Overview
- A May study led by Stefan Rahmstorf found that changes in ocean heat transport tied to the Atlantic meridional overturning circulation are the most likely explanation for the persistent cold patch south of Greenland.
- Climate models and new simulations forecast a continued AMOC decline this century with the cold blob’s largest temperature shift projected in some runs by around 2067.
- Melting from the Greenland ice sheet pours cold, fresh water into the subpolar North Atlantic that sits on the surface, reduces salinity-driven sinking and weakens the ocean’s conveyor that moves warm water north.
- A weaker AMOC and the cold blob can alter the jet stream to produce more frequent cold snaps and shifted seasonal patterns in Europe while also increasing the risk of extreme summer heat and disrupting fisheries and marine food webs.
- Scientists warn that direct ocean records are short (about 25 to 30 years), a sudden AMOC collapse is seen as low probability but very high impact, and cutting greenhouse gas emissions is the only known way to lower the risk.