On July 16, 2012 the Petermann Glacier in Greenland calved another gigantic island of ice, about twice the size of Manhattan in New York, or about 46 square miles. Climatologists armed with NASA satellite imagery have been following the glacier for many years, and first spotted the break-off point around 8 years ago. The Petermann Glacier calved a previous huge iceberg, twice this size, in 2010.
According to NASA average temperatures in northern Greenland and the Canadian Arctic have increased by about 4 degrees Fahrenheit in the last 30 years.
So, driven by climate change or not, regardless of whether it is short-term or long-term, temporary or irreversible, man-made or a natural cycle, the trend is clear — the Arctic is warming, the ice cap is shrinking and sea-levels are rising.
STANDING ON THE Greenland ice cap, it is obvious why restless modern man so reveres wild places. Everywhere you look, ice draws the eye, squeezed and chiselled by a unique coincidence of forces. Gormenghastian ice ridges, silver and lapis blue, ice mounds and other frozen contortions are minutely observable in the clear Arctic air. The great glaciers impose order on the icy sprawl, flowing down to a semi-frozen sea.
The ice cap is still, frozen in perturbation. There is not a breath of wind, no engine’s sound, no bird’s cry, no hubbub at all. Instead of noise, there is its absence. You feel it as a pressure behind the temples and, if you listen hard, as a phantom roar. For generations of frosty-whiskered European explorers, and still today, the ice sheet is synonymous with the power of nature.
The Arctic is one of the world’s least explored and last wild places. Even the names of its seas and rivers are unfamiliar, though many are vast. Siberia’s Yenisey and Lena each carries more water to the sea than the Mississippi or the Nile. Greenland, the world’s biggest island, is six times the size of Germany. Yet it has a population of just 57,000, mostly Inuit scattered in tiny coastal settlements. In the whole of the Arctic—roughly defined as the Arctic Circle and a narrow margin to the south (see map)—there are barely 4m people, around half of whom live in a few cheerless post-Soviet cities such as Murmansk and Magadan. In most of the rest, including much of Siberia, northern Alaska, northern Canada, Greenland and northern Scandinavia, there is hardly anyone. Yet the region is anything but inviolate.
A heat map of the world, colour-coded for temperature change, shows the Arctic in sizzling maroon. Since 1951 it has warmed roughly twice as much as the global average. In that period the temperature in Greenland has gone up by 1.5°C, compared with around 0.7°C globally. This disparity is expected to continue. A 2°C increase in global temperatures—which appears inevitable as greenhouse-gas emissions soar—would mean Arctic warming of 3-6°C.
Almost all Arctic glaciers have receded. The area of Arctic land covered by snow in early summer has shrunk by almost a fifth since 1966. But it is the Arctic Ocean that is most changed. In the 1970s, 80s and 90s the minimum extent of polar pack ice fell by around 8% per decade. Then, in 2007, the sea ice crashed, melting to a summer minimum of 4.3m sq km (1.7m square miles), close to half the average for the 1960s and 24% below the previous minimum, set in 2005. This left the north-west passage, a sea lane through Canada’s 36,000-island Arctic Archipelago, ice-free for the first time in memory.
Scientists, scrambling to explain this, found that in 2007 every natural variation, including warm weather, clear skies and warm currents, had lined up to reinforce the seasonal melt. But last year there was no such remarkable coincidence: it was as normal as the Arctic gets these days. And the sea ice still shrank to almost the same extent.
There is no serious doubt about the basic cause of the warming. It is, in the Arctic as everywhere, the result of an increase in heat-trapping atmospheric gases, mainly carbon dioxide released when fossil fuels are burned. Because the atmosphere is shedding less solar heat, it is warming—a physical effect predicted back in 1896 by Svante Arrhenius, a Swedish scientist. But why is the Arctic warming faster than other places?
Consider, first, how very sensitive to temperature change the Arctic is because of where it is. In both hemispheres the climate system shifts heat from the steamy equator to the frozen pole. But in the north the exchange is much more efficient. This is partly because of the lofty mountain ranges of Europe, Asia and America that help mix warm and cold fronts, much as boulders churn water in a stream. Antarctica, surrounded by the vast southern seas, is subject to much less atmospheric mixing.
The land masses that encircle the Arctic also prevent the polar oceans revolving around it as they do around Antarctica. Instead they surge, north-south, between the Arctic land masses in a gigantic exchange of cold and warm water: the Pacific pours through the Bering Strait, between Siberia and Alaska, and the Atlantic through the Fram Strait, between Greenland and Norway’s Svalbard archipelago.
That keeps the average annual temperature for the high Arctic (the northernmost fringes of land and the sea beyond) at a relatively sultry -15°C; much of the rest is close to melting-point for much of the year. Even modest warming can therefore have a dramatic effect on the region’s ecosystems. The Antarctic is also warming, but with an average annual temperature of -57°C it will take more than a few hot summers for this to become obvious.