A new study published in Science shows that marine heatwaves have caused major economic losses around the world, and researchers say global action needs to be taken to ease the impacts of extreme warming events on ocean life and benefits people derive from the oceans.

Professor Thomas Wernberg, from the Oceans Institute and School of Biological Sciences at The University of Western Australia, was one of the researchers on the study which provides the first global perspective of the socioeconomic impacts of marine heatwaves.

“Extreme weather events are becoming increasingly common around the world due to climate change,” Professor Wernberg said. “Marine heatwaves are periods of unusually high seawater temperatures, and these events have increased 50 per cent over the past century and this has caused widespread negative ecological impacts.”

These events have increased 50 per cent over the past century and this has caused widespread negative ecological impacts.

Professor Thomas Wernberg

The study, involving researchers from five countries and nine institutes, showed that ecological impacts of marine heatwaves often have caused major economic losses and wider effects on society across the world.

The research team examined biological responses to 34 marine heatwaves and explored the related socio-economic impacts. They found impacts in all major ocean basins and that most events resulted in loss of fisheries, destruction of kelp forests, seagrass meadows, and coral reefs, or mass mortalities of wildlife, often causing significant economic loss to multiple industries.

“We have seen devastating impacts of marine heatwaves on our kelp forests, seagrass meadows and coral reefs, and this has affected the ecological, economic and cultural benefits Australian’s derive from the oceans,” Professor Wernberg said. “These extreme events are having a profound effect on us a marine nation.”

Image: Bleached coral. Destruction of coral reefs if just one of the impacts of marine heatwaves.

The paper also revealed that there were some benefits, including increased recreational opportunities or fisheries prospects, as some important species changed their geographic range in response to warming.

Lead author Dr Katie Smith from the Marine Biological Association of the UK said the impacts of marine heatwaves were far-reaching.

“The knock-on effects can last for decades,” Dr Smith said. “The loss of coastal habitats such as seagrass meadows and kelp forests impacts fisheries, tourism, and natural capacity to store carbon.

“During marine heatwaves ocean temperatures can become so high that some species become stressed or even die, which in turn can affect foodwebs.  For example, a change in microscopic marine animals can ricochet up the foodweb, causing mass mortalities in important fisheries species, endangering sea lions and seabirds and leading to huge financial loss to fisheries and tourism.”