More than 4 million acres of California went up in flames in 2020 – about 4 percent of the state's land area and more than double its previous wildfire record.
Climate change intensified dry-hot extremes<p>We are <a href="https://scholar.google.com/citations?user=tGGNDyUAAAAJ&hl=en" target="_blank">scientists</a> <a href="https://scholar.google.com/citations?user=5M5ynb8AAAAJ&hl=en" target="_blank">and</a> <a href="https://scholar.google.ca/citations?user=ZaW8ZbsAAAAJ&hl=en" target="_blank">engineers</a> who study climate extremes, including wildfires. <a href="http://doi.org/10.1126/sciadv.aaz4571" target="_blank">Our research</a> shows that the probability of a drought and heat wave occurring at the same time in the U.S. has increased significantly over the past century.</p><p>The kind of dry and hot conditions that would have been expected to occur only once every 25 years on average have occurred five to 10 times in several regions of the U.S. over the past quarter-century. Even more alarming, we found that extreme dry-hot conditions that would have been expected only once every 75 years have occurred three to six times in many areas over the same period.</p><p>We also found that what triggers these simultaneous extremes appears to be changing.</p>
The U.S. Drought Monitor is jointly produced by the National Drought Mitigation Center at the University of Nebraska-Lincoln, the United States Department of Agriculture, and the National Oceanic and Atmospheric Administration. (Credit: NDMC)
2020 wasn’t normal, but what is normal?<p>If 2020 has proved anything, it is to expect the unexpected.</p><p>Before this year, Colorado had not recorded a fire of over 10,000 acres starting in October. This year, the East Troublesome fire grew from about 20,000 acres to over 100,000 acres in less than 24 hours on Oct. 21, and it was nearly 200,000 acres by the time a <a href="https://www.cpr.org/2020/10/26/snow-blankets-cameron-peak-and-east-troublesome-fires-as-crews-regroup/" target="_blank">snowstorm stopped its advance</a>. Instead of going skiing, hundreds of Coloradans evacuated their homes and nervously watched whether that fire would merge with another giant blaze.</p><p>This is not "the new normal" – it's the new abnormal. In a warming climate, looking at what happened in the past no longer offers a sense of what to expect in the future.</p><p>"The growth that you see on this fire is unheard of," <a href="https://www.npr.org/2020/10/22/926838887/colorado-fire-grows-by-over-100-000-acres-in-1-day-hits-rocky-mountain-national-" target="_blank" rel="noopener noreferrer">Grand County Sheriff Brett Schroetlin said of the East Troublesome fire on Oct. 22</a>. "We plan for the worst. This is the worst of the worst of the worst."</p>
Credit: Alizadeh, et al, Science Advances 2020<p>There are other drivers of the rise in fire damage, as well. More people moving into wildland areas means there are more cars and power lines and other potential ignition sources. Historical efforts to control fires have also meant more undergrowth in areas that would have naturally burned periodically in smaller fires.</p><p>The question now is how to manage this "new abnormal" in the face of a warming climate.</p><p>In the U.S., one in three houses are <a href="https://www.pnas.org/content/115/13/3314.short" target="_blank">built in the wildland-urban interface</a>. Development plans, construction techniques and building codes can do more to account for wildfire risks, including avoiding flammable materials and potential sources of sparks. Importantly, citizens and policymakers need to tackle the problem at its root: That includes cutting the greenhouse gas emissions that are warming the planet.</p>