The Slatest

A “Heat Dome” and Drought Are Threatening to Ignite the West

A person walks in a near-dry lake bed
A person walks near a buoy that was once surrounded by water at Echo Bay on Monday in the Lake Mead National Recreation Area, Nevada. Ethan Miller/Getty Images

Wildfires erupted this past weekend across 10 states—including California, Colorado, Arizona, and Oregon—as record-high temperatures continue to bake many areas in the West and Southwest United States. By Monday, 7 million people were under fire danger warnings, as the record-shattering temperatures—stretching from Palm Springs to Tucson to Denvermigrate north into Oregon and Washington.

The scorching temperatures are the result of a “heat dome”—a persistent ridge of high pressure that traps hot air while also blocking the formation of rain clouds. Heat domes often contribute to record-breaking temperatures in the later summer months, but this particular system is exceptional for its early arrival and expansiveness. “It’s not only unusual for June, but it is pretty extreme even in absolute terms,” Daniel Swain, a climate scientist at the UCLA Institute of the Environment and Sustainability, told NPR.

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The heat wave itself poses a wildfire threat, which is exacerbated by the long-term drought conditions across the region. As of Thursday, more than half of the U.S. was classified as being in a state of either “severe,” “extreme,” or “exceptional” drought.

And as the heat dome has shifted north and east, wildfires have extended their reach as well. A fire raging southeast of Oregon’s Mount Hood had scorched 6,200 acres by Monday. In Washington, moisture levels tested in soil and fallen branches clocked in at 10 percent, which is “really, really dry”—especially this early in the year, Vaughn Cork, a Washington Department of Natural Resources fuels analyst, told Seattle news station King 5. An ominous forecast for the coming week suggests  “obscene temperatures” and thunderstorms, deepening the threat of fire. The National Interagency Fire Center reports that as of Tuesday, 50 large fires have burned more than half a million acres across the country.

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So what’s to blame for this slew of alarming adjectives? A partial answer is climate change. A study led by Columbia bioclimatologist A. Park Williams compared the current state of the drought to what it would be in a hypothetical, computer-generated world that didn’t burn fossil fuels, and the researchers found that an average of 47 percent of the Western U.S.’s “megadrought” was attributable to global warming. Moisture is evaporating from the ground much faster than in the past, thanks to temperatures that are 2.9 degrees hotter compared to those of the “mythical” non-fossil fuel-burning world that the study imagines. So, while a drought isn’t necessarily cause for climate alarm, the current drought is, especially in combination with an unrelenting heat dome and thunderstorms threatening lightning strikes on parched land.

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Another major concern is resources. The heat wave (likely only the first of many to come this summer) and enduring drought conditions may cause more concurrent fires across Western states. In previous decades, fire seasons were shorter and staggered, allowing neighboring states to lend essential firefighting help across borders. But this mutual aid could be a thing of the past, if (or when) large-scale wildfires rage simultaneously.

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States have prepared for the extreme heat, potential wildfires, and smoke across the Pacific Northwest by opening public facilities to help people cool down and encouraging “home hardening”—an umbrella term for measures that range from keeping gutters clear of dry leaves to renovations that rebuild roofs, walls, and decks with ignition-resistant alternatives to wood. Longer-term measures to address the ongoing and worsening dangers posed by wildfires are also in the works: Democrats in Oregon’s state Legislature are attempting to pass a bill that would allot nearly $200 million in funding to new programs aimed at wildfire mitigation.  In D.C., Utah Sen. Mitt Romney introduced legislation that would establish a national committee to review wildfire policy and make recommendations to Congress, and Oregon Sen. Ron Wyden pressed the Forest Service to develop a written plan to address the likely catastrophic year for wildfires. Though, like much of the U.S. response to climate change, these measures will fall far short of what’s needed to address this crisis.

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