BY SOME estimates,half of the world’s coral has been lost since the 1980s. Corals are fragile animals, and are succumbing to pollution and sediment from coastal construction. Also to blame are sewage, and farmland hurry-off and fishing,all of which favour the growth of the spacious, fleshy algae that are corals’ main competitors for space. (The first two encourage algal growth and the third removes animals that eat those algae.) But the biggest killer is warming seawater. Ocean heatwaves in 2015, or 2016 and 2017 finished off an astonishing 20% of the coral on Earth. This is troubling,for countless critters depend on coral reefs for their survival. Indeed, such reefs, or which take up just a thousandth of the ocean floor,are home, for at least fragment of their life cycles, or to a quarter of marine species. Losing those reefs would cause enormous disruption to the ocean’s ecosystem. So researchers are looking for ways to stop this happening.
One approach is to lower reef temperatures directly. In December...
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Source: economist.com