Wildfires and Climate Change
The trend is projected to increase in the years ahead, according to Rong Fu, a UCLA professor of atmospheric and marine sciences and the study’s corresponding author. “I’m afraid that the recent record fire seasons are just the beginning of what’s to come as a result of climate change, and our civilization is unprepared for the rapid increase in weather that contributes to wildfires in the American West.”
The U.S. Geological Survey data confirms the substantial increase in wildfire destruction. In the 17 years between 1984 and 2000, an average of 1.69 million acres per year were burned in 11 western states. The average burned area every year over the next 17 years, from 2001 to 2018, was around 3.35 million acres.
According to a study from the National Interagency Coordination Center, wildfires in the West burnt 8.8 million acres in 2020, an area larger than the state of Maryland.
However, the factors that contributed to the massive increase have been a source of contention: how much of the trend was caused by human-caused climate change, and how much could be explained by changing weather patterns, natural climate variation, forest management, earlier springtime snowmelt, and reduced summer rain?
Wildfires and Climate Change Researchers
The researchers used artificial intelligence to analyze climate and fire data in order to estimate the roles that climate change and other factors play in determining the key climate variable linked to wildfire risk: vapor pressure deficit. The findings were published in the journal Proceedings of the National Academy of Sciences on Nov. 9.
The vapor pressure deficit is the difference between the amount of moisture in the air and the amount of moisture it can store when it is saturated. The air can pull more moisture from soil and plants when the vapor pressure deficit, or VPD, is bigger. Large wildfire-burned areas, particularly those not close to cities, have substantial vapor pressure deficits, which are associated with warm, dry air.
According to the study, human-caused global warming was responsible for 68 percent of the increase in vapor pressure deficit over the western United States between 1979 and 2020. The remaining 32% difference was most likely caused by naturally occurring changes in weather patterns, according to scientists.
Wildfires and Weather
The data imply that rising fire weather in the western United States is primarily due to human-caused climate change.
“And our estimates of the human-induced influence on the increase in fire weather risk are likely to be conservative,” said Fu, who is also the head of UCLA’s Joint Institute for Regional Earth System Science and Engineering, a NASA-funded cooperation.
The researchers looked at the so-called August Complex wildfire in Northern California in 2020, which burnt over a million acres. They came to the conclusion that human-caused warming was responsible for 50% of the region’s previously unheard-of high VPD during the month the fire started.
Even while wetter and cooler temperatures may provide small respites, Fu anticipates wildfires to become more fierce and frequent in the western states overall. And, despite the increased vapor pressure deficit, locations where great expanses of plant life have already been lost to fires, drought, heatwaves, and road construction are unlikely to witness an increase in wildfires.
“Our findings show that the western United States has crossed a key barrier,” researchers said, adding that “human-induced warming is now more responsible for the increase in vapor pressure deficit than natural changes in atmospheric circulation.” “Our research demonstrates that this shift has been occurring since the beginning of the twenty-first century, much earlier than we expected.”
recentclimate – Wildfires and Climate Change,Wildfires and Climate Report