Australia’s Great Barrier Reef (大堡礁) is one of the world’s greatest natural wonders. But if you haven’t been there, you’d better be quick before it’s too late. According to scientists at Griffith University in Queensland, Australia, algae (海藻) is slowly killing the corals (珊瑚) through chemicals it gives out, and this is down to the Earth’s rising level of carbon dioxide (CO2).