Five hundred miles south of South America’s Cape Horn, a narrow strip of land and a smattering of islands form the tip of the Antarctic Peninsula, a forbidding realm of ice and permafrost best known as a popular penguin breeding ground. Recently, however, the southern continent’s northernmost reaches, currently basking in summer, have been in the news for something far more exotic than armies of large, flightless birds: 70-degree weather.
The Antarctic Peninsula is recovering from a heat wave that has redefined t-shirt weather on the world’s largest frozen landmass and raised alarm bells about its future. Weather stations near the northern tip of the peninsula and on neighboring islands recently logged temperatures in the mid-60s and even one near 70-degree reading. If confirmed, they will stand as new high temperature records for the continent.
Video: Antarctic penguin colonies in decline (Evening Standard)
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A mix of meteorological factors, from warm mountain winds to larger patterns in the ocean and atmosphere, are responsible for the balmy blast. But the bizarre weather is also consistent with a long-term trend. While summertime temperatures across the Antarctic Peninsula normally hover around freezing or rise just a few degrees above, the region has experienced dramatic warming in recent decades, making it easier for heat spells to veer into record-breaking territory. And with Earth’s climate continuing to warm as atmospheric carbon levels soar, any newly minted records probably won’t last long.
“I think it’s not at all surprising,” says Peter Neff, an Antarctic glaciologist at the University of Washington. “It’s part of the trend, and we’re going to see more of those warm events than cold events” in the future.
Attack of the warm air
The roots of the recent Antarctic heat wave can be traced hundreds of miles north.
Toward the beginning of February, a ridge of high pressure air migrated over South America’s southern tip, enveloping the region in warm weather. According to Xavier Fettweis, a polar climatologist at the University of Liège in Belgium, this happens several times a summer. Normally, the effects aren’t aren’t felt on the Antarctic Peninsula, which is protected from warm air incursions by the Southern Hemisphere westerlies, a belt of strong winds encircling the continent.
But in recent months, those westerlies have been in a weakened state around the South Pole, part of a recurring pattern known as the Antarctic Oscillation. This has helped warm air spill south in an “exceptional” manner, Fettweis says.