John Metcalfe was CityLab’s Bay Area bureau chief, covering climate change and the science of cities.
Development and climate change are creating the perfect conditions for widely destructive infernos.
Of all the threats the earth's changing climate poses for the American West, perhaps none is graver than an onslaught of hot weather. A predicted pattern of long-term baking is not just dreadful news to farmers struggling with the ongoing drought, but could also set the stage for decades of frequent and more-devastating wildfires.
There's a couple of reasons for that. Hotter and drier conditions turn forests into vast reservoirs of tinder, just waiting for lightning or a careless human to set them alight. And when desiccated vegetation builds to a certain mass, it becomes hard for humans to plan for its eventual flare-up. This danger is underscored in the new U.S. National Climate Assessment, which includes this warning: "Given strong relationships between climate and fire, even when modified by land use and management, such as fuel treatments, projected climate changes suggest that western forests in the U.S. will be increasingly affected by large and intense fires that occur more frequently."
As to why these fires might be more destructive, that relates to "wildland-urban interface"—a term for areas where nature and development abut. People are building more and more next to the country's wild areas, putting more and more properties and lives at risk of incineration. There is already a noticeable trend in fire-borne destruction. Take a look at California, where there's been a vast surge in structural decimation since the 1990s. This graph shows the escalation in building loss for the 25 most destructive wildland-urban interface fires in California from 1960 to 2007:
America's more-humid East will likely avoid this kind of inferno, but many areas in the West are right in its path. To see what the future could bode, take a look at the past: The below visualization, which is based on satellite data, shows fire intensity in North America from 2000 to 2013. The red dots show lower-intensity fires, often prescribed fires set for agricultural or forest-management purposes, while the orange and yellow dots represent the kind of mega-ferocious blazes that fiercely resist containment efforts. Notice how many of these monster fires are have historically occurred in California, Colorado, Nevada, the Southwest, and beyond:
Map courtesy of NASA. Top image: Inmate firefighters head toward California's giant Rim Fire in August, 2013. (Jae C. Hong / Associated Press)