Yep you're right! But net zero is compatible (and driven) with a significant release of young physosynthetic oxygen to the atmosphere. Which we are breathing! So I think both things make sense and we should be advocating for the importance that that has

The ocean is not a net source of oxygen to the atmosphere. But... primary producers at the surface need to release a non-negligible fraction of the oxygen they produce to air in order to compensate for the upwelling of oxygen depleted waters. I think makes our both viewpoints compatible:)

There is no need to burry organic matter in the sea floor to lock carbon away from the atmosphere. Organic matter remineralised within the water column is locked in as inorganic carbon, until circulation and mixing bring it back to the surface. The same goes for oxygen, the other way round

Most of respiration happens at the surface, but a non negligible fraction of respiration (10-20%?) occurs in the ocean interior. There, oxygen is depleted from water and can't get back in straight away. Therefore, there is a net release of oxygen to air. Maybe it is 10-20%×50%=5-10%. But not zero!

I disagree on the net zero claim. The bulk of the ocean is depleted in oxygen (oxygen concentration is below atmospheric equilibrium). This is because photosynthesis happens close to the surface, where oxygen leaves to the atmosphere.

@aguadvances.bsky.social

[7/7] Our results shed new light on the intricate nature of SAMWs, helping to predict and understand their role in slowing down future climate change.

[6/7] Subtropical source waters release heat into the atmosphere, whilst Antarctic waters absorb heat. Because of their different relative contribution to Indian and Pacific SAMWs, these SAMW pools play a different role in the climate system, as sources and sinks of atmospheric heat, respectively.

[5/7] Subtropical waters are the main precursor of Indian Ocean SAMWs (70%) but contribute a smaller amount (<40%) to Pacific SAMWs, which are mainly sourced from the upwelled CDW.

[4/7] We found that both subtropical and Antarctic sources contribute to SAMW formation and strong inter‐basin contrasts in their contributions, between the Indian and Pacific SAMW pools.

[3/7] We performed a flow-tracking experiment with a Southern Ocean model (B-SOSE) to address a long standing question about SAMWs: the extent to which they originate from southward‐flowing subtropical waters vs northward‐flowing Antarctic waters sourced by Circumpolar Deep Water (CDW) upwelling.

[2/7] Sub-Antarctic Mode Waters (SAMWs) form in the Southern Ocean, north of the Antarctic Circumpolar Current. These water masses are critical for the climate system, absorbing -and holding away from the atmosphere- vast amounts of anthropogenic heat and carbon dioxide.

Great to have you onboard @gaelforget.net!