[taylorlapeyre]

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).

[mturmon]

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.

[gus_massa]

Just to confirm, Does "Pg C yr⁻¹" mean "Peta grams Carbon per Year"?

It's the mass of only "C" or the mass of "CO2"? (There is like a x3 difference, 12 vs 44. Probably not very relevant, but I'd like to understand the meaning correctly.)

[WithinReason]

And why petagram instead of the more common gigaton?

[vertnerd]

Where, exactly, is this deep-ocean vent south of Antarctica. I checked my map but couldn't find anything south of Antarctica at all.

[cwmoore]

Northern Antarctica lol

[dang]

(This was originally a reply to https://news.ycombinator.com/item?id=44461309, but we downweighted that subthread. Since this is a fine comment, I detached it so it wouldn't share the same fate.)

[ImaCake]

Thanks for the clarification, these click-bait titles pop up again and again around very interesting technical climate science, causing not only pointless panic but allowing denialists to drive doubt by pointing out the BS.

Its doubly frustrating because these studies invariably indicate that climate change is happening, getting worse, and triggering feedback loops that amplify CO2.

[cedilla]

Isn't a bit premature to jump to "it's BS" just because one random commenter on some forum says it's wrong?

Journalists make lots of mistake, and it's good to keep that in mind, but random people in forums are even worse.

[vixen99]

I won't put words in your mouth but given what you say - doesn't this imply calamity? So how do we explain why Net Zero is essentially collapsing? Why do a number of countries say one thing and do another? There's certainly no consensus that survival is at stake.

[irthomasthomas]

As water is more dense than ice, wouldn't the sea level drop when the ice shelf melts?

[_fizz_buzz_]

Floating ice will displace exactly as much water as it does when it melts to water. Ice that melts on a land mess such as Greenland and Antarctica will raise the ocean level when it melts.

[Matumio]

Only one way to find out... float some ice cubes in a glass of water and observe.

(Edit: I'm back to report the results. There was either no change in the water level, or a change below my measurement tolerance ;)

(Edit2: Here is a more serious take of that experiment: https://skepticalscience.com/Sea-level-rise-due-to-floating-...)

[Avshalom]

Not sea ice obviously but there are places where sea level is "dropping" https://en.m.wikipedia.org/wiki/Post-glacial_rebound