Preprints
https://doi.org/10.5194/egusphere-2022-579
https://doi.org/10.5194/egusphere-2022-579
 
27 Jul 2022
27 Jul 2022

Anthropogenic climate change drives non-stationary phytoplankton variance

Geneviève W. Elsworth1, Nicole S. Lovenduski2, Kristen M. Krumhardt3, Thomas M. Marchitto1, and Sarah Schlunegger4 Geneviève W. Elsworth et al.
  • 1Department of Geological Sciences and Institute of Arctic and Alpine Research, University of Colorado Boulder, Boulder, Colorado, USA
  • 2Department of Atmospheric and Oceanic Sciences and Institute of Arctic and Alpine Research, University of Colorado Boulder, Boulder, Colorado, USA
  • 3Climate and Global Dynamics Laboratory, National Center for Atmospheric Research, Boulder, Colorado, USA
  • 4Department of Atmospheric and Oceanic Sciences, Princeton University, Princeton, New Jersey, USA

Abstract. Multiple studies conducted with Earth System Models suggest that anthropogenic climate change will influence marine phytoplankton over the coming century. Light limited regions are projected to become more productive and nutrient limited regions less productive. Anthropogenic climate change can influence not only the mean state, but also the variance around the mean state, yet little is known about how variance in marine phytoplankton will change with time. Here, we quantify the influence of anthropogenic climate change on internal variability in marine phytoplankton biomass from 1920 to 2100 using the Community Earth System Model 1 Large Ensemble (CESM1-LE). We find a significant decrease in the internal variance of global phytoplankton carbon biomass under a high emission (RCP8.5) scenario, with heterogeneous regional trends. Decreasing variance in biomass is most apparent in the subpolar North Atlantic and North Pacific. In these high-latitude regions, zooplankton grazing acts as a top-down control in reducing internal variance in phytoplankton biomass, with bottom-up controls (e.g., light, nutrients) having only a small effect on biomass variance. Grazing-driven declines in phytoplankton variance are also apparent in the biogeochemically critical regions of the Southern Ocean and the Equatorial Pacific. Our results suggest that climate mitigation and adaptation efforts that account for marine phytoplankton changes (e.g., fisheries) should also consider changes in phytoplankton and zooplankton variance driven by anthropogenic warming, particularly on regional scales.

Geneviève W. Elsworth et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-579', Anonymous Referee #1, 09 Aug 2022
  • RC2: 'Comment on egusphere-2022-579', Anonymous Referee #2, 05 Oct 2022
  • RC3: 'Comment on egusphere-2022-579', Nicholas Bock, 28 Oct 2022

Geneviève W. Elsworth et al.

Geneviève W. Elsworth et al.

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Short summary
Anthropogenic climate change will influence marine phytoplankton over the coming century. Here, we quantify the influence of anthropogenic climate change on marine phytoplankton variance using an Earth System Model ensemble, identifying a decline in global phytoplankton biomass variance with warming. Our results suggest that climate mitigation efforts that account for marine phytoplankton changes should also consider changes in phytoplankton variance driven by anthropogenic warming.