How ocean circulation changed atmospheric CO2
https://www.climatescience.org.au/content/917-how-ocean-circulation-changed-atmospheric-co2#overlay-context=content/257-national[font face=Serif][font size=5] How ocean circulation changed atmospheric CO₂[/font]
Submitted by astone on Thu, 09/24/2015 - 23:19
[font size=3]Scientists have struggled for the past few decades to understand why air temperatures around Antarctica over the past one million years were almost perfectly in synch with atmospheric CO₂ concentrations. Both dipped down during glacial ice ages and back up again during warm interglacials.
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This relationship between Antarctica temperature and CO₂ suggested that somehow the Southern Ocean was pivotal in controlling natural atmospheric CO₂ concentrations, said Dr Maxim Nikurashin from the ARC Centre of Excellence for Climate System Science.
The key that unlocked the mystery was the colder atmosphere and extensive sea ice around Antarctica during the glacial period. Together they fundamentally changed top to bottom ocean circulation and enabled more CO₂ to be drawn from the atmosphere.
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The biological processes that take up carbon from the atmosphere even take place in and under the ice, if that ice is not too thick, which is why the biological processes persisted for a lot longer during cooler periods, the authors said.
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http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2538.html