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More than marine heatwaves: A new regime of heat, acidity, and low oxygen compound extreme events in the Gulf of Alaska
  • +4
  • Claudine Hauri,
  • Remi Pages,
  • Katherine S. Hedstrom,
  • Scott C. Doney,
  • Sam Dupont,
  • Bridget Ferriss,
  • Malte Stuecker
Claudine Hauri
University of Alaska Fairbanks

Corresponding Author:chauri@alaska.edu

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Remi Pages
University of Alaska Fairbanks
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Katherine S. Hedstrom
University of Alaska Fairbanks
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Scott C. Doney
University of Virginia
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Sam Dupont
University of Gothenburg
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Bridget Ferriss
NOAA Fisheries
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Malte Stuecker
U. Hawaii
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Recent marine heatwaves in the Gulf of Alaska have had devastating and lasting impacts on species from various trophic levels. As a result of climate change, total heat exposure in the upper ocean has become longer, more intense, more frequent, and more likely to happen at the same time as other environmental extremes. The combination of multiple environmental extremes can exacerbate the response of sensitive marine organisms. Our hindcast simulation provides the first indication that more than 20 % of the bottom water of the Gulf of Alaska continental shelf was exposed to quadruple heat, positive [H+], negative Ωarag, and negative [O2] compound extreme events during the 2018-2020 marine heat wave. Natural intrusion of deep and acidified water combined with the marine heat wave triggered the first occurrence of these events in 2019. During the 2013-2016 marine heat wave, surface waters were already exposed to widespread marine heat and positive [H+] compound extreme events due to the temperature effect on the [H+]. We introduce a new Gulf of Alaska Downwelling Index (GOADI) with short-term predictive skill, which can serve as indicator of past and near-future positive [H+], negative Ωarag, and negative [O2] compound extreme events on the shelf. Our results suggest that the marine heat waves may have not been the sole environmental stressor that led to the observed ecosystem impacts and warrant a closer look at existing in situ inorganic carbon and other environmental data in combination with biological observations and model output.
08 Sep 2023Submitted to ESS Open Archive
11 Sep 2023Published in ESS Open Archive