Preprints
https://doi.org/10.5194/bg-2021-285
https://doi.org/10.5194/bg-2021-285

  03 Nov 2021

03 Nov 2021

Review status: this preprint is currently under review for the journal BG.

Observed and forecasted global warming pressure on coastal hypoxia

Michael M. Whitney Michael M. Whitney
  • Department of Marine Sciences, University of Connecticut, 1080 Shennecossett Road, Groton, CT, USA

Abstract. Coastal hypoxia is a major environmental problem of increasing severity. A global 40-year observational gridded climate data record and 21st century forecasts from the Community Earth System Model under RCP 8.5 forcing are analyzed for long-term linear trends with a focus on warming-related pressures on coastal oxygen conditions. The forecasted median trends along the global coast are 0.32 °C, −1.6 mmol m−3, and −1.2 mmol m−3 per decade for sea-surface temperature (SST), surface oxygen capacity, and vertical-minimum oxygen concentration, respectively. These trends point to more rapid deterioration in coastal conditions than experienced over the last four decades; the forecasted median coastal trends for SST and oxygen capacity are 48 % and 18 % faster than the corresponding observed rates. Median rates for the coast and documented hypoxic areas are higher than in the global ocean. Warming and oxygen declines tend to be fastest at high latitudes, one region where new hypoxic areas may emerge as oxygen conditions deteriorate. Over 19 % of the coast has extremely rapid forecasted change upwards of 0.60 °C per decade warming and −3.0 mmol m−3 per decade oxygen change. There is considerable pressure on current hypoxic areas since future oxygen declines of any magnitude will make hypoxia more severe. The coastal forecasts can inform coastal environmental management strategies to protect future water quality and ecosystem services.

Michael M. Whitney

Status: open (until 19 Dec 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

Michael M. Whitney

Michael M. Whitney

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Short summary
Coastal hypoxia is a major environmental problem of increasing severity. The 21st century forecast analyzed indicates global coastal waters will warm and experience rapid declines in oxygen. The forecasted median coastal trends for increasing sea surface temperature and decreasing oxygen capacity are 48 % and 18 % faster than the rates observed over the last four decades. Existing hypoxic areas are expected to worsen and new hypoxic areas likely will emerge under these warming-related pressures.
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