Perspectives and Guidance for Climate Change Analysis

California’s water managers face a climate that changes and is changing as a result of both natural and anthropogenic influences. In some settings and for some variables, California’s natural climate variability still dominates anthropogenic influences and will continue to do so for the foreseeable future. In other cases, anthropogenic influences are already evident in important aspects of California’s climate. Much research is still required to unravel this tangled web of atmospheric interactions. In any case, California water planning under a changing climate needs to recognize that the causes of variations and changes include both anthropogenic and natural drivers.

This technical information record summarizes the scientific and technical guidance and perspectives of the California Department of Water Resources’ (DWR’s) Climate Change Technical Advisory Group (CCTAG) on the use of climate models and associated technical tools for water resource planning. DWR values the work of the members of the CCTAG and will consider this advice as it moves forward in developing specific actions.

DWR empaneled this CCTAG in February 2012 to advise DWR on the scientific aspects of climate change, its impacts on water resources, the use of planning approaches and analytical tools, and the development of adaptation responses.

DWR requested specific assistance with developing:
• A set of future climate scenarios and analysis procedures appropriate for DWR planning.
• An approach to extreme climate change scenarios to provide “stress tests.”
• Interim guidance on modeling extreme weather events that cause flooding (time permitting within the tenure of the CCTAG).