'Red Alert': Great Barrier Reef Severe Bleaching Raised To Highest Threat Level

The world's biggest coral reef ecosystem is experiencing "severe" bleaching as a result of climate change, environmental groups and Australian government officials are warning. According to the Great Barrier Reef Marine Park Authority, recent underwater surveys have detected "substantial levels of coral mortality" in remote far north areas of the reef, due in part to higher-than-average sea surface temperatures. The Authority on Sunday raised its bleaching threat level to three—the highest level in its response plan, indicating "severe regional bleaching."