When marine biologist Mads Peter Heide-Jørgensen began studying the boreal waters that surround Greenland 40 years ago, an inflatable raft carried him through vast expanses of polar pack ice, with narwhals and walruses frequently passing by. The astounding blue sea ice seemed almost inviolable in its grandeur.
But with Greenland reaching its highest temperatures in the past 1,000 years, the scene is changing. Arctic sea ice, which is responsible for maintaining cool polar temperatures, is dwindling rapidly. The oldest and thickest of it has declined by 95 percent during three decades of global warming.
