5.7 Summary of Section 5
The Arctic climate is strongly seasonal, and many processes such as river flow virtually stop in winter. However, the region is warming and this is affecting many aspects of the local and global environment. The area of the Greenland ice cap that is melting is increasing, and the melt water is contributing to global sea-level rise. The amount of sea ice in summer is consistently decreasing due to increasing temperatures amplified by the positive ice–albedo feedback loop. A summer ice-free Arctic is almost certain, and the only question is how soon it will be. The permafrost is in all probability retreating in extent, causing problems both for humans and for the natural environment. An additional consequence is that the permafrost is releasing methane which, through a positive feedback mechanism, may further amplify the greenhouse effect.