Ninety-five percent of wildfires that ravaged California in the past 100 years were caused by humans, according to a forthcoming study in the International Journal of Wildland Fire. “In most of California, if we could stop ignition during extremely high winds and drought and heat spells, like now, that will be an effective approach,” lead author and U.S. Geological Survey wildfire expert Jon Keeley told The San Jose Mercury News of his soon-to-be-published study. While the public debate largely rages around global warming’s role in wildfires, Keeley’s study shows that human interaction with the landscape, no matter the climate, is causing most fires.
Bjorn Lomborg, president of the Copenhagen Consensus Center, compiled data from 1926-2017 showing that the acreage burned by U.S. wildfires has dropped fourfold since peaking in the 1930s, which was posted on the skeptics’ website Climate Depot.
“The destructive fires in California are not unexpected given the wet winter last year and resultant plant growth, followed by hot and dry weather since then in which the vegetation dried out,” University of Colorado Boulder meteorologist Roger A. Pielke Sr. said. “An important issue is the extent humans have deliberately or inadvertently started the fires,” Mr. Pielke said. “If these were not started by people (including sparks from power lines), how many fires would there have been naturally? Probably none.” “As to whether this is a ‘new normal,’ it is easy (and inaccurate) to blame climate change just from added CO₂,” said Mr. Pielke, “when in reality the reasons for the fires and the damage they are causing are more complex.”