For most of us, the colourful, otherworldly marinescapes of coral reefs are as remote as the alien landscapes of the moon. We rarely, if ever, experience these underwater wonderlands for ourselves – we are, after all, air-breathing, terrestrial creatures mostly cocooned in cities. It is easy, therefore, not to notice the perilous state they’re in: we’ve lost 50% of coral reefs in the past 20 years; more than 90% are expected to die by 2050 according to a presentation at the Ocean Sciences Meeting in San Diego, California earlier this year. As the oceans heat further and turn more acidic, owing to rising carbon dioxide emissions, coral reefs are tipped to become the world’s first ecosystems to become extinct because of us.
Just because we don’t see them doesn’t mean we won’t miss them. For, as we are belatedly discovering, the nice, dry human world that we’ve made for ourselves is dependent on the planet’s natural systems and coral reefs are no exception. They protect our coastlands from erosion, they are the nurseries for the fish we eat and they harbour the plankton that produce the oxygen we breathe. Globally, coral reefs support a quarter of all marine life and the livelihoods of a billion people.
Coral reefs are ancient and highly adaptable – they first emerged nearly 500 million years ago; those corals went extinct, and the corals that we have now first appeared 240 million years ago. The difference now is the extreme pace of change. Coral is slow growing and a reef takes about 10 years to recover fully after a single bleaching event. By 2049, we are expecting annual bleaching events in the tropics, pushing reefs beyond recovery. It’s a grim prospect and one of the reasons that in 2015 the world’s nations pledged to limit global warming to 1.5C above preindustrial levels, a temperature that would enable coral reefs to survive. It remains far from clear whether we will meet this goal.
However, while we still have reefs, we still have hope. Some will do better than others – some already are – and scientists are trying to work out why in a bid to build resilience elsewhere. As with climate change, human activity is implicated. For instance, studies show that reefs are more likely to recover from a heating event if they are protected from other stresses, such as overfishing, pollution from agriculture and boat damage.
With the future of the world’s ecological and human systems now so deeply interconnected, a new movement in reef conservation is putting social systems at its heart and explicitly building resilience into human and ecological systems in tandem. In other words, protecting nature means protecting people. The Coral Reef Alliance, for instance, is working with reef-dependent fishing communities in Honduras. Overfishing hits reefs in a number of ways, including by removing herbivores, such as parrotfish, whose