In a surprising development, the Atlantic Ocean is cooling at an unprecedented rate, leaving scientists scrambling for explanations.

The phenomenon comes after more than a year of record-high global sea temperatures and concerns over the potential collapse of the Atlantic Meridional Overturning Circulation.

Typically, ocean temperatures fluctuate throughout the year. However, the current cooling trend, referred to as the “Atlantic Niña,” is progressing much faster than usual, MSN reports. The pattern appears to be preceding the expected transition to a cooler La Niña phase in the Pacific Ocean. While the drop in temperatures is welcome, it may lead to various weather effects globally.

The Atlantic’s cooling trend marks the end of a 15-month period of unprecedented ocean temperatures. With El Niño conditions dissipating in May and La Niña projected to develop between September and November, cooler waters are expected to be pushed by stronger winds from the equator.

The prospect of simultaneous La Niña events in both the Atlantic and Pacific Oceans has piqued scientific interest. The long-standing record-high temperatures have added to the unpredictability, leaving scientists eager for further data.

Although a La Niña in the Atlantic is not entirely unexpected, its timing has caught many off guard. With the Atlantic cooling rapidly and the Pacific anticipated to follow suit within months, scientists foresee a “tug of war” between the two oceans as they attempt to stabilize their temperatures.