Warm Atlantic waters wage a new assault on Arctic ice from below 
 
 A new enemy is undermining ice floating on the Arctic Ocean: heat from below. “Water pathways are changing, the ecology is changing, all driven by the declining sea ice field.” 
 
 This article is reproduced with permission from Climate Central. The ocean has become gradually less stratified since the 1970s. Warm Atlantic waters, delivered by an offshoot of the Gulf Stream, have long been known to prevent ice formation north of Scandinavia, on the western side of the Eurasian basin. But over the last decade, ice has also begun to disappear here, too. In winter from 2013-2015, the cap separating the deep water and surface water disappeared completely in some locations, allowing the warm Atlantic waters to reach the surface and cut further into sea ice pack. Underneath it sits a pool of warm, salty Atlantic water that until recently hasn’t been able to find a way to surface. The currents lurked at a depth of about 150 meters, but they didn’t mix much with surface layers, because of a barrier called the cold halocline layer (CHL)—a boundary between salty deep waters and fresher water on top. “2015 was a really anomalous year when we had problems finding a suitable ice flow to launch our drifting buoys,”Igor Polyakov, an oceanographer at the University of Alaska who led the new study, said. “The new data show this layer has disappeared in winter.” 
 
 The result, he says, is an increased “Atlantification” of the Arctic, where the eastern side of the Eurasian basin is becoming more like the western side, the team reports today in Science . Polyakov says a positive feedback loop is underway, in which less summer sea ice will lead to warmer winter waters and even less summer ice in subsequent years. One unknown is how the addition of massive flows of freshwater from Siberian rivers, bolstered by thawing permafrost, could affect the system, says study co-author Eddy Carmack, an oceanographer with Fisheries and Oceans Canada in Sidney.
– The "Atlantification" of the Arctic Ocean is underway. And no, that doesn't mean we're about to get the polar bear version of Outkast, but rather that the Arctic Ocean is rapidly becoming more like the Atlantic Ocean, according to new research published Thursday. The Arctic Ocean has historically been separated into two layers: a cold, less salty layer on top with a salty, warmer layer of Atlantic water underneath, Scientific American reports. The barrier between the two is called the cold halocline layer, and it's been responsible for preserving Arctic sea ice, according to Science. But the separation between the layers has been quickly breaking down over the past decade or so. The temperature difference between the two layers has lessened by 2 degrees since 2002, and the top layer of cold water has gotten thinner in the past decade—possibly by as much as 180 feet. From 2013 to 2015, the layers merged completely in some areas. The loss of the cold halocline layer means sea ice in the Arctic is getting attacked from both sides. Warming air and warming surface ocean temperatures are creating a "positive feedback loop" that is decimating the ice. Sea ice in the Arctic is decreasing by 13% every decade, and soon the Arctic Ocean could be entirely ice-free during the summer. Between warmer water with more nutrients and no more ice to block the sun, it's unclear what will happen to the Arctic's ecosystem, Inverse reports. (One woman's desperation advanced Arctic exploration.)