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Climate of the Past An interactive open-access journal of the European Geosciences Union
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Volume 5, issue 1
Clim. Past, 5, 85–96, 2009
© Author(s) 2009. This work is distributed under
the Creative Commons Attribution 3.0 License.
Clim. Past, 5, 85–96, 2009
© Author(s) 2009. This work is distributed under
the Creative Commons Attribution 3.0 License.

  17 Mar 2009

17 Mar 2009

Exploring the climatic impact of the continental vegetation on the Mezosoic atmospheric CO2 and climate history

Y. Donnadieu1, Y. Goddéris2, and N. Bouttes1 Y. Donnadieu et al.
  • 1Laboratoire des Sciences du Climat et de l'Environnement (LSCE), unité mixte CNRS-CEA-UVSQ, Gif/Yvette, France
  • 2Laboratoire des Mécanismes et Transferts en Géologie (LMTG), Toulouse, France

Abstract. In this contribution, we continue our exploration of the factors defining the Mesozoic climatic history. We improve the Earth system model GEOCLIM designed for long term climate and geochemical reconstructions by adding the explicit calculation of the biome dynamics using the LPJ model. The coupled GEOCLIM-LPJ model thus allows the simultaneous calculation of the climate with a 2-D spatial resolution, the coeval atmospheric CO2, and the continental biome distribution. We found that accounting for the climatic role of the continental vegetation dynamics (albedo change, water cycle and surface roughness modulations) strongly affects the reconstructed geological climate. Indeed the calculated partial pressure of atmospheric CO2 over the Mesozoic is twice the value calculated when assuming a uniform constant vegetation. This increase in CO2 is triggered by a global cooling of the continents, itself triggered by a general increase in continental albedo owing to the development of desertic surfaces. This cooling reduces the CO2 consumption through silicate weathering, and hence results in a compensating increase in the atmospheric CO2 pressure. This study demonstrates that the impact of land plants on climate and hence on atmospheric CO2 is as important as their geochemical effect through the enhancement of chemical weathering of the continental surface. Our GEOCLIM-LPJ simulations also define a climatic baseline for the Mesozoic, around which exceptionally cool and warm events can be identified.

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