Guardian: A fifth of the world’s coral reefs have died or been destroyed and the remainder are increasingly vulnerable to the effects of climate change, a new study says. The Global Coral Reef Monitoring Network says many surviving reefs could be lost over the coming decades as CO2 emissions continue to increase. “If nothing is done to substantially cut emissions, we could effectively lose coral reefs as we know them, with major coral extinctions,” said Clive Wilkinson of the …