Rising lake levels in the McMurdo Dry Valleys affect science, field camps
Posted February 24, 2012
It’s certainly not a flood of biblical proportions, but rising lake levels and pulses of flooding events in the McMurdo Dry Valleys are threatening established field camps — and could eventually change the nature of the cold desert ecosystem.
After what appears to have been a decade or so of aberrant cooling until the early 2000s, the Dry Valleys seem to have resumed a long-term trend of warming, according to John Priscu , a professor of ecology at Montana State University in Bozeman and an expert on the ice-covered lakes.
“They’re roughly changing together, although Lake Bonney, because of its steep sides and water input from the Taylor Glacier, is rising the fastest,” said Priscu of the three major lakes in the Taylor Valley, which harbors the most studied lakes of the ice-free valleys.
The McMurdo Dry Valleys have been the site of a Long Term Ecological Research (LTER) program beginning in 1993, though scientists have conducted studies there since the late 1950s. The exploration of the valleys, which sit at the edge of the massive East Antarctic Ice Sheet, dates back even further, to the turn of the 20th century, when Briton Robert F. Scott led an expedition through the region.
In fact, thanks to Scott, whose team in 1903 measured a section of Lake Bonney, the westernmost lake in Taylor Valley, scientists today are able to extrapolate its growth during the intervening decades.
Between 1903 and 1973, when systematic monitoring began, the lake level rose about 12 meters, representing a 4 percent per year increase in flow, according to Diane McKnight , a professor at the University of Colorado at Boulder and the principal investigator for the McMurdo Dry Valleys LTER .
Lake Bonney appears to be rising faster than either Lake Fryxell or Lake Hoare to the east, partly due to its proximity to the Taylor Glacier. In fact, scientists have discovered that the glacier itself is adding water to the lake, which is about seven kilometers long and up to 900 meters wide. A narrow channel — the place where Scott’s men conducted their survey — separates the lake into east and west lobes.
“The Taylor Glacier is doing some very strange things. It’s adding a lot of water,” said Priscu, who has made 27 trips down to the Antarctic since 1983. “It’s gaining water from melting underneath.”
A field camp built in 1988 on the shores of Lake Bonney to support Priscu’s early research is slowly being moved to higher ground until a new facility is eventually constructed, according to Woody Haywood, who oversees the planning and building of science field camps for the U.S. Antarctic Program (USAP) .
“About four years ago, it became painfully obvious that the trend was such that at Lake Bonney the water was rising at something measurable, and we’d soon have to address it,” Haywood said.
Over the last several years, the science construction team has removed two labs and replaced them with larger structures away from the shore. Haywood said the National Science Foundation (NSF) , which manages the USAP, has initiated planning for new camps at Bonney and Fryxell, which is also being threatened by higher water levels.