The future of coral reefs under climate change

Image: Shutterstock.com/Chatuphon Neelasri

Coral reefs are an important part of the ocean ecosystem. They provide homes and food to millions of different species of animals around the world. Their brilliant color and biodiversity is a huge part of what makes the ocean the magnificent thing that it is. And that’s not to mention the huge economic impact that the reefs have, providing fish and other resources that communities all around the world depend on.

But like so many things, reefs are being seriously affected by the changes being caused by climate change. The rising temperatures of ocean water and higher levels of carbon dioxide produce an effect called “coral bleaching” in the reefs.

Coral bleaching is caused when changing conditions cause the reefs to reject the algae that usually covers them. This leaves the coral bone white instead of the brilliant colors you usually associate with coral reefs, effectively bleaching it. This increases the risk that the reefs will die and reduces the health of the ecosystem.

And coral bleaching has been a serious problem for reefs around the world. In fact, the impact of coral bleaching on the Great Barrier Reef, the world’s largest reef, was so severe that it prompted Outside Magazine to write an obituary for the reef, declaring it dead. Experts say that was a little premature, but that the reef is in serious trouble, like so many others.

And as climate change is the greatest cause of coral bleaching, the continuing upwards trend in temperature poses a serious threat to reefs all over the world. A recent study suggests that 99% of the world’s reefs will face annual bleaching by the end of the century if current climate trends continue.

The role of climate change in the death of coral reefs is undeniable and the report suggests that if the rise in temperature could be slowed or halted, reefs might be able to recover. For instance, if the requirements set forth in the Paris Accords are adhered to and the projections for how it will limit climate change are accurate, then the report estimates that reefs would have an extra eleven years before annual bleaching occurs.

Regardless of how much emissions can be limited, certain reefs will face annual bleaching sooner than others. Reefs near the equator already face the threat of annual bleaching, and as the century progresses, reefs farther and farther from the equator will face the same fate. So reefs closer to the equator will die sooner than reefs farther away.

But with the rate at which the climate is changing, all reefs will eventually be living in waters with temperatures that are too high for the algae and bleaching will be a threat to all coral reefs on Earth. And the complex ecosystems that call coral reefs home will be threatened as well. That’s a serious problem for people as well, as the coral reefs are estimated to bring billions of dollars of economic opportunity to communities that live near them.

Conservationists hope that the fact that some reefs will live longer than others will give coral reefs in colder areas the chance to adapt to warming temperatures. And efforts are being made to prepare reefs for the rising temperature whenever possible. Reefs are living organisms, and like any organism may be able to adapt to a changing environment with time. Unfortunately, there may not be enough time for many coral reefs in warmer areas.

But one thing is clear, climate change will threaten coral reefs all over the world and at the moment, it seems like little can be done to protect one of the ocean’s most important habitats.