Preprints
https://doi.org/10.5194/bg-2021-14
https://doi.org/10.5194/bg-2021-14

  08 Feb 2021

08 Feb 2021

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

Oceanic primary production decline halved in eddy-resolving simulations of global warming

Damien Couespel1, Marina Lévy1, and Laurent Bopp2 Damien Couespel et al.
  • 1Sorbonne Université, LOCEAN-IPSL, CNRS/IRD/MNHN, Paris, France
  • 2LMD-IPSL, École Normale Supérieure/PSL University, CNRS, École Polytechnique, Sorbonne Université, Paris, France

Abstract. The decline in ocean primary production is one of the most alarming consequences of anthropogenic climate change. This decline could indeed lead to a decrease in marine biomass and fish catch, as highlighted by recent policy-relevant reports. Because of computational constraints, current Earth System Models used to project ocean primary production under global warming scenarios have to parameterize flows occurring below the resolution of their computational grid (typically 1°). To overcome these computational constraints, we use an ocean biogeochemical model in an idealized configuration representing a mid-latitude double-gyre circulation, and perform global warming simulations under increasing horizontal resolution (from 1° to 1/27°) and under a large range of parameter values for the eddy parameterization employed in the coarse resolution configuration. In line with projections from Earth System Models, all our simulations project a marked decline in net primary production in response to the global warming forcing. Whereas this decline is only weakly sensitive to the eddy parameters in the eddy-parameterized coarse resolution, the simulated decline in primary production in the subpolar gyre is halved at the finest eddy-resolving resolution (−12 % at 1/27° vs −26 % at 1° at the end of the 70 years long global warming simulations). This difference stems from the high sensitivity of the sub-surface nutrient transport to model resolution. Our results call for improved representation of the role of eddies on nutrient transport below the seasonal mixed-layer to better constrain the future evolution of marine biomass and fish catch potential.

Damien Couespel et al.

Status: open (until 22 Mar 2021)

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

Damien Couespel et al.

Damien Couespel et al.

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Short summary
An alarming consequence of climate change is the oceanic primary production decline projected by Earth System Models. Due to computational constraints, these models parameterize flows occurring below their computational grid resolution (1°). Idealized global warming simulations with increasing resolution (from 1° to 1/27°) show a strong sensitivity of primary production decline to resolution. This stems from the high sensitivity of the subsurface nutrient transport to model resolution.
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