Marine Heatwaves

Our work seeks to understand the drivers and impacts of marine heatwaves, to develop prediction systems for marine heatwaves, and to work with marine stakeholders to minimise the impact of these extreme events.

Current Projects

  • International marine heatwaves working group (

    Marine heatwaves are periods of above average temperatures. This schematic shows the classification defining categories of events.

  • Forecasting marine heatwaves – dynamical modelling in partnership with the BOM – Project page
  • Forecasting marine heatwaves – statistical modelling and machine learning – Project page

What are marine heatwaves?

Marine heatwaves (MHWs) are prolonged extreme oceanic warm water events (Hobday et al 2016). They can have devastating impacts on marine ecosystems — for example, causing mass coral bleaching and substantial declines in kelp forests and seagrass meadows — with implications for the provision of ecological goods and services (Smale et al 2019). This explainer by the BOM provides a good overview.

Drivers of marine heatwaves

Anomalously warm ocean waters can result from a range of ocean and atmosphere processes, including enhanced solar radiation into the ocean and increased horizontal transport (advection) of heat in ocean currents.  Large scale climate drivers, such as El Nino-La Nina (ENSO), are also known to modulate the frequency, intensity and duration of MHWs. (see Holbrook et al 2019).

Prediction of marine heatwaves

Effective adaptation and mitigation efforts by marine managers can benefit from improved MHW predictions. While there may be potential predictability of MHWs days to years in advance, accuracy will vary dramatically depending on the regions and drivers. Skillful MHW prediction has the potential to provide critical information and guidance for marine conservation, fisheries and aquaculture management.

Additional resources

Overview articles

Maps of marine heatwaves in real-time – global maps

Definition of marine heatwaves

  • Hobday, A. J., L. V. Alexander, S. E. Perkins, D. A. Smale, S. C. Straub, E. C. J. Oliver, J. Benthuysen, M. T. Burrows, M. G. Donat, M. Feng, N. J. Holbrook, P. J. Moore, H. A. Scannell, A. S. Gupta and T. Wernberg (2016). A hierarchical approach to defining marine heatwaves. Progress in Oceanography 141: 227-238. doi:210.1016/j.pocean.2015.1012.1014.
  • Hobday, A. J., E. C. J. Oliver, A. S. Gupta, J. A. Benthuysen, M. T. Burrows, M. G. Donat, N. J. Holbrook, P. J. Moore, M. S. Thomsen, T. Wernberg and D. A. Smale (2018). Categorizing and Naming Marine Heatwaves. Oceanography 31(2):

Summary of marine heatwave science

  • Holbrook, N. J., A. S. Gupta, E. C. J. Oliver, A. J. Hobday, J. A. Benthuysen, H. A. Scannell, D. A. Smale and T. Wernberg (2020). Keeping Pace with Marine Heatwaves as Oceans Warm. Nature Reviews Earth & Environment:
  • Oliver, E. C. J., J. A. Benthuysen, S. Darmaraki, M. G. Donat, A. J. Hobday, N. J. Holbrook, R. W. Schlegel and A. Sen Gupta (2021). Marine Heatwaves. Annual Review of Marine Science 13: 20.21–20.30

Drivers of marine heatwaves

  • Holbrook, N. J., H. A. Scannell, A. S. Gupta, J. A. Benthuysen, M. Feng, E. C. J. Oliver, L. V. Alexander, M. T. Burrows, M. G. Donat, A. J. Hobday, P. J. Moore, S. E. Perkins-Kirkpatrick, D. A. Smale, S. C. Straub and T. Wernberg (2019). A global assessment of marine heatwaves and their drivers. Nature Communications 10: 2624

Ecosystem impacts of marine heatwaves

  • Smale, D. A., T. Wernberg, E. C. J. Oliver, M. Thomsen, B. P. Harvey, S. C. Straub, M. T. Burrows, L. V. Alexander, J. A. Benthuysen, M. G. Donat, M. Feng, A. J. Hobday, N. J. Holbrook, S. E. Perkins-Kirkpatrick, H. Scannell, A. S. Gupta, B. Payne and P. J. Moore (2019). Marine heatwaves threaten global biodiversity and the provision of ecosystem services. Nature Climate Change:

The biggest marine heatwaves

  • Sen Gupta, A., M. Thomsen, J. A. Benthuysen, A. J. Hobday, L. V. Alexander, E. Oliver, M. T. Burrows, M. G. Donat, M. Feng, N. Holbrook, S. Perkins-Kirkpatrick, P. J. Moore, R. Rodrigues, H. A. Scannell, A. S. Taschetto, C. C. Ummenhofer, T. Wernberg and D. A. Smale (2020). Extreme Marine Heatwaves – the most intense, largest and longest events. Scientific Reports 10: 19359.