After at least 200 years of stable water levels, sudden dessication sets in
By Summit Voice
FRISCO — In another sign of abrupt climate disruption, scientists say some of Canada’s subarctic lakes are drying up at a rate not seen for at least 200 years, as snowfall in the region declines.
A research team studied about 70 lakes near Old Crow, Yukon, and Churchill, Manitoba, most of them less than one meter deep. More than half of the lakes located on relatively flat terrain and surrounded by scrubby vegetation showed signs of desiccation.
The problem stems chiefly from a decline in meltwater; for instance, from 2010 to 2012 average winter precipitation in Churchill decreased by 76 millimeters compared to the averages recorded from 1971 to 2000. The drying of some lakes, which first became visible to the naked eye in 2010, was even more pronounced in summer 2013.
“With this type of lake, precipitation in the form of snow represents 30% to 50% of the annual water supply,” explained the study’s lead author, Frédéric Bouchard, a postdoctoral fellow at Université Laval‘s Department of Geography and the Centre for Northern Studies.
The kind of desiccation seen by the researchers is without precedent in 200 years. Isotopic analyses conducted on the remains of phytoplankton accumulated in lakebed sediment show that the lakes have maintained water balance for 200 years. This stability was abruptly disrupted a few years ago.
If the trend of dry summers and less snowy winters continues, as climate models forecast, many of the subarctic’s shallowest lakes could dry out completely.
“It’s difficult to predict all the repercussions of this habitat loss,” Bouchard said. “But it’s certain that the ecological consequences will be significant.”