The Earth's transition from the last glacial period to its present climate was a turbulent era of rapid climate change, according to University of Pittsburgh geologists.
The findings will be used to help scientists compare current climate changes with those of the ancient past.
Pitt PhD geology student David Pompeani studied soil extracted from the bed of Rantin Lake, in the Yukon Territory of Canada. Pompeani said his team found evidence that a currently deep part of the lake was once very shallow.
"What we found was that about 8,400 years ago, this distinctive shallow-water sediment had formed in water that was about ten meters deep in 2006," said Pompeani. "So, that suggests that the lake fell substantially in the early Holocene, suggesting that it got very, very dry."
The Pitt researchers looked up fossil records from the time and found that this "megadrought" of the early Holocene also strongly influenced vegetation in the Yukon, having a major impact on the ecosystem's development. The area is now a boreal forest — not quite a taiga, but not temperate either.
Pompeani said the team ventured to the nearly empty Yukon Territory in 2006 to collect cores of sediment from Rantin Lake. He said the researchers boated out onto the subarctic lake to collect the samples.
"We basically shoved tubes into the mud," said Pompeani. "It's essentially the same thing as putting a straw in a slushie, and putting your finger on top of the straw, and then pulling up the straw, and you have a 'core' of the slushie."
Comparing Ancient Climate Shifts to Modern Changes
Pompeani said the study is one part of a larger project to compare the "unprecedented" climate changes now taking place in the Arctic with natural fluctuations that happened in millennia past.
"We want to know what it takes to cause megadroughts to happen," said Pompeani. "What do you have to tweak in the climate system, whether it be natural or man-made, and if you tweak something a little bit, what kind of changes will happen?"
The National Science Foundation funds the studies under the Holocene Climate Project, which focuses on the Alaska/Yukon area as well as the islands of Baffin, Greenland, and Iceland in the northwestern Atlantic Ocean. The project is managed by the Arctic Research Consortium of the United States.