A simplified permafrost-carbon model for long-term climate studies with the CLIMBER-2 coupled earth system model

K. Crichton (1, 2) , Didier M. Roche (3, 4) , G. Krinner (2) , J. Chappellaz (2)

1 UGA [2016-2019] - Université Grenoble Alpes [2016-2019]
2 LGGE - Laboratoire de glaciologie et géophysique de l'environnement
3 LSCE - Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette]
4 CLIM - Modélisation du climat

We present the development and validation of a simplified permafrost-carbon mechanism for use with the land surface scheme operating in the CLIMBER-2 earth system model. The simplified model estimates the permafrost fraction of each grid cell according to the balance between modelled cold (below 0 °C) and warm (above 0 °C) days in a year. Areas diagnosed as permafrost are assigned a reduction in soil decomposition rate, thus creating a slow accumulating soil carbon pool. In warming climates, permafrost extent reduces and soil decomposition rates increase, resulting in soil carbon release to the atmosphere. Four accumulation/decomposition rate settings are retained for experiments within the CLIMBER-2(P) model, which are tuned to agree with estimates of total land carbon stocks today and at the last glacial maximum. The distribution of this permafrost-carbon pool is in broad agreement with measurement data for soil carbon content. The level of complexity of the permafrost-carbon model is comparable to other components in the CLIMBER-2 earth system model.

Domaines: Sciences de l'environnement

K. Crichton, Didier M. Roche, G. Krinner, J. Chappellaz. A simplified permafrost-carbon model for long-term climate studies with the CLIMBER-2 coupled earth system model. Geoscientific Model Development, 2014, 7 (6), pp.3111-3134. ⟨10.5194/gmd-7-3111-2014⟩. ⟨insu-01204694⟩