Site icon Conservation news

Summers in arctic getting longer and hotter

Summers in arctic getting longer and hotter

Summers in arctic getting longer and hotter
University of Alaska Fairbanks release
September 23, 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.

Related articles:

Number of tourists visiting Antarctica surges over past decade – 15-September-2005
The number of sightseers visiting Antarctica has surged 308 percent since 1992 according to figures released in a report by the UN. For the 2004-2005 year, more than 27,000 people visited the icy continent.

Humans impacted climate thousands of years ago – 9-September-2005
New research suggests humans were influencing the world’s climate long before the Industrial Revolution. Atmospheric levels of methane, a potent greenhouse gas, climbed steadily during the first millennium due to massive fires set by humans clearing land agriculture.

Vegetation growth in Arctic could add to global warming – 8-September-2005
Warming in the Arctic is stimulating the growth of vegetation and could affect the delicate energy balance there, causing an additional climate warming of several degrees over the next few decades. A new study indicates that as the number of dark-colored shrubs in the otherwise stark Arctic tundra rises, the amount of solar energy absorbed could increase winter heating by up to 70 percent. The research will be published 7 September in the first issue of the Journal of Geophysical Research-Biogeosciences, published by the American Geophysical Union.
American Geophysical Union press release

Glaciers melting at alarming rates, water problems feared – 7-September-2005
Global Warming is melting glaciers in every region of the world, putting millions of people at risk from floods, droughts and lack of drinking water says a report from WWF.
WWF Release

Arctic ocean could have ice-free summers by 2100 says new study – 24-August-2005
The current warming trends in the Arctic may shove the Arctic system into a seasonally ice-free state not seen for more than one million years, according to a new report. The melting is accelerating, and a team of researchers were unable to identify any natural processes that might slow the de-icing of the Arctic.
University of Arizona release

“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?

This is a modified press release from the University of Alaska, Fairbanks. This original can be found at

Exit mobile version