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.
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).
2023-12-21 21:00:03
Post from phys.org rnrn