In January, the polar vortex broke down. This is a mass of air that normally rotates around the North Pole. It will often break down in late February or early March, which is what causes very cold arctic air to slide south and collide with warmer air beginning to move up from the south. This results in blizzards and northeasters in the US northeast and the Canadian maritimes. However, this year, it broke down earlier than ever before observed, which is why so much cold air has appeared further south than normal.
The result is that, while record low temperatures are being recorded in the mid-latitudes of the northern hemisphere, the arctic is experiencing record heat. This is not only causing frightening outgassing of methane, but also spectacular ice melt and glacial destabilization in Greenland. Should the Greenland glaciers slide into the ocean, the result will be a dramatic increase in sea levels worldwide, with an average increase of twenty feet.
This video shows the calving of a gigantic berg off the floating face of the Ilulisat glacier in Western Greenland, one of the largest calving events ever recorded.