Thanks a lot! We look at the global ocean, so we didn't check whether AABW might counteract this, but the net effect is to recuce carbon uptake. The main difference to LGM studies is that we have emissions scenarios, so the downwelling water is relatively more carbon-rich than the upwelling water.

thanks!

[11/11]

Of interest? @ayeshatandon.carbonbrief.org @daisydunne.carbonbrief.org @klimareporter.bsky.social @fionaharvey.bsky.social @jonathan-watts.bsky.social @dpcarrington.bsky.social @muellerjung.bsky.social @sventitz.bsky.social @jonaswaack.bsky.social @fischblog.bsky.social @revkin.bsky.social

[10/11]

📖 If you are still curious, check out the news items by the CEN research center @cenunihh.bsky.social of the University of Hamburg @uni-hamburg.de and the Max Planck Institute for Meteorology (mas.to/@MPI_Meteo@w...).

[9/11] Where to go from here?

With one more impact channel of AMOC weakening - probably not the most relevant - the picture already changes quite a bit.

A lot of other impacts remain, and we should research them if we want to properly understand the risks that are associated with a changing AMOC.

[8/11]

The SCC is raised by about 1% because of the AMOC carbon feedback (right panel).

This is of similar magnitude, but of opposite sign, to the previous economic impact estimates of AMOC weakening (left panel):

[7/11] What do we find? Economic impacts

Looking at the additional (Burke) economic damages induced by this feedback, we estimate numbers in the range of trillion US dollars, cumulated over this century.

But the more important economic indicator is the social cost of carbon (SCC).

[6/11]

But the cumulative effect for this century is - depending on the projection of AMOC strength - between 4 and 12 PgC.

For context: Every year we emit around 10 PgC, so by 2100, AMOC weakening could reduce ocean storage by up to a full year of current emissions to the atmosphere.

[5/11] What do we find? Carbon cycle impacts

We find that, in a year with a 1 Sv weaker AMOC, 0.023 PgC less will flow into the ocean. That doesn't sound like much, maybe 0.2% of current anthropogenic CO2 emissions.

[4/11] How do we do it?

Our methods in a cartoon:

a) freshwater hosing in a biogeochemically-only coupled ESM
b) yearly carbon flux changes as a function of yearly AMOC strength
c) cumulative carbon flux reductions in the 21st century following CMIP6 AMOC projections
d) changes in SCC estimates

[3/11]

But what about all the other climate impacts that AMOC weakening would have, beyond just surface temperatures?

They have yet to be integrated into economic impact assessments, and we start by looking at the carbon cycle.

[2/11] Why is this relevant?

Existing economic impact estimates deem AMOC weakening globally beneficial. Why?

Because a weaker AMOC would reduce temperatures in the Northern Hemisphere and thereby locally offset parts of global warming and the associated economic damages.