The Intergovernmental Panel on Climate Change, an international body established by the U.N. in 1988, presented a summary of its latest assessment on climate change on Sept. 27. Here are the key findings:
- Global warming is "unequivocal," and since the 1950's it's "extremely likely" that human activities have been the dominant cause of the temperature rise.
- Concentrations of CO2 and other greenhouse gases in the atmosphere have increased to levels that are unprecedented in at least 800,000 years. The burning of fossil fuels is the main reason behind a 40 percent increase in C02 concentrations since the industrial revolution.
- Global temperatures are likely to rise by 0.3 to 4.8 degrees C, or 0.5-8.6 F, by the end of the century depending on how much governments control carbon emissions.
- Most aspects of climate change will continue for many centuries even if CO2 emissions are stopped.
- Sea levels are expected to rise a further 10-32 inches (26-82 centimeters) by the end of the century.
- The Greenland and Antarctic ice sheets have been losing mass over the past two decades. Glaciers have continued to melt almost all over the world. Arctic sea ice has shrunk and spring snow cover has continued to decrease, and it is "very likely" that this will continue.
- It's "virtually certain" that the upper ocean has warmed from 1971 to 2010. The ocean will continue to warm this century, with heat penetrating from the surface to the deep ocean.