In 1989, a 185-page California climate report warned that a warming would slash the state's spring runoff by a full third. 30 years later, its warnings proved right, with mountain snow cover falling by half as droughts, floods and fires worsened

California received climate change warnings thirty years ago. These projections accurately predicted droughts, floods, and heat waves. The state's ambitious efforts to address global warming began then. Many regret the slow societal response to these warnings…