Farmers in many parts of the world, like this one in the Peruvian Amazon, routinely use fire to clear land. Over past decades, many areas of the forested Amazon basin have become a patchwork of farms, pastures and second-growth forest as people have moved in and cleared land--but now many are moving out, in search of economic opportunities in newly booming Amazonian cities. The resulting depopulation of rural areas, along with spreading road networks and increased drought are causing more and bigger fires to ravage vast stretches, say researchers in a new study. The study, focusing on the Peruvian Amazon, is the latest to suggest that land-use changes and other factors, including possibly climate change, are driving increasingly destructive wildfires in many parts of the earth. An interdisciplinary team at Columbia University's Earth Institute will publish the paper this week in the Proceedings of the National Academy of Sciences.