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480 points riffraff | 1 comments | | HN request time: 0.273s | source
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taylorlapeyre ◴[] No.44461488[source]
The deep-ocean vent south of Antarctica is real but small, on the order of a few-tenths Pg C yr⁻¹. The claim that it could double atmospheric CO₂ exaggerates the flux by three orders of magnitude relative to observed values and known physical limits.

The most optimistic estimate of deep-water outgassing south of 60 ° S is 0.36 Pg C yr⁻¹. Even if that rate tripled and persisted unabated, it would take more than 800 years to add 895 Pg C (which would be what it would require to justify the press release’s claims of “doubling”)

What the salinity reversal can do is:

- Expose ice shelves to warmer subsurface water, accelerating sea-level rise.

- Reduce the Southern Ocean’s role as a sink by a few tenths Pg C yr⁻¹, nudging the global ocean sink (~2.7 Pg C yr⁻¹) downward.

- Perturb atmospheric circulation patterns, with knock-on effects for the Atlantic overturning (but those links remain speculative).

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1. mturmon ◴[] No.44461661[source]
I read TFA and looked over the PNAS article (https://www.pnas.org/doi/10.1073/pnas.2500440122) it is based on.

I believe the deep-ocean vents you mention are beside the point. The article is discussing the upwelling of cold, CO2-rich water in the Southern Ocean - not emissions from vents.

Also, it’s worth noting that the PNAS article does not mention CO2 per se, only upwelling. The article summary of the press release does draw the CO2 connection.

Besides the connections you mention, the PNAS article points out that this result illustrates that current models of ice/ocean interaction are not producing these observational trends.