FACTBOX-U.N. climate panel report
Source: Reuters
Feb 2 (Reuters) - Following are details of a report by the U.N. climate panel on Friday. The Intergovernmental Panel on Climate Change (IPCC) groups 2,500 researchers from more than 130 nations. The last IPCC report was in 2001. EVIDENCE OF HUMAN CAUSES - "Most of the observed increase in globally averaged temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic (human) greenhouse gas concentrations," it says. The IPCC says "very likely" means at least a 90 percent probability. - "The level of confidence that humans are causing global warming has increased a lot," lead author of the report Peter Stott told Reuters. TEMPERATURE RISES - It is "very likely" that extremes such as heatwaves and heavy rains will become more frequent. - The range of possible temperature increases this century has increased to 1.1 to 6.4 degrees Celsius, with the top end up from the IPCC's past reports. - The projected temperature increase to 2100 has risen largely because it is expected that global warming will impair nature's ability to absorb carbon dioxide. This alone could raise estimates by more than 1 degree this century. - For the first time the IPCC gives "best estimates" for six scenarios, giving greater certainty than predictions in earlier reports. The best estimate range is for a 1.8 to 4.0 degrees temperature rise by 2100. - The scenarios assume different levels of economic and population growth and of fossil fuels versus clean energy use. No scenarios include implementation of additional climate policies, such as the Kyoto Protocol. - Only one of the scenarios generated a best estimate of less than 2 degrees warming this century (1.8 degrees). - "For the first time we have a best estimate of what we can achieve if we keep emissions levels lower," report Chair Susan Solomon told Reuters. - The report does not include possible warming from methane, a potent greenhouse gas, escaping from melting permafrost. - Warming is expected to be greatest over land and at high northern latitudes, and least over the Southern Ocean and North Atlantic. SEA LEVEL RISES - The report cites six models with core projections of sea level rises ranging from 18 to 59 cm this century. That is a narrower and lower band than the 9 to 88 cm gain (3.5-34.6 inches) forecast in 2001 - If the Greenland ice sheet melts proportionally to the temperature rises, then sea levels would rise by up to 79 cm, not 59 cm, this century. - Some models show an ice-free Arctic in summer by 2100, meaning that sea ice floating in the water disappears, but not ice resting on Greenland. - If the Greenland ice sheet melted completely that would lead to a 7 metre sea level rise CHANGING OCEAN CURRENTS - The report predicts a gradual slow-down this century in ocean currents such as the one which carries warm water to north-west Europe. - "It's very unlikely there will be an abrupt breakdown in ocean currents in the 21st century," Jurgen Willebrand, the report's author with special expertise in ocean effects, told Reuters. HURRICANES - The report says it is "more likely than not" that a trend of increasing intense tropical cyclones and hurricanes has a human cause. - It expects such tropical cyclones to become more intense in the future. - "There may not be an increase in number, there may be a re-distribution to more intense events -- which is what has been observed in the Atlantic since 1970," lead author Stott said.
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