According to the latest report released by the Smithsonian Institution (Smithsonian) on February 15, 2026, a strong global marine heat wave has caused widespread coral bleaching around the world, and about half of the coral reefs have been damaged as a result. Scientists warn that a new round of marine heat waves that started in 2023 is still continuing and is more intense than before.
The international study, co-led by the Smithsonian Tropical Research Institute (STRI), Australia's James Cook University, and the former head of the U.S. National Oceanic and Atmospheric Administration's (NOAA) Coral Reef Watch program, provides the first comprehensive assessment of bleaching levels globally. The results have been published in the journal Nature Communications.
Coral reefs are not only colorful underwater ecosystems, but also important resources that support fisheries, promote tourism, protect coastlines from storms, and develop new drugs. Their total value is approximately US$9.8 trillion per year. However, when ocean temperatures get too high, corals expel the microscopic algae that provide them with energy, causing themselves to turn white, or "bleaching." This process will weaken the coral's ability to grow and reproduce. If thermal stress continues or intensifies, it will directly lead to widespread death of corals.
To understand the specific impacts of the "third global coral bleaching event" that occurred from 2014 to 2017, the research team brought together nearly 200 scientists from 41 countries and regions and analyzed data from more than 15,000 coral reef surveys. By combining satellite-monitored ocean surface temperatures with underwater field surveys, researchers have successfully linked heat exposure data detected from space to actual damage to coral reefs. The findings showed that 80% of the reefs tested experienced moderate or severe bleaching, and 35% suffered moderate or higher levels of mortality. Based on this extrapolation, more than 50% of the world's coral reefs experienced significant bleaching during this period, and about 15% suffered massive mortality.
C. Mark Eakin, the study's first author and former director of NOAA's Coral Reef Watch program, pointed out that the heat stress during this heat wave was so extreme that the monitoring system had to set a new alert level. Scott Heron, professor of physics at James Cook University, added that about half of the affected reefs had suffered two or more bleaching strikes in three years, leaving corals with little time to recover before the next heat wave hits. Taking Australia's Great Barrier Reef as an example, three more bleaching events have occurred since then, and the living environment has deteriorated day by day.
Even more worryingly, global data shows that the Earth is currently experiencing the “fourth global coral bleaching event.” Sean Connolly, a senior scientist at the Smithsonian Institution, said that although the third bleaching event was the most severe on record at the time, the fourth event that began in early 2023 is showing more destructive power. In the past 30 years, the earth has lost about 50% of its corals. The ocean absorbs much of the excess heat from burning fossil fuels, without which global temperatures would have soared to 50 degrees Celsius. Joshua Tewksbury, director of the Smithsonian Tropical Research Institute, emphasized that the scientific community must be as closely connected as this global collaboration, using various technical means from satellite observations to underwater surveys to continue to track changes in these critical ecosystems because they are critical to the global economy and natural health.