How global warming sealed the fate of reefs

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Animal, vegetable and mineral, a pristine tropical coral reef is one of the natural wonders of the world. Bathed in clear, warm water and thick with a psychedelic display of fish, sharks, crustaceans and other sea life, the colourful coral ramparts that rise from the sand are known as the rainforests of the oceans.

And with good reason. Reefs and rainforests have more in common than their beauty and bewildering biodiversity. Both have stood for millions of years, and yet both are poised to disappear.

If you thought you had heard enough bad news on the environment and that the situation could not get any worse, then steel yourself. Coral reefs are doomed. The situation is virtually hopeless. Forget ice caps and rising sea levels: the tropical coral reef looks like it will enter the history books as the first major ecosystem wiped out by our love of cheap energy.

Today, a report from the Australian government agency that looks after the nation’s emblematic Great Barrier Reef reported that “the overall outlook for the reef is poor and catastrophic damage to the ecosystem may not be averted”. The Great Barrier Reef is in trouble, and it is not the only one.

Within just a few decades, experts are warning, the tropical reefs strung around the middle of our planet like a jewelled corset will reduce to rubble. Giant piles of slime-covered rubbish will litter the sea bed and spell in large distressing letters for the rest of foreseeable time: Humans Were Here.

“The future is horrific,” says Charlie Veron, an Australian marine biologist who is widely regarded as the world’s foremost expert on coral reefs. “There is no hope of reefs surviving to even mid-century in any form that we now recognise. If, and when, they go, they will take with them about one-third of the world’s marine biodiversity. Then there is a domino effect, as reefs fail so will other ecosystems. This is the path of a mass extinction event, when most life, especially tropical marine life, goes extinct.”

Alex Rogers, a coral expert with the Zoological Society of London, talks of an “absolute guarantee of their annihilation”. And David Obura, another coral heavyweight and head of CORDIO East Africa, a research group in Kenya, is equally pessimistic: “I don’t think reefs have much of a chance. And what’s happening to reefs is a parable of what is going to happen to everything else.”

These are desperate words, stripped of the usual scientific caveats and expressions of uncertainty, and they are a measure of the enormity of what’s happening to our reefs.

The problem is a new take on a familiar evil. Of the billions of tonnes of carbon dioxide spewed from cars, power stations, aircraft and factories each year, about half hangs round in the thin layer of atmosphere where it traps heat at the Earth’s surface and so drives global warming. What happens to the rest of this steady flood of carbon pollution? Some is absorbed by the world’s soils and forests, offering vital respite to our overcooked climate. The remainder dissolves into the world’s oceans. And there, it stores up a whole heap of trouble for coral reefs.

Often mistaken for plants, individual corals are animals closely related to sea anemones and jellyfish. They have tiny tentacles and can sting and eat fish and small animals. Corals are found throughout the world’s oceans, and holidaymakers taking a swim off the Cornish coast may brush their hands through clouds of the tiny creatures without ever realising.