The number of hot days that carry greatly increased risk of wildfire spread and ignition in California’s Sierra Nevada mountains will increase because of climate change, new research shows. The study, published in Science Advances, found the number of fires could increase by 20% by the 2040s with an even greater increase in acreage burned. “What makes this novel is that we were trying to identify the role of individual temperature extremes on individual dates,” Jim Randerson, UC-Irvine earth systems professor and senior author of the paper, told the New York times. (New York Times $; Climate Signals background: Extreme heat and heatwaves, Wildfires)