Perma Frost is melting and we have a problem.

Alaska may sometimes look as cold as ever at a glance, but underground, it’s melting, and as it melts, it sinks.
Several feet underneath much of Alaska is a layer of soil known as the permafrost, which as the name implies, is permanently frozen throughout the year — or at least it used to be. Over the last fifty years, Alaska has warmed twice as fast as the lower 48 and ground temperatures have been steadily increasing since the 1970s. Some models predict that by mid-century one-third of Alaska’s permafrost will have thawed and that by 2100, two-thirds will be gone.


http://thinkprogress.org/climate/2013/10/09/2759181/alaska-permafrost-arctic-hudson-bay/