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Northern Hemisphere Land Snow Cover: Simulations vs. Reality
Brutel-Vuilmet, C., Menegoz, M. and Krinner, G. 2013. An analysis of present and future seasonal Northern Hemisphere land snow cover simulated by CMIP5 coupled climate models. The Cryosphere 7: 67-80.

Noting that "the fifth phase of the Coupled Model Intercomparison Project (CMIP5), linked to the preparation of the fifth IPCC assessment report, is currently ongoing [and] running with the most recent versions of more than 30 state-of-the-art coupled climate models and a new set of climate forcing scenarios," the authors say "it is thus timely to address the following questions: how well do CMIP5 models capture present-day seasonal snow extent and observed recent trends?"

What was done
In pursuit of this goal, Brutel-Vuilmet et al. proceed to provide what they describe as "a short assessment of the simulated present-day snow cover, including its current trends," as well as an analysis of "the dominant factors determining the future evolution of Northern Hemisphere spring snow cover as simulated by the CMIP5 models."

What was learned
Among a number of disheartening findings, the three French researchers determined that "the significant trend towards a reduced spring snow cover extent over the 1979-2005 period is underestimated (simulated -1.0±0.3% per decade; observed -3.4±1.1% per decade)," and this finding, as they describe it, "is linked to the simulated Northern Hemisphere extra-tropical spring land warming trend over the same period, which is also underestimated. In addition, they note that the simulated linear relationship between the hemispheric seasonal spring snow cover extent and global mean annual surface air temperature is itself underestimated at present (simulated -5.1±3.0% per °C; observed -11.8±2.7% per °C).

What it means
In commenting further on their findings, Brutel-Vuilmet et al. write that "in many respects, the simulated snow covers in the coupled models used in CMIP3 as analyzed by Roesch (2006) and CMIP5 have similar qualities and deficiencies," causing us to wonder why so little progress has been made in so many different aspects of the climate-modeling enterprise, as testified by the host of pertinent papers for which we have produced reviews that are archived under the general heading of Climate Models (Inadequacies) in our Subject Index.

Roesch, A. 2006. Evaluation of surface albedo and snow cover in AR4 coupled climate models. Journal of Geophysical Research 111: 10.1029/2005JD006473.

Reviewed 24 July 2013