In February, 2021 it was reported that never before in over 1000 years had the Atlantic Meridional Overturning Circulation (AMOC or Gulf Stream System), been as weak as in the last decades. It seems likely that its weakening during the last century is associated with loss of dynamical stability implying that the AMOC has approached its critical threshold, beyond which a substantial and, in practice, likely irreversible transition to the weak mode could occur with severe consequences. And now researchers believe it could completely shut down by 2300, causing disaster to the marine ecosystem on much of the planet. The ocean’s ability to remove CO2 from the atmosphere would be severely limited, intensifying and extending climate change. Over time nutrients supporting marine ecosystems would increasingly become trapped in the deep ocean, leading to declining global-ocean biological productivity. Reducing greenhouse gas emissions now could prevent this complete shutdown of the deep circulation in the future.
www.sciencedaily.com/releases/2021/02/210225113357.htm
www.sciencedaily.com/releases/2021/08/210805115420.htm
news.uci.edu/2023/01/04/climate-change-could-cause-disaster-in-the-worlds-oceans-say-uc-irvine-scientists/
According to the article, very significant (i.e., seriously bad) impacts are expected well before 2300:
**”If we continue to drive global warming, the Gulf Stream System will weaken further — by 34 to 45 percent by 2100 according to the latest generation of climate models,” concludes Rahmstorf. This could bring us dangerously close to the tipping point at which the flow becomes unstable.**
The destabilization and weakening of the Gulf Stream contributes to more rapid sea level rise on the U.S. East Coast and to more extreme weather patterns (storms, drought) in the UK and elsewhere on the east side of the Artlantic.