There is still time for coral reefs, if we act soon

Coral reefs are on the front lines of the climate crisis. We’ve long known they can be vulnerable to local pressures like water pollution, overfishing, and irresponsible tourism; but climate change has become their biggest threat—and countries all over the world have taken notice. At last year’s global biodiversity summit, hundreds of governments spent weeks in heated negotiations aimed at curbing rampant biodiversity loss. One of the outcomes of those talks was a new global “30x30” commitment—an agreement to protect 30% of the world’s land and oceans by 2030. During talks, governments also singled out some of the earth’s most biodiversity-rich ecosystems, systems that need to be prioritised above all others for their value for people and planet. Front and centre on that short list? Coral reefs. 

Their importance is paramount. Though reefs cover less than 0.1% of ocean area, they are home to more than 25% of all marine life. The same coastal waters where we find most coral reefs also contain 70% of all ocean biodiversity and 100% of the world’s mangrove forests and seagrass beds.

Simply put: coral reefs and the waters around them underpin food and life in our oceans. This makes the recent widely reported El Niño heatwaves that have bleached corals all over the world even more alarming.

But, how good is the evidence that coral reefs will largely disappear by 2050?

From scientists to late-night comedians, this doom prognosis is widely repeated. But is there strong evidence to support this pessimistic outlook for our oceans? A culmination of over four decades of science and data now tells us: while reefs are being hit hard by climate change, the future is more hopeful than commonly thought. 

Many are surprised to learn that much of the evidence used to predict the disappearance of our coral reefs in coming decades is based largely on a single “excess heat” model. The prevailing theory has been this: as climate change intensifies and sea-surface temperatures rise, excess heat accumulates, eventually passing a proposed threshold and tipping us into temperatures that scientists believed were impossible for healthy coral reefs to survive in. This has been the theory, but the simple excess heat model has been weakly supported by real-life field tests and newer data.

Over the many years that the United Nations International Panel on Climate Change has evaluated climate change, their original heat model proposed before 1999 remains largely unchanged. In the past two decades, several major studies have failed to prove that “coral cover”—the proportion of ocean area covered by corals, and the main metric used to measure coral-reef health—is majorly impacted by excess heat. Surprisingly, other environmental conditions have shown to be much more impactful than heat, including levels of oxygen in sea water and how clear and clean the water is.

What does this mean for corals? While heat can hurt our reefs, it’s not the only deciding factor in whether or not a coral reef thrives or dies. To adapt to climate change, we need new models that can help us predict a more accurate future for our oceans and reefs, models that take into account how complex and dynamic underwater ecosystems are, and that move beyond overly simple temperature thresholds.

When we move beyond the old model, a new landscape of hope for coral reefs comes into view.

Previously, the global community assumed that only rare reefs located in lucky underwater cool spots could survive climate change by avoiding heat. We now know there are more corals that can survive. There are reefs all over the world that aren’t avoiding heat, but are actively resisting it. Evolved adaptations are allowing those corals to take hot-water events in their stride and defy bleaching and other impacts. There are still more reefs that have bleached during warm-water events, or been levelled by climate change induced mega-storms, only to shock communities and scientists by recovering—growing back in record time where there was once only rubble.

Each of these three types of coral reefs, which we’re calling climate refuges, have the ability to survive and fight back against the impacts of climate change—if we find them and protect them.

The clock is ticking. Countries are now mobilising to make good on their 30x30 commitments, plotting and planning where new ocean protections will be rolled out. The Philippines is an early leader in this space and launched their national 30x30 Roadmap this September, work that WCS and the Bloomberg Ocean Initiative were proud to support at an initial implementation workshop. We need every government in the world with coral reefs to follow suit, and to put those reefs front and centre of their plans—to make sure that new protected areas shelter these rare climate refuges. And in order to do that, we first need to find them all.

For over five years, Bloomberg Philanthropies and WCS have been working together to tackle this issue and restore hope for our reefs; first finding climate refuges, and then working hand in hand with local communities and national governments to protect them. We need to scale up this work, and quickly, in a new global network of partners for coral. Satellite data is incredibly useful, but we need people under water looking for the subtle signs of resilience and recovery in our corals, and we need them to share that data on platforms like MERMAID so that their governments can take data-driven action to save those reefs.

All of this comes down to one simple message: despite what you’ve heard, if we act soon we can still save our reefs. To get 30x30 right, we need to do this right. 

When we talk about coral reefs, we aren’t talking about just an ecosystem, or just a species—we’re talking about the source of life and biodiversity in our oceans, 70% of our world. The fish that feed us, the underwater structures that protect our shorelines from storms, the countless medicines discovered and yet to be discovered, beauty that boggles the imagination, thousands of years of stories and myths and legends of people and their reefs.

So much has been, and will be lost, to climate change. But coral reefs aren’t lost yet. And if we act now, we can make sure they never are.

Views or opinions expressed are those of the author and any individuals cited, and do not necessarily reflect those of Economist Impact or any other member of The Economist Group.

Tim McClanahan directs WCS’ global Marine Science programmes where he leads the conservation science that underpins policy and management decisions. WCS science provides real solutions for tackling some of the world’s largest issues, including fisheries sustainability, climate change resilience, and equitable governance and management that meet the needs of coastal communities.

Antha N. Williams leads the Environment programme at Bloomberg Philanthropies. Under Williams’ direction, Bloomberg Philanthropies supports environmental initiatives to improve sustainability of cities around the world, to accelerate the transition to clean energy, to combat overfishing and protect coral reefs, and to help businesses and investors better understand climate-related financial risks and opportunities.

Views or opinions expressed are those of the author and any individuals cited, and do not necessarily reflect those of Economist Impact or any other member of The Economist Group.