Nighttime fires have become more intense in recent decades, as hot, dry nights are more commonplace, according to a new CIRES Earth Lab-led study.
Forty years ago, cool, moist nights regularly provided relief to firefighters—and “flammable nights” were rare. Now, due to a changing climate, nights are warming faster than days are, and there are 11 more flammable nights every year in the U.S. West—a 45 percent spike, the team found.
“Night is the critical time for slowing a speeding fire—and wildfire’s night brakes are failing,” said Jennifer Balch, CIRES Fellow, Director of CIRES’ Earth Lab and lead author on the study out today in Nature.
The new analysis relied on a key measurement of the thirst of the atmosphere—the Vapor Pressure Deficit or VPD. When VPD is relatively low, the air is moist, and fires cannot thrive. Fire suppression operations take advantage of these nighttime conditions to squelch flames. But when the VPD is high, the air is dry, parched and primed for burning.
Read more at University of Colorado at Boulder
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