The vanishing North

ORIGINAL: The Economist

There are benefits in the melting of the Arctic, but the risks are much greater

Jun 16th 2012

NOW that summer is here, the Arctic is crowded with life. Phytoplankton are blooming in its chilly seas. Fish, birds and whales are gorging on them. Millions of migratory geese are in their northern breeding grounds. And the area is teeming with scientists, performing a new Arctic ritual.

Between now and early September, when the polar pack ice shrivels to its summer minimum, they will pore over the daily sea ice reports of America’s National Snow and Ice Data Centre (NSIDC). Its satellite data will show that the ice has shrunk far below the long-term average. This is no anomaly: since the 1970s the sea ice has retreated by around 12% each decade. Last year the summer minimum was 4.33m square km (1.67m square miles)—almost half the average for the 1960s.

Graph: NSIDC

The Arctic’s glaciers, including those of Greenland’s vast ice cap, are retreating. The land is thawing: the area covered by snow in June is roughly a fifth less than in the 1960s. The permafrost is shrinking. Alien plants, birds, fish and animals are creeping north: Atlantic mackerel, haddock and cod are coming up in Arctic nets. Some Arctic species will probably die out.

Perhaps not since the 19th-century clearance of America’s forests has the world seen such a spectacular environmental change. It is a stunning illustration of global warming, the cause of the melt. It also contains grave warnings of its dangers. The world would be mad to ignore them.

As our special report shows in detail, the Arctic is warming roughly twice as fast as the rest of the planet. Since the 1950s the lower atmosphere has warmed by a global average of 0.7 degrees Celsius; Greenland’s air has warmed by 1.5 degrees. The main reason appears to be a catalytic warming effect, triggered by global warming. When snow or ice melt, they are replaced by darker melt-water pools, land or sea. As a result, the Arctic surface absorbs more solar heat. This causes local warming, therefore more melting, which causes more warming, and so on. This positive feedback shows how even a small change to the Earth’s systems can trigger much greater ones.

Photo: NSIDC