Researchers dig into Canadian North to understand carbon storage in permafrost

Scientists have long suspected thawing permafrost is bad news for the environment.

A new study, recently published in Nature Communications, looks to understand how carbon locked in the frozen ground is released into the atmosphere by studying core samples from across northern Canada.

"This study has really augmented the knowledge of the permafrost carbon pools across a large swath of Canada that was previously ... never examined before," said Melissa Lafrenire, the study's principal investigator. The study was written and led by Julien Fouch with Queen's University.

When carbon in the soil is converted to carbon dioxideit can contribute to climate warming, saidLafrenire.

The study found carbon is not only being released in the thawing soil, it's also ending up in water andpotentially beingflushed into lakes and rivers where it's quickly broken down into carbon dioxide.

Twenty-five core samples were taken from nine regions across Canada, including the High Arctic, Churchill, Man., Nunavik, Que., Daring Lake, N.W.T., and Baker Creek in Yukon, near the Alaska border.

The landscape ranges from boreal forest to peatlands to tundra vegetation.

The sample size is small, but Lafrenire says when it comes to calculating how much carbon is stored in permafrost globally, few samples come from within Arctic Canada.

"There is a major gap in the knowledge," said Lafrenire, including understanding the potential for carbon in thawing permafrost to be released and eventually end upinlakes, rivers and the atmosphere.

"This new research helps fill that gap," she said.

Like tea seeping from a teabag

The study focused on permafrost up to three meters deep in the ground.

It found higher levels of carbon and nutrients such as nitrogen in areas one to two metres deep the areas "most vulnerable" to thawing, said Lafrenire.

When the carbon-rich soil mixes with water, that soil breaks down into smaller pieces and can potentially move into aquatic systems, such as lakes and rivers, like tea seeping from a teabag, said Lafrenire.

This dissolved organic matteris more easily digested by microorganisms, such as bacteria and fungi, she said. When microorganisms eat that matter, it'sbroken down and carbon dioxide is released, said Lafrenire.

"It's just further proof really of the potential for permafrost to fuel this positive feedback," she said.

The Northwest Territories has some of the most ice-rich permafrost in Canada, said Ashley Rudy, a permafrost geotechnical data scientist who studies landslides from permafrost degradation and infrastructure corridors across the N.W.T.

She's observed tea-coloured water in lakes while flying over the Central Mackenzie Valley region of the N.W.T., more evidence that dissolved organic carbon is getting into the water system.

"We know that this area is accelerating in respect to permafrost degradation"due to the thaw of ice-rich permafrost, said Rudy.

"It's warming at a quicker rate," she said. "We're seeing evidence of degradation, landslides, all this change every year."

Understanding how and why these changes are happening is critical in planning and adapting, said Rudy.

The study did not make predictions for how much total carbon in permafrost could be released into the atmosphere in Canada.

But theamount of carbon in the shallow permafrostthat could be dissolved and carried by water upon thawingcould be around 10 to 40times the annual carbon emitted as carbon dioxide in Canada, said Lafrenire.

"This is going to potentially fuel even more rapid climate change," she said. "It's important to understand these systems so we can adapt and mitigate appropriately."