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CMIP5 Models Predict the Future of the Northwest Atlantic Ocean

Paper Reviewed
Loder, J.W., van der Baaren, A. and Yashayaev, I. 2015. Climate Comparisons and Change Projections for the Northwest Atlantic from Six CMIP5 Models. Atmosphere-Ocean 53: 529-555.

Working with four "historical" and two future Representative Concentration Pathway (RCP) climate simulations provided by six Earth System Models (ESMs) available through Phase 5 of the Climate Model Intercomparison Project (CMIP5), Loder et al. (2015) describe how "the models represent the detailed structure of some important Northwest Atlantic (NWA) ocean and ice features poorly, such that caution is needed in the use of their projected future changes."

More specifically, the three Canadian researchers state that "monthly 'climate change' fields between the bi-decades 1986-2005 and 2046-2065 are described, using ensemble statistics of the changes across the six ESMs." And they further report that "the results point to warmer air temperatures everywhere, warmer surface ocean temperatures in most areas, reduced sea-ice extent and, in most areas, reduced surface salinities and mixed-layer depths." However, they write that "it is clear from the discrepancies between the historical simulations and observations for a number of key variables in the NWA that the present generation of AOGCMs continues to have problems with resolving important features (e.g., Arctic outflows, sea ice, ocean convection zones, ocean gyre boundaries, decadal variability) of the region's coupled atmosphere-ice-ocean system."

And so it is that the Canadian scientists are forced to acknowledge that "the magnitudes of the intermodal differences in the projected changes are comparable to those of the ensemble-mean changes in many cases," with the result that "robust quantitative projections are generally not possible for the NWA."

Posted 27 April 2016