An international team of scientists has mapped more than 64,000 square miles of coral reefs that can withstand severe heat stress. These findings provide an important plan for saving marine life while the world’s oceans experience their worst bleaching crisis ever.The study used artificial intelligence to analyze decades of environmental data. The AI identified unique underwater sanctuaries in 71 countries and 100 territories. These areas have unique natural features that help coral ecosystems survive, protect, or recover from marine heat waves.The research was presented at the Our Ocean Conference in Mombasa, Kenya, and published on the preprint server EcoEvoRxiv. These findings challenge the common scientific belief that coral reefs cannot be saved. Instead, the new maps show exactly where governments should spend conservation money to protect marine life.“Coral reefs are often framed as ecosystems beyond saving,” study co-author Emily Darling, director of coral conservation at the Wildlife Conservation Society, said at the conference. “This research shows otherwise.”
Using computers to find climate sanctuaries
Coral reefs cover only 1 percent of the ocean floor but support a quarter of all marine life. They are vital to the global food supply and protect coastlines from storms. Their biggest threat is rising water temperatures, which cause mass bleaching.When the seawater gets too warm, corals expel the tiny, colorful algae that live inside them. Due to this, corals are deprived of their main food source. This causes their bones to turn white, they become extremely stressed and are likely to die from hunger or disease.To find habitats that can survive this heat, researchers defined three types of natural shelters, known as climate refugia:
- Rescue Refuge: Areas with physical features, such as cold water currents, that protect corals from heat.
- Resistance refugia: Areas where corals have naturally evolved to handle high temperatures.
- Recovery Refugia: Areas where coral may bleach but are healthy enough to grow back quickly.
Darling and his team trained an AI model to look for these three types of sanctuaries. They entered about 45,000 coral observations recorded since 1960 into the computer. The system looked at 42 different environmental factors, including water chemistry, temperature changes, and local human activity.The AI model evaluated global maps to predict coral health for the year 2050. The results showed that these flexible rocks are highly concentrated. About 61 percent of these protected areas are located in the waters of just five countries: Australia, the Bahamas, Cuba, Indonesia and the Philippines.The models also discovered entirely new, highly resilient reef zones in Belize, Nicaragua, and the Turks and Caicos Islands. It expands on data from the 2018 “50 Reefs” study, which was the first major effort to find heat-resistant corals.
Coral reefs and their associated ecosystems
A plan for targeted conservation funding
Finding these specific areas provides a clear plan for environmental groups. This is especially helpful for small island nations that do not have the money or resources to protect their entire waters.“Climate-resilient rocks are not evenly spread,” study co-author Joseph Maina, an environmental scientist at Macquarie University in Australia, told the conference. “And countries need to understand…those differences are such that when they plan where conservation investments should go in the future, they consider this unequal distribution.”Independent scientists have welcomed the accuracy of the new data. He notes that this shifts the focus from recording the destruction of the oceans to actively protecting them.“This study accelerates decades of work on reef resilience to climate change,” says David Obura, a marine ecologist and chair of the Intergovernmental Platform on Biodiversity Ecosystem Services, who was not part of the research team. “It focuses on the critical question: Will climate refuges cover 10 percent, 1 percent, or even less of the former extent of coral reefs?”However, local conservationists in these newly found protected areas say the consequences should be considered carefully. Alizie Zimmerman, executive director of the Turks and Caicos Reef Fund, wants to examine the data closely because her region lacks long-term monitoring. He warned that good news should not make governments complacent.Zimmerman said, “The statement that Caribbean reefs are simply ‘dead’ is false and could be detrimental to the progress of reef restoration and protection initiatives in the region.” “However, it would be equally disingenuous to say that they are thriving.”
background of global destruction
The discovery of these flexible pockets came at a time of great urgency. More than 80 percent of the world’s reefs face bleaching-level warming by 2023, according to a report by the National Oceanic and Atmospheric Administration (NOAA) and the International Coral Reef Initiative. This makes it the worst global bleaching event in history.Mass deaths have affected tropical regions. Florida reefs suffered a severe heat wave in 2023, causing 100 percent bleaching in the Florida Keys. Australia’s Great Barrier Reef faces catastrophic bleaching in 2024. Extensive damage was also reported across wide parts of the Persian Gulf, the Red Sea, and the Caribbean.The current crisis has eclipsed the previous record set between 2014 and 2017, when 70 percent of global reefs were exposed to extreme heat. Melanie McField, founder of the Healthy Reefs for Healthy People initiative, described the terrifying sight of a reef damaged by the heat.“There is usually an absence of fluttering fish and vibrant colors on the reef,” McField said. “It’s an ashy yellowness and stillness that should be a riotously vibrant reefscape.”
navigating uncharted waters
Since the current marine heat wave is still ongoing, scientists don’t know when water temperatures will drop enough for the corals to recover.Mark Eakin, corresponding secretary of the International Coral Reef Society, warned, “We may never see the heat stress causing bleaching fall below the threshold that triggers a global event.” “We are witnessing something that is completely changing the face of our planet and the ability of our oceans to sustain life and livelihoods.”Britta Scheufelke, a researcher at the Australian Institute of Marine Science, agrees that the sheer size of the heatwave takes marine ecosystems into completely uncharted waters.Still, proponents of the new mapping study say corals have escaped mass extinction in Earth’s history. If these specific protected areas are protected from overfishing and pollution, the corals can eventually spread and repopulate other areas.“The ancestors of today’s corals survived the asteroid impact that wiped out the dinosaurs on land and many other creatures in the sea,” says marine biologist George Widenmann of the University of Southampton. “So, if we manage to reduce ocean temperatures, there’s always a chance that corals can recover.”In the long term, saving these newly mapped areas depends on global political action to cut greenhouse gas emissions. Valeria Pizarro, senior coral scientist at the Perry Institute for Marine Science, stressed that world leaders must invest heavily in clean energy and reduce fossil fuel use to give these sanctuaries a real chance.However, these protections face immediate political obstacles in the United States, where the Trump administration has moved to increase fossil fuel production and reduce clean energy initiatives. Coral researchers see these political changes as a direct threat to global conservation.“Removing these protections is going to have devastating consequences,” Eakin said.