Permafrost more vulnerable than thought: scientists

Frozen, sub-Arctic wastelands loaded with planet-heating greenhouse gases are more susceptible to global warming than previously understood, scientists warned on Monday.Sometimes called a climate change time bomb, the northern hemisphere's 15 million square kilometres (six million square miles) of increasingly misnamed permafrost contains roughly twice as much carbon -- mainly in the form of methane and carbon dioxide (CO2) -- as Earth's atmosphere."We estimate that four million square kilometre