Fire is a fundamental natural process across the Western U.S., one that serves an important ecological purpose. But climate change has significantly altered the wildfire season, experts say, and is leading to larger and more frequent fires. "If you're concerned about wildfires then you need to be concerned about climate change and take it seriously," said Don Falk, a professor in the University of Arizona School of Natural Resources and the Environment. He researches fire history, fire ecology and ecological restoration and resilience in a changing world.