June 06, 2005
"This is the first paper that demonstrates that the changes we are seeing in Alaskan lakes in response to a warming climate is also occurring in Siberia," said Hinzman, who has also compared satellite data of tundra ponds on the Seward Peninsula near Council, Alaska, and found that the surface pond area there had decreased over the last 50 years.
In this latest study, comparing data from 1973 with findings from 1997-1998, the total number of large lakes decreased by around 11 percent. While many did not disappear completely they shrank significantly. The overall loss of lake surface area was a loss of approximately 6 percent. In addition, 125 lakes vanished completely and are now re-vegetated.
Laurence Smith, an associate professor of geography at the University of California Los Angeles, is the article's lead author. Smith and his co-authors were surprised by the overall loss in surface water.
"We were expecting the lake area to have grown with climate change," said Smith. "And while it did do so in the north where the permafrost remains intact, lake area did not increase in the south where permafrost is warming."
In permafrost regions, summer thaw produces meltwater, which is typically unable to infiltrate into the ground because of the ice-rich frozen soils found in permafrost. Data gathered from the latest measurements indicate that warming temperatures lead to increased numbers of surface water bodies in the colder permafrost regions.
Many lakes decreased in size or dried up completely, while other lakes actually increased in size. Researchers say as the climate warms, additional meltwater accumulated in the lakes located in the colder regions of thicker permafrost increase their size; however, if climate warming continues, even those lakes would eventually be susceptible to loss.
"We expect areas of continuous permafrost to continue to thin and move steadily northward, resulting in the disappearance of more lakes," said Smith.
In regions with thin or discontinuous permafrost, surface soils also become drier as the permafrost degrades.
Co-authors include Yongwei Sheng, an assistant professor of environmental science and forestry at State University of New York, and Glen MacDonald, chair of UCLA's geography department. The study was funded by the National Science Foundation. Researchers will discuss their findings this week at the Spring 2005 Freshwater Initiative All-Hands Meeting at Bell Harbor International Conference Center in Seattle, Wash.
Source of News:
Publish A Letter on SitNews Read Letters/Opinions
Submit A Letter to the Editor