Patrick Brown, a climate scientist and former assistant professor from San Jose State University, and other researchers, including myself, recently published a paper in Nature that identifies the impact warmer temperatures have on the frequency of extreme wildfire days. For example, 6% of the Camp Fire’s risk can be tied back to warmer temperatures, whereas 38% of the risk for the CZU Lightning Complex was attributable to a warmer climate.To uncover these results, the study used machine learning. It took into account a number of fuel, weather, and topography variables to teach a model to predict whether there would be an extreme wildfire day or not. Then, the study turned the dials on factors like temperature or fuel moisture, according to various climate scenarios, to create a new prediction for wildfire risk that we could then compare with the old one.Some of the results were exactly as you would expect. With more emissions, you get warmer temperatures. With warmer temperatures, you get drier fuels. With drier fuels, you get more extreme wildfire days.But some of the results were surprising.The impact of a warming climate varied greatly depending on the fire. For some fires, an increase in temperature had little to no increase in risk. For others, a small increase in temperature made the difference in having an extreme wildfire or not.This result can be explained in a single word: thresholds.If your temperatures are cold and there’s a large amount of moisture in your fuels, and you slightly increase temperature, it won’t matter because it’s still too cold and moist to have an extreme wildfire.If your temperatures are hot and your fuels are extremely dry, and you slightly increase temperature, this also won’t matter because conditions are ripe for an extreme wildfire either way.It’s when you’re right on the boundary between those two, on the threshold, where it makes all the difference. Here, a small increase in temperature can tip the scale and turn a day where you normally wouldn’t have had a big fire into a day where extreme growth is likely.For example, 6% of the risk on the Carr Fire and 26% of the risk on the North Complex Fire were attributable to a warmer climate. On the Carr Fire, levels were well below the fuel moisture threshold, with extremely dry fuels every day. On the North Complex Fire, levels were hovering right around the threshold. The Carr Fire had very little increase in wildfire risk in a warmer climate, whereas the North Complex Fire had a large increase in risk depending on the day.Brown’s current research continues to look into these issues and is already showing some surprising and encouraging results. By engaging in fuel reduction practices like prescribed burning, we could significantly reduce our extreme wildfire risk. He says, “You could potentially not only offset, but completely negate the influence of climate change in certain locations. So we could potentially have a future with less fire danger despite climate change.”