Reuters posts this article that the Arctic summer sea ice could vanish within five years! Prior estimates recently suggested 10-20 years, but like most warming and ice melting feedback loops, it's happening faster than expected.

"Some of this is unstoppable. We're in a train of events at the moment where there are changes taking place that we are unable to reverse, the loss of these ice shelves, for example," he said.

"But what we can do is slow down this process and we have to slow down this process because we need to buy more time. We simply don't have the technologies as a civilization to deal with this level of instability that is ahead of us."

Disappearance of the Arctic summer sea ice will greatly accelerate melting of Arctic permafrost, and bodes ill for the 1000 gigatons of carbon frozen as organic material. Upon warming, this organic carbon will escape as methane and further accelerate warming.