Arctic permafrost thaw a climate threat

The permafrost in the Arctic, which has one of the largest natural reserves of organic carbon in the world in its soils, is thawing and diminishing.

So what's the problem? When permafrost (or frozen dirt) melts, soil microbes trapped in it become active again and eat their way through the available organic material (or carbon), turning it into carbon dioxide and methane. These greenhouse gases then enter into the atmosphere and intensify global warming.

In other words, thawing softens permafrost, and turns ice into water causing the surface area to collapse, or subside. The resultant sinkhole then turns into a lake - a thermokarst lake - that in turn hastens the overall melting process. Indeed, a vicious circle.