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Arctic Clouds and Sea Ice in CMIP5 Climate Models
Karlsson, J. and Svensson, G. 2013. Consequences of poor representation of Arctic sea-ice albedo and cloud-radiation interactions in the CMIP5 model ensemble. Geophysical Research Letters 40: 4374-4379.

The authors write that "clouds significantly influence the Arctic surface energy budget and a realistic representation of this impact is a key for proper simulation of the present-day and future climate." However, they say that "considerable across-model spread in cloud variables remains in the fifth phase of the Coupled Model Intercomparison Project ensemble and partly explains the substantial across-model spread in the surface radiative effect of the clouds," which further impacts sea-ice extent and albedo.

What was done
"The main focus of this study," in the words of Karlsson and Svensson, was "on how model differences in the parameterization of sea-ice albedo in the fifth phase of the Coupled Model Intercomparison Project (CMIP5) influence the cloud radiative effect on the surface energy budget and the annual cycle of sea-ice concentration."

What was learned
The two researchers report that "the across-model spread in Arctic cloud cover and cloud condensates is substantial, and no improvement is seen from previous model intercomparisons (Karlsson and Svenson, 2011)." And they note that "this diversity of simulated Arctic clouds in the CMIP5 ensemble contributes to a spread in the models' cloud influence on the surface energy budget."

What it means
In the concluding sentence of Karlsson and Svenson's most recent paper, the two Stockholm (Sweden) University scientists state that "the fact that present-day sea-ice albedo is so badly constrained in GCMs [global climate models] impacts the fidelity of future scenario assessments of the Arctic region and should therefore be a concern for the modeling community." In other words, we're not there yet ... and we've been stalled in our forward progress for several years.

Karlsson, J. and Svensson, G. 2011. The simulation of Arctic clouds and their influence on the winter surface temperature in present-day climate in the CMIP3 multi-model dataset. Climate Dynamics 36: 623-635.

Reviewed 4 December 2013