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 Center. Its satellite data will show 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 per cent each decade. Last year the summer minimum was 1.67 million square miles, almost half the average for the 1960s.
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 -- and some Arctic species probably will 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.
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, but 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 meltwater pools on 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.
Some scientists also see a tipping-point, another feared term in the climatology lexicon, in the accelerating diminution of the sea ice. The term describes the moment at which the planet shifts from one environmental state to another -- in this case, from an Arctic with summer sea ice to one without it. By the end of this century, perhaps much sooner, there will probably be frequent summers with no sea ice at all.
Arctic peoples have also noticed what is going on. Inuit hunters are finding the sea ice too thin to bear their sleds. Arctic governments are starting to see a bonanza in the melt. The Arctic is stocked with minerals hitherto largely inaccessible, including an estimated 30 per cent of undiscovered reserves of natural gas and 13 per cent of undiscovered oil reserves. A combination of high commodity prices, proactive governments, technological progress and melting ice will help bring these to market.
Encouraged by Arctic governments and dwindling reserves elsewhere, oil companies are flocking north like migrating geese to explore the continental shelves of Alaska, Canada, Greenland, Norway and Russia.
Canada and Russia also hope to develop their Arctic shipping lanes, which the melt is making accessible. Russia's Northern Sea Route, hugging the Siberian coast, cuts the normal distance between Europe and Asia by more than a third. It will help ferry Russia's Arctic resources to Asian markets, and could one day be a wider boost to world trade.
These exciting developments carry risks, however. Many fear for Arctic cultures -- a Canadian Inuit argues despairingly for her "right to be cold." Others foresee conflict between Arctic countries scrambling for the region's resources. Greens warn of environmental risks in developing them: A big oil spill would be disastrous for fragile Arctic ecosystems.
Such fears are reasonable, but often exaggerated. Traditional Arctic peoples have been changed far more by Westernization than they will be by melting ice. No one lives in igloos these days, and everywhere except Russia their rights have been recognized.
Nor is conflict much of a worry. The Arctic is no terra nullius. Most of it is demarcated, and Arctic countries have a commercial incentive to keep the peace. Last year Russia and Norway settled an old dispute over their maritime border, and soon they will open the border region to oil firms.
The risks of pollution from bilge water, mining effluent and spilled oil are real. Yet the Arctic is not unprotected: It is, by and large, among the most regulated oil provinces. Its development will also be slower and more cautious than greens fear. Even with little sea ice, the Arctic will remain forbiddingly cold, remote, stormy and therefore an expensive place in which to operate.
The worry that needs to be taken most seriously is climate change itself. The impact of the melting Arctic may have a calamitous effect on the planet. It is likely to disrupt oceanic circulation -- the mixing of warm tropical and cold polar waters, of which the Gulf Stream is a part -- and thawing permafrost will lead to the emission of masses of carbon dioxide and methane, thus further warming the planet.
It is also raising sea levels. The Greenland ice sheet has recently shed around 200 gigatons of ice a year, a four-fold increase on a decade ago. If the warming continues, it could eventually disintegrate, raising the sea level by seven meters. Many of the world's biggest cities would be inundated long before that happened.
Some scientists argue the perils are so immediate mankind should consider geoengineering the atmosphere to avert them. They may turn out to be right, but there could be enormous risks involved.
A slower but safer approach would be to price greenhouse-gas emissions, preferably through a carbon tax, which would encourage the adoption of cleaner technologies. That shift would be costly, but the costs of inaction are likely to be larger.
In the end the world is likely to get a grip on global warming. The survival instinct demands it. But it is likely to lose much of the unique Arctic first. That would be a terrible pity.