Climate pathways behind phytoplankton-induced atmospheric warming

• Main Authors: Asselot, Rémy, Lunkeit, Frank, Holden, Philip B., Hense, Inga
• Format: Text
• Language: English
• Published: 2021
• Subjects: Sea ice
• Online Access: https://doi.org/10.5194/bg-2021-118; https://bg.copernicus.org/preprints/bg-2021-118/

We investigate in which ways marine biologically-mediated heating increases the surface atmospheric temperature. While the effects of phytoplankton light absorption on the ocean have gained attention over the past years, the impact of this biogeophysical mechanism on the atmosphere is still unclear. Phytoplankton light absorption warms the surface of the ocean with consequences for the air-sea heat exchange and CO 2 flux. We focus on the ocean-atmosphere interface and study the importance of air-sea heat exchange versus air-sea CO 2 flux. To shed light on the role of phytoplankton light absorption on the surface atmospheric temperature, we performed different simulations with the EcoGENIE Earth system model. We configure the model without a seasonal cycle and, if not stated otherwise, the atmospheric CO 2 concentration is allowed to evolve freely. The climate pathways examined are: heat exchange, dissolved CO 2 , solubility of CO 2 , and sea-ice covered area. Overall we show that the air-sea CO 2 exchange has a larger effect on the biologically-induced atmospheric warming than the air-sea heat flux. Moreover, we notice that the freely evolving solubility of CO 2 has a cooling effect on the surface atmospheric temperature.