Earth will warm 3 degrees by 2050, says leaked report
Global temperatures will rise by 2-4.5 degrees centigrade over the next 44 years, according to a draft report by the Intergovernmental Panel on Climate Change leaked by the US government this week.The mid-range estimate of a 3-degree increase would most likely cause drought, famine and mass extinction, according to an earlier report by the UK's chief scientific adviser Sir David King.
Positive feedback effects, such as the melting of ice increasing the amount of solar radiation absorbed by an ever-darker earth, push the estimate up to 6 degrees, climate experts say in the draft IPCC report.
This compares with previous estimates of 1.4-5.8 degrees over the next 100 years made by the traditionally conservative IPCC in its latest reprot in 2001.
The draft that emerged this week deals with the physical causes of climate change and will feed into the IPCC's Fourth Assessment Report, to be completed by 2007.
It was made public by a US government committee, which justified the action by saying it wanted as many people to be able to give feedback as possible.
The draft also contains stronger language than previous IPCC statements on the causes of climate change.
"There is widespread evidence of anthropogenic warming of the climate system in temperature observations taken at the surface, in the free atmosphere and in the oceans," it says.
"It is very likely that greenhouse gas forcing has been the dominant cause of the observed global warming over the past 50 years."
"2005 and 1998 were the warmest two years on record. Five of the six warmest years have occurred in the past five years (2001-2005)," the report reads.
The IPCC took pains to point out that the leaked report is only a draft and that its contents cannot be considered "findings" of the IPCC before they are seen and approved by experts and governments:
"Since the IPCC is an intergovernmental body, IPCC Reports are reviewed by governments as well as experts. Comments received from both are taken into account by lead authors when preparing revised drafts," the IPCC said in a statement.