What is marine heatwave? Know how superheated oceans can harm human health

Marine heatwaves occur when ocean temperatures stay unusually high for prolonged periods, disrupting ecosystems and potentially affecting human health through heat exposure, seafood risks and air quality.

Marine Heatwave.

Marine heatwaves are not solely an environmental issue impacting the marine biota and coral reefs. Researchers say that extended periods of unusually warm ocean conditions can also impact human health, food security, livelihoods and mental health. A team of researchers from Adelaide University and the University of Hong Kong have published a paper in Nature Sustainability that addresses marine heatwaves. It also stresses the chain reaction they can reach to coastal communities and people who rely on the ocean.

What is a marine heatwave?

A marine heat wave is defined as when sea surface temperatures are higher than usual for that time and place for an extended period of time. According to scientists these events may impact large populations and marine ecosystems. They have been associated with coral bleaching, widespread deaths of marine organisms, harmful algal blooms (HABs) and significant disturbances in fisheries and aquaculture.

As global temperatures rise experts suggest that the frequency, length and severity of marine heatwaves may increase by reaching greater intensity. This implies that their impacts may extend beyond the ocean and pose a threat to human populations.

How can marine heatwaves impact human health?

Researchers have discovered several direct and indirect impacts of marine heatwaves on humans. According to the findings warm ocean temperatures can fuel storms and other extreme events. This may result in injuries, fatalities, uprooting and destruction of houses and property. For instance, Hurricane Otis in 2013 was unusually warm and rapidly strengthened seawater in Mexico which triggered estimated damages of US$15 billion. Whereas Typhoon Doksuri which has been linked to exceptionally warm ocean waters impacted over 2 million people in Asia in 2023.

Is seafood safe during marine heatwaves?

The team of researchers claim that there is a major concern about the impacts of marine heatwaves on seafood safety and availability. Researchers note that warm waters can lead to blooms of algae that can produce toxins making seafood dangerous to human health. Marine heatwaves can also impact fisheries and aquaculture activities by impacting seafood production and community livelihoods that depend on the ocean for their food and livelihoods. In addition experts caution that such weather conditions can be a food security issue particularly for those who rely on seafood as a primary source of food.

Could marine heatwaves impact mental wellbeing?

What is more concerning about this study is that scientists point out that marine heatwaves may also manifest in mental health. Individuals with strong ties to the ocean including those whose living activities, cultural practices and play are tied to the sea might suffer from emotional hardship when the marine ecosystem is degraded. Possible outcomes of repeated environmental damage are highlighted as anxiety, grief, frustration and depression. Eco anxiety and emotional struggles as well as physical health issues like respiratory irritation and asthma were also linked to the toxic algal bloom in 2025 in South Australia.

The authors suggest that governments and public health organisations should take account of marine heatwave predictions in their health emergency preparedness. Improved collaboration among ocean researchers, health officials, and coastal resource managers may also enable communities to be more proactive in their response to events.

Disclaimer: This article is for informational purposes only and does not replace medical advice, diagnosis or treatment.