29 Nov 2012

Thaw in permafrost detected

6:03 am on 29 November 2012

A United Nations report says the world's permafrost is beginning to thaw, bringing with it the threat of a big increase in global warming by 2100.

Permafrost, which is a deep layer of frozen soil covering about a quarter of the northern hemisphere, is thought to contain twice the amount of carbon already in the atmosphere.

If organic matter trapped for thousands of years thaws and decays, it would potentially release large amounts of CO2 and methane into the atmosphere.