Scientists at the University of Colorado’s National Snow and Ice Data Center and NASA said that, as of Sunday, the Arctic sea ice cover had shrunk to 1.58 million square miles, the smallest area since satellite measurement began in 1979. With the melting season not yet over, the ice will almost certainly contract further in the coming weeks before it begins to re-form.
The previous record low, recorded in September 2007, was 1.61 million square miles.
Walt Meier, a research scientist at the federally funded center, said a long-term warming trend was largely responsible for the sharp reduction in ice, though recent weather conditions, including a strong storm, also contributed. Higher temperatures produced more open water, which, he said, absorbs more heat and makes the ice thinner.
The ice has become “increasingly vulnerable to extreme conditions,” Meier told reporters during a telephone conference. He said that “parts of the Arctic have become like a giant slushy” that can melt much more easily than the 10-foot-thick ice that used to compose 20 to 25 percent of the surface of the water. “The Arctic Ocean is really a very different place than it used to be.”
The ice’s fragility is one reason the storm had such a big impact, he said. Even without the storm, he added, “we were already tracking along the 2007 trajectory,” so a record was within reach.
The area covered by Arctic summer sea ice usually reaches its low point around Sept. 13, when the region begins to cool. But the ice melted at an unprecedented 38,600 square miles per day during the first part of August, which is why the low point occurred earlier this year.
The reduction in ice is already transforming the Arctic. On Saturday, a Royal Dutch Shell drill ship, the Noble Discoverer, departed Alaska’s Dutch Harbor and headed to the Chukchi Sea off the state’s northwest coast in anticipation of final federal approval for oil-exploration activities there. The increase in open water makes oil exploration easier.
‘A profound moment’
The record-low Arctic ice is sure to intensify the debate over whether to curb greenhouse gas emissions linked to global warming. Rafe Pomerance, former deputy assistant secretary of state for environment and development under President Bill Clinton, called the record ice loss “a profound moment that will change the debate” over climate change.
“It is very troubling, because the refrigerator of the Northern Hemisphere has been unplugged, so we will keep warming,” he said.
But the record isn’t likely to convince some global-warming skeptics. Patrick Michaels, director of the Center for the Study of Science at the libertarian Cato Institute, noted that sea ice has been expanding at the South Pole. “The overall loss in sea ice from the planet is less than people often assume,” he said.
Meier, the research scientist, countered that the two poles have different climate systems. Antarctica is land surrounded by ice, while the Arctic is an ice-covered ocean surrounded by land. He said an overall number for global sea ice has little meaning.