Rising ocean temperatures are leading to historic coral bleaching

On Monday morning, the National Oceanic and Atmospheric Administration (NOAA) confirmed that the world is undergoing a global bleaching event. This is the fourth bleaching event on record, and the second in the past ten years.

Global bleaching events are catastrophic for coral reefs and our oceans across the world. When coral are stressed by rising ocean temperatures, they expel the algae from their tissue and turn completely white. Though bleaching does not kill coral, the organisms become less resilient and are more susceptible to death while bleached.

For a bleaching event to be considered ‘global’, there must be significant bleaching in all three major ocean basins (Atlantic, Pacific, and Indian). Last year’s event has impacted more than 54% of the coral reefs on the planet. In NOAA’s press release, Dr. Derek Manzello, Ph.D., NOAA’s Coral Reef Watch coordinator said, “From February 2023 to April 2024, significant coral bleaching has been documented in both the Northern and Southern Hemispheres of each major ocean basin.”

Rising ocean temperatures are not slowing down, and that will likely mean bleaching events such as this one will become more frequent. According to NASA, 90% of the planet’s global warming occurs in the ocean. Marine temperatures have risen approximately 1.5 degrees Fahrenheit since 1901, and 2023 was the warmest year on record. 

Coral bleaching has a severe impact on the health of marine habitats. When at-risk coral die off en masse, the surviving organisms struggle to reproduce and the reef deteriorates. This is a massive loss for ocean ecosystems, impacting wildlife and humanity alike.

Reef habitats are essential for thousands of marine species. Wildlife such as sea turtles, crustaceans, fish, and invertebrate species rely on reef ecosystems for shelter, protection from predators, and space to reproduce. Without these valuable habitats the entire food chain, from plankton to sharks, face the risk of extinction.

The loss of coral reefs also threatens human lives. Reefs act as natural barriers against large waves and storm surges. Without the coral’s natural protection, human-made storm walls need to be constructed, which harm the surrounding environment and are expensive to build and maintain. Coral reefs also provide a buffer from the overfishing crisis, since they’re hotspots for ocean biodiversity and growth. Without coral reefs, fish populations can’t recover from their losses as effectively.

Coral reefs are one of the defining images of our world’s oceans. Brightly colored coral and other wildlife help us all realize the beauty of the ocean, but bleaching events leave these special places devoid of color and of life. Marine wildlife is forced to find a new home, but no place in the ocean is safe from the dangers of rising temperatures. The only way to fix this problem is to combat the impacts of climate change. Lowering emissions, reducing our carbon footprint and cleaning up the natural spaces we’ve dumped our waste into are the only choices we have. Otherwise, global bleaching events like this one will happen more and more frequently, and soon, there could be no coral left to bleach.