Abrupt melting of the permafrost layer is leading to erosion, landslides and craters in the Arctic landscape. As the permafrost melts, greenhouse gases are released into the environment. Current climate change forecasts may underestimate the emissions from permafrost because they only take into account gradual thawing of the ice layer. More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.