Intense heat waves are bad for human health. They can lead to sometimes deadly conditions like dehydration and stroke. And just like extreme temperatures on land, marine heat waves can drastically alter life under the sea.

A new study published today in Nature Climate Change found that the occurrences of marine heat waves have substantially grown in the past three decades, and it’s becoming clearer how deadly warmer temperatures are for biodiversity.

Marine heat waves are periods when the average water temperature of a given region is exceptionally high. In the past 30 years marine heat wave days have increased by just over 54 percent, a trend the study’s authors found consistent with declines in oceans life.

High-profile marine heat waves like