How Ocean Circulation Changed Atmospheric CO2
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.
(From Science Daily) — Both dipped down during glacial ice ages and back up again during warm interglacials. By contrast, temperatures in the tropics and Northern Hemisphere were less closely tied to atmospheric CO2 concentrations.
“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.”
The researchers found that during glacial periods when the atmosphere was colder and sea ice was far more extensive, deep ocean waters came to the surface much further north of the Antarctic continent than they do today.
Read the full article here: http://www.sciencedaily.com/releases/2015/09/150928123434.htm