Scientists warned that the massive amounts of greenhouse gases from thawing permafrost will accelerate and amplify global warming, according to a study in Wednesday's journal Nature.

Those heat-trapping gases under the frozen Arctic ground may be a bigger factor in global warming than deforestation, said the study based on a survey of 41 permafrost scientists from around the world.

Arctic warming of 7.5 degrees Celsius (13.5 degrees Fahrenheit) this century may unlock the equivalent of 380 billion tons of carbon dioxide as soils thaw, allowing carbon to escape as CO2 and methane.

Scientists predict that over the next three decades, a total of about 45 billion metric tons of carbon from methane and carbon dioxide will seep into the atmosphere when permafrost thaws during summers, which is about the same amount of heat-trapping gas the world spews in five years of burning coal, gas and other fossil fuels.

"Our survey outlines the additional risk to society caused by thawing of the frozen north, and underscores the urgent need to reduce atmospheric emissions from fossil-fuel use and deforestation," the scientists said. "This will help to keep permafrost carbon frozen in the ground."

"The survey provides an important warning that global climate warming is likely to be worse than expected," said Jay Zwally, a NASA polar scientist who was not part of the study. "Arctic permafrost has been like a wild card."

The study adds to pressure on United Nations climate treaty negotiators from more than 190 countries and regions now attending two weeks of talks in Durban, South Africa, beginning Nov. 28.