Warming blamed for shrinking lakes
An accelerating Arctic warming trend over the past quarter-century has dramatically dried up more than a thousand large lakes in Siberia, probably because the permafrost beneath them has begun to thaw, according to a paper set to be published today in the journal Science.
Comparing satellite images captured in the early 1970s to those from recent years, a team of American scientists determined that the number of large lakes in a vast, 200,000-square-mile region of Siberia diminished by about 11 percent – from 10,882 to 9,712.
About 125 of the 1,170 shrunken lakes disappeared altogether, and most are now considerably smaller than the study’s baseline of 40 hectares, or roughly 99 acres, the researchers found. If Arctic temperatures continue to rise, the scientists warned, many of the lakes that are now ubiquitous in high northern latitudes could eventually disappear.
“An 11 percent decline may not sound like much, but in the time-scale in which landscapes naturally change, this is extraordinarily fast,” said the paper’s lead author, Laurence C. Smith, an associate geology professor at the University of California, Los Angeles. He conducted the research with UCLA colleague Glen M. MacDonald, Yongwei Sheng of the State University of New York, and Larry Hinzman of the University of Alaska, Fairbanks.
While the researchers did not determine the cause of the losses, they found that the location of disappearing lakes in areas of Siberia where permafrost, formerly frozen as solid as concrete, is now known to be softening. They believe the lakes are receding because the water is seeping into the increasingly mushy ground, a finding that scientists already have confirmed in portions of Alaska where Arctic lakes are also drying up.