Drought stokes fears of severe fire season in West

The details: Set against the backdrop of a long-term, human-enhanced drought, the current drought is forecast to expand and become more severe across much of the West, from Colorado to Montana, southwestward to California and Arizona.

• Already, 40% of the West is classified as being in "extreme" to "exceptional" drought, the two most severe categories.
• With the arrival of the warm season, the prospects for widespread precipitation are rapidly dwindling, and scientists are raising alarms about a repeat of the deadly 2020 wildfire season.

"There is a vanishingly small likelihood that things will improve significantly as we move into the warm season when water demands from ecosystems and people are likely to really ramp up," said Ben Cook, a climate researcher at Columbia University, in an email.

• California, for example, has now had two back-to-back winters that have been drier than average, and temperatures have been consistently running above average there.
• The Colorado River Basin is already seeing its snowpack melt quickly, earlier than the typical melt season start date, which could lead to a more severe fire season there as well.

Context: "On the wildfire front: I am very concerned about what might transpire this year, especially from mid-summer into autumn," said Daniel Swain, a climate scientist at UCLA, in an email. "I fully expect another very severe fire season across the West in 2021."

• An added concern is that, due in large part to the effects of human-driven climate change, the fall rainy season in the West is arriving later in the year, which adds to the number of days with extreme fire danger, Swain said.
• While more than 4.2 million acres burned in California in 2020, there are still a lot of forests that didn't burn recently, or burned a few years ago and have seen regrowth.
• “We see especially in the forests of the West, drought really loads the dice for large wildfires," said Park Williams, a geographer at UCLA.

Yes, but: In some areas, it's so dry that new grass and brush are not growing in the spring as they normally would. That could actually reduce the fire threat in those so-called "fuel limited" locations, which are areas that tend to have more lower amounts of combustible material.

Of note: California has adapted to the repeated instances of wildfire ignitions from electrical equipment by instituting rolling blackouts during periods of high fire danger.

• As part of its far-reaching climate plans, the state is also adding large quantities of batteries for energy storage. These could reduce some of the impacts of planned power shutoffs, Bloomberg reports.

What to watch: The intensity of the California drought may have repercussions for agricultural producers, which are the biggest users of water resources in the state. They could see their water allocations cut in order to conserve more water for species protection in rivers and drinking water supplies.

How it works: Climate change is intensifying drought, heat waves and wildfires as warmer temperatures dry soils faster and weather patterns shift.

• According to research by Cook and several colleagues, the period since the year 2000 has been the second-driest 22-year period across a multistate region in the West during the last 1,200 years.
• According to Williams, soil moisture content during the month of March was at its lowest level across the West in at least 120 years.
• That study found that the ongoing drought is the first-ever human-driven "megadrought" on record -- and it won't be the last.

Go deeper: A very, very, very dry future for the U.S. West