Shifts in wind, ozone hole affect Antarctic
WASHINGTON – The ice goes on seemingly forever in a white pancake-flat landscape, stretching farther than ever before. And yet in this confounding region of the world, that spreading ice may be a cockeyed signal of man-made climate change, scientists say.
This is Antarctica, the polar opposite of the Arctic.
While the North Pole has been losing sea ice over the years, the water nearest the South Pole has been gaining it. Antarctic sea ice hit a record 7.51 million square miles in September. That happened just days after reports of the biggest loss of Arctic sea ice on record.
Climate change skeptics have seized on the Antarctic ice to argue that the globe isn’t warming and that scientists are ignoring the southern continent because it’s not convenient. But scientists say the skeptics are misinterpreting what’s happening and why.
Shifts in wind patterns and the giant ozone hole over the Antarctic this time of year – both related to human activity – are probably behind the increase in ice, experts say. This subtle growth in winter sea ice since scientists began measuring it in 1979 was initially surprising, they say, but makes sense the more it is studied.
“A warming world can have complex and sometimes surprising consequences,” researcher Ted Maksym said this week from an Australian research vessel surrounded by Antarctic sea ice. He is with the Woods Hole Oceanographic Institution in Massachusetts.
Many experts agree. Ted Scambos of the National Snow and Ice Data Center in Colorado adds: “It sounds counterintuitive, but the Antarctic is part of the warming as well.”
Sea ice is always melting near one pole while growing around the other. But the overall trend year to year is dramatically less ice in the Arctic and slightly more in the Antarctic.
It’s most noticeable in September, when northern ice is at its lowest and southern ice at its highest. For more than 30 years, the Arctic in September has been losing an average of 5.7 square miles of sea ice for every square mile gained in Antarctica.
While the Arctic is open ocean encircled by land, the Antarctic – about 1.5 times the size of the U.S. – is land circled by ocean, leaving more room for sea ice to spread. That geography makes a dramatic difference in the two polar climates.
The Arctic ice responds more directly to warmth. In the Antarctic, the main driver is wind, Maksym and other scientists say. Changes in the strength and motion of winds are now pushing the ice farther north, extending its reach.
Those changes in wind are tied in a complicated way to climate change from greenhouse gases, Maksym and Scambos say. Climate change has created essentially a wall of wind that keeps cool weather bottled up in Antarctica, NASA’s Abdalati said.