Current Generation of Climate Models Predict Loss of Permafrost
The current generation of climate models all predict loss of permafrost with warming, but the wide range in the magnitude of model predictions underscores the need to improve permafrost physics in these models. Climate warming may lead to loss of permafrost and act as a carbon cycle feedback, but no large, multi-model syntheses have been conducted yet to assess the physical vulnerability of permafrost. Our objective here was to look at the CMIP5 models for: (1) the range of predictions for permafrost response to climate change; and (2) understand differences in the physical representation of permafrost between the models and observations in order to understand differences in the dynamics. We developed several diagnostics that could be applied to each model, and to different sets of benchmark data.
All CMIP5 models show some loss of permafrost with warming, but the range of predictions for permafrost extent in the current climate is large and indicative of a range of qualities in the model representation of permafrost physics. We identify several key areas of disagreement between the model physics, including snow insulation and frozen soil hydrology, and propose that significant development needs to focus on these processes.
This research was supported by the Director of the Office of Biological and Environ- mental Research, Office of Science, U.S. Department of Energy, under Contract DE-AC02-05CH11231 as part of the Regional and Global Climate Modeling Program (RGCM). We acknowledge the World Climate Research Programme’s Working Group on Coupled Modelling, which is responsible for CMIP, and we thank the climate modeling groups (listed in Table 1 of this paper) for producing and making available their model output. Thanks to Igor Aleinov, Eleanor Burke, Stefan Hagemann, Masahiro Hosaka, Weiping Li, Chris Milly, Kazuyuki Saito, Diana Verseghy, and Evgeny Volodin for information on the model structures reported in Table 1. For CMIP the U.S. Department of Energy’s Program for Climate Model Diagnosis and Intercomparison provided coordinating support and led development of software infrastructure in partnership with the Global Organization for Earth System Science Portals. Thanks to Vladimir Romanovsky for helpful discussion and for sharing IPY-TSP data and to Andrew Slater and David Lawrence for helpful discussion.