As bad as last year’s record-breaking fire season was, the western United States is starting this year worse off.
The soil in the West is record dry for this time of year. In much of the region, the plants that fuel the fires are also the driest that scientists have seen. The vegetation is ready to ignite, especially in the southwest where the dead junipers are full of flammable needles.
“It’s like having gasoline in there,” said Brian Steinhardt, wildfire zone manager for the Prescott and Coconino National Forests in Arizona.
A mega-drought fueled by climate change for more than 20 years is making the conditions that lead to fires even more dangerous, scientists have said. Rainfall in the Rockies and further west was the second lowest on record in April, according to the National Oceanic and Atmospheric Administration.
“That means the dice are loaded for a lot of wildfires this year,” said Park Williams, a UCLA climate and fire specialist, who calculated that the soil in the western half of the country is the drier since 1895. “This summer we enter fire season with drier fuels than we were at this time last year.
In addition, the drought in the west is worsening week by week.
At the end of March, less than a third of California was suffering from extreme or exceptional drought. Today, more than 73% are, according to the National Drought Monitor, which is based on measurements of precipitation, temperature, soil moisture and flow. A year ago, as we approached the record-breaking fire year of 2020 when more than 4% of California was on fire, only 3% of the state was in extreme or exceptional drought.
But the outlook is worse elsewhere.
“I think the Southwest is really ready for a bad fire season,” said Phil Dennison, fire specialist at the University of Utah. This is because last year’s normal monsoon season, which brings much of the year’s precipitation, never materialized.
A year ago, none of Arizona, Nevada, and Utah were in extreme or exceptional drought conditions, but now over 90% of Utah, 86% of Arizona, and 75% of Nevada are in these highest drought categories, according to the Drought Monitor. New Mexico has gone from 4% extreme or exceptional drought a year ago to over 77% now.
UCLA meteorologist Daniel Swain, who also works for the National Center for Atmospheric Research and The Nature Conservancy, said the key factors entering the fire season are soil and plant moisture.
“So is the soil moisture very low? Is the vegetation extremely dry? Absolutely yes. Clearly, yes. All over California and the Southwest, ”Swain said. “So this box is checked thoroughly in a way that will massively increase the potential background flammability … given a spark, given the extreme weather conditions.”
This does not necessarily guarantee that the 2021 fire season will be worse than 2020. Last year, more than 15,800 square miles (40,960 square kilometers) of the United States burned, an area the size of Maryland and Delaware. combined. Several scientists said last year’s fires were fueled not only by hot, dry conditions, but unusual situations that made a bad year horrible:
Two intense heat waves – one that almost set a record for the hottest temperature on Earth in Death Valley – set the stage, and a barrage of lightning in California provided plenty of sparks.
The lightning outbreak was of the type that has only happened a few times in history and is unlikely to happen two years in a row, Swain said.
“Maybe it won’t be the hottest summer,” he said, adding. “I really grab the straws here. All we’ve got going for us is stupid luck.
When scientists see extremely dry or dying trees, they worry even more.
In Arizona, junipers are succumbing to the 20-year drought and its two-year intensification, said Joel McMillin, area manager of forest health for the US Forest Service. Officials haven’t done an accurate count, but anecdotally, the mortality is 5% to 30% with some fixes up to 60%.
Until the dead needles fall to the ground, which takes about a year, the risk of fire increases, fire chief Steinhardt said. “So you’ve got something that’s highly flammable that’s … 20, 30, 40 feet high and each of those needles now becomes an ember that can be thrown.”
“This is probably one of the driest and potentially toughest situations I’ve been in,” said the 32-season firefighter veteran.
In California, normally drought tolerant blue oaks are dying in the San Francisco Bay Area, said Scott Stephens, professor of fire science at the University of California at Berkeley. “They don’t have access to water. Soil moisture is so low. When you start to see the blue oak dying, it grabs your attention.
Man-made climate change and decades of fire suppression that increase fuel loads are worsening fire conditions in the West, scientists said.
Global warming has contributed to the mega-drought and makes plants more prone to burn.
Normally, a good deal of the sun’s energy removes water from plants and soil, but when they’re already dry, that energy makes the air warmer, which creates a feedback loop, Swain said.
And drier conditions lead to beetle infestations that further weaken and kill trees, said Dennison of the University of Utah.
For decades, U.S. firefighting agencies have tried to put out fires as quickly as possible, and it generally worked, Williams of UCLA said. But the practice has resulted in the accumulation of dense trees, brush and other potential fuels.
“The fire is getting out of our control more and more often,” he said. “And part of the reason for that could be because of the increasing density of fuels. But we’re also finding that these fires get out of our control during record heat waves – and it’s the hottest, driest years where we have the hardest time controlling fires.