The world's top carbon producers have made the climate of western North America more fire prone—and contributed 37 percent of the total forest area burned in the region since 1986.

Vapor pressure deficit is the difference between the amount of moisture in the air and the amount of moisture that air could hold based on its temperature.

Since the mid-1980s, 53 million acres of forested land in the western United States and southwestern Canada has burned—an area larger than the state of Idaho.