that anthropogenic greenhouse gases are responsible for most of the observed|
|temperature increase since the middle of the twentieth century, and that natural phenomena such as solar variation and volcanoes probably |
|had a small warming effect from pre-industrial times to 1950 and a small cooling effect afterward. These basic conclusions have been |
|endorsed by more than 40 scientific societies and academies of science, including all of the national academies of science of the major |
|industrialized countries. |
|Climate model projections summarized in the latest IPCC report indicate that global surface temperature will likely rise a further during |
|the twenty-first century. The uncertainty in this estimate arises from the use of models with differing climate sensitivity, and the use of|
|differing estimates of future greenhouse gas emissions. Some other uncertainties include how warming and related changes will vary from...