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FACTBOX - UN Climate Panel to Blame Humans for Warming |
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| INTERNATIONAL: January 29, 2007 | ||
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Following are details of a draft report by the UN climate panel due for release in Paris on Feb. 2.
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The Intergovernmental Panel on Climate Change (IPCC) groups 2,500 researchers from more than 130 nations and is the most comprehensive overview of climate change for guiding policy-makers. The last IPCC report was in 2001. Scientists and government officials will meet to review and approve the draft in Paris next week. The following details were given by scientific sources on Thursday: - "It is very likely that anthropogenic (human) greenhouse gas increases caused most of the observed increase in globally averaged temperatures since the mid-20th century". The IPCC says "very likely" means at least a 90 percent probability. The 2001 report said it was "likely" that human activities were the dominant cause of warming in the last 50 years, or at least a 66 percent probability. - "Warming of the climate system is unequivocal, as is now evident from increases in global average air and ocean temperatures, melting of snow and ice, and rising sea levels." - It is likely that greenhouse gases would have caused more warming in recent decades but were partly offset by dust from volcanoes and pollution which reflects heat back into space.
- Temperatures are likely to rise by 2-4.5 Celsius (3.6-8.1 Fahrenheit) above pre-industrial levels if carbon dioxide concentrations are kept at 550 parts per million in the atmosphere, against about 380 now. The "best estimate" for the rise is about 3C (5.4F). - The warming is very unlikely to be less than 1.5C (2.7F). Rises much above 4.5C cannot be ruled out but those computer projections do not fit well with observations. Main uncertainties are whether more clouds will form in a warmer world -- and bounce heat back into space. - The report cites six models with core projections of sea level rises ranging from 28 to 43 cms (11.0-16.9 inches) by 2100. That is a narrower and lower band than the 9 to 88 cms gain (3.5-34.6 inches) forecast in 2001. - It is "very likely" that extremes such as heatwaves and heavy rains will become more frequent. Arctic sea ice could disappear in summer by the latter part of the 21st century in some projection. Warming is expected to be greatest over land and at high northern latitudes, and least over the Southern Ocean and North Atlantic. - Antarctica is likely to stay too cold for wide surface melting and is expected to gain in mass due to more snow. - A system of Atlantic currents including the Gulf Stream, bringing warm waters northwards, are very likely to slow by 2100 but an overall warming will more than offset any cooling effect. The draft says that an abrupt shift is "very unlikely".
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REUTERS NEWS SERVICE
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