Coming to the Arctic near you: The longer, hotter summer

September 22, 2005

FAIRBANKS, AK--In a paper that shows dramatic summer warming in arctic Alaska, scientists synthesized a decade of field data from Alaska showing summer warming is occurring primarily on land, where a longer snow-free season has contributed more strongly to atmospheric heating than have changes in vegetation.

Arctic climate change is usually viewed as caused by the retreat of sea ice, which reduces high-latitude albedo - a measure of the amount of sunlight reflected off a surface - a change most pronounced in winter.

"Summer warming is more pronounced over land than over sea ice, and atmosphere and sea-ice observations can't explain this," said Terry Chapin, professor of ecology at the University of Alaska Fairbanks' Institute of Arctic Biology and lead author of the paper which appears in the September 22, 2005 advance online publication Science Express.

Using surface temperature records, satellite-based estimates of cloud cover and energy exchange, ground-based measurements of albedo and field observations of changes in snow cover and vegetation, Chapin and co-authors argue that recent changes in the length of the snow-free season have triggered a set of interlinked feedbacks that will amplify future rates of summer warming.

"It's the changes in season length rather than increases in vegetation that explains this observation," Chapin said. Summer warming correlates with a lengthening of the snow-free season that has increased atmospheric heating locally by an amount similar in magnitude to the regional heating expected over multiple decades from a doubling of atmospheric carbon dioxide, say the authors.

"Snowmelt is 2.5 days earlier for each decade we studied," Chapin said.

Two mechanisms explain the pronounced warming over land during the summer. First, the early snow melt increases the length of time the land surface can absorb heat energy. Second, the increase in snow-free ground permits increases in vegetation such shrubs and advances of treelines.

"Continuation of current trends in shrub and tree expansion could further amplify this atmospheric heating 2-7 times," Chapin said.

"This mechanism should be incorporated into climate models," Chapin said. Improved understanding of the controls over rates of shrub expansion would reduce the likelihood of surprises in the magnitude of high-latitude amplification of summer warming.

Researchers were funded by the National Science Foundation, Office of Polar Programs, ARCtic System Science program - the goal ARCSS is to answer the question: What do changes in the arctic system imply for the future?
-end-
Journalists may obtain a copy of the paper by contacting Science at: 202-326-6440 or by e-mail: scipak@aaas.org

Contact:

F. Stuart (Terry) Chapin III, Professor of Ecology, Institute of Arctic Biology, University of Alaska Fairbanks. 907-474-7922, terry.chapin@uaf.edu.

Dr. Matthew Sturm, Research Physical Scientist, U.S. Army, Cold Regions Research and Engineering Laboratory Alaska. 907-353-5183, Matthew.Sturm@erdc.usace.army.mil

Marie Gilbert, Publications and Information Coordinator, Institute of Arctic Biology, University of Alaska Fairbanks. 907-474-7412, marie.gilbert@uaf.edu.

University of Alaska Fairbanks

Related Sea Ice Articles from Brightsurf:

2020 Arctic sea ice minimum at second lowest on record
NASA and the National Snow and Ice Data Center (NSIDC) at the University of Colorado Boulder shows that the 2020 minimum extent, which was likely reached on Sept.

Sea ice triggered the Little Ice Age, finds a new study
A new study finds a trigger for the Little Ice Age that cooled Europe from the 1300s through mid-1800s, and supports surprising model results suggesting that under the right conditions sudden climate changes can occur spontaneously, without external forcing.

How much will polar ice sheets add to sea level rise?
Over 99% of terrestrial ice is bound up in the ice sheets covering Antarctic and Greenland.

A snapshot of melting Arctic sea ice during the summer of 2018
A study appearing July 29 in the journal Heliyon details the changes that occurred in the Arctic in September of 2018, a year when nearly 10 million kilometers of sea ice were lost throughout the summer.

Antarctic penguins happier with less sea ice
Researchers have been surprised to find that Adélie penguins in Antarctica prefer reduced sea-ice conditions, not just a little bit, but a lot.

Seasonal sea ice changes hold clues to controlling CO2 levels, ancient ice shows
New research has shed light on the role sea ice plays in managing atmospheric carbon dioxide levels.

Artificial intelligence could revolutionize sea ice warnings
Today, large resources are used to provide vessels in the polar seas with warnings about the spread of sea ice.

Antarctic sea ice loss explained in new study
Scientists have discovered that the summer sea ice in the Weddell Sea sector of Antarctica has decreased by one million square kilometres -- an area twice the size of Spain -- in the last five years, with implications for the marine ecosystem.

Antarctic sea-ice models improve for the next IPCC report
All the new coupled climate models project that the area of sea ice around Antarctica will decline by 2100, but the amount of loss varies considerably between the emissions scenarios.

Earth's glacial cycles enhanced by Antarctic sea-ice
A 784,000 year climate simulation suggests that Southern Ocean sea ice significantly reduces deep ocean ventilation to the atmosphere during glacial periods by reducing both atmospheric exposure of surface waters and vertical mixing of deep ocean waters; in a global carbon cycle model, these effects led to a 40 ppm reduction in atmospheric CO2 during glacial periods relative to pre-industrial level, suggesting how sea ice can drive carbon sequestration early within a glacial cycle.

Read More: Sea Ice News and Sea Ice Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.