There has been a lot of speculation that the whole AMOC (otherwise known as the Gulf Stream), could come to a halt. The AMOC brings warm water to Europe from the equator, and when it stops flowing that will lead to a mini-ice age in Europe with winter temperatures dropping by 10-30C. While scientists are 98% certain that the AMOC will stop flowing by 2100, recent studies suggest that the collapse could come as soon as this year, or at least in the next few decades.
The ICM report warns that the reversal of the DWBC [Deep Western Boundary Current] could also unleash vast amounts of carbon dioxide currently trapped in deep-ocean reservoirs. The reversal will undermine the ocean’s role as a carbon sink, which currently absorbs about 25% of all anthropogenic CO₂ emissions.