Fourth Global Coral Bleaching Event

This is the most geographically comprehensive analysis of coral bleaching studies conducted to date. Data from around the world shows that the planet is now in the fourth global coral bleaching event, reported the STRI. During the so-called 'Third Global Coral Bleaching Event,' which occurred from 2014 to 2017, 15% of the world's reefs experienced significant mortality, according to research by an international team led by scientists from the STRI, Australia's James Cook University, and former director of the U.S. National Oceanic and Atmospheric Administration's (NOAA) Coral Reef Watch, C. Mark Eakin. This included consecutive events on Australia's Great Barrier Reef. 'Our results show that the third global bleaching event was, by far, the most severe and widespread on record,' said Eakin, former director of NOAA Coral Reef Watch and chief science advisor to the Netflix documentary 'Chasing Coral.' He added, 'The levels of thermal stress were so extreme during this event that Coral Reef Watch had to create new, higher levels of bleaching alerts that had not been necessary in previous events.' Fifty percent of the world's reefs suffered 'significant bleaching' between 2014 and 2017 due to a global marine heatwave, and are now facing an even worse crisis, said the Smithsonian Tropical Research Institute (STRI), based in Panama, on Tuesday. The global decline of coral reefs affects many of the services they provide, such as tourism and food supply. This study combined satellite images of ocean water temperature from the Coral Reef Watch system with reef observations obtained through underwater and aerial studies in different parts of the world to estimate the extent of coral bleaching during a global marine heatwave. 'The benefits that coral reefs provide to society—including fisheries, tourism, coastal protection, drug discovery, and others—are estimated at about $9.8 trillion per year,' added the scientific body. 'Since then, three other bleaching events have been recorded there,' said Scott Heron from James Cook University. He explained, 'Approximately half of the reefs affected by bleaching-level thermal stress were exposed two or more times during the three-year event, often with devastating consequences. Bleaching occurs under thermal stress when the partnership breaks down, the energy source is lost, and the coral turns white, leading to reduced growth, lower reproduction, and even death when it is especially severe or prolonged. We are seeing that reefs do not have enough time to recover properly before the next bleaching event occurs.' Over the past 30 years, the Earth has lost 50% of its corals because the oceans absorb most of the heat generated by burning fossil fuels. A coral is made up of a small animal related to jellyfish that secretes a hard structure and even smaller algae that convert sunlight into the energy the animal needs to live, explained the STRI in its statement. If the oceans did not absorb the heat, air temperatures would be around 50°C (122°F). However, reefs are currently experiencing a fourth, even more severe event that began in early 2023,' assured Connelly. 'Nearly 200 co-authors from 143 institutions in 41 countries and territories contributed data,' explained Sean Connolly, a senior scientist at the Smithsonian.