On the Vital Importance of Southern Ocean Antarctic Circumpolar Current (ACC) in our Climate System
Paul Beckwith Paul Beckwith
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 Published On Apr 1, 2024

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A fascinating peer-reviewed scientific paper was just published on how the Antarctic Circumpolar Current (ACC) has changed over the past 5.3 million years.

This massive and profoundly important ocean current system transports between 165 and 182 Sverdrup’s of water which is over 100 times more than the combined flow rate of all the rivers on our planet. One Sverdrup is a million cubic meters of water per second, so the ACC is of vital importance for heat flow on our planet.

Basically, the ACC flow has increased as our planet continues to warm at accelerated rates.

Links:

1) Key Ocean Current Contains a Warning on Climate: https://news.climate.columbia.edu/202...

2) Google Earth

3) Earth Nullschool

4) Where is Point Nemo?: https://oceanservice.noaa.gov/facts/n....

5) Dynamics of Pacific Antarctic Circumpolar Current: https://iodp.tamu.edu/scienceops/expe...

6) ANDRILL (ANtarctic DRILLing Project): https://en.wikipedia.org/wiki/ANDRILL

7) Explainer: how the Antarctic Circumpolar Current helps keep Antarctica frozen: https://theconversation.com/explainer...

8) Open Source Peer Reviewed Scientific Paper: Five million years of Antarctic Circumpolar Current strength variability: https://www.nature.com/articles/s4158...

“Abstract
The Antarctic Circumpolar Current (ACC) represents the world’s largest ocean-current system and affects global ocean circulation, climate and Antarctic ice-sheet stability. Today, ACC dynamics are controlled by atmospheric forcing, oceanic density gradients and eddy activity. Whereas palaeoceanographic reconstructions exhibit regional heterogeneity in ACC position and strength over Pleistocene glacial–interglacial cycles, the long-term evolution of the ACC is poorly known. Here we document changes in ACC strength from sediment cores in the Pacific Southern Ocean. We find no linear long-term trend in ACC flow since 5.3 million years ago (Ma), in contrast to global cooling and increasing global ice volume. Instead, we observe a reversal on a million-year timescale, from increasing ACC strength during Pliocene global cooling to a subsequent decrease with further Early Pleistocene cooling. This shift in the ACC regime coincided with a Southern Ocean reconfiguration that altered the sensitivity of the ACC to atmospheric and oceanic forcings. We find ACC strength changes
to be closely linked to 400,000-year eccentricity cycles, probably originating from modulation of precessional changes in the South Pacific jet stream linked to tropical Pacific temperature variability. A persistent link between weaker ACC flow, equatorward-shifted opal deposition and reduced atmospheric CO2 during glacial periods first emerged during the Mid-Pleistocene Transition (MPT). The strongest ACC flow occurred during warmer-than-present intervals of the Plio-Pleistocene, providing evidence of potentially increasing ACC flow with future climate warming.”

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