Marine heatwaves a growing threat to physical, mental health of humans: Experts

Marine heatwaves, once viewed largely as a crisis for oceans and marine ecosystems, are emerging as a growing threat to human health, with prolonged spells of unusually high sea temperatures capable of setting off a chain reaction that reaches far beyond the shoreline, researchers have warned.

In a comment published in Nature Sustainability, researchers from the University of Adelaide and the University of Hong Kong outlined how increasingly frequent, intense and longer-lasting marine heatwaves could affect both the physical and mental well-being of millions of people.

The researchers said extreme ocean temperatures can intensify weather systems, heightening the risk of powerful storms, flooding, injuries, deaths and displacement. At the same time, warming seas can disrupt fisheries, reduce seafood supplies and livelihoods, and fuel psychological distress in coastal communities whose lives are closely intertwined with the ocean.

“Marine heatwaves are no longer just recognised as an environmental issue; they are increasingly also perceived as a human health issue,” said lead author Laura Falkenberg of the University of Adelaide’s School of Physics, Chemistry and Earth Sciences.

From warming seas to human suffering

As global temperatures continue to rise, marine heatwaves are becoming more frequent, persistent and intense. Their ecological toll is already evident in mass mortality events among marine species, widespread coral bleaching, harmful algal blooms and severe disruptions to fisheries and aquaculture.

But the researchers warn that the consequences do not stop with marine ecosystems.

Harmful algal blooms, which are expected to become more prevalent as oceans warm, can contaminate seafood and expose people to potentially serious health risks. Declining fish stocks and falling seafood production could also pose a long-term threat to food security for billions of people around the world.

For coastal communities, the damage can be particularly profound. Disrupted fisheries and aquaculture can undermine livelihoods, while the destruction of marine ecosystems can strike at the heart of communities whose cultural identity and economic survival are bound to the sea.

A growing mental health burden

The researchers also drew attention to the less visible psychological scars left by marine heatwaves.

Witnessing the degradation and disappearance of marine ecosystems, coupled with the uncertainty surrounding livelihoods and food supplies, can contribute to anxiety, grief and other mental health challenges. These impacts may be especially acute among people with deep economic, cultural or emotional connections to the marine environment.

Falkenberg said marine heatwaves can influence human health through multiple pathways, both direct and indirect. Beyond intensifying storms and atmospheric heatwaves, they can affect the availability and safety of seafood, disrupt livelihoods and deepen psychological distress in ocean-dependent communities.

“When marine ecosystems suffer, the impacts ripple through communities,” Falkenberg said, pointing to growing evidence of eco-anxiety, grief and other mental health challenges.

Call for health-focused preparedness

The researchers argued that governments and public health agencies should begin treating marine heatwaves with the same urgency accorded to heatwaves on land.

That would require integrating marine heatwave forecasts into public health planning, factoring health consequences into marine and coastal management decisions, and strengthening coordination between ocean scientists, health authorities and resource managers.

The researchers said acting before marine heatwaves trigger wider crises could help coastal communities build resilience and prepare for an increasingly volatile ocean environment.

As the seas continue to warm, the warning from researchers is becoming increasingly stark: what happens in the ocean does not remain in the ocean — its ripples can reach human health, livelihoods, food security and mental well-being far beyond the coastline.

With PTI inputs