The Atlantic Ocean is cooling at an exponential rate, and nobody is sure why. It’s been more than a year of record-high global sea temperatures, including being close to the collapse of the AMOC. Despite those troubles, though, the Atlantic is now experiencing something quite baffling-temperatures are cooling, and scientists are scrambling to figure out what’s going on.

The ocean typically changes temperature throughout the year. However, this year, scientists say that the emerging “Atlantic Niña” has happened a lot quicker than in the past. The new pattern also appears to be coming ahead of the expected transition to a much cooler La Niña in the Pacific Ocean. While the cooling temperatures are very welcome, they may also cause some different weather effects around the world.

The change in the Atlantic’s cooling rate brings an end to the 15-month streak of record-high ocean temperatures. And with El Niño fading away in May and La Niña set to kick off and develop between September and November, the colder waters will be driven up by stronger winds coming in from along the equator.

It is the potential of two La Niñas that has scientists so intrigued about what the climate and ocean temperatures will look like for the rest of the year, especially since the record-high temperatures have gone on for so long. There’s also a lot of unpredictability here that has left scientists scrambling, too, and while a La Niña in the Atlantic isn’t wholly unexpected, scientists don’t seem to have been expecting it this year.

And with the Atlantic’s cooling rate already speeding up and the Pacific set to start cooling off in the next couple of months, we’re likely going to end up with a bit of a “tug of war” between the two oceans as they fight to cool themselves off, scientists say.