Arctic island under threat

YUKON — Researchers are looking toward Herschel Island, the northernmost point of Yukon, to understand how coastal erosion is contributing to the release of carbon dioxide into the atmosphere.

Erosion across Arctic coastlines could be the sleeping giant of carbon dioxide release, which, in turn, leads to a warmer planet.

Herschel, a 116-squarekilometre island made up of mostly permafrost, is receding by about one metre per year, said Hugues Lantuit, a researcher with the Alfred Wegener Institute for Polar and Ocean Research.

On one stretch of the island, which is located off the Yukon coast in the Beaufort Sea, researchers believe erosion is happening at up to 15 metres per year.

“We see that for the entire coast of the Yukon,” Lantuit said.

This makes it an ideal place to research the relationship between permafrost erosion and carbon dioxide production.

Permafrost holds huge stores of carbon — it’s made up of layers of compounded plant and animal matter that’s been encased in the icesediment mix for thousands of years. In a frozen state, this carbon-rich matter doesn’t decay to create carbon dioxide. But as permafrost meets warmer temperatures and crashing waves, a thaw follows, allowing carbon dioxide to be produced.

Along the coast and in nearshore waters, this production is happening at a faster rate than on land, researchers have found.

By 2100, carbon dioxide that’s likely to be produced from thawing permafrost across the circumpolar Arctic could contribute 0.3 degrees to global warming, Lantuit told The Narwhal. This estimate doesn’t even include the possible release of carbon dioxide from coastal erosion.

The United Nations Intergovernmental Panel on Climate Change report doesn’t account for carbon dioxide released by permafrost in general, Lantuit added. That report, released in 2018, says that warming must not exceed 1.5 degrees in order to stem more extreme weather, rising sea levels and poverty.

To understand the levels of carbon dioxide released from the eroding coastlines,

Lantuit’s team mixed samples of permafrost from Herschel Island with seawater and left them to degrade for four months. The goal was to simulate the natural environment and process of erosion in the area.

From this, researchers found a 50 per cent increase of carbon dioxide production in samples left at 4 C and a 15 per cent increase in samples at 16 C, compared to permafrost samples not mixed with seawater, simulating inshore conditions, explained George Tanski, a colleague of Lantuit’s and lead author of the study.