El Niño is coming, and ocean temps are already at record highs – that can spell disaster for fish and corals

Marine heat waves can reach the ocean floor as well as surface waters. Sebastian Pena Lambarri via Unsplash, CC BY

It’s coming. Winds are weakening along the equatorial Pacific Ocean. Heat is building beneath the ocean surface. By July, most forecast models agree that the climate system’s biggest player – El Niño – will return for the first time in nearly four years.

El Niño is one side of the climatic coin called the El Niño-Southern Oscillation, or ENSO. It’s the heads to La Niña’s tails.