Sea-level rise causing frozen grounds along Arctic coastlines to thaw, study suggests

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In a new study, researchers at Dalhousie University have found that sea-level rise is causing permafrost along Arctic coastlines “to thaw and retreat,” threatening northern ecosystems.

Permafrost, which is any ground that remains completely frozen — 0 C or colder — for at least two years straight, plays an important role in stabilizing coastlines.

According to NASA, these permanently frozen grounds are most common in regions with high mountains and in Earth’s higher latitudes — near the North and South poles.

They help regulate groundwater flow and lock carbon and greenhouse gases in the sediment.

“Sea-level rise is causing saltwater to move into terrestrial environments and freshwater reservoirs along coastlines around the world — a concerning phenomenon that has been studied extensively,” Alison Auld, the senior research reporter, said in a release.

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“Little is known, however, about how this saltwater intrusion affects high-latitude permafrost environments like the Arctic.”

By studying how sea-level rise affects these environments, researchers will gain a better understanding of how climate change is impacting Arctic ecosystems and communities.

Julia Guimond, a National Science Foundation postdoctoral fellow in Dal’s department of civil and resource engineering and lead author of the paper, said permafrost thaw may have potential implications for coastal infrastructure.

“The presence of permafrost can impact the stability of the land. And so … this loss of permafrost can trigger fast slumps or increased erosion in these areas that are already experiencing really rapid erosion,” said Guimond.

“So just heightening the vulnerability of coastal communities, coastal infrastructure that’s now on land, that’s not held stable by permafrost.”

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In addition, she explained that saltwater intrusion triggering permafrost thaw can also have implications for global warming.

“Permafrost literally holds tons of carbon in the sediments. And so any time you find another driver of permafrost thaw, which we’re showing that sea-level rise can trigger thaw, you get the release of carbon into the environment,” Guimond said.

Despite these concerning implications, Guimond said she’s generally an optimistic person.

Being in it every day and seeing the science that happens and the brilliance of colleagues and the creativity, I have to have hope.”

Guimond said what’s worrisome is the “feedback,” which is the effect that change in one part of an ecosystem has on another, that researchers don’t fully understand yet.

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“When you think about a changing climate, what we’ve shown in this study is that here is just yet another potential feedback where you have sea-level rise driving permafrost thaw,” she said.

So her hope is to draw attention to these dynamic coastal systems.

“The natural world is filled with so many feedbacks that have potential potentially large implications for global climate and sort of the trajectory that we’re facing in the coming years.”

You can read the full study online.

Guimond said that “any opinions, findings, and conclusions, or recommendations expressed in the study or in this interview are those of the author and do not necessarily reflect the views of the National Science Foundation.”

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