Scientists report that as Arctic sea ice declines, weather impacts spread into northern mid-latitudes

By Nick Sundt
Climate Change Communications Director, WWF US
In the annual “Arctic Report Card” issued by the National Oceanic and Atmospheric Administration (NOAA) on October 21, researchers report that the decline in Arctic Sea Ice appears to be favoring atmospheric conditions that paradoxically tend to bring colder weather to some areas well outside the Arctic.  The report links this emerging “Warm Arctic-Cold Continents” pattern to the cold air outbreaks and heavy snows experienced in parts of the U.S. and elsewhere in the Northern Hemisphere in December 2009 and February 2010.
In the Atmosphere portion of the Arctic Report Card, the authors J. Overland (NOAA, Pacific Marine Environmental Laboratory), M. Wang (Joint Institute for the Study of the Atmosphere and Ocean, University of Washington), and J. Walsh (International Arctic Research Center, Fairbanks, Alaska), say:
“While individual weather extreme events cannot be directly linked to larger scale climate changes, recent data analysis and modeling suggest a link between loss of sea ice and a shift to an increased impact from the Arctic on mid-latitude climate. Models suggest that loss of sea ice in fall favors higher geopotential heights over the Arctic. With future loss of sea ice, such conditions as winter 2009-2010 could happen more often. Thus we have a potential climate change paradox. Rather than a general warming everywhere, the loss of sea ice and a warmer Arctic can increase the impact of the Arctic on lower latitudes, bringing colder weather to southern locations.”
Additional Findings of the Arctic Report Card
In addition to a discussion of the impacts on atmospheric circulation discussed above, the Arctic Report Card reported in its Greenland section on extraordinary changes occurring there:
Greenland climate in 2010 is marked by record-setting high air temperatures, ice loss by melting, and marine-terminating glacier area loss. Summer seasonal average (June-August) air temperatures around Greenland were 0.6 to 2.4°C above the 1971-2000 baseline and were highest in the west. A combination of a warm and dry 2009-2010 winter and the very warm summer resulted in the highest melt rate since at least 1958 and an area and duration of ice sheet melting that was above any previous year on record since at least 1978. The largest recorded glacier area loss observed in Greenland occurred this summer at Petermann Glacier, where 290 km2 of ice broke away. The rate of area loss in marine-terminating glaciers this year (419 km2) was 3.4 times that of the previous 8 years, when regular observations are available. There is now clear evidence that the ice area loss rate of the past decade (averaging 120 km2/year) is greater than loss rates pre-2000.”
In a teleconference today, Jason Box, a glaciologist with the Byrd Polar Research Center at The Ohio State University (Columbus, Ohio), said that the developments would compel researchers once again to increase their estimates of the likely rate of future sea level rise. The melting of ice from Greenland is a major contributor to rising global sea levels.
The other key sections and findings of the Arctic Report Card, produced by a team of 69 international scientists and based on 176 published scientific references, include:

Online Resources:
Arctic Report Card Update 2010.  Issued by the National Oceanic and Atmospheric Administration on 21 October 2010.