The threat to climate change posed by thawing permafrost, which could release stocks of stored carbon, is greater than estimated, a group of scientists said on November 30.
By 2100, the amount of carbon released by permafrost loss could be "1.7-5.2 times larger than those reported," depending on how swiftly Earth's surface warms, they said. The impact on climate could be 2.5 times greater, as much of the gas will be methane, which is 25 times more efficient at trapping solar heat than carbon dioxide (CO2), they said.
Deforestation today accounts for up to 20 percent of total greenhouse-gas emissions that contribute to global warming.
The study, published in the British journal Nature, coincides with a 12-day UN conference on climate change, unfolding in Durban, South Africa. It touches on one of the biggest sources of concern, but also a major area of uncertainty, in climate science.
Permanently iced land covers around a quarter of the land in the northern hemisphere. In essence, it is a carbon store, holding in icy stasis the organic remains of plants and animals that died millions of years ago.