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Struggling to Model Antarctic Surface Air Temperature Trends

Paper Reviewed
Smith, K.L. and Polvani, L.M. 2017. Spatial patterns of recent Antarctic surface temperature trends and the importance of natural variability: lessons from multiple reconstructions and the CMIP5 models. Climate Dynamics 48: 2653-2670.

In an effort to develop climate models that can accurately represent surface air temperature trends over Antarctica, Smith and Polyani (2017) compared observed Antarctic surface air temperature trends over the two distinct time periods of 1960-2005 and 1979-2005 with those produced by 40 models that participated in Phase 5 of the Coupled Model Inter-comparison Project (CMIP5). And what did they find by so doing?

The two U.S. researchers report that (1) an observed East-West asymmetry differs substantially between the two time periods and (2) is completely absent from the forced response of the CMIP5 multi-model mean. In addition, they examined the relationship between the Southern Annular Mode (SAM) and Antarctic temperature trends in both models and re-analyses. And the fruits of this undertaking reveled that (3) "there is little evidence of anthropogenic SAM-induced driving of the recent temperature trends."

As for the significance of these findings, Smith and Polyani say they (4) "offer new, compelling evidence pointing to natural climate variability as a key contributor to the recent warming of West Antarctica and of the Peninsula." And in addition, they write that (5) the CMIP5 multi-model mean (MMM) temperature for each Antarctic region "shows a persistent cold bias of a couple of degrees."

Posted 27 July 2017