National Geographic : 2016 Jan
Into Thin Ice 117 awoke to discover that the latest ice floe they’d attached to was disintegrating too. They scram- bled to salvage their gear before it became flot- sam. It was time to pack up anyway. The vessel by that point had spent 111 days in the ice, teth- ered to different floes for several weeks at a time—logging altogether some 4,000 nautical miles across the Arctic. Polar bears had crossed its path, sometimes pausing to play with the sci- entists’ strange-looking electronic instruments. Storms had bulldozed huge blocks of ice high against the ship, elevating it above the surface. The Lance’s crew had bested the researchers in a soccer match on the floe. Over the next couple of years the 68 scientists involved will be hun- kered in their warm labs, making sense of all the data they gathered. One morning in March, under a dusky blue sky, I had joined Gunnar Spreen and another NPI researcher, Anja Rösel, on one of their periodic forays to measure changes in the ice floe’s thickness. We each wore insulated armor—jumpsuit, balaclava, goggles, gloves, mittens over the gloves. The scientists brought along a snow-depth probe, a GPS device, and an orange plastic sled carrying the ice-thickness instrument, which works by inducing an elec- tric current in the seawater below. I carried a flare gun and a .30-06-caliber rifle: bear protec- tion. Following a mile-long path staked by bam- boo poles, we trudged over dunelike snowdrifts and pressure ridges—slabs of sea ice pushed up by colliding floes—that looked like crumbling stone walls. Every few feet Spreen stopped and plunged the depth gauge into the snowpack un- til it beeped to indicate that the measurement was complete. Arctic warming seemed an abstract concept that day—I couldn’t really feel my toes—but across the icescape, Spreen saw evidence of change. “This is an unusual amount of snow,” he noted. Two feet of it lay beneath our moon boots, twice the amount in a typical year. One data point doesn’t make a trend, but this one was consistent with model forecasts: As sea ice shrinks, the extra heat and water vapor released from the open water into the lower atmosphere should generate more precipitation. More snow falling on a glacier on land would be a good thing, because that’s how glaciers grow—by accumulating layers of snow so thick that the stuff at the bottom gets compressed into ice. But sea ice forms when cold air freezes seawater, and snow falling on top of it acts as an insulating blanket that slows the growth of the ice. As it happened, two weeks after my walk with Spreen, the National Snow and Ice Data Center in Colorado announced that Arctic sea ice had already reached its maximum extent for the winter in late February—much earlier than usual. It was the lowest maximum the satellites had ever recorded. j The drastic shrinking of Arctic sea ice led to big changes in the tenth edition of National Geographic’s Atlas of the World, published in 2015. The first edition of the atlas was published in 1963. In a fracture behind the Lance, water vapor meets chill air and freezes to “sea smoke.” As dark water replaces ice, the Arctic Ocean absorbs more heat in summer and releases more in fall and winter— perhaps affecting weather elsewhere.