It was thought for a long time that the Arctic Ocean is one of the key carbon sinks of the world. However, with climate change, the region may become a major carbon source instead, increasing the greenhouse effect.
A carbon sink is a natural or artificial reservoir that absorbs CO2 from the air and then stores the carbon in organic matter. The most popular example of the sink is a forest. A territory inhabited by trees and plants on land, as well as marine plants and phytoplankton in the oceans may serve absorption of CO2.
For example, official data says that Russian forests are responsible for the annual consumption of 1.6 billion tonnes of CO2. It is said that over 13.8 billion tonnes of carbon are stored in Siberian forests, 10.8 billion in the Far East, and 5.8 billion in the North-West of Russia.
Put simply, a carbon sink means that more carbon goes in than out, making the carbon cycle more one-sided.
Naturally, the Arctic region was seen as a major carbon sink, as the Arctic Ocean itself and the sparse vegetation of the region could store carbon but not emit it back in large amounts. This may have changed recently.
Two major factors have contributed to the fact that the Arctic Ocean is no longer a reliable carbon sink: rising water temperatures and freshwater influx.
The 2020 study shows that despite the rise of CO2 in the air, the stored amount of carbon in the water has decreased. This fact goes against all expectations. The supposed reason for this is that warmer water break the carbon cycle and it is not able to store as much carbon, stimulating further thawing of glaciers and a subsequent change in the water's chemical structure.
The scientific data shows that due to the influx of freshwater, the alkalinity of the water has decreased, which signifies acidification of the water. That, in turn, also decreases the carbon-storing capabilities of the Arctic Ocean.
Joint research by Russian universities, including the Kurchatov Institute, Moscow State University, Northern Federal University, and Tomsk State University shows that CO2-emitting microorganisms react to warmer temperatures and increase their activity in the Barents Sea.
This data was acquired during the Floating University expedition in 2022, which provided valuable scientific data for many fields of research. The 2024 expedition has just set off for the Arctic on 20 July.
In the tundra, the same effect can be seen on CO2-emitting microbes. As more ground is uncovered from ice and permafrost, more microbes are exposed to the sun. The rapid pace of thawing (as high as four times faster than in other parts of the world) only makes the situation more unstable and snowball-like.
In summary, both cases of changes in the ocean and land in the Arctic show a tendency that the region might become a source of greenhouse emissions rather than a safe haven, as was thought before. The photosynthesis processes from scarce vegetation and marine plants may not be enough to offset or somehow balance the activity of microorganisms. This process has been going on for around 15-20 years and will likely enhance in the future.
The issue with studying this problem is that too many factors contribute with different capacities in different places, as was seen in the CO2-emitting Barents, while some other seas absorb more carbon dioxide than they let out. This calls for more research and effort in decreasing greenhouse emissions across the world.
The Editorial Board of the Arctic Century
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