The reasons that the desert Southwest is having another extreme fire season are complex. They include decades of poor forestry and livestock grazing practices, misguided federal firefighting efforts that have prevented low-intensity fires in Ponderosa pine forests from clearing out underbrush and small trees, and prolonged, exceptional droughtcaused by climate change.
John Fleck, a science writer for the Albuquerque Journal, grasps the complexity of the fire story, and Andrew Freedman does a superb job unpacking the scorching Southwestern drought in a must-read post at the WaPo's Capital Weather Gang blog:
The drought was caused in part by La Nina conditions in the tropical Pacific Ocean, which altered the main storm track across North America, helping to steer storms across the northern tier, leaving southern areas desperate for rain. Although La Nina has waned, there are increasing signs that it may redevelop this fall or winter, according to the latest outlook from the Climate Prediction Center. However, La Nina wasn't the only force behind the drought, says [Marty] Hoerling, who leads a group of climate change attribution sleuths at NOAA. For now, though, the co-conspirators remain unknown. Although climate science research shows that droughts are likely to become more intense and more frequent in a warming world, particularly in the Southwestern US, observational evidence does not yet show clear trends in drought conditions in the U.S. to date. Hoerling says his quick analysis led him to conclude that climate change has not played a major role in this event. "This is not a climate change drought by all indications," he said, adding that this view does not in any way refute the fact that global warming is occurring, either. Hoerling noted that as average temperatures increase due to climate change, drought impacts would likely get worse. Drought plus heat "is just going to make a bad situation that much worse," he said, since higher temperatures dry soils out much more rapidly. "We haven't necessarily dealt with drought and heat at the same time in such a persistent way." He said the drought serves as a reminder that society needs to be more prepared for significant, relatively rare events such as this one, regardless of whether they are due to global warming or natural climate variability.