Vegetation growth in Arctic could add to global warming
American Geophysical Union press release
September 8, 2005
WASHINGTON — 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.
The study in western Alaska during the winters in 2000-2002 shows how the increasing abundance of high-latitude vegetation, particularly shrubs, interacts with the snow and affects Earth’s albedo, or the reflection of the Sun’s rays from the surface. The paper, which also analyzes the ramifications of continued plant growth in the tundra regions, written by researchers at the U.S. Army Cold Regions Research and Engineering Laboratory and at Colorado State University. It presents the first evidence that shrub growth could alter the winter energy balance of the Arctic and subarctic tundra in a substantial way.
The authors measured five adjacent sites in subarctic Alaska. They included areas covered by continuous forest canopy, others dotted with shrubs, and some of barren tundra. They found that mid-winter albedo was greatly reduced where shrubs were exposed and that melting began several weeks earlier in the spring at these locations, as compared to snow-covered terrain. The researchers note, however, that the shrubs’ branches produced shade that slowed the rate of melting, so that the snowmelt finished at approximately the same time for all the sites they examined.
Matthew Sturm, lead author of the study, notes that warming in the region seems to have stimulated shrub growth, which further warms the area and creates a feedback effect that can promote higher temperatures and even more growth. This feedback could, in turn, accelerate increases in the shrubs’ range and size over the four million square kilometer [1.5 million square mile] tundra and effect significant changes over the region.
RELATED CLIMATE CHANGE ARTICLES
An Earth System model developed by researchers at the University of Illinois at Urbana-Champaign indicates that the best location to store carbon dioxide in the deep ocean will change with climate change. The direct injection of carbon dioxide deep into the ocean has been suggested as one method to help control rising carbon dioxide levels in the atmosphere and mitigate the effects of global warming. But, because the atmosphere interacts with the oceans, the net uptake of carbon dioxide and the oceans’ sequestration capacity could be affected by climate change.
San Diego has been hit by hurricanes in the past and may be affected by such storms in the future according to data from the National Oceanic and Atmospheric Administration (NOAA). While a hurricane in San Diego would likely produce significantly less damage that Hurricane Katrina in New Orleans, it could still exact a high cost to Southern California especially if the region was caught off guard.
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.
Global warming will cause gasses trapped beneath the ocean floor to release into the atmosphere according to research presented at the Annual Conference of the Royal Geographical Society. The impact could trigger catastrophic climate change.
The tropical rainforests of Kalimantan have long been threatened and increasingly endangered by deforestation and other invasive types of human activity. However, a lesser known ecosystem in the region that is literally coming under fire, is the tropical peat lands, particularly in the central area of the province of Indonesian Borneo.
New evidence suggests human evolution was caused by specific periods of climatic change in Africa according to research presented at the Annual Conference of the Royal Geographical Society. These climatic influences played a crucial part in enhancing human development says Dr Mark Maslin, Senior Lecturer in Geography at University College London.
Late last month an atmospheric scientist at Massachusetts Institute of Technology released a study in Nature that found hurricanes have grown significantly more powerful and destructive over the past three decades. Kerry Emanuel, the author of the study, warns that since hurricanes depend on warm water to form and build, global climate change might increase the effect of hurricanes still further in coming years.
A dramatic rise in carbon dioxide 250 million years ago may have caused global temperatures to soar and result in Earth’s greatest mass extinction, according to a study published in the September issue of Geology. Global warming, which may have produced temperatures 10 to 30 degrees Celsius higher than today, would have had a significant impact both on oceans, where about 95% of lifeforms became extinct, and on land, where almost 75% of species died out.
An article in The Sunday Times reports that a scientist is working a cloud manufacturing technique to counter global warming. Professor Stephen Salter, professor emeritus of Engineering Design at Edinburgh University, has proposed that “highly reflective clouds could be used to bounce more of the sun’s rays back into space — counteracting rising temperatures caused by a build-up of greenhouse gasses in the Earth’s atmosphere.
“Basically, if tundra is converted to shrubland, more solar energy will be absorbed in the winter than before,” Sturm says. And while previous research has shown that warmer temperatures during the Arctic summer enhance shrub growth, “our study is important because it suggests that the winter processes could also contribute to and amplify the rate of the [growth].”
Sturm cites satellite and photographic evidence showing increasing plant growth across the Alaskan, Canadian, and Euro-Asian Arctic and notes that continued warming will likely produce thicker stands of brush that protrude above the snow. The new, brushy landscape would replace the smooth, white environment that currently dominates the Arctic during its 8-10 month winter.
In addition, the increasing shrub cover would impact more than just the energy balance in the Arctic. With nearly 40 percent of the world’s soil carbon is stored in Arctic soils, any change in vegetation and energy is likely to trigger a response in the Arctic carbon budget. Scientists are still trying to understand the nature of this response, but Sturm and his coauthors conclude that the feedback effects they describe would undoubtedly accelerate its rate. They conclude that combined effects of increasing shrubs on both energy and carbon could change the Arctic in a way that affects the rest of the world.
The research was supported by the National Science Foundation.
Sturm, M., T. Douglas, C. Racine, and G. E. Liston (2005), Changing snow and shrub conditions affect albedo with global implications, J. Geophys. Res., 110, G01004, doi:10.1029/2005JG000013.
This is a modified press release from the American Geophysical Union. This original can be found here
Contact information for author
msturm [at] crrel.usace.army.mil
+1 (907) 353-5183.