 Close to the shore however, where the permafrost seal tapers to as little as , there are significant amounts of gas leakage.Sea ice, and the cold conditions it sustains, serves to stabilise methane deposits on and near the shoreline, preventing the clathrate breaking down and outgassing methane into the atmosphere, causing further warming.Melting of this ice may release large quantities of methane, a powerful greenhouse gas into the atmosphere, causing further warming in a strong positive feedback cycle.