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

• Published in: Geoscientific Model Development
• Main Authors: K. A. Crichton, D. M. Roche, G. Krinner, J. Chappellaz
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2014
• Subjects: Geology; QE1-996.5; permafrost
• Online Access: https://doi.org/10.5194/gmd-7-3111-2014; https://doaj.org/article/7c13e3287116480ca54d1502a9fe0119

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.