Coral reefs are a crucial part of the marine ecosystem, providing habitats for all sorts of marine life and protecting coastlines from storm damage. But scientists say rising ocean temperatures are posing a grave threat to the future of the world’s reefs.

Harmful bleaching of the world’s coral has now grown to include 84% of the ocean’s reefs in the most intense event of its kind in recorded history.

Bleached coral dies when exposed to heat stress for too long, threatening the bountiful marine ecosystem that depends on it for survival.