Discovering the Arctic Carbon Conveyor Belt – ScienceDaily

Each year, the trans-shelf transport of carbon-rich particles from the Barents and Kara Seas can bind up to 3.6 million metric tons of carbon dioxide.2 In the depths of the Arctic seas for thousands of years. In this region alone, a previously unknown transport route uses the biological carbon pump and ocean currents to absorb atmospheric carbon dioxide.2 on a measure of Iceland’s total annual emissions, as reported by researchers from the Alfred Wegener Institute and partner institutes in the current issue of the journal Natural Earth Sciences.

Compared to other oceans, the biological productivity of the central Arctic Ocean is limited, since sunlight is often scarce – either because of the polar night or because of the sea ice cover – and available nutrient sources are scarce. Thus, microalgae (phytoplankton) in upper water layers have less access to energy than their counterparts in other waters. As such, it came as a great surprise when large amounts of particulate matter – that is, stored in plant remains – were discovered in the ARCTIC2018 mission in August and September 2018 aboard the Russian research vessel Akademik Tryoshnikov in the Nansen Basin in the central Arctic. Subsequent analyzes revealed a water mass with large amounts of carbon particles to depths of up to 2 km, composed of bottom waters from the Barents Sea. The latter results when sea ice forms in winter, then sinks cold, heavy water, which then flows from the shallow coastal shelf down the continental slope into the deep Arctic basin.

“Based on our measurements, we calculated that through this water mass transfer, more than 2,000 metric tons of carbon flow into the Arctic deep seas per day, equivalent to 8,500 metric tons of carbon dioxide in the atmosphere.2. The total annual amount of carbon dioxide detected was extrapolated to 13.6 million metric tons2which is the same measure as Iceland’s total annual emissions,” explains Dr. Andreas Ruge, first author of Natural Earth Sciences Study and oceanographer at the Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research (AWI). This carbon-rich water column extends from the shelf of the Barents and Kara Seas to nearly 1,000 kilometers into the Arctic Basin. In light of this newly discovered mechanism, the Barents Sea – already known to be the most productive marginal sea in the Arctic – appears to effectively remove approximately 30 percent more carbon than previously thought. Moreover, model-based simulations determined that outflow manifests itself in seasonal pulses, because in Arctic coastal seas, CO uptake is2 By phytoplankton occurs only in the summer.

Understanding the transport and transformation processes within the carbon cycle is essential for establishing global carbon dioxide budgets, and therefore also global warming projections. Unicellular algae absorb carbon dioxide at the ocean surface2 from the atmosphere and sink to the depths of the sea as they age. Once the carbon bound in this way reaches deeper waters, it stays there until an inversion of currents returns the water to the ocean’s surface, which takes many thousands of years in the Arctic. And if carbon is deposited in deep-sea sediments, it can even be trapped there for millions of years, as only volcanic activity can release it. This process, also known as the biological carbon pump, can remove carbon from the atmosphere for long periods of time and represents a vital sink in our planet’s carbon cycle. The process also serves as a food source for native deep-sea animals such as sea stars, sponges, and worms. What percentage of carbon an ecosystem actually absorbs is something only more research can tell us.

The seas of the polar shelf harbor other, largely unexplored areas where benthic waters form and flow into the deep sea. As such, it can be assumed that the global impact of this mechanism as a carbon sink is actually much greater. “However, due to continued global warming, less ice is being formed and thus less bottom water. At the same time, more light and nutrients are available to phytoplankton, which allows more carbon dioxide to pass through.2 to be binding. Accordingly, it is currently impossible to predict how this carbon sink will evolve, and identification of potential tipping points urgently requires additional research,” says Andreas Ruge.

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