With more than half of all Arctic coastline along its northern shores, Russia has long sought economic and military dominance in part of the world where as much as $35 trillion worth of untapped oil and natural gas could be lurking. Now China is pushing its way into the Arctic, announcing last month its ambitions to develop a "Polar Silk Road" through the region as warming global temperatures open up new sea lanes and economic opportunities at the top of the world.

At play is between one-fifth and a quarter of the world's untapped fossil-fuel resources, not to mention a range of mineable minerals, including gold, silver, diamond, copper, titanium, graphite, uranium and other valuable rare earth elements. With the ice in retreat, those resources will come increasingly within reach.

At a December meeting of climate scientists in New Orleans, a team from the National Oceanic and Atmospheric Administration declared that the Arctic as we've known it is now a thing of the past. Coining a new phrase — the New Arctic — they described the uptick in ocean surface warming and decline in sea ice since 2000 as unprecedented in the past 1,500 years. The Arctic, they wrote, "shows no sign of returning to [the] reliably frozen region of past decades."