Current and future impacts of extreme events in California

In the next few decades, it is likely that California must face the challenge of coping with increased impacts from extreme events such as heat waves, wildfires, droughts, and floods. This study presents new projections of changes in the frequency and intensity of extreme events in the future across climate models, emissions scenarios, and downscaling methods, and for each California county. Consistent with other projections, this study finds significant increases in the frequency and magnitude of both high maximum and high minimum temperature extremes in many areas. For example, the frequency of extreme temperatures currently estimated to occur once every 100 years is projected to increase by at least ten-fold in many regions of California, even under a moderate emissions scenario. Under a higher emissions scenario, these temperatures are projected to occur close to annually in most regions. Also, consistent with other projections, analyses of precipitation extremes fail to detect a significant signal of change, with inconsistent behavior when comparing simulations across different GCMs and different downscaling methods.