In the middle of a heat wave, nothing feels better than jumping into cool water. But it turns out heat waves don’t just happen on land, they’re also happening under the sea.

A recent study found that the number of marine heat wave days that occur each year has increased by more than 50% over the past nine decades. But it’s not just the number of marine heat wave days that scientists are concerned about.

Marine heat waves are also happening more frequently and lasting longer, according to the study. Researchers responsible for the report predict that things will only get worse, unless climate change is stopped.

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“We can expect further increases in marine heat wave days under continued global warming,” the study says.

Though the effects of land heat waves can be devastating, marine heat waves can have a much longer lasting impact.

According to data from the Environmental Protection Agency, sea temperatures around the world have risen substantially over the last 100 years. Kevin Trenberth, a climate scientist at the National Center for Atmospheric Research, told the Washington Post that ocean temperatures hit a record high in 2017.

Many scientists have attributed the rise in temperature to the effects of man-made climate change and global warming. With sea temperatures already higher than usual, marine heat waves can further exacerbate the situation, harming underwater creatures and eco-systems.

Marine life that can’t stand the heat can’t simply “get out of the kitchen” — they’re stuck and they’re suffering.

Read more: Huge Ocean ‘Dead Zones' Have Quadrupled in Size Since the 1950s

The heating up of the Pacific Ocean has caused the mortality rate of whales, sea lions, and marine birds to rise, experts have said. Warming seas are also destroying coral reefs, which take years of dedicated resources and meticulous care to restore.

Without a concerted effort to combat climate change and reverse global warming, the researchers predict that sea temperatures will keep rising and oceans will continue to be hit by marine heat waves with increasing frequency.

Global Citizen campaigns in support of climate action to stop global warming and to address the harmful effects of climate change. You can take action here by pledging to become an ocean guardian.