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Planet Ark World Environment News Factbox: Governments meet on climate after scientists' warnings

Date: 07-Nov-13
Country: POLAND
Author: Alister Doyle

Almost 200 nations will meet in Warsaw from November 11-22 to work on a deal due to be agreed in 2015 to fight climate change.

Following are the main findings of a report in September by leading scientists - the U.N.'s Intergovernmental Panel on Climate Change (IPCC) - that are meant to guide the talks:

HUMAN RESPONSIBILITY - The panel raised the probability that human activities, led by the burning of fossil fuels, are the dominant cause of global warming since the mid-20th century to "extremely likely", or at least 95 percent, from "very likely" (90 percent) in its previous report in 2007 and "likely" (66 percent) in 2001.

SLOWING WARMING THIS CENTURY - The panel said that a slowing in the pace of warming at the Earth's surface this century was probably linked to natural swings in the climate. It said short periods, such as the 15 years since 1998 which was a very warm year, do not usually reflect long-term trends.

PROJECTED WARMING - The panel said temperatures were likely to rise by between 0.3 and 4.8 degrees Celsius (0.5 to 8.6 Fahrenheit) by the late 21st century. The report uses new computer models that are not directly comparable with scenarios used in 2007.

CARBON BUDGET - The report said cumulative carbon emissions needed to be limited to about 1 trillion tonnes to give a likely chance of limiting global warming to 2 degrees Celsius (3.6F) above pre-industrial times. More than 50 percent has already been emitted.

SEA LEVEL RISE - Sea levels are likely to rise by between 26 and 82 cm (10 to 32 inches) by the late 21st century, after a 19 cm rise in the 19th century. In the worst case, seas could be 98 cm higher in the year 2100. The 2001 report projected a rise of 18 to 59 cm, but did not take full account of the potential thaw of Antarctica and Greenland.

CLIMATE SENSITIVITY - The report estimates that a doubling of carbon dioxide concentrations in the atmosphere would lead to a warming of between 1.5 and 4.5 degrees Celsius (2.7 and 8.1F), lowering the bottom of the range from 2.0 degrees (3.6F) estimated in 2007 report. The new range, however, is the same as in other IPCC reports before 2007.

(Reporting By Alister Doyle)

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