Revealing and reducing uncertainties in climate impact assessments

Abstract:

Water resources planning and management involves understanding the vulnerability of water resource systems to a wide range of different stresses. A key responsibility is to identify defensible options for the design and management of systems under an uncertain and changing climate. In the water resources sector this requires defining a range of different climate change narratives in order to evaluate the vulnerability of infrastructure and the effectiveness of different management strategies to climate-related stresses.

Recent research is just now beginning to reveal how different methodological choices can impact portrayals of climate risk. We present research showing that the common approaches to climate change assessments in the water sector are affected by substantial uncertainties in methods used for climate downscaling and hydrologic modeling, and suggest that many of these uncertainties are reducible. For example, improving continental scale hydrologic model parameters can reduce one source of uncertainty. We also present research to improve characterization of uncertainty, in order to reduce the extent to which the portrayal of climate change impacts depends on ad hoc methodological choices and provide a holistic estimate of the degree to which the climate change signal emerges from the envelope of uncertainty. We hope that this presentation stimulates discussion on the best practices for climate impact assessments, and ways to improve the robustness of water resources planning under a changing climate.