The world’s coral reefs are currently facing a severe global bleaching event driven by record-high ocean temperatures. Along coastlines from Australia to Kenya and Mexico, many of the world’s coral reefs have turned white in the fourth global bleaching event in just three decades. This mass bleaching has affected reefs across at least 54 countries and territories since February 2023. According to the National Oceanic and Atmospheric Administration (N.O.A.A.) and its international partners, this phenomenon may impact more reefs than ever before.

“From February 2023 to April 2024, significant coral bleaching has been documented in both the Northern and Southern Hemispheres of each major ocean basin,” said Derek Manzello, Ph.D., N.O.A.A. Coral Reef Watch coordinator. “When these events are sufficiently severe or prolonged, they can cause coral mortality, which hurts the people who depend on the coral reefs for their livelihoods.”

In response to the intensifying coral crisis, N.O.A.A.’s Coral Reef Conservation Program has increased its focus on resilience-based management practices. Since the 2019 publication of the ‘Interventions to Increase the Resilience of Coral Reefs’ study by the National Academies of Sciences, significant strategic efforts have been made, including the relocation of coral nurseries to deeper, cooler waters and the implementation of sunshades to shield corals from excessive heat. These actions are part of a comprehensive agenda to address the impacts of marine heatwaves and local stressors, which was critically tested during the extraordinary 2023 heatwave in Florida.

Global sea surface temperatures have soared over the past year, partly due to the oceans’ absorption of excess atmospheric carbon from greenhouse gas emissions. The U.S. N.O.A.A. Coral Reef Watch, in partnership with the International Coral Reef Initiative, reports that 54% of global reef areas are experiencing heat stress at bleaching levels. They noted that for an event to be considered global, significant bleaching must occur across all three ocean basins: the Atlantic, Pacific, and Indian Oceans. Like this year’s bleaching event, the last three events—in 1998, 2010, and 2014-2017—also coincided with El Niño climate patterns, which typically bring warmer sea temperatures.

“The announcement of the fourth global bleaching event is an urgent call to do two things: reduce greenhouse gas emissions and work together to prioritize resilient coral reefs for conservation,” says Dr. Emily Darling, Director of Coral Reefs at the Wildlife Conservation Society (W.C.S.).  The future of coral reefs remains uncertain, and scientists emphasize the urgent need for climate action to prevent further damage and ensure the survival of these precious ecosystems. Dr. Stacy Jupiter, Executive Director of the W.C.S. Marine Conservation, states, “Saving coral reefs requires a global collaborative effort. Now more than ever before we need donors, governments, researchers, civil society, and the people most dependent on reef systems for their food and livelihoods to come together with the resources, policies, knowledge, and tools to coordinate action in places where reefs are most likely to persist into the future.”