The Gulf Stream plays a significant role in maintaining the climate of the US East Coast and Western Europe. “We conclude with a high degree of confidence that Gulf Stream transport has indeed slowed by about 4% in the past 40 years.” The full study is Here
The consequences are unpredictable. More extreme weather is about the only certainty.
The energy of the heat transfer will not just be missing in Europe. It’ll also be in excess in the Caribbeans, perhaps creating stronger winds worldwide.
Imagine a house with water radiators, where you turn off the circulation pump while keeping the furnace on full blast. It’s gotta go somewhere.
Read the article in my above comment. it could throw Europe into another ice age, and cause mass starvation. Not to mention the AMOC feeds plankton which is the basis for all of sea life food-webs and so the ripples of this could be very very vast.