New Delhi, Oct. 23 -- It's the latest dose of bad news for coral reefs, which are critical sources for seafood and tourism and often serve as buffers from coastal erosion and storms. Sometimes dubbed "rainforests of the sea," they have some of the world's richest biodiversity. They support a quarter of marine species as well as coastal communities and businesses.

Some 96% of shallow-water reef systems are already critically endangered and could disappear by 2075, the International Union for Conservation of Nature announced on the sidelines of a U.N. biodiversity conference in Albania.

Most of the world's famous reef systems - including the Great Barrier Reef in Australia, the Coral Triangle in the Western Pacific Ocean and Southeast Asi...