Deep Ocean Heatwaves Associated with Eddies

While marine heatwaves have been studied at the sea surface for more than a decade, new research published in Nature has found 80% of those occurring below 100 meters are independent of surface events, highlighting a previously overlooked aspect of ocean warming.

The study was conducted by Australia’s national science agency CSIRO and the Chinese Academy of Sciences and analyzed observational data from more than two million ocean temperature profiles from global oceans.

Marine heatwaves are prolonged temperature events that can cause severe damage to marine habitats, such as impacts to coral reefs and species displacement. These events are becoming more frequent due to global warming, with notable occurrences off Australia’s East Coast and Tasmania, as well as the northeast Pacific coast and North Atlantic.  

Traditionally, they have been tracked via satellite data focusing on surface temperatures. This new research indicates that deep-water heatwaves may be significantly underreported.

The research also highlights the influence of ocean currents, in particular eddies, on marine heatwaves, indicating they are a key driver of subsurface events.

In the East Australian Current region, data from Australia's Integrated Marine Observing System reveals more than 70% of marine heatwaves below the surface occur in ocean eddies.

Ocean eddies can impact acidification, oxygen levels and nutrient concentrations in the ocean.