Permafrost across Alaska, Canada, Siberia, and other cold regions is thawing as the Arctic warms roughly four times faster than the global average. Frozen ground that held dead plants and animals for centuries is now decomposing and releasing methane and carbon dioxide. Scientists cited in this AP story say permafrost stores about three times the carbon currently in the atmosphere, and the region has shifted from a carbon sink to a net source of greenhouse gases. The article also covers the physical damage from thawing ground. Roads, homes, and pipelines that once sat on firm permafrost are now dealing with collapses and slumps, with researchers identifying tens of thousands of these features by satellite. Studies cited in the piece project permafrost emissions could add roughly 0.25 C of warming by 2100, on top of fossil fuel driven warming. That extra warming is not included in most global projections, which makes the permafrost feedback loop harder to ignore.
