Oct. 7 -20, 2005
Vol. 35, Issue 17
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IN THIS ISSUE
Marshall wins award for discovering link between ulcers and bacteria
Board discusses diversity, salaries, benefits and more

Faculty Senate focuses on diversity issues

Beattie wins $30,000 Rea Award for the short story
Hot topics subject of education conference
Letter to the editor
Digest
Harvey sees his role as catalyst and coordinator
Tundra getting greener & warmer
Gorman releases new study of gender bias in hiring
Fiddlin' Beethoven
Lampkin family becomes Lawnies --- again
New additions will address space needs and highlight faculty design excellence
The many sides of 'In/Justice'
Poet W.S. Merwin to read on Oct. 13
Hugo live concert
Campaign struts Health System's stuff

 

Tundra getting greener & warmer
Epstein co-author of the national study

By Fariss Samarrai

arctic river
The Alaska tundra, a rolling treeless plain, is losing its snow earlier each year.

A gradual lengthening of the snow-free season in Alaska’s tundra, and a corresponding northward progression of the growth of shrubs and trees, may be creating a cycle of warmer and longer summers in the Alaskan Arctic, according to a new study published in the Sept. 22 issue of Science Express.

The resulting atmospheric heating in the region of northern Alaska is equivalent to what might be observed if there was a doubling of carbon dioxide in the atmosphere. Continuation of this trend could further amplify atmospheric heating in the region by two to seven
times and could possibly contribute to broader changes in climate.

Howard Epstein
C-Ville Weekly/Jack Looney
Howard E. Epstein

“We suggest that a noticeable summer warming trend in Alaska is best explained by a lengthening of the snow-free season there,” said Howard E. Epstein, an associate professor of environmental sciences and a co-author of the new study. The scientists determined that the increasing summer temperatures in northern Alaska could not be attributed to regional atmospheric circulation patterns or to a reduction in sea ice in the summer or to an increase in cloud cover.

The observed summer temperature increases are likely related to a global warming trend that has led to a longer snow-free season and an increase in the extent of woody vegetation. Both of these changes increase the amount of solar radiation that goes into heating rather than being reflected back to the atmosphere.

Epstein said that since the early 1960s the spring thaw in Alaska’s tundra country is arriving an average of 2.3 days earlier each decade.

As a result, plants in the region now “leaf out” about 2.7 days earlier than in previous decades. Likewise, the first freeze each year is arriving slightly later, allowing plants to extend their growing season.

The longer growing season is allowing shrubs and trees to slowly migrate northward. The increasing woody vegetation is further warming the near-surface atmosphere by absorbing rather than reflecting incoming solar radiation.

“The vegetation change is pretty dramatic,” Epstein said. “The tundra is getting greener, and there is a noticeable increase in shrubs. This is observable from satellite data and by observations on the ground.”
Because there is a shorter period of snow on the ground, solar radiation is absorbed by the land surface more readily and contributes to heating, thus accelerating the melting of snow and allowing for more plant growth. Over time, as the permafrost begins to melt, ancient organic matter that has been frozen for thousands of years is exposed, potentially adding more carbon dioxide to the atmosphere.

The result is a positive feedback loop that could continue to raise temperatures in the region and further lengthen the snow-free period each year.

Since the early 1960s, scientists have identified “hotspots” of slowly increasing average summer temperatures in the Arctic, from 0.15 degrees Celsius to about 2 degrees Celsius for an average increase of 1.2 degrees Celsius in the summertime.

“We know that certain parts of the Arctic are warming pretty substantially and more so than in other regions around the globe,” Epstein said. “This is significant because conditions in the Arctic affect global atmosphere conditions.”

Investigators from several universities and other institutions conducted the research, which was funded by the National Science Foundation through its Arctic Transitions of the Land/Atmosphere System project.



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