The Kara and Barents seas are proving to be active greenhouse gas sinks

Oceanologists at the Alfred Wegener Institute for Polar and Marine Research (AWI) have discovered a so-called ‘carbon conveyor belt’ in the Barents and Kara Seas. Alfred Wegener Institute (AWI) have discovered that there is a so-called ‘carbon conveyor’ in the Barents and Kara Seas that productively transports carbon to the ocean depths. Thanks to this, both bodies of water capture more than 13.6 million tonnes of CO2 from the atmosphere each year, the equivalent of Iceland’s annual emissions.

“Our observations showed that more than 2,000 tonnes of carbon equivalent, equivalent to 8,500 tonnes of atmospheric carbon dioxide, are on the bottom of these seas every day,” said AWI researcher Andreas Rogge.

In 2018, scientists embarked on the ARCTIC2018 expedition to Russia’s northern shores aboard the research vessel Akademik Treshnikov, during which they tracked a stream of very dense and cold water moving towards the bottom of the Arctic Ocean in the Barents Sea and following it towards the Northern Land and Laptev Sea. Scientists collected water samples along the path of this deep current, and measured the number of organic particles and the speed of the water using special cameras and scientific instruments.

Calculations have unexpectedly shown that this water flow has transported an enormous mass of organics towards the deepest regions of the Arctic Ocean floor. This plume of carbon-rich water extends from the shelf of the Barents and Kara Seas some 1,000 kilometres deep into the Arctic Basin.

Understanding CO2 transport is crucial for predicting global warming. At the surface of the ocean, phytoplankton absorbs CO2 from the atmosphere, eventually sinking deeper. Once the carbon bound in this way enters deep water, it remains there until the current lifts the water back to the ocean surface, which in the Arctic takes several thousand years. And if CO2 remains in deep-sea sediments, it can remain there for millions of years, as only volcanic activity can release it.

Such a ‘carbon conveyor belt’ is capable of absorbing CO2 from the atmosphere for long periods of time. It also provides food for local deep-sea fauna such as starfish, sponges and worms. However, exactly what percentage of the carbon is actually absorbed by the ecosystem can only tell us with further research.

“Due to ongoing global warming, less ice is forming and therefore less benthic water. At the same time, more light and nutrients are becoming available for phytoplankton, allowing them to sequester more CO2. It is therefore currently impossible to predict how this carbon conveyor belt will develop in the future,” says Andreas Rogge.

Cover photo: NASA