Also covered in the Guardian today, the letter itself starts with a fairly stark plot of what happens after the AMOC collapses.
Recent research since the last IPCC report does suggest that the IPCC has underestimated this risk and that the passing of this tipping point is a serious possibility already in the next few decades.
The paper cites the work by the Ditlevsens et al. last year, already noted on the BBS. Rahmstorf’s recent work is also cited, a paper that I found easy to read and fairly alarming.
Of the latest model generation (CMIP6), in four out of the 35 models, subpolar gyre convection breaks down—and all four are in the group of the 11 best models in terms of reproducing the vertical density profiles in the subpolar gyre (Swingedouw et al., 2021). That’s in 36% of those high-quality models. In the previous model generation (CMIP5), that number was 45%. What’s more, it typically happens as soon as the year 2040 and for moderate emission scenarios—even without properly accounting for Greenland melt.
