A recent study found that intense carbon dioxide emissions in the Arctic Ocean are being caused by runoff from one of the largest rivers in North America.

The Arctic is one of Earth’s most important carbon sinks; estimates place its annual carbon absorption at up to 180 million metric tons, more than three times the amount that New York City emits. However, new research indicates that thawing permafrost and carbon-rich runoff from the Mackenzie River in Canada cause a portion of the Arctic Ocean to release more carbon dioxide than it takes in.

The study looks at how researchers are utilizing cutting-edge computer modeling to study rivers like the Mackenzie, which empties into the Beaufort Sea, a section of the Arctic Ocean. The Mackenzie River and its delta, like many other Arctic regions, have experienced exceptionally high temperatures in recent years during all seasons, which has caused more waterways and landscapes to melt and thaw.

The southeast Beaufort Sea is considered by scientists to be a weak-to-moderate sink of carbon dioxide, meaning that it takes in more of the gas than it emits. However, a dearth of information from the far-off area has led to a great deal of uncertainty.

The study team filled that gap by adapting the global ocean biogeochemical model known as ECCO-Darwin, which was created at the Massachusetts Institute of Technology in Cambridge and NASA’s Jet Propulsion Laboratory in Southern California.

Researchers from the United States, France, and Canada discovered that the river discharge was causing the southeastern Beaufort Sea to experience such intense outgassing that it tipped the carbon balance, resulting in a net release of 0.13 million metric tons of CO2 annually. This is approximately the same as the yearly emissions produced by 28,000 cars running on gasoline. Seasons affected how much CO2 was released into the atmosphere; during warmer months, when river discharge was higher and there was less sea ice to cover and trap the gas, the release was more noticeable.

Lead author Clément Bertin is a scientist at Littoral Environnement et Sociétés in France. “With our model, we are trying to explore the real contribution of the coastal peripheries and rivers to the Arctic carbon cycle,” Bertin stated.

These kinds of insights are vital because coastal waters, which form the complex embrace where land meets sea, make up approximately half of the Arctic Ocean’s area. Furthermore, even though the study’s focus was a specific area of the Arctic Ocean, it can still be used to illustrate a bigger picture of the region’s ongoing environmental change.