Glacial rivers absorb carbon faster than rainforests, scientists find

(The Guardian, 25 Oct 2019) ‘Total surprise’ discovery overturns conventional understanding of rivers.

In the turbid, frigid waters roaring from the glaciers of Canada’s high Arctic, researchers have made a surprising discovery: for decades, the northern rivers secretly pulled carbon dioxide from the atmosphere at a rate faster than the Amazon rainforest.

The findings, published in the Proceedings of the National Academy of Sciences, flip the conventional understanding of rivers, which are largely viewed as sources of carbon emissions.

“It was a total surprise,” said Dr Kyra St Pierre, a biologist at the University of British Columbia and lead researcher on the project. “Given what we know about the rivers though … the findings are intuitive when you think about it. But we were initially very surprised to see what we did.”

The discovery came from time spent collecting meltwater samples on Ellesmere Island, in Canada’s Nunavut territory, where several glaciers flow into Lake Hazen. The team of researchers also gathered samples in the Rocky Mountains and Greenland.

“We have a pretty good understanding of the state of glaciers globally,” said St Pierre. “One thing we don’t know much about is the meltwaters and what happens when it … flows into rivers and downstream lakes.”

In temperate rivers, a bounty of organic material – plant life and fish – results in higher levels of decomposition, meaning the bodies of water emit a far greater amount of carbon dioxide into the atmosphere than they absorb.

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The Guardian, 25 Oct 2019: Glacial rivers absorb carbon faster than rainforests, scientists find