Almost three-quarters of Japan’s biggest coral reef has died, according to a report that blames its demise on rising sea temperatures caused by global warming. The Japanese environment ministry said that 70 percent of the Sekisei lagoon in Okinawa had been killed by a phenomenon known as bleaching. Bleaching occurs when unusually warm water causes coral to expel the algae living in their tissues, causing the coral to turn completely white. Unless water temperatures quickly return to normal, the coral eventually dies from lack of nutrition.
— source climatecentral.org