Global heating pushes coral reefs towards worst planet-wide mass bleaching on record

The percentage of reef areas experiencing bleaching-level heat stress is increasing by about 1% a week, scientists say

Global heating has pushed the world’s coral reefs to a fourth planet-wide mass bleaching event that is on track to be the most extensive on record, US government scientists have confirmed.

Some 54% of ocean waters containing coral reefs have experienced heat stress high enough to cause bleaching, the National Oceanic and Atmospheric Administration’s Coral Reef Watch said.

A global bleaching event is declared when at least 12% of corals in each of the main ocean basins – Pacific, Atlantic and Indian – experience bleaching-level heat stress within a 12-month period. The declaration also requires confirmed reports of bleaching.