Global warming could mean powerful fires are in our near future. As the subtropics of North America—in the U.S., that's the Southwest—continue to dry out, the parched Arizona climate and desert brush, combined with thunderstorm-fueled lightning and gusting winds, create the ideal conditions for a sequel to the Great Fire of 1910. Back then, 3 million acres in Idaho and Montana went up in flames in two days.
But scientists theorize that the average lifespan of wildfires is increasing, from one week to five. Five weeks of the Great Fire, and 52.5 million acres would be destroyed. And Tucson is right in the hot spot, so to speak. The Aspen Fire of 2003, a mere 17 miles from the city, sizzled for two weeks, torching 25,000 acres of land and hundreds of commercial and residential buildings before thousands of firefighters finally quelled the beast. Given the worst conditions, they may not be able to manage an out-of-control blaze before it does catastrophic damage.