Global warming is "very likely" to have been caused by human activity, the most authoritative global scientific body studying climate change said in a report today.The likelihood that the phenomenon has been created by the burning of fossil fuels and other actions is greater than 90%, the Intergovernmental Panel on Climate Change (IPCC) concluded in its fourth report.
In 2001, the body - which brings together 2,500 scientists from more than 30 countries - said global warming was only "likely", or 66% probable, to have been caused by humans.
The study said global warming is an "unequivocal" fact and likely to continue for centuries, warning of a likely rise in world average temperatures of up to 4C.In comparison, the world is currently around 5C warmer than during the last ice age.
Environmental and science groups said the report meant the main arguments on global warming were now effectively over.
"This day marks the removal from the debate over whether human action has anything to do with climate change," Achim Steiner, the head of the UN environment programme, said.
Stephanie Tunmore, of Greenpeace, said. "If the last IPCC report was a wakeup call, this one is a screaming siren."
The 21-page summary (pdf)
of the findings, called Climate Change 2007: The Physical Science Basis, was formally agreed by the IPCC in Paris yesterday and released earlier today.