Permafrost collapse is speeding climate change: study

Permafrost in Canada, Alaska and Siberia is abruptly crumbling in ways that could release large stores of greenhouse gases more quickly than anticipated, researchers have warned.Scientists have long fretted that climate change -- which has heated Arctic and subarctic regions at double the global rate -- will release planet-warming CO2 and methane that has remained safely locked inside Earth's frozen landscapes for millennia.It was assumed this process would be gradual, leaving humanity time to d