Extreme Marine Heatwaves –common characteristics, drivers and impacts

Alexander Sen Gupta, ARC Centre of Excellence for Climate Extremes, Sydney, NSW, Australia, Mads S Thomsen, School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch, New Zealand, New Zealand, Jessica Benthuysen, Australian Institute of Marine Science, Perth, Western Australia, Australia, Alistair J Hobday, CSIRO Environment, Hobart, TAS, Australia, Eric Oliver, Dalhousie University, Department of Oceanography, Halifax, NS, Canada, Lisa Alexander, University of New South Wales, ARC Centre of Excellence for Climate Extremes, Sydney, NSW, Australia, Michael T Burrows, Scottish Marine Institute, Department of Ecology, Oban, United Kingdom, Markus Donat, Barcelona Supercomputing Center, Barcelona, Spain, Ming Feng, CSIRO, Environment, Crawley, Western Australia, Australia, Neil John Holbrook, University of Tasmania, Institute for Marine and Antarctic Studies, Hobart, TAS, Australia, Sarah Perkins-Kirkpatrick, University of New South Wales, Climate Change Research Centre and ARC Centre of Excellence for Climate System Science, Sydney, NSW, Australia, Pippa J Moore, Aberystwyth University, Institute of Biological, Environmental and Rural Sciences, Aberystwyth, United Kingdom, Regina Rodrigues, Federal University of Santa Catarina, Florianopolis, SC, Brazil, Hillary A Scannell, University of Washington, School of Oceanography, Seattle, WA, United States, Andrea Taschetto, University of New South Wales, Sydney, NSW, Australia, Caroline Ummenhofer, WHOI, Woods Hole, United States, Thomas Wernberg, The University of Western Australia, UWA Oceans Institute and School of Biological Sciences, Perth, Western Australia, Australia and Dan E Smale, Marine Biological Association of the United Kingdom, The Laboratory, Citadel Hill, Plymouth, United Kingdom
Abstract:
Strong, long and large scale MHWs can have serious impacts on marine ecosystems and reliant industries. But what are the strongest and longest MHWs? Have they been examined in the literature? Do they have common characteristics, driving mechanisms and biological responses?
In this work we use a common MHW framework to catalogue the strongest, longest and largest events over the Satellite era. We find that characteristics of the most extreme events are strongly modulated by ENSO and that there is a warm season bias in the occurrence of these events, likely linked to shallower mixed layers. Most extreme subtropical MHW are triggered by persistent high pressure systems that are associated with increased insolation, weaker surface winds (that lead to less turbulent heat fluxes) and increased warm water Ekman transport. More broadly, almost all of the most extreme MHW are associated with weaker surface winds. Finally we also find a significant response in primary productivity to these events, with reduced production at low to mid latitudes and some enhanced productivity at high latitudes.
Back to: Marine Heat Waves and Ocean Biogeochemical Extremes I