The National Oceanic and Atmospheric Administration (NOAA) has issued a warning this week about the potential onset of another widespread coral bleaching event, anticipated within the next few months. This would occur just a year after the conclusion of the previous event, marking the fifth such occurrence in recorded history.
According to NOAA, a U.S. federal agency involved in climate and weather research, their updated forecast indicates that coral reefs are highly susceptible to bleaching this summer, particularly in the northern Pacific Ocean, including areas like Hawaii. Additionally, reefs in Florida and the Caribbean may face similar risks, as outlined in the latest report.
Coral reefs are crucial marine ecosystems that play a significant role in supporting diverse marine life, providing habitats for approximately 25% of all marine species. However, elevated ocean temperatures can induce stress in these ecosystems, leading to the loss of their vibrant colors and resulting in a bleached appearance.
In recent decades, instances of visible coral bleaching have become increasingly common, a trend that many researchers attribute to the effects of climate change. Last October, scientists from the University of Exeter identified coral reefs as the first environmental system to have surpassed a climate “tipping point” following years of degradation.
Derek Manzello, who oversees the Coral Reef Watch initiative that generated NOAA’s bleaching forecast, stated that monitoring mass bleaching events is becoming increasingly difficult due to the rising frequency of heat stress. He noted that the upcoming El Niño phenomenon, which typically brings warmer ocean temperatures, suggests that another bleaching event could soon occur.
“We have entered an era where coral reefs are likely to experience bleaching nearly every year, making it challenging to determine the start and end of global bleaching events,” Manzello explained. “Moving forward, we will rely on field observations of bleaching to identify and track these global events.”
Recent research indicates that the last global bleaching incident, which affected 84% of the world’s reefs and set new records, concluded around mid-2025. If El Niño develops as expected this summer, NOAA predicts that significant coral bleaching could reappear between June and September.
While scientists are confident that El Niño will manifest before the onset of fall, they are still assessing the exact timing and intensity of the event. NOAA emphasized that a stronger El Niño increases the likelihood of global coral bleaching, as previous strong El Niño occurrences since 1998 have coincided with such bleaching events.
The intensity of heat stress has intensified and spread, with current sea surface temperatures exceeding those recorded during the first mass bleaching event nearly 30 years ago.
Although the detrimental effects of rising ocean temperatures on coral health are well recognized, scientists have also identified instances of resilience within coral populations. During the unprecedented bleaching event that took place from 2024 to 2025, some reefs managed to withstand bleaching despite the high ocean temperatures, according to NOAA.
Jennifer Koss, the director of NOAA’s reef conservation program, stated that the agency is investigating various aspects of heat tolerance in corals. “This research will enhance our understanding of coral resilience and improve restoration strategies and techniques nationwide,” she added.
