as Record-Breaking Temperatures Reach the North Pole

Scientists interviewed for this story say that the Arctic warming event, technically known as a warm air intrusion, may be a common feature of the Arctic climate, as comparatively mild and moist air from the mid-latitudes is transported north by storm systems. However, this event was not like the others, researchers said.

mashable.com: Arctic warm event stuns scientists, as record warmth reaches North Pole