"This is just not something you can stop. We're just going to have to live with it," said Trenberth, the director of climate analysis for the National Center for Atmospheric Research in Boulder, Colo. "We're creating a different planet. If you were to come up back in 100 years time, we'll have a different climate."
The scientists said global warming was "very likely" caused by human activity, a phrase that translates to a more than 90 percent certainty that it is caused by man's burning of fossil fuels. That was the strongest conclusion to date, making it nearly impossible to say natural forces are to blame.
It also said no matter how much civilization slows or reduces its greenhouse gas emissions, global warming and sea level rise will continue on for centuries.
"Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global mean sea level," the scientists said.