Marine Heatwaves' Hidden Depths Unveiled in Study

As the ocean warms under climate change, a better understanding of how damaging marine heatwaves develop and last may help scientists predict them more accurately and forecast their impacts on marine ecosystems.

In a new review paper for Communications Earth & Environment , AIMS oceanographer Dr Jessica Benthuysen and co-authors found that researchers are developing their understanding of the 3D structure of marine heatwaves using observations and models.

"Marine heatwaves are damaging to critical ecosystems like coral reefs, driving mass bleaching events like the five we have seen on the Great Barrier Reef since 2016 . We need to keep building our understanding of them through sustained and targeted monitoring. This can inform management actions," said Dr Benthuysen.

a long yellow and black round-ended cylinder with short 'fins' is just under the surface of the ocean
A glider deployed in the ocean. Image: UWA

The scientists described how a range of data sources were used to capture temperatures and how they changed during a marine heatwave on the Great Barrier Reef in February 2020. These included temperature loggers on reefs, AIMS weather stations, and Integrated Marine Observing System (IMOS) moorings. Underway systems on AIMS' Research Vessel Cape Ferguson measured surface water temperatures, providing near real time data, as it steamed across the Reef. Scientists also instigated the targeted deployment of IMOS ocean gliders to understand how deep the marine heatwave reached as part of the IMOS Event Based Sampling Facility .

Animation of glider mission data from the Great Barrier Reef in January and February 2020. Source: AODN

"Together these temperature measurements provided a comprehensive dataset for assessing the marine heatwave's characteristics and impacts during the 2020 mass coral bleaching event on the Reef," said Dr Benthuysen.

"These different kinds of publicly-accessible data highlights how Australia is a world leader in the monitoring of marine heatwaves in real time."

The paper, 'A global overview of marine heatwaves in a changing climate', was a collaboration of international scientists who are a part of the Climate and Ocean Variability, Predictability, and Change (CLIVAR) project and was led by Dr Antonietta Capotondi of the University of Colorado Boulder in the United States.

An aerial viewo of a coral reef with a metal structure on the reef and two vessels in the distance
Weather station on the Great Barrier Reef. Image: S. Hahn
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