Parts of Antarctica have been 40°C warmer than their March average

The concordia research station is one of the most inhospitable places on Earth. At 3,000m above sea level on the Antarctic Plateau, the temperature rarely rises above -25°C even in the summer. In midwinter it can fall to around -80°C. The air is painfully dry, and fingers, toes and noses can freeze in minutes. The dozen or so crew, mainly French and Italian, who live and work in the station would normally venture out only for essential work. But Concordia, where winter is approaching, has recently experienced a heatwave. On March 18th the temperature reached a high of -11.8°C—more than 40°C warmer than the average for this time of year. The air was so mild that the station’s research doctor went for a jog.

Similarly freakish weather was recorded across eastern Antarctica. Temperatures at the Russian-run Vostok research station rose to -17.7°C, more than 15°C above the previous record for March, set in 1967. Across the continent temperatures were 4.5°C higher than usual (though in recent days they have returned to a normal range).

Meteorologists have attributed the latest heatwave to an atmospheric “river” of warm, damp air blowing towards Antarctica from the Southern Ocean near Australia. It is difficult to know whether climate change is to blame for one-off weather events. But over the past 65 years or so there has been an increase in the number of “high temperature” days at Antarctic stations.

Most regions of Antarctica have been spared global warming. In the late 20th century a large hole opened up in the ozone layer above the South Pole. This has a regional cooling effect, which has offset much of the heating caused by rising concentrations of greenhouse gases in the atmosphere. Temperatures on the continent rarely clamber above freezing, which preserves its vast ice sheets (although rising sea temperatures do threaten some areas). Even in the recent surge, temperatures stayed well below zero.

But a heatwave at the opposite pole may pose a bigger problem. Last week some Arctic stations were 30°C hotter than the season’s average between 1979 and 2000. In polar regions near Russia the mercury was pushed above freezing, at what should be one of the coldest months of the year. In Svalbard, an archipelago north of mainland Norway, the temperature hit a record 3.9°C.

The most recent data show that the Arctic is now warming three to four times faster than the global average. Heatwaves are becoming more common and—as more ice melts during the summer and less forms in the winter—Arctic sea ice is in rapid retreat. This matters for regions south of the Arctic circle as well. Shrinking ice caps further accelerate warming because white ice reflects heat from the sun, whereas dark patches of open water absorb it. Ocean currents are being disrupted, which changes weather patterns across Europe and North America. What happens in the Arctic does not always stay in the Arctic. ■

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