Redwoods in Yosemite Park threatened by wildfire amid heatwave in western US

High temperatures in the southwestern and western United States posed a challenge to firefighters in California and Utah, with regulators in Texas warning of possible power outages on Monday.

In California, a heat wave was developing but winds were light as firefighters battled a wildfire that threatens a grove of giant sequoias and a small community in Yosemite National Park.

The Washburn Fire on the western flank of the Sierra Nevada Mountains had burned about 5.8 square kilometers as of Monday morning, an increase of about 120 hectares overnight, according to an update on the incident.

The fire threatened more than 500 mature redwood trees in the park’s Mariposa Grove and the nearby community of Wawona, which was evacuated.

The area in the southern part of Yosemite was closed to visitors, but the rest of the national park remained open.

Grove protected since 1864

Mariposa Grove and Yosemite Valley have been protected since President Abraham Lincoln signed a law in 1864.

A sprinkler system was installed in the grove to maintain humidity, and no serious damage was reported to any named trees, including the 3,000-year-old Grizzly Giant.

“Fortunately, Mariposa Grove has a long history of prescribed burning and studies have shown that these efforts reduce the impacts of unwanted high-severity fires,” a National Park Service statement said.

A heat advisory was issued for the Central Valley extending below the Sierra Nevada, while in the fire zone a high of 31°C was forecast for Wawona.

The giant sequoias, native to only about 70 groves spread along the western slope of the Sierra Nevada, were once considered impervious to flames, but have become increasingly vulnerable to wildfires, fueled by a buildup of undergrowth. century of fire suppression and the impact of drought exacerbated by climate change, have become more intense and destructive.

Lightning-triggered wildfires over the past two years have killed up to a fifth of an estimated 75,000 tall redwoods, which are the largest trees by volume and a major draw for tourists.

2 major wildfires in Utah

There was no obvious natural spark for the fire that broke out Thursday next to the park’s Washburn Trail. Smoke was reported from visitors walking through the grove.

A violent windstorm tore through the grove more than a year ago and toppled 15 giant sequoias, along with countless other trees.

The downed trees, along with a large number of pines killed by bark beetles, provided enough fuel for the flames.

So far in 2022, more than 35,000 wildfires have burned nearly 1.9 million hectares in the United States, according to the National Interagency Fire Center, well above the average for wildfires and the acres burned.

In Utah, smoke and ash from a growing wildfire in rural Tooele County blew through Salt Lake City on Saturday. By Sunday afternoon, the Jacob City Fire had grown to 15.3 square kilometers, without any containment, officials said.

Elsewhere in Utah, firefighters battling high winds battled the 32.2 sq km Halfway Hill Fire in Filmore. Law enforcement arrested four men on Saturday who investigators believe abandoned a campfire that started the blaze.

Texas close to energy reserve capacity

Meanwhile, the Texas power grid operator on Sunday called on state residents for the second time this year to conserve energy, warning of potential blackouts amid forecast record temperatures Monday.

The state faces a « potential shortage of reserve capacity with no market solution available, » the Electric Reliability Council of Texas (ERCOT) said on its website, adding an energy emergency alert that flagged the potential for continuous breakdowns.

ERCOT oversees the supply of more than 26 million customers.

Temperatures across the state hit record highs on Sunday, with 40.6C recorded at Houston’s Bush Intercontinental Airport, surpassing a record set in 1909, according to the US National Weather Service (NWS).

High or dangerous heat levels are predicted for much of the state on Monday, with temperatures expected to exceed 37C.

ERCOT asked residents to conserve power between 2 p.m. and 8 p.m., saying demand could reach 79,934 megawatts (MW) on Monday and 80,104 MW on Tuesday, not far from the 80,200 MW of available reserves expected on Monday. One megawatt can power about 1,000 US homes on a typical day, but only about 200 homes on a hot Texas summer day.

Houston Mayor Sylvester Turner advised police and fire chiefs in the nation’s fourth most populous city « to be prepared in case the state’s power grid fails during extreme heat. »

The state grid operator demanded more electricity from suppliers and asked large industrial consumers to reduce their energy consumption.