Fourth mass coral bleaching prompts UN alarm

Research this year shows that 77% of the world’s coral reefs are affected by bleaching, mainly due to warming ocean waters amid human-caused climate change.

It’s the largest and fourth mass global bleaching on record and is impacting both hemispheres, United Nations Capital Development Fund said.

The findings prompted a U.N. special emergency session on Wednesday — typically called to address escalating conflicts or natural disasters…