"Warming of the climate system is unequivocal as it is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global sea level," said a representative from the IPCC at the report's launch today in Paris.
The last IPCC report, issued in 2001, predicted that temperatures would rise between 1.4°C and 5.8°C by 2100, relative to 1990 temperatures. But the new report says temperature rises by 2100 could, in the most extreme scenarios, range from 1.1°C to 6.4°C. The most likely range is between 1.8°C and 4.0°C with the report predicting that 4°C is most likely if the world continues to burn fossil-fuels at the same rate.
In 2001, the IPCC predicted that sea levels would rise by between 9 and 88 centimetres by 2100, relative to 1990 levels. The new report says rises could range from 18cm to 59cm.
The fact that sea level projections have been revised down are the reports most controversial findings. A recent report from Stefan Rahmstorf, a lead author of the paleoclimate section of the upcoming report, found that rises of up to 140cm are possible. Such a rise would devastate cities such as London and New York and cause devastation to Bangladesh and other low lying countries.
Politically the most important announcement the IPCC made today was to revise its stance on the causes of climate change. In its 2001 report, the IPCC claimed that “on balance” the causes of climate change were human. In this report that has been changed to " a very high confidence" meaning a "9 out of 10 chance" that climate change is man made.
This leaves no room for denial or inaction. Business, governments and people who do not act do so in the knowledge that they condemn future generations to death and poverty.
This article first appeared in the Ecologist February 2007