Atlantic ocean currents are weakening — and it could make the climate in some regions unrecognizable

A "warming hole" in the North Atlantic has baffled scientists for decades .

It was colder between 1901 and 2021 than during the late 1800s , even as the seas around it became warmer.

The warming hole is one piece of evidence suggesting the AMOC has already weakened.

Weaker currents could unleash freezing weather in parts of Europe , exacerbate sea level rise along the U.S. East Coast .

Cooling in the North Atlantic and Northwest Europe could offset some of the warming from climate change.

The amount of cooling will depend on how much strength the AMOC loses.

As the Northern Hemisphere cools, tropical and subtropical regions could also be thrown into chaos.

A 50% reduction would be far more substantial of an impact on regional climate, Marsh said.

Researchers say the AMOC will weaken significantly before 2100 , but pinpointing exactly when the biggest change will happen is tricky.

North Atlantic sediments from the last ice age ( 120,000 to 11,500 years ago ) suggest that abrupt shifts in climate linked to AMOC have occurred in the past.