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.

Roberts’s first student dives in 1982 were made off the Saudi coast of the Red Sea, counting reef fish with a waterproof whiteboard. He writes of the traditional Arab attitude towards the desert as an endless waste disposal and how one of his heroes, Jacques Cousteau, saw the sea the same way. Cousteau regretted this much later, writing: ‘Water and air, the two essential fluids on which all life depends, have become global garbage cans.’

The chief pleasure of this book is Roberts’s rich descriptive power. He was an adviser for Blue Planet 2, and his writing does more than justice to those stunning films. Nature’s throne rooms are thrown open by Roberts’s prose. Here he describes a dive in the Hol Chan Marine Reserve off Belize: