Lakes document and contribute to climate change


Lakes and reservoirs play an often overlooked role in climate change.


Credit: Wing-Chi Poon

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Lakes, reservoirs and other inland waters hold a wealth of information about past climate changes, while contributing to global warming themselves, researchers have found.

Lakes are particularly important in unveiling climate history because their sediments store signs of prehistoric fluctuations, and although the world’s 304 million lakes cover only a tiny portion of the Earth’s surface, they are also important contributors to greenhouse gas emissions, said biogeochemist David Schindler, co-author of the work published this week in the US journal Science.

"They release at least as much carbon as the oceans sequester," said Schindler, from the University of Alberta in Edmonton, Canada.

Inland waters receive four times as much carbon as the world's oceans do, and release about half of it back into the atmosphere. This makes them important to greenhouse emissions, and yet they are often not considered in global climate models, Schindler said.

"Incorporating lakes [into climate models] will cause huge changes to global carbon dynamics... Warming could be much faster and last much longer than previously predicted."

As well as being important sinks and sources of carbon, lakes have another important role to play: "They contain libraries of fossils in lake muds...they record fires, changes in vegetation, changes in species of algae," Schindler said.

In dry times, salt-tolerant algae thrive, while in wetter periods, other species are more common – changes that are reflected in the fossil record at the bottom of a lake.

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