Preprints
https://doi.org/10.5194/esd-2021-91
https://doi.org/10.5194/esd-2021-91
 
30 Nov 2021
30 Nov 2021
Status: this preprint is currently under review for the journal ESD.

A missing link in the carbon cycle: phytoplankton light absorption

Rémy Asselot1,a, Frank Lunkeit2, Philip Holden3, and Inga Hense1 Rémy Asselot et al.
  • 1Institute for Marine Ecosystem and Fishery Science, Center for Earth System Research and Sustainability, University of Hamburg, Hamburg, Germany
  • 2Meteorological Institute, Center for Earth System Research and Sustainability, University of Hamburg, Hamburg, Germany
  • 3Environment, Earth and Ecosystems, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK
  • anow at: Ifremer, University of Brest, CNRS, IRD, Laboratoire d’Océanographie Physique et Spatiale (LOPS), UMR6523, Centre de Bretagne, 29280 Plouzané, France

Abstract. Marine biota and biogeophysical mechanisms, such as phytoplankton light absorption, have attracted increasing attention in recent climate studies. Under global warming, the impact of phytoplankton on the climate system is expected to change. Previous studies analyzed the impact of phytoplankton light absorption under prescribed future atmospheric CO2 concentrations. However, the role of this biogeophysical mechanism under freely-evolving atmospheric CO2 concentration and future CO2 emissions remain unknown. To shed light on this research gap, we perform simulations with the EcoGEnIE Earth system model and prescribe CO2 emissions following the four Representative Concentration Pathways (RCP) scenarios. Under all the RCP scenario, our results indicate that phytopankton light absorption increases the surface chlorophyll biomass, the sea surface temperature, the atmospheric CO2 concentrations and the atmospheric temperature. Under the RCP2.6, RCP4.5 and RCP6.0 scenarios, the magnitude of changes due to phytoplankton light absorption are similar. However, under the RCP8.5 scenario, the changes in the climate system are less pronounced due to the temperature limitation of phytoplankton growth, highlighting the reduced effect of phytoplankton light absorption under strong warming. Additionally, this work evidences the major role of phytoplankton light absorption on the climate system, suggesting a highly uncertain feedbacks on the carbon cycle with uncertainties that are in the range of those known from the land biota.

Rémy Asselot 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 esd-2021-91', Pearse Buchanan, 07 Jan 2022
  • RC2: 'Comment on esd-2021-91', Anonymous Referee #2, 07 Jan 2022
  • RC3: 'Comment on esd-2021-91', Anonymous Referee #3, 07 Jan 2022

Rémy Asselot et al.

Model code and software

Source code Rémy Asselot https://zenodo.org/record/5676165

Rémy Asselot et al.

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Short summary
Phytoplankton absorbing light can influence the climate system but its future effect on the climate is still unclear. We use a climate model to investigate the role of phytoplankton light absorption under global warming. We find out that the effect of phytoplankton light absorption is smaller under a high greenhouse gas emissions compared to reduced and intermediate greenhouse gas emissions. Additionally, we show that phytoplankton light absorption is an important mechanism for the carbon cycle.
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