THE STUDY APRIL 19, 2011
Large wildfires are still threatening many parts of Texas, as firefighters struggle to contain what the AP called "some of the worst wildfire conditions in state history." Today, officials announced that the estimated size of one fire creeping closer to the Dallas-Fort Worth area has doubled in the past 24 hours, to about 150,000 acres, threatening hundreds of homes. After one of the driest Marches in Texas history, the New York Times says, "National Weather Service meteorologists expected a “lull” in the high winds on Wednesday, and a cold front could bring rain that evening. But the critical fire conditions are likely to return on Thursday." Wildfires have been on the rise in recent years, with many blaming climate change. Fortunately for scientists seeking to resolve this debate, sedimentary charcoal records allow scientists to gather historical data on wildfires. What do these records tell us about the causes and future trends of wildfires?
Two scientists from NASA's Godard Institute for Space Studies at Columbia University used the charcoal data to construct models of global wildfire activity from 844-2100. In pre-Industrial Revolution times, the authors found that global fire activity was driven by precipitation, not temperature. "For instance, the cold and dry climate during the late 15th century...corresponds with increased global fire activity (in both the model-based and the charcoal-based reconstruction), whereas during the cold but humid 17th–early 18th centuries global fire activity decreased." The future picture is not pretty: "Rapidly rising temperatures and regional drying reverse the recent fire activity decline, driving a rapid increase after ∼2050," the authors write. Somewhat counterintuitively, scenarios with less population growth and "milder warming result in greater biomass burning due to reversal of land conversion and declining population [growth] (and hence fire suppression)." The growth is not uniform though: "in the eastern United States fire activity declines, while rising considerably in the western United States." No one ever said Mother Nature was fair.