Controlled burns may hold the key to manageable wildfire seasons

Saskatchewan fires
In this photo taken on June 29, 2015, provided by the Saskatchewan Ministry of Highways and Infrastructure, forest fires throw flames above a tree-line along Highway 969 in southern Saskatchewan, Canada.
Saskatchewan Ministry of Highways and Infrastructure via The Canadian Press via AP

The big wildfires in California are just the latest in a series of fires that have spread around North America this year. MPR News' Kerri Miller examines the science behind forest fires.