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What the megadrought in the West means for wildfire season

Get your air filter ready — wildfire season is likely to start early this year.

A fire truck in front of a home in Snow Creek after a fire started in the mountains west of Palm Springs, California, on September 18, 2020.
Frederic J. Brown/AFP via Getty Images

Just as the freshly vaccinated start to resume barbecues and vacation travel in the coming months, wildfires are likely to force residents of Western states back inside.

The warning signs are written in the parched landscape from New Mexico to California. This time last year, 27 percent of the West was in drought — now that has risen to 76 percent, turning forests into matchsticks.

With the pandemic dominating headlines, the severe drought has gotten little attention. “This one threatens to catch people by surprise who are exhausted by the events of the past year,” said Daniel Swain, a climate scientist at the University of California Los Angeles.

But this latest episode in a two-decade megadrought is precisely what scientists like Swain have been warning about: Rising temperatures from climate change are making droughts more frequent and severe and increasing the likelihood of extended megadroughts. Heightened dryness, in turn, is contributing to an increased risk of wildfires.

These trends threaten all Western states, but California faces uniquely severe fire impacts due to its dry summers and population density. Here’s what the state and the rest of the Western US should be bracing for in the coming months and how you can start preparing.

How we got to this drought: Two dry years and a hot summer

Before we talk about how bad this fire season could get, it’s important to understand just how severe the current drought is. It started building last year when California experienced light winter precipitation and the Southwest had a weak summer rainy season, which typically brings strong monsoon thunderstorms. At the same time, intense heat waves rolled through the whole region.

“If I had to pinpoint one thing that really drove the drought to where we are right now, it was the heat of last summer,” Brian Fuchs, a climatologist at the University of Nebraska’s National Drought Mitigation Center, told Vox in March. These high summer temperatures evaporated the moisture from the soil, further drying out vegetation.

Then, over the past few months, the typical rainy season in California once again came up short. This was due, in part, to La Niña — a weather pattern that occurs roughly every few years when cooler eastern Pacific ocean surface temperatures shift the trade winds, driving storms farther north.

But this drought is also being driven by larger climate trends. Scientists say that it is part of a megadrought — a decades-long dry spell, punctuated by severe droughts. This current megadrought began around 2000, and the majority of the land in the West has been at some level of drought ever since.

And this striking drought bears the fingerprints of climate change. Using tree ring data, a study published in Science in April 2020 found that “anthropogenic warming was critical for placing 2000–2018 on a trajectory consistent with the most severe past megadroughts,” and that megadrought has extended to today.

This fits in with a grim picture laid out by the latest National Climate Assessment, authored by 13 US federal agencies in 2018. Rising temperatures will increase the likelihood of megadroughts in the Southwest and make droughts more frequent and severe, according to the scientific literature cited.

This year’s drought has primed the landscape for big burns

As the latest drought episode within the larger megadrought has deepened, it has left plants and trees desiccated. And the biggest problem is forests.

“When talking about forest fires, for example, the link between dryness and more frequent and severe fires is just crystal clear,” said Swain.

In some ecosystems, the grass and brush growth will be stunted by the lack of moisture, creating less fuel for fires to burn. But that’s only a small silver lining, Swain said, because forests dominate land cover in the West.

The chart below shows how dire the situation has become this year. The current level of vegetation flammability in northern California (blue line) is at near the maximum levels recorded for this time of year (red line).

In its April 1 seasonal fire outlook, the National Interagency Fire Center predicted that these dry materials are going to cause significant problems for the West — and soon. The drought will bring up the start date for fire seasons, they wrote.

As the map below shows, the worst of the drought has been concentrated in the Southwest so far, and that’s where the fire danger will spike soonest. A wildfire spanning more than 500 acres already broke out north of Tucson, Arizona, last week.

National Drought Mitigation Center

The Fire Center projects that the Southwest will see above-average fire potential through June until the monsoon (hopefully) arrives. But the region might still get relief from summer monsoon rains, whereas the coming months tend to be dry in central and northern California.

Starting in June, they project that parts of the Pacific Northwest will see heightened fire risk and then the fire season will pick up in California in July.

The rapid melting of California’s snowpack is laying the groundwork for the early arrival of fires. Data from a snow survey on April 1 showed that the water content in Sierra Nevada snow was only 59 percent of the average. And the snow is melting quickly — the chart below shows that this year’s water content levels (dark blue line) are well below average (aqua blue) and dropping across all three regions of the state to levels typically seen around mid- to late May. With snow disappearing sooner, higher-elevation landscapes will be at a greater risk of fires, the Washington Post reported.

The wildfire risk is serious across the West, but California faces a unique set of threats: “a combination of climate and vegetation and intersection with highly populous areas that makes California sort of uniquely prominent in the wildfire impacts realm,” Swain said. And as the state continues to dry out and the winds pick up in the fall, the risks will continue to build.

It’s time to get your air filter out and keep those masks handy

Even with dry landscape inviting fires, the ultimate severity of the fire season is hard to predict. For one thing, because the vast majority of wildfires are human-caused, where those sparks are ignited will shape how damaging the fires are. But wind, heat, and other variables will also play a role — as last year highlighted.

It was a rash of rare dry lightning that set off the major blazes that hit California in late August. Coupled with a record warm August and dry winds, the fire season escalated quickly to record levels. “Last August and then into September, every single possible factor came together in the worst possible way,” said Swain.

It’s unlikely that we will see the same level of destruction this year, but not impossible, he said.

However, Swain also cautioned that the number of acres burned shouldn’t be the sole criterion for how severe a fire season is. Western states actually have a major backlog of land that needs to be burned, due to the history of limiting the use of fire to manage forests (“prescribed burning”) — an approach that American Indians have historically practiced.

“The goal is not to vanquish fire from the landscape. The goal really should be to decouple wildfire from catastrophe,” he said. Therefore, he suggests we judge our management of fires by their impact on structures and human health, rather than just acres burned.

Just two weeks ago, California Gov. Gavin Newsom announced a deal to allocate $536 million to help the state manage wildfires by staffing up fire crews, thinning forests, and hardening homes to withstand fires. Newsom has proposed a total of $1 billion in spending on fire management this year.

“This is a good start, but this is only Year One,” Michael Wara, the director of the climate and energy policy program at Stanford’s Woods Institute for the Environment, told the Los Angeles Times. “We need sustained funding at this scale and maybe even larger for a decade.”

With the fire season rapidly approaching, residents of Western states can get ahead of the smoke by dusting off their air filters, stocking up on N95 respirator masks, and consulting this preparation checklist from the Environmental Protection Agency. In the meantime, it’s a good time to get outside before the fire season truly descends upon us again...