EGU2020-1951, updated on 12 Jun 2020
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Terrestrial Biological Nitrogen Fixation in CMIP6 Models

Taraka Davies-Barnard1,2, Johannes Meyerholt2, Sönke Zaehle1, Pierre Friedlingstein1,3, Victor Brovkin4, Yuanchao Fan5,6, Rosie Fisher7,8, Chris Jones9, Hanna Lee8, Daniele Peano10, Benjamin Smith11, David Wårlind12, Andy Wiltshire9, and Tilo Ziehn13
Taraka Davies-Barnard et al.
  • 1University of Exeter, University of Exeter, College of Engineering, Mathamatics and Physical Sciences, Bristol, United Kingdom of Great Britain and Northern Ireland (
  • 2Max Planck Institute for Biogeochemistry, Jena, Germany
  • 3Laboratoire de Meteorologie Dynamique, Institut Pierre-Simon Laplace, CNRS-ENS-UPMC-X, Departement de Geosciences, Ecole Normale Superieure, 24 rue Lhomond, 75005 Paris, France
  • 4Max Planck Institute for Meteorology, Hamburg, Germany
  • 5NORCE Norwegian Research Centre, Bjerknes Centre for Climate Research, Bergen, Norway
  • 6Harvard University, Cambridge, USA
  • 7National Center for Atmospheric Research, Boulder, Colorado, USA
  • 8Centre Européen de Recherche et de Formation Avancée en Calcul Scientifique, Toulouse, France
  • 9Met Office Hadley Centre, Exeter, UK
  • 10Fondazione Centro euro-Mediterraneo sui Cambiamenti Climatici, Bologna, Italy
  • 11Department of Physical Geography and Ecosystem Science, Lund University, Lund, Sweden
  • 12Hawkesbury Institute for the Environment, Western Sydney University, Richmond, Australia
  • 13CSIRO Oceans and Atmosphere, Aspendale, VIC, 3195, Australia

Biological nitrogen fixation (BNF) is a key contributor to sustaining the terrestrial carbon cycle, providing nitrogen input that plants require. This is particularly salient for projections of carbon uptake under increased atmospheric carbon dioxide concentrations, which may allow for so-called ‘carbon dioxide fertilisation’ if other plant requirements, such as nitrogen, do not prevent increases in productivity. The amount, processes, and global distribution of BNF is highly disputed and consequently land surface models represent it in varying ways. Looking at the latest generation of CMIP6 earth system models with terrestrial nitrogen cycles, we consider their performance with regard to BNF. We assess models against a new comprehensive meta-analysis of BNF field measurements that gives a global range and site-specific values. We find that compared to the wide range of upscaled observations, the models still have a larger range, with under and overestimates.

How to cite: Davies-Barnard, T., Meyerholt, J., Zaehle, S., Friedlingstein, P., Brovkin, V., Fan, Y., Fisher, R., Jones, C., Lee, H., Peano, D., Smith, B., Wårlind, D., Wiltshire, A., and Ziehn, T.: Terrestrial Biological Nitrogen Fixation in CMIP6 Models, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1951,, 2020


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