Modelling the impact of global warming on the trophic state of the upper ocean
Final Report Abstract
The goal of this research project was to quantitatively estimate the potential impact of global warming on the trophic balance of the surface ocean. To address this complex topic, we combined the application of a global marine ecosystem model with experimental work in mesocosms. By applying an earth system model (UVic ESCM) in different configurations of the marine ecosystem, we could demonstrate that the representation of temperature sensitivity of biological processes can have a profound impact on the simulated response of marine NPP to global warming. This work could highlight the crucial role of the interplay between temperature and metabolic rates within the ecosystem - and demonstrated that current models lack the ability to even reliably predict the direction of change in NPP in response to climate change. The study also pointed out the problems of determining a correct “community-wide” temperature response curve in common marine ecosystem models. This notion could be underpinned in a mesocosm experiment, which indicated the large influence of species-specific differences in temperature sensitivity on biogeochemical responses of the entire ecosystem. In our study, we observed a positive effect of increasing temperatures on net carbon uptake and production of organic carbon biomass by a natural plankton community, which was in sharp contrast to findings from a previous similar study by Wohlers et al. [2009]. Thereby, the study could demonstrate that the response to global warming might yield very different outcomes, depending on the physiological properties and temperature response of the dominant species in a given plankton community. Altogether, the work carried out in this project highlighted the crucial role of temperature sensitivity in a changing ocean. At the same time, we could identify important gaps in our knowledge about the response of marine ecosystems to ocean warming, that should be investigated in future research.
Publications
- (2011), Can we predict the direction of marine primary production change under global warming?, Geophys. Res. Lett., 38
Taucher, J., and A. Oschlies
- (2012), Enhanced carbon overconsumption in response to increasing temperatures during a mesocosm experiment, Biogeosciences, 9(9), 3531-3545
Taucher, J., K. G. Schulz, T. Dittmar, U. Sommer, A. Oschlies, and U. Riebesell
(See online at https://doi.org/10.5194/bg-9-3531-2012) - (2015), Combined effects of CO2 and temperature on carbon uptake and partitioning by the marine diatoms thalassiosira weissflogii and dactyliosolen fragilissimus, Limnology and Oceanography, 60(3), 901-919
Taucher, J., J. Jones, A. James, M. A. Brzezinski, C. A. Carlson, U. Riebesell, and U. Passow
(See online at https://doi.org/10.1002/lno.10063)
