"Climate warming is degrading permafrost, and roads, runways and building foundations in many parts of the North have been buckling and cracking as the top layer of the ground thaws. The increasingly mushy ground also has created "drunken forests," where trees now lean at strange angles.

At least 30 per cent of all the carbon stored in soils worldwide is found in the North -- and scientists worry rising temperatures will release carbon dioxide and methane, both potent greenhouse gases, now locked in the permafrost.

"To me, probably the biggest uncertainty is whether methane emissions are going to go up, and if they are, by how much," says Lawrence.

Last summer, the Arctic sea ice shrank to more than 30 per cent below average, setting a modern-day record. Temperatures over land in the western Arctic also were unusually warm, reaching more than 2 C above the 1978-2006 average and raising questions about whether the ice retreat was tied to the warming temperatures over land."