Arctic Moving Toward Tipping Point

The record loss of sea ice and thinning of ice throughout the Arctic this summer are only two brush strokes in the mosaic of scientific data that depict the Arctic as a "system under significant stress from warming atmosphere," as the chief editor of the State of the Arctic report card put it.

"I don’t think there’s anything in this report that would suggest there’s a reversal in the thought that we’re working toward a tipping point, if we’re not already there," said Jacqueline A. Richter-Menge, the chief editor of the report said during a conference call with reporters this morning about the one-year update to the landmark 2006 State of the Arctic report.

The data -- from the atmosphere, ice, permafrost and wildlife of the Arctic -- is nearly uniform in depicting a trend, realized sometimes in fits and starts, of global warming's role in altering a part of the world that is among the most sensitive to climatic changes.

And, the scientists made clear, what happens in the Arctic has important implications for the land, sea and wildlife at mid-latitudes as well.

"The old saying 'What happens in Las Vegas stays in las Vegas' does not apply to the Arctic," said Richard Spinrad, the assistant administrator for oceanic and atmospheric research for the National Oceanographic and Atmospheric Administration. "What happens in the Arctic does not stay in the Arctic."

The "tipping point" is an oft-debated point when the loss of ice and the increase in warmth will result in a permanently changed polar region that defies the ebb and flow of freezing and unfreezing that characterizes the region. Scientists could not say whether that point has been reached, or when it might be reached -- but they agreed that the trend toward a tipping point is consistent across the Arctic, and that no data point to a reversal in the trend. (Though the Bering Sea did cool, and the data from Greenland is still poorly understood.)

"The (sea ice) loss we had this year was so extreme it would take a long time to get back to where we were 20 years ago," said James Overland, a scientist with NOAA's Pacific Marine Environmental Laboratory. "It won't necessarily be a continued acceleration of more ice lost, but we're certainly not going to go back to where we were before."

Some of the observations detailed in the report:

• Arctic sea ice retreated to a new record minimum. Sea ice covered 23% less than the previous record, in 2005, and 39% less than the average. The thickness of remaining ice also decreased to record levels.
• The Arctic is warmer, across the entire region and in all seasons -- a condition that is unique in at least the last 100 years, when any year-to-year warming was restricted to certain seasons or geographic locations within the Arctic.
• Permafrost continues a warming trend documented over at least 15 years, causing coastal erosion, across every region, from Siberia to Alaska to Greenland.
• Arctic tundra is increasingly filling with shrubs and other greenery.
• Caribou and reindeer populations, though highly variable under all conditions, seem to be declining, with some herds losing as much as 80% of their population, possibly due to changes in the freeze-thaw cycle that create crusty snow that is difficult for them to move through and forage under.
• Global goose populations, which are highly dependent on the Arctic, have doubled since the 1970s, as changes in the Arctic and elsewhere have favored them.

Like the mosaic of individual research that contributed to the State of the Arctic report card, the report card itself fits into a larger mosaic of scientific work -- both for the International Polar Year studies of the earth's high latitudes and the Global Earth Observation System of Systems, and also for the U.N. Intergovernmental Panel on Climate Change, which is now producing the synthesis of its fourth assessment on climate change science.

Scientists said a continuation and expansion of these observations are priorities, given the steady indication of changes due to global warming, the startling and surprising recession of sea ice this summer, and the implications for a cascade of changes elsewhere on the globe due to changes in the Arctic.

"We have recognized that in principle for some years," Spinrad said. "This report adds an exclamation point."

Related Link

Arctic Report Card 2007

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