Arctic Tipping Point: A North Pole Without Ice Fen Montaigne - Yale Environment 360
go to original September 3, 2012

This NASA map, based on satellite data, shows the new record-low summer sea ice extent of 1.58 million square miles in the Arctic Ocean, as recorded on August 26. The amount of sea ice covering the Arctic Ocean at the end of summer is now 45 percent lower than the average from 1979 to 2000. The black dot represents the region surrounding the North Pole. (NASA)

Scientists say this year’s record declines in Arctic sea ice extent and volume are powerful evidence that the giant cap of ice at the top of the planet is on a trajectory to largely disappear in summer within a decade or two, with profound global consequences.

As the northern summer draws to a close, two milestones have been reached in the Arctic Ocean — record-low sea ice extent, and an even more dramatic new low in Arctic sea ice volume. This extreme melting offers dramatic evidence, many scientists say, that the region’s sea ice has passed a tipping point and that sometime in the next decade or two the North Pole will be largely ice-free in summer.

NASA and U.S. ice experts announced earlier this week that the extent of Arctic sea ice has dropped to 4.1 million square kilometers (1.58 million square miles) — breaking the previous record set in 2007 — and will likely continue to fall even farther until mid-September. As the summer melt season ends, the Arctic Ocean will be covered with 45 percent less ice than the average from 1979 to 2000.

Even more striking is the precipitous decline in the volume of ice in the Arctic Ocean. An analysis conducted by the University of Washington’s Pan Arctic Ice Ocean Model Assimilation System (PIOMAS) estimates that sea ice volumes fell in late August to roughly 3,500 cubic kilometers — a 72-percent drop from the 1979-2010 mean.

Peter Wadhams, who heads the Polar Ocean Physics Group at the University of Cambridge and who has been measuring Arctic Ocean ice thickness from British Navy submarines, says that earlier calculations about Arctic sea ice loss have grossly underestimated how rapidly the ice is disappearing. He believes that the Arctic is likely to become ice-free before 2020 and possibly as early as 2015 or 2016 — decades ahead of projections made just a few years ago.

Mark Drinkwater, mission scientist for the European Space Agency’s CryoSat satellite and the agency’s senior advisor on polar regions, said he and his colleagues have been taken aback by the swiftness of Arctic sea ice retreat in the last 5 years. “If this rate of melting [in 2012] is sustained in 2013, we are staring down the barrel and looking at a summer Arctic which is potentially free of sea ice within this decade,” Drinkwater said in an e-mail interview.

A small number of climate scientists say that natural variability may be playing a significant role in the rapid retreat of Arctic sea ice, intensifying human-caused climate change, and they caution against predicting the imminent demise of the region’s summer sea ice. But an overwhelming majority of Arctic ice experts say that recent data offer powerful evidence that summer sea ice has passed a point of no return.

Read more at Yale Environment 360

Fen Montaigne is senior editor of Yale Environment 360 and author of the book Fraser’s Penguins: A Journey to the Future in Antarctica. His work has appeared in The New Yorker, National Geographic, Outside, Smithsonian, and other magazines.

We invite you to add your charity or supporting organizations' news stories and coming events to PVAngels so we can share them with the world. Do it now!