Featured Research

from universities, journals, and other organizations

Lands Surface Change On Alaska Tundra Creating Longer, Warmer Summers In Arctic

Date:
September 26, 2005
Source:
University of Virginia
Summary:
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 to be published in the Sept. 22, 2005, issue of Science Express.

A meteorological station in Alaska's tundra. The snow-free season in the region is gradually growing longer as average temperatures slowly increase.
Credit: Image courtesy of University of Virginia

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 to be published in the Sept. 22, 2005, issue of Science Express.

Related Articles


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.

"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 at the University of Virginia 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. Native American people in the region and nearby areas also have noted the changes in weather and vegetation."

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. The Arctic is dominated by snow and ice, and if this condition were to change, even subtly, there is potential for further change to the global climate."

###

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.

Editors note: Photos of the tundra are available by request.


Story Source:

The above story is based on materials provided by University of Virginia. Note: Materials may be edited for content and length.


Cite This Page:

University of Virginia. "Lands Surface Change On Alaska Tundra Creating Longer, Warmer Summers In Arctic." ScienceDaily. ScienceDaily, 26 September 2005. <www.sciencedaily.com/releases/2005/09/050926081228.htm>.
University of Virginia. (2005, September 26). Lands Surface Change On Alaska Tundra Creating Longer, Warmer Summers In Arctic. ScienceDaily. Retrieved March 28, 2015 from www.sciencedaily.com/releases/2005/09/050926081228.htm
University of Virginia. "Lands Surface Change On Alaska Tundra Creating Longer, Warmer Summers In Arctic." ScienceDaily. www.sciencedaily.com/releases/2005/09/050926081228.htm (accessed March 28, 2015).

Share This


More From ScienceDaily



More Earth & Climate News

Saturday, March 28, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Antarctic Ice Is Melting Faster Than Ever

Antarctic Ice Is Melting Faster Than Ever

Newsy (Mar. 27, 2015) A new study of nearly two decades of satellite data shows Antarctic ice shelves are losing more mass faster every year. Video provided by Newsy
Powered by NewsLook.com
Raw: Homes Near Landslide in Washington

Raw: Homes Near Landslide in Washington

AP (Mar. 27, 2015) Aerial footage from KOMO shows several homes near a landslide in Washington. KOMO reports that at least one of the homes has been damaged. (March 27) Video provided by AP
Powered by NewsLook.com
Clean-Up Follows Deadly Weather in Okla.

Clean-Up Follows Deadly Weather in Okla.

AP (Mar. 26, 2015) Gov. Mary Fallin has declared a state of emergency for 25 Oklahoma counties after powerful storms rumbled across the state causing one death, numerous injuries and widespread damage. (March 26) Video provided by AP
Powered by NewsLook.com
At Least Four Dead After Floods in Northern Chile

At Least Four Dead After Floods in Northern Chile

Reuters - News Video Online (Mar. 26, 2015) At least four people have been killed by severe flooding in northern Chile after rains battered the Andes mountains and swept into communities below. Rob Muir reports. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins