The world is experiencing a global coral bleaching event, and this is what that means for us

A report, released this week, states we are currently experiencing a worldwide coral bleaching event. This is the fourth global event on record and the second in the last decade.

Florida, specifically, experienced its most severe mass coral bleaching event in 2023. There was record setting heat stress everywhere in Florida, and the impacts were severe, primarily in the lower Florida Keys area. During the bleaching event, the National Oceanic and Atmospheric Administration (NOAA) participated in interventions to mitigate harm to corals.

Why are coral reefs important?

“Coral reefs provide habitat for a lot of really important species. So things like spiny lobsters and snow crabs – they’re all dependent on this coral reef habitat for their survival,” says Dr. Derek Manzello, a coordinator at NOAA Coral Reef Watch. “Coral reefs are also incredibly important to people. It’s estimated that coral reefs in the United States are contributing more than 3 billion a year annually to the economy due to things like tourism and fishing.”

The other economic benefit of coral reefs is that they are providing coastal protection from storms. 

“It’s estimated that coral reefs can dissipate about 97 percent of the wave energy during things like hurricanes and tropical storms,” says Dr. Manzello. “So what that means is healthy coral reefs are living breakwater. That is really protecting people in places like the Florida Keys, in southeast Florida, from more severe damaging impacts from storms.” 

Furthermore, coral reefs are now important for medical research. 

“A lot of new experimental cancer drugs are being derived from corals and coral reef organisms,” says. Dr. Manzello. So when you have coral bleaching and coral mortality events, this is going to have direct impacts on people’s livelihoods as well as the U.S. economy.”

What happens during a coral bleaching event?

Coral bleaching happens when corals are stressed by changes in their environment, such as temperature or light. This causes them to expel symbiotic algae and turn completely white.

All it takes is temperatures to be about one degree Celsius, which is equivalent to about two to three degrees Fahrenheit, above the normal maximum temperature they experience on average during the warmest month of the year,” says Dr. Manzello. “So if that heat is sustained for about a month or more, this can lead to coral bleaching.”

Coral bleaching is not a death sentence for corals, however.

“Corals can recover from bleaching events if the heat stress is not too severe or not too prolonged,” says Dr. Manzello. But in those cases, it’s been found that corals will have lasting physiological impacts from a bleaching event. [Such as], slower growth rates for about two to four years. They’ll have depressed reproductive output for upwards of five years, and then they become immunocompromised for about one to two years. So what that means is they become more susceptible to disease.”

What’s being done?

Through its Mission: Iconic Reefs program, NOAA is moving coral nurseries to deeper, cooler waters, and providing sunshades to protect them.

Dr. Manzello adds that there are a lot of individuals in Florida also working on coral restoration. 

“They basically grow corals in nursery environments, and then they plant them back out onto the reefs where they hopefully can recover and restore some of those ecological functions to the reefs,” he says.

Additionally, the International Coral Reef Initiative (ICRI) has implemented a Plan of Action to advance coral interventions and restoration in the face of climate change.