The Practitioner’s Dilemma: How to Assess the Credibility of Downscaled Climate Projections

Suppose you are a city planner, regional water manager, or wildlife conservation specialist who is asked to include the potential impacts of climate variability and change in your risk management and planning efforts. What climate information would you use? The choice is often regional or local climate projections downscaled from global climate models (GCMs; also known as general circulation models) to include detail at spatial and temporal scales that align with those of the decision problem. A few years ago this information was hard to come by. Now there is Web-based access to a proliferation of highresolution climate projections derived with differing downscaling methods. From our experience, often, the “practitioner’s dilemma” is no longer the lack of downscaled projections; it is how to choose an appropriate data set, assess its credibility, and use it wisely. In practice, products are sometimes selected on the basis of availability, convenience of format, and familiarity with the provider. Sorting through the downscaling literature for guidance is challenging even for the expert, and often, that literature is insufficient to lead the practitioner to the most appropriate product. Systematic comparisons of downscaling methods are rare and not easily accessible. To address the practitioner’s dilemma, we posit a need for a comprehensive and comparative evaluation of downscaled climate projections at local and regional scales that is accessible and informative to practitioners and climate scientists alike.