An international science conference has been told that the severity of global warming has been seriously underestimated.
Professor Chris Field, an author of a 2007 landmark report on climate change, said future temperatures "will be beyond anything" predicted.
Speaking to fellow scientists at a conference in Chicago Professor Field said scientists seriously underestimated the reality of global warming when it published the report.
The report didn't have access to data on emissions of carbon dioxide between 2000 and 2007 which show far more rapid rises than had been predicted.
Professor Field says that a warming planet will dry out forests in tropical areas making them much more likely to suffer from wildfires.
The rising temperatures could also speed up the melting of the permafrost, vastly increasing the amount of carbon in the atmosphere.