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What baseline time period should I use to compare future climate projections?

Cal-Adapt typically represents the historical baseline as a thirty-year window from 1961 to 1990. In this period, most of California’s critical infrastructure was developed and the first signals of anthropogenic climate change were beginning to be felt. We also have observed and modeled climate data for this period. 1986 to 2005 is another common baseline period.

The historical baseline you use for your analysis will be specific to your context, depending on the insights you’re working toward and the climate history of your location. No matter what baseline you select, you should use a multi-decade (e.g., 30-year) period to create your baseline, as any given year may not typify long-term climate conditions. For more information, read this definition of climate normals in the glossary.