We've updated our Privacy Policy to make it clearer how we use your personal data. We use cookies to provide you with a better experience. You can read our Cookie Policy here.


As the Arctic Warms, Its Waters Are Emitting Carbon

An iceberg under a stormy sky.
Credit: Jennifer Latuperisa-Andresen/ Unsplash
Listen with
Register for free to listen to this article
Thank you. Listen to this article using the player above.

Want to listen to this article for FREE?

Complete the form below to unlock access to ALL audio articles.

Read time: 2 minutes

Runoff from one of North America’s largest rivers is driving intense carbon dioxide emissions in the Arctic Ocean.

When it comes to influencing climate change, the world’s smallest ocean punches above its weight. It’s been estimated that the cold waters of the Arctic absorb as much as 180 million metric tons of carbon per year – more than three times what New York City emits annually – making it one of Earth’s critical carbon sinks. But recent findings show that thawing permafrost and carbon-rich runoff from Canada’s Mackenzie River trigger part of the Arctic Ocean to release more carbon dioxide (CO2) than it absorbs.

The study, published earlier this year, explores how scientists are using state-of-the-art computer modeling to study rivers such as the Mackenzie, which flows into a region of the Arctic Ocean called the Beaufort Sea. Like many parts of the Arctic, the Mackenzie River and its delta have faced significantly warmer temperatures in recent years across all seasons, leading to more melting and thawing of waterways and landscapes.

In this marshy corner of Canada’s Northwest Territories, the continent’s second largest river system ends a thousand-mile journey that begins near Alberta. Along the way, the river acts as a conveyor belt for mineral nutrients as well as organic and inorganic matter. That material drains into the Beaufort Sea as a soup of dissolved carbon and sediment. Some of the carbon is eventually released, or outgassed, into the atmosphere by natural processes.

Scientists have thought of the southeastern Beaufort Sea as a weak-to-moderate CO2 sink, meaning it absorbs more of the greenhouse gas than it releases. But there has been great uncertainty due to a lack of data from the remote region.

To fill that void, the study team adapted a global ocean biogeochemical model called ECCO-Darwin, which was developed at NASA’s Jet Propulsion Laboratory in Southern California and the Massachusetts Institute of Technology in Cambridge. The model assimilates nearly all available ocean observations collected for more than two decades by sea- and satellite-based instruments (sea level observations from the Jason-series altimeters, for example, and ocean-bottom pressure from the GRACE and GRACE Follow-On missions).

The scientists used the model to simulate the discharge of fresh water and the elements and compounds it carries – including carbon, nitrogen, and silica – across nearly 20 years (from 2000 to 2019).

Want more breaking news?

Subscribe to Technology Networks’ daily newsletter, delivering breaking science news straight to your inbox every day.

Subscribe For FREE
The researchers, from France, the U.S., and Canada, found that the river discharge was triggering such intense outgassing in the southeastern Beaufort Sea that it tipped the carbon balance, leading to a net CO2 release of 0.13 million metric tons per year – roughly equivalent to the annual emissions from 28,000 gasoline-powered cars. The release of CO2 into the atmosphere varied between seasons, being more pronounced in warmer months, when river discharge was high and there was less sea ice to cover and trap the gas.

Ground Zero for Climate Change

Scientists have for decades studied how carbon cycles between the open ocean and atmosphere, a process called air-sea CO2 flux. However, the observational record is sparse along the coastal fringes of the Arctic, where the terrain, sea ice, and long polar nights can make long-term monitoring and experiments challenging.

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

Reference: Bertin C, Carroll D, Menemenlis D, et al. Biogeochemical river runoff drives intense coastal Arctic ocean CO2 outgassing. Geophys Res Lett. 2023;50(8):e2022GL102377. doi: 10.1029/2022GL102377

This article has been republished from the following materials. Note: material may have been edited for length and content. For further information, please contact the cited source.