The current Super El Niño event is intensifying marine heatwaves, leading to significant health concerns beyond environmental damage, according to a report from Adelaide University and the University of Hong Kong. These extreme ocean temperature fluctuations, lasting from days to months, are increasingly recognized as a direct human health issue, researchers state.
Data from the EU's Copernicus Climate Change Service indicates that sea surface temperatures have reached record highs for July, contributing to severe marine heatwaves around Europe and conditions predicted to worsen. These events can supercharge the exchange of heat and moisture between water and air, intensifying storms and heatwaves over land.
For example, marine heatwaves in 2023 contributed to the intensification of Hurricane Otis, causing widespread displacement and damage in Mexico. Similarly, Typhoon Doksuri's impact in Southeast Asia was worsened by an intense marine heatwave, leading to long-lasting health consequences for over two million people.
Marine heatwaves also trigger sudden and intense algal blooms. These blooms, fueled by warmer temperatures, produce toxins that can contaminate seafood and pose a serious health risk to coastal populations. With approximately 3.2 billion people relying on seafood for 20% of their dietary protein, disruptions to marine ecosystems threaten food sustainability.
Beyond physical ailments such as respiratory and cardiac issues, researchers are highlighting the mental health impacts associated with marine heatwaves. Dr. Laura Falkenberg, lead author of the report, noted that communities dependent on healthy oceans for livelihoods, recreation, and cultural identity can experience anxiety, grief, and post-traumatic stress disorder when these ecosystems suffer.
One notable instance occurred in 2025, when a marine heatwave off the coast of South Australia contributed to an unprecedented algal bloom. This event, lasting nearly a year, led to documented cases of 'eco-anxiety,' grief, frustration, and depression among residents, in addition to physical symptoms like respiratory irritation.
El Niño is a recurring climate phenomenon characterized by the warming of the ocean surface in the central and eastern tropical Pacific Ocean. This warming disrupts global weather patterns, leading to shifts in temperature, winds, and precipitation.
The researchers are calling for marine forecasts to be integrated into public health planning, advocating for a proactive approach similar to how land-based heatwaves are managed. "If we only respond after disasters occur, we will continue to experience greater impacts than if we had acted proactively," Dr. Falkenberg stated.