New research may have found the key to how the Southern Ocean absorbs carbon dioxide from human activity.
Scientists estimate that as much as 40% of the carbon dioxide absorbed into oceans takes place within the Southern Ocean region.
But until now, they did not understand how this carbon was drawn down from the surface of the ocean to the deep waters beneath.
New research, published in Nature Geoscience, has found that rather than being absorbed uniformly over vast areas into the deep ocean, it is drawn down by plunging currents a thousand kilometres wide.
The researchers, from both the UK and Australia, say deep currents and massive whirlpools that carry warm and cold water around the ocean – known as eddies – create localised pathways (or funnels) for carbon to be stored.
Acting as a carbon sink, as much as 30-50% of the CO2 emitted by human activity is stored in the oceans globally.
This process limits the amount of CO2 in the atmosphere and therefore limits the impacts of climate change.
The researchers say this new study, which used data from 80 floats deployed in the Southern Ocean, will help them to better understand the future effects of climate change.
“The Southern Ocean is a large window by which the atmosphere connects to the interior of the ocean below,” said Dr Jean-Baptiste Sallée from the British Antarctic Survey. “Until now we didn’t know exactly the physical processes of how carbon ends up being stored deep in the ocean.
“Now we have an improved understanding of the mechanisms for carbon draw-down we are better placed to understand the effects of changing climate and future carbon absorption by the ocean.”
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