| |
In short order the arctic-science and the global-change communities were galvanized, says Richard Moritz, polar oceanographer with the UW’s Applied Physics Laboratory and lead author of a review of recent Arctic climate change in the Aug. 30 special polar-science issue of Science.
"We’ve learned more about the dynamics of post-glacial arctic climate change in the last five years than in the 50 years previous," Moritz says. "For example, the recent trend in the Arctic Oscillation explains the warming observed in the Arctic better than anything else."
Advances in understanding arctic climate change are particularly timely, with some studies indicating that the recent trend in the Arctic Oscillation results partly from human activities that generate greenhouse gases and sulfate particles, and deplete stratospheric ozone. Scientists, planners and policymakers need to know what the changes of the last 30 years portend.
Thus climate modelers have redoubled their efforts to determine the physics behind the patterns of change. Although their models portray realistic day-to-day and month-to-month variations in the Arctic Oscillation, they fail to capture the magnitude of the longer term trend in the Arctic Oscillation that was observed from 1970 to 2000. While paleoclimatologists studying the climate record of the past 1,000 years have not reached a consensus on the importance of the Arctic Oscillation pattern over this longer period, some surprising findings indicate that past Arctic warmings and coolings tended to coincide with low-frequency El Nino-Southern Oscillation events in the tropical Pacific.
The review by Moritz and co-authors Cecilia Bitz, a sea-ice expert with the UW’s Applied Physics Laboratory, and Eric Steig, assistant professor with the UW’s Quaternary Research Center, refers to more than 80 published papers, most appearing in just the last two years. The co-authors say that warming of the surface from 1970 to 2000 in the Northern Hemisphere was greatest in the Arctic, causing changes in precipitation, snow cover and the extent of sea ice.
The Arctic Oscillation is a seesaw pattern in which atmospheric pressure at the polar and middle latitudes fluctuates between positive and negative phases. The wind patterns associated with the Arctic Oscillation affect the surface temperature over North America and Eurasia, as well as the Arctic. The Arctic Oscillation was first described in a 1998 article by David Thompson, then a graduate student at the UW and now an assistant professor at Colorado State University, and John M. Wallace, a UW professor.
"The
Arctic Oscillation provides a very fruitful framework and the
result is that a tremendous amount of work has been done in a
relatively short period of time," Moritz says. "Attempts to
model the pattern of recent Arctic and global warming have to
come to grips with the problem of the Arctic Oscillation."
Climate modelers have benefited from a growing understanding
of sea-ice physics and the best-ever measurements of how heat
from the sun and the atmosphere affects the pack ice that
covers the Arctic Ocean.
Moritz, for example, is
director of the SHEBA (Surface Heat Budget of the Arctic
Ocean) Project Office funded by the National Science
foundation and Office of Naval Research. Now in its analysis
phase, SHEBA locked an icebreaker into the pack ice for a
full year in the late '90s to measure the interactions of the
ice, atmosphere and the ocean during all four
seasons.
Because so many climate modelers worldwide are working on the Arctic Oscillation, Moritz says it’s conceivable that in a year or two we will understand the fundamental physics of the Arctic Oscillation, and be able to account for its recent trend. "If we can’t, it won’t be for lack of trying."
###
Moritz, 206-543-8023, dickm@apl.washington.edu
Bitz,
206-543-1339, bitz@apl.washington.edu
Steig,
206-685-3715, steig@ess.washington.edu
###
Click here to view the article in Science.
Images
for use by news media only.
Photo credit required: University of
Washington
Efforts in the late 1990s contributing to a better understanding of climate dynamics in the Arctic included the SHEBA (Surface Heat Budget of the Arctic Ocean) project sponsored by the National Science Foundation and Office of Naval Research to learn how the ocean, pack ice and atmosphere interact during the course of an entire year. Richard Moritz, lead author of an Aug. 30 review of the dynamics of recent climate change in the Arctic, is director of the SHEBA project office based at the University of Washington. The project is now in its analysis phase.
http://www.washington.edu/newsroom/news/images/168_10.jpg
Two
researchers walk to their research hut from the Canadian
icebreaker that served as floating hotel, power source,
communications base and science headquarters for Ice Station
SHEBA.
http://www.washington.edu/newsroom/news/images/170_14.jpg
The
Canadian icebreaker that served as floating hotel, power
source, communications base and science headquarters for Ice
Station SHEBA is surrounded by huts and tents used for
research, storage and as garages for snowmobiles.
http://www.washington.edu/newsroom/news/images/moritz4a.jpg
Life
preservers were a necessity during summer melting as Ice
Station SHEBA researchers and crew skirted open water, melt
ponds and slushy snow, all part of the summer melting of the
ice pack.
http://www.washington.edu/newsroom/news/images/moritz20.jpg
As
summer melting of the ice pack progressed, Ice Station SHEBA
is riddled with rivers of open water and melt ponds that had
to be crossed to reach research huts and equipment.
http://www.washington.edu/newsroom/news/images/moritz2a.jpg
As
summer melting of the ice pack progressed, Ice State SHEBA
research huts and logistics structures were floated on
barrels when the ice melted out from under them.
