Marine Heatwaves Sicken Populations Through Storms and Shellfish: No Health System Tracks Them

When a heat wave bakes a city, the public health machinery activates: cooling centers open, hospitals brace for surge, emergency alerts go out across text and television. When the ocean heats up - and increasingly, it does - the machinery stays silent. No hospital is warned. No mental health service is pre-positioned. No emergency manager adjusts their forecast. A landmark paper published Monday in Nature Sustainability argues that silence is costing lives, and that it must change. Read the Falkenberg and Russell paper here.Researchers from Adelaide University and the University of Hong Kong are calling on governments and public health agencies worldwide to formally recognize marine heatwaves as a major public health threat - on par with the land-based extreme heat events that already trigger emergency protocols. Their analysis maps a chain of cascading harm that runs from warming ocean temperatures directly to human bodies and minds: intensified tropical storms that kill and displace people, shellfish rendered toxic by algal blooms, and a deepening psychological crisis among coastal communities whose livelihoods and identities are bound to waters that are becoming unrecognizable."Marine heatwaves are no longer just recognised as an environmental issue; they are increasingly also perceived as a human health issue," said lead author Dr. Laura Falkenberg, of Adelaide University's School of Physics, Chemistry and Earth Sciences. "Our paper highlights that these events can influence people's health in many different ways, both directly and indirectly."Marine Heatwaves Have Doubled in Frequency - and Are AcceleratingMarine heatwaves - defined as prolonged periods when sea surface temperatures exceed the 90th percentile of a 30-year historical baseline for a given location - are not new. But their scale, frequency, and intensity have accelerated sharply. The IPCC's sixth assessment report, which documented marine heatwave trends, found that frequency has doubled since the 1980s and projects a four- to eight-fold further increase by the end of this century.The oceans bear an outsized share of the climate burden. Since 1955, the world's oceans have absorbed approximately 93 percent of the excess heat generated by greenhouse gas emissions - a thermal accumulation now expressing itself as more frequent and more ferocious marine extremes. From 1982 to 2023, the annual cumulative intensity of marine heat waves increased in most coastal US waters, with the largest changes occurring off the northeastern US and Alaskan coasts. Similar trends have been documented in virtually every ocean basin globally.Marine heatwaves have already been linked to mass marine mortality events, widespread coral bleaching, harmful algal blooms, and major disruptions to fisheries and aquaculture. What the Falkenberg paper does - and what distinguishes it from the substantial ecological literature on marine heatwaves - is draw a systematic line from those ocean conditions to human bodies and human minds.Storms Supercharged by Warm WaterOne of the most direct human health pathways runs through tropical storm intensification. The mechanism is straightforward: warm ocean surface water provides thermodynamic energy to cyclonic systems through latent heat released as water evaporates. Higher sea surface temperatures mean more energy available for a forming or traveling hurricane or typhoon to absorb - producing faster intensification, stronger winds, heavier rainfall, and more destructive storm surge.The consequences are not theoretical. The intensification of Hurricane Otis in 2023 and its destruction across Mexico - with damage estimated at more than US$15 billion - has been directly linked to a marine heatwave that kept waters in the cyclone's path abnormally warm. Separately, Typhoon Doksuri in 2023 affected more than two million people across Asia through flooding and displacement, and its ferocity has similarly been attributed in part to elevated ocean temperatures along its track.These are not isolated cases. As marine heatwaves grow more frequent, the probability that a tropical storm will encounter warmer-than-historical water increases - meaning the window between catastrophic storm seasons may narrow, and the storms within each season may intensify more rapidly than the systems designed to track and warn about them can predict.Poisoned Shellfish: What You Need to Know Before You EatA second, and more intimate, health pathway runs directly to the kitchen table. Warm, stable ocean water - the condition a marine heatwave creates - is ideal breeding ground for harmful algal blooms (HABs): rapid proliferations of toxic algae, particularly dinoflagellates and diatoms, that contaminate the shellfish and finfish that filter through the water column.The toxins produced by these blooms are specific and dangerous. Domoic acid, produced by Pseudo-nitzschia diatoms, causes amnesic shellfish poisoning in humans - with symptoms ranging from nausea and disorientation to seizures, memory loss, and, in severe cases, death. Crucially, domoic acid is not destroyed by cooking. Paralytic shellfish toxins (PSTs), produced by dinoflagellates such as Alexandrium species, can cause paralytic shellfish poisoning (PSP), which has been fatal. Both toxins are tracked by NOAA shellfish programs.HABs that were historically associated with summer peak temperatures are now occurring earlier, lasting longer, and expanding into new geographic ranges. An earlier-than-usual toxic algal bloom hit Southern California in 2025, killing hundreds of sea lions, dolphins, and seabirds and triggering shellfish-harvest closures along the coast. The researchers warn this is a preview of a much larger problem: harmful algal blooms are expected to grow more common as oceans warm, and the seafood safety monitoring systems in place to detect them were not designed for the pace and geographic expansion now unfolding.For American shellfish consumers: the practical guidance remains constant - check your state's shellfish safety advisories before harvesting or purchasing local shellfish, particularly mussels, clams, and oysters from coastal waters. During marine heatwaves, that advisory matters more than it ever did.In South Australia, the consequences of a 2025 marine heatwave-driven algal bloom were documented with unusual specificity. The bloom generated not only elevated rates of respiratory irritation and asthma among beachgoers but also something less visible: what researchers described as widespread eco-anxiety, grief, frustration, and depression among coastal residents. An Adelaide University survey of more than 600 South Australians found high levels of eco-anxiety during the peak of the 2025 bloom, with many participants reporting persistent worry, sadness, and feelings of helplessness. The public health system had no protocol for any of it.The Mental Health Toll Nobody Is CountingPerhaps the most underappreciated dimension of the crisis is psychological. The Falkenberg paper dedicates substantial attention to what researchers are now calling the mental health ripple effects of ocean ecosystem loss - and it draws on a scholarly framework that has been building for two decades.The key concept is solastalgia: a term coined by Australian philosopher and environmental scholar Glenn Albrecht in 2003, derived from the Latin solacium (comfort) and the Greek algos (pain). The solastalgia concept is defined as the distress produced by environmental degradation in one's home environment - the specific grief of watching the place you still inhabit transform in ways that feel like a loss. It is distinct from nostalgia (missing a home you have left) and from eco-anxiety (fear of future environmental threats). Solastalgia is the grief of environmental change in the present tense, with no clear endpoint because the degradation continues.For fishing families, Indigenous coastal communities, and marine-dependent workers, a degraded ocean is not merely an environmental inconvenience - it is the erosion of livelihood, heritage, and identity simultaneously. "Many people rely on healthy oceans not only for food and income, but also for recreation, cultural identity and their overall sense of wellbeing," Dr. Falkenberg said. "When marine ecosystems suffer, the impacts ripple through communities."Research has linked solastalgia to affective disruption, identity loss, and elevated mental illness risk, and has argued for its formal integration into mental health science. Coastal communities whose relationships with marine environments are central to cultural identity - fishing villages, Indigenous Pacific island nations, subsistence-dependent communities - are among the most solastalgia-exposed populations on Earth. They are also among those with the least access to mental health infrastructure and the least political leverage to demand public health responses to ocean-driven distress.None of this appears in any existing marine heatwave emergency protocol, because no such protocol exists.An Emergency System Designed for Land, Not SeaThe paper's central policy argument is structurally simple and practically radical: marine heatwaves should be treated with the same institutional seriousness as the terrestrial heatwaves that already trigger public health emergency responses in cities around the world.When a land-based heat wave is forecast, the existing machinery responds: hospitals prepare for surge capacity, cooling centers are identified and opened, vulnerable populations are checked on, emergency alert systems activate, and public health agencies issue guidance. Marine heatwaves receive none of this. Monitoring systems for ocean temperature extremes - maintained by NOAA, Copernicus, and regional agencies - are oriented toward ecological outcomes: coral bleaching alerts, fishery management advisories, cyclone formation tracking. They have no formal integration into public health infrastructure.This means that when a marine heatwave triggers a HAB that contaminates a regional shellfish harvest, the public health response is reactive and slow - detection happens after consumption, not before. When a marine heatwave supercharges a storm, emergency managers are operating without the ocean temperature dimension in their forecast. And when a marine heatwave degrades a reef or empties fishing grounds and coastal communities begin to grieve, there is no mental health preparedness protocol activated, because the trigger - ocean warming - is invisible to the systems designed to protect human health on land.The authors of the Nature Sustainability study argue that governments and public health agencies should begin incorporating marine heatwave forecasts into public health planning, considering health impacts in marine and coastal management decisions, and building collaboration between ocean scientists, health authorities, and resource managers."Recognising these health impacts is the first step towards better protecting communities," Dr. Falkenberg said. "If we only respond after disasters occur, we will continue to experience greater impacts than if we had acted proactively. By understanding the links between ocean health and human health, we can develop better policies that protect both people and the marine ecosystems they depend on."What Does Parity With Land Heatwaves Actually Require?The Falkenberg paper does not prescribe a single policy model, but its argument implies a set of concrete operational gaps that any parity system would need to close.First, marine heatwave forecasts - already produced by NOAA's Physical Sciences Laboratory and the Copernicus Climate Change Service - need to be formally integrated into the same emergency management tier that receives land-based heatwave alerts. That means hospital administrators, county emergency managers, and state public health agencies receiving marine heatwave advisories alongside air quality alerts and terrestrial extreme heat warnings.Second, HAB early warning needs to connect more directly to food safety alerts at the consumer level. Existing shellfish safety closure systems are functional but slow and under-resourced relative to the expanding geographic range of bloom events. A marine heatwave forecast should automatically trigger enhanced HAB monitoring in the affected coastal zone - before contaminated shellfish reach market, not after.Third, mental health preparedness in marine-dependent communities needs to be recognized as a legitimate public health function during ocean heatwave events, with the same kind of community outreach and services access that is pre-positioned for land heatwave vulnerable populations.None of these steps require new science. The science is what the Falkenberg paper provides. What they require is institutional willingness to recognize that the ocean is not just a victim of climate change - it is also a vector through which climate change reaches human bodies and human minds, and that those of us who eat from it, work on it, or live beside it are not protected by systems designed only for the land.Frequently Asked QuestionsAre marine heatwaves actually dangerous to people directly - or only to ocean ecosystems?Marine heatwaves create multiple pathways to direct human harm. The most immediate for most people is food safety: warm ocean water accelerates harmful algal blooms (HABs), which produce toxins - including domoic acid and paralytic shellfish toxins - that accumulate in shellfish and finfish. These toxins are not destroyed by cooking and can cause neurological damage, paralytic illness, and death. A second pathway runs through tropical storm intensification: warmer sea surfaces provide more energy to hurricanes and typhoons, increasing their destructive potential. Hurricane Otis in 2023, linked to a marine heatwave, caused more than US$15 billion in damage in Mexico. A third pathway is psychological: coastal communities whose livelihoods and identities are tied to healthy oceans experience documented grief, anxiety, and depression when those ecosystems degrade - a phenomenon scholars call solastalgia, which Albrecht first defined in 2003.Should I avoid eating shellfish during a marine heatwave?You should check your state's current shellfish safety closure advisories before harvesting or purchasing local shellfish, particularly during periods when your region's coastal waters are experiencing elevated temperatures. Your state's department of public health or department of fish and wildlife will post current closures tied to toxin monitoring. This precaution applies to both commercially harvested and recreationally gathered shellfish - mussels, clams, oysters, and razor clams are the highest-risk species because they filter-feed and concentrate algal toxins. The risk is not uniform across all shellfish at all times; the advisories exist precisely to communicate when and where contamination is occurring. The important point from this research is that marine heatwaves increase the frequency and geographic range of these events, so check NOAA shellfish guidance and your state's advisories as a regular precaution during warm ocean conditions.What would it take for emergency systems to respond to marine heatwaves the way they respond to land heatwaves?The key institutional change would be integrating marine heatwave forecasts - already produced by NOAA's Physical Sciences Laboratory and the Copernicus Climate Change Service - into the same tier of emergency management alerts that public health agencies and hospital systems receive for land-based extreme heat events. This would mean marine temperature alerts reaching hospital administrators and county emergency managers, not just oceanographers and fisheries managers. It would also mean automatically triggering enhanced HAB monitoring when a marine heatwave is forecast in a region with active aquaculture or shellfish harvest, and pre-positioning mental health outreach for marine-dependent communities when ocean ecosystem degradation events occur. The research establishing why these steps are necessary exists; what the Nature Sustainability paper argues is that the policy and institutional will to implement them is what is currently absent.How is the mental health impact of ocean degradation different from general climate anxiety?Researchers distinguish several related but distinct psychological phenomena. Eco-anxiety is broadly defined as chronic fear of environmental doom - future-oriented distress about what climate change will bring. Solastalgia, coined by philosopher Glenn Albrecht in 2003, is specifically the grief of watching one's home environment transform in ways that feel like a loss - present-tense distress, not anticipatory fear. For a fish farmer watching their harvest die, a diver watching reefs bleach, or an Indigenous community watching fishing grounds empty, the experience is more accurately described as solastalgia than eco-anxiety: the loss is already happening, it is visible and ongoing, and it cannot be resolved by emotional coping strategies alone because the environmental degradation continues. Solastalgia is not a DSM-5 medical diagnosis, but research links it to elevated depression, anxiety, and identity disruption - and it is disproportionately experienced by the communities least likely to have access to mental health support.