When vapor pressure deficit, or VPD, is higher, the air can draw more moisture from soil and plants. Vapor pressure deficit measures the amount of moisture the air can hold when it is saturated minus the amount of moisture in the air. 9 edition of the journal Proceedings of the National Academy of Sciences, the researchers applied artificial intelligence to climate and fire data in order to estimate the roles that climate change and other factors play in determining the key climate variable tied to wildfire risk: vapor pressure deficit. And in 2020, according to a National Interagency Coordination Center report, the amount of land burned by wildfires in the West reached 8.8 million acres - an area larger than the state of Maryland.īut the factors that have caused that massive increase have been the subject of debate: How much of the trend was caused by human-induced climate change and how much could be explained by changing weather patterns, natural climate variation, forest management, earlier springtime snowmelt and reduced summer rain?įor the study, published in the Nov. For the next 17 years, through 2018, the average burned area was approximately 3.35 million acres per year. In the 17 years from 1984 to 2000, the average burned area in 11 western states was 1.69 million acres per year. The dramatic increase in destruction caused by wildfires is borne out by U.S. "I am afraid that the record fire seasons in recent years are only the beginning of what will come, due to climate change, and our society is not prepared for the rapid increase of weather contributing to wildfires in the American West." Rong Fu, a UCLA professor of atmospheric and oceanic sciences and the study's corresponding author, said the trend is likely to worsen in the years ahead.