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Could geoengineering 'ice arches' help preserve Arctic sea ice?
In 2011, Malcolm Davidson of the European Space Agency was flying over the Nares Strait, a channel between Greenland and Canada’s northernmost island, Ellesmere, to check the accuracy of satellite observations. He saw that broad, low-lying pieces of sea ice had jammed together to block the strait. Looking down from above, this jigsaw of ice floes looked like an arch curving across the channel. North of the arch, sea ice was backed up into the frozen Arctic Ocean. South of it, the sea was mostly free of ice. Such “ice arches” typically form at the northern and southern ends of the strait in winter. When they break up in spring or summer, they allow sea ice to flush out of the Arctic “like a toilet,” says Davidson. In the past two decades, the arches haven’t been lasting as long, and in three of the years they didn’t form at all. As a result, an estimated 95,000 square kilometres of ice on average now flows through the strait to melt every year. But each ice arch is only about 20 to 50 kilometres wide. Somehow strengthening one could preserve more sea ice and reflect more sunlight away from Earth, thought Davidson...