In February, the California Climate Change Center released a study commissioned by the California Energy Commission and the California EPA. It forecasts "serious risks" in the form of increased fires, floods and agricultural damage that can be moderated by prompt reduction in greenhouse gas (GHG) and other global warming pollution emitted by human use of fossil fuels.
From the Introduction:
"It is now apparent that the increasing atmospheric concentration of GHGs, resulting from human activities, is changing the climate in ways that pose serious risks to California’s health, economy, and environment. However, the most severe impacts that are expected with greater temperature rises could be avoided if the rate of GHG emissions is reduced. To help identify the potentially avoidable climate impacts in California, this paper summarizes some of the impacts expected under lower, medium, and higher ranges of projected warmings, as determined by different GHG emissions scenarios and different global climate models."
Scenarios of Climate Change in California: An Overview (Feb. 2006).