Researchers warned Saturday that the global warming situation is much worse that previously anticipated. Carbon dioxide and other gases added to the air by industrial and other activities have been blamed for rising temperatures, increasing worries about possible major changes in weather and climate.

"The consequence of that is we are basically looking now at a future climate that is beyond anything that we've considered seriously," Chris Field, a member of the Intergovernmental Panel on Climate Change, or IPCC, told the American Association for the Advancement of Science meeting in Chicago. Fresh data has shown that greenhouse gas emissions have grown by an average of 3.5 percent a year from 2000 to 2007, Field told reporters.

That's "far more rapid than we expected" and more than three times the 0.9 growth rate in the 1990's, he said. Unexpectedly large amounts of carbon dioxide are being released into the atmosphere as the result of "feedback loops" that are speeding up natural processes.

Prominent among these, evidence indicates, is a cycle in which higher temperatures are beginning to melt the arctic permafrost, which could release hundreds of billions of tons of carbon and methane into the atmosphere, said several scientists on a panel at the meeting.

He said the increases in carbon dioxide have been caused, principally, by the burning of coal for electric power in India and China. He 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, Prof Field warns.