Popular Science: With so much focus on sea ice and ice shelves, the role of permafrost in the global climate cycle is often not on the public’s radar screen. But according to a new study published last week in the journal Bioscience, permafrost in the Northern Hemisphere contains more than two times the amount of carbon in the atmosphere, and rapid thawing could make it a significant contributor to global climate change. Permafrost is defined as permanently frozen ground that remains at or below zero …