Paper in Press
GEOPHYSICAL RESEARCH LETTERS, doi:10.1029/2012GL052979
California heat waves in the present and future
- The flavor of California heat waves is changing.
- Coastal heat waves are projected to intensify relative to background warming.
- This trend is already observed due to coastal penetration of inland heat waves.
Current and projected heat waves are examined over California and its sub-regions in observations and downscaled global climate model (GCM) simulations. California heat wave activity falls into two distinct types: (1) typically dry daytime heat waves and (2) humid nighttime-accentuated events (Type I and Type II, respectively). The four GCMs considered project Type II heat waves to intensify more with climate change than the historically characteristic Type I events, although both types are projected to increase. This trend is already clearly observed and simulated to various degrees over all sub-regions of California. Part of the intensification in heat wave activity is due directly to mean warming. However, when one considers non-stationarity in daily temperature variance, desert heat waves are expected to become progressively and relatively less intense while coastal heat waves are projected to intensify even relative to the background warming. This result generally holds for both types of heat waves across models. Given the high coastal population density and low acclimatization to heat, especially humid heat, this trend bodes ill for coastal communities, jeopardizing public health and stressing energy resources.
Received 6 July 2012; accepted 20 August 2012.
Citation: (2012), California heat waves in the present and future, Geophys. Res. Lett., doi:10.1029/2012GL052979, in press.