A world without coral?

Coral reefs cover less than 0.1% of the ocean floor, but they’re home to a quarter of all the marine species on Earth. This makes them incredibly biodiverse ecosystems, supporting a complex food web of organisms that includes us humans. 
 
Around 850 million people around the world are thought to rely on coral reefs for their food and livelihoods. 
 
Healthy reefs directly support around 30 million small-scale fishing jobs. Reef tourism is a £36 billion industry, providing work for thousands of people in some of the world’s poorest countries.  
 
As well as helping to fill our bellies, reefs also feed our souls. They are central to the cultures of many Indigenous People, and a source of wonder for all of us who love the natural world. 
 
Coral extracts are increasingly being used to improve our physical well-being too, providing treatments for asthma, arthritis, cancer and many other diseases.  
 
These huge living structures even provide humanity with a physical barrier from harm. 
 
Research has shown that coral reefs reduce wave energy by as much as 95%, giving coastal communities vital protection from tsunamis and storms.  
 
In short, the importance of our coral reefs is enormous. Unfortunately, so are the threats they face.  
 

Why should we worry? 
 
The Earth has warmed by an average of 1.2°C since pre-industrial times, and in the last 40 years we have lost 50% of our coral reefs.  
 
If average global temperature rises by 1.5°C, the loss will be somewhere between 70% and 90%. In a world with 2°C of warming, only 1% or our coral reefs will remain. 

Crown-of-thorns starfish pose a significant threat to coral.© Jürgen Freund / WWF

Marine Heatwaves are breaking records as the climate crisis accelerates and sea temperatures are hitting all-time highs. 
 
Rising sea temperatures leads to frequent damage to coral reefs in the form of ‘"coral bleaching". 
 
Healthy reefs get their bright colour from the microscopic algae that live in a coral's hard external structure.  
 
Covered by increasingly hot water, they get very stressed, and expel the beneficial algae that live with them. 
 
This takes away the coral’s main food source and they lose their healthy, bright colours and turn bone white - a phenomenon known as coral bleaching. Reefs can survive short periods of bleaching but, long term, the situation is fatal. 
 
Further exposure to high temperatures or just one big storm could be all it takes to wipe out the coral for good. 
 
With the coral populations gone, the fish that many coastal communities depend on move away or don’t survive. 
 
Other threats come from unsustainable development: people drilling for oil, building ports, dredging, shipping and, of course, fishing. Discarded fish traps, nets and other debris can seriously damage coral reefs, and over-fishing certain species has a major impact too. 
 
For example, some fish eat marine algae - so if too many of these fish are taken from the reef, the algae can overwhelm the coral it lives on. 

 
Why should we be hopeful? 
 
So, how can we help coral reefs survive? Tackling climate change is the biggest step and that means drastically reducing our greenhouse gas emissions. 
 
At the same time, we must accept that it won’t be possible to save some reefs. 
 
Which makes it all the more important to protect those reefs that we can. 
 
This means identifying reefs that are less exposed to climate change, and working with communities to protect them from threats such as poor water quality, unsustainable coastal development and overfishing. 
 
The WWF-led Coral Reef Rescue Initiative is doing just that. Together with partners, they have mapped reefs in seven countries that may be more resilient to a warming ocean. 
 
They are connected by currents to other reef systems and may be able to “seed” and regenerate reefs that have been damaged by climate change.  
 
In partnership with governments, other organisations, scientists, researchers and coastal communities, the initiative is working to reduce the strain placed on these coral reefs and help ensure coastal communities have the tools and resources to manage them sustainability. 
 

Local heroes 
 
These resilient reefs are often close to communities that face challenges of their own. 
 
For some fishers and farmers, looking after coral may feel like a secondary concern compared to the immediate pressure of making ends meet.  
 
Data is a key tool in our belt to understand and help communities sustainably manage coral reefs. 
 
Members of the UN Convention on Biological Diversity are now measuring their reefs’ size, live coral cover and the number of fish they support. 
 
By checking their progress against global biodiversity targets, these nations can see which interventions are really working and focus their conservation work more effectively. 
 
This approach also makes global and regional data more consistent, giving a more reliable picture of how reef systems change over time. 

Beautiful coral reef of shallow Bismarck Sea, Papua New Guinea. © Jürgen Freund / WWF

The next generation of coral 
 
Florida’s Coral Restoration Foundation is taking more direct action. Here, divers are growing new coral in underwater nurseries, ready to be replanted on damaged reefs. 
 
Meanwhile, scientists at the University of Hawaiʻi at Mānoa are studying a more controversial approach, called "assisted evolution". 
 
This involves finding corals that seem more resilient to warming, and bringing them into the lab for exposure to even warmer water. 
 
If they can adapt to the increased temperatures, these more resilient corals might be used to breed stronger generations of coral for the future.  
 
So, while there’s no doubt that the threats to our coral reefs are serious, with a concerted effort, we can help to turn the tide.