Share In Canada's North, landscapes such as caribou habitat found in Yukon's Tombstone Territorial Park, seen here, are increasingly at risk of dramatic change as permafrost melts. Scientists are now researching what's known as the permafrost carbon feedback loop, in which melting permafrost releases greenhouse gases that further amplify climate change. Photo: Jimmy Thomson / The Narwhal In-Depth Fighting the feedback loop: why scientists are sounding the alarm on Canada’s melting permafrost Nearly half of Canada’s land mass lies above permafrost. As it thaws, greenhouse gases stored for centuries in the frozen ground are released and once-stable land is susceptible to collapse