Even as climate change causes sea levels to rise, inundating coastlines, new research suggests it will also cause a periodic drop in sea levels in the tropical southwestern Pacific.

The culprit is El Niño, a cyclical weather pattern triggered by warming ocean surface temperatures. In normal, non-El Niño years, the winds blow towards the west across the tropical Pacific piling up warm surface water in such a way that sea levels are roughly five feet higher near Indonesia than near Ecuador. During an El Niño, however, the winds don’t blow as strongly, allowing Pacific waters, like a pendulum, to shift to the east. In the western Pacific, however, this triggers precipitous, sudden drops in sea levels and tides that last for up to a year.

According to research led by Matthew Widlansky at the International Pacific Research Center, University of Hawaiʻi at Mānoa, El Niño—and its see-saw oceanic effect—will happen more frequently under climate change.

This wouldn’t be a problem if El Niño events were benign, but the sudden drop in sea level exposes the region’s coral reefs leading to their rapid die off. Locals in Samoa, where the drop in levels is most common, call it taimasa after the dank effluvia of coral death. As sea levels rise, El Niño events will become more frequent leading to more taimasa occurrences and hastening the coral’s decline. Slow growing, some coral species add as little as a tenth of an inch a year. In its current configuration, Australia’s Great Barrier Reef took roughly 5,000-6,000 years to form, yet it’s taken humans only thirty years to destroy half of it.

Coral reefs are not just one of the world’s most beautiful ecosystems; they’re also some of its most productive. Coral reefs account for 25 percent of the world’s marine life and half a billion people depend on them for food. But human encroachment has imperiled almost all of the world’s reefs.

Earlier this week the U.S. National Oceanographic and Atmospheric Administration (NOAA) declared a global bleaching, or coral die off, event. It began in Hawaii and is poised to stretch west to the Maldives and east to the Caribbean. It is only the third global bleaching event in recorded history. Scientists are still hesitant to blame this year’s El Niño, but because this bleaching event is intensifying earlier than usual, many are predicting that it might be the worst ever.

“More frequent extreme conditions as predicted in Widlansky’s article will definitely have negative consequences for corals,” says Sun Wook Kim a researcher at the University of Queensland familiar with the subject area.