The earth's atmosphere is warming faster than expected and evidence is mounting that human activity is responsible, the United Nations Environment Programme said today.
The UN's Intergovernmental Panel on Climate Change (IPCC) now projects the earth's average surface temperature will rise 1.4 to 5.8 degrees Celsius between 1990 and 2100, higher than its 1995 estimate of a one to 3.5 degree rise.
"There's no doubt the earth's climate is changing," IPCC chairman Mr Robert Watson told a news conference in Shanghai.
"The decade of the 1990s was the hottest decade of the last century and the warming in this century is warmer than anything in the last 1,000 years in the Northern Hemisphere," he said.
Mr Watson said the IPCC's latest report on climate change released today showed the main reason behind the faster than expected temperature rise was a fall in sulphur dioxide emissions.
Greenhouse gases such as carbon dioxide tend to warm the earth's atmosphere whereas sulphur dioxide tends to cool it.
Reuters