After More Than A Decade Studying "Last Ice Area" In Arctic, Scientists Find It's Going Fast [View all]

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st July, glaciologist Derek Mueller made his fourteenth annual quest to gather samples from Milne Fjord, a research station on the coastal margin of the “Last Ice Area”— a 400,000-square-mile region north of Greenland and the Canadian Arctic Archipelago. The facility sits about 500 miles from the North Pole, nestled between tremendous ice flows. The landscape is rich with harsh beauty: Melt ponds, underlined by glistening ice, rest between white hillocks. Contrasted against the vivid white ice and dark, churning sea, each pool glows with its own crystal-blue light.

Mueller’s work had focused on Milne Fjord’s only known epishelf lake — a microbially rich ecosystem that arises when an ice shelf creates a dam, allowing a thin layer of freshwater to float above seawater connected to the open ocean. As with the rest of the Arctic, they are threatened by climate change. But there was reason to hope for Milne Fjord: For years, scientists believed this area, home to the oldest and thickest ice in the northern hemisphere, would survive the worst effects of global warming. But as Mueller and his team approached their old testing grounds, they could tell something was amiss. Where there had once been fingers of turquoise, there was now only the vivid white of ice and the ghostly remnants of melt water. Milne Fjord’s epishelf lake had all but disappeared.

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There are myriad reasons why the Arctic is warming so quickly (a phenomenon scientists often refer to as Arctic amplification), but a leading culprit is sea ice melt. The Arctic’s sea ice, typically 3 to 15 feet thick, freezes during winter and melts each summer. The white, snow-covered sheets reflect roughly 85 percent of incoming solar radiation back out to space. The open ocean, on which the ice floats, is so dark that it absorbs 90 percent of it. As the region’s sea ice melts, solar absorption rates create a positive feedback loop: The warmer the ocean, the less ice. The less ice, the more heat is absorbed. The more heat, the warmer the ocean.

Even accounting for this cycle, most climate models predicted the Last Ice Area would remain relatively frozen, acting as a seasonal stronghold for ice-dependent animals. In the summer ice flows from continental ice shelves near Siberia tend to pile up in the area, forming frozen ridges more than 30 feet high. But it seems Milne Fjord’s thick ice isn’t enough to shield it from the current pace of warming. “The glaciers melting are bringing freshwater down, adding heat into the fjord and the epishelf lake,” Mueller said. “Having weaker ice in the fjord would mean that the glacier could advance faster, thin out faster, and break up faster. ”

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https://grist.org/science/last-ice-area-disappearing-arctic-lake-permafrost-thaw-science/