The browser you are using is not supported by this website. All versions of Internet Explorer are no longer supported, either by us or Microsoft (read more here: https://www.microsoft.com/en-us/microsoft-365/windows/end-of-ie-support).

Please use a modern browser to fully experience our website, such as the newest versions of Edge, Chrome, Firefox or Safari etc.

Default user image.

David Wårlind

Researcher

Default user image.

Nitrogen cycling in CMIP6 land surface models : Progress and limitations

Author

  • Taraka Davies-Barnard
  • Johannes Meyerholt
  • Sönke Zaehle
  • Pierre Friedlingstein
  • Victor Brovkin
  • Yuanchao Fan
  • Rosie A. Fisher
  • Chris D. Jones
  • Hanna Lee
  • Daniele Peano
  • Benjamin Smith
  • David Wärlind
  • Andy J. Wiltshire
Show all

Summary, in English

The nitrogen cycle and its effect on carbon uptake in the terrestrial biosphere is a recent progression in earth system models. As with any new component of a model, it is important to understand the behaviour, strengths, and limitations of the various process representations. Here we assess and compare five land surface models with nitrogen cycles that are used as the terrestrial components of some of the earth system models in CMIP6. The land surface models were run offline with a common spin-up and forcing protocol. We use a historical control simulation and two perturbations to assess the model nitrogen-related performances: a simulation with atmospheric carbon dioxide increased by 200 ppm and one with nitrogen deposition increased by 50 kgN ha-1 yr-1. There is generally greater variability in productivity response between models to increased nitrogen than to carbon dioxide. Across the five models the response to carbon dioxide globally was 5 % to 20 % and the response to nitrogen was 2 % to 24 %. The models are not evenly distributed within the ensemble range, with two of the models having low productivity response to nitrogen and another one with low response to elevated atmospheric carbon dioxide, compared to the other models. In all five models individual grid cells tend to exhibit bimodality, with either a strong response to increased nitrogen or atmospheric carbon dioxide but rarely to both to an equal extent. However, this local effect does not scale to either the regional or global level. The global and tropical responses are generally more accurately modelled than boreal, tundra, or other high-latitude areas compared to observations. These results are due to divergent choices in the representation of key nitrogen cycle processes. They show the need for more observational studies to enhance understanding of nitrogen cycle processes, especially nitrogen-use efficiency and biological nitrogen fixation.

Department/s

  • eSSENCE: The e-Science Collaboration
  • Dept of Physical Geography and Ecosystem Science
  • MERGE: ModElling the Regional and Global Earth system
  • BECC: Biodiversity and Ecosystem services in a Changing Climate

Publishing year

2020

Language

English

Pages

5129-5148

Publication/Series

Biogeosciences

Volume

17

Issue

20

Document type

Journal article

Publisher

Copernicus GmbH

Topic

  • Physical Geography
  • Climate Research

Status

Published

ISBN/ISSN/Other

  • ISSN: 1726-4170