The Great Barrier Grief — and countless other marine disasters

In the last, wrenching episode of BBC’s Blue Planet 2, there’s a distressing moment when a young Australian diver, expert in his patch of the Great Barrier Reef, admits ‘I cried in my mask’ as he swam over an ossuary of recently bleached-out coral bones. Professor Callum Roberts’s memoir of a life devoted to the study of our oceans, and in particular their coral reefs, is a ravishing, alarming account of these underwater palaces of wonder, and the existential threat they face from humanity and our warming climate.

Reefs take up just 0.1 per cent of our planet’s surface, yet provide home and breeding grounds for more than a quarter of all sea life. They are also the canaries in the carbon dioxide coal mine. As ocean temperatures rise, corals bleach and die, the tiny organisms that feed them (zooxanthellae) expelled from their chalky hosts. Further, the acidification of the seas weakens the very structures the coral relies on for support and reduces the amount of calcium carbonate available in the seawater to make new coralline homes.