Yosemite’s Giant Sequoias expected to survive wildfire which official confirms was human-caused

An iconic grove of giant sequoia trees seems to have escaped the worst-case scenario as wildfire blazes through Yosemite National Park.

A park official said this week that the fire was started by humans although the official cause has yet to be determined.

The Washburn Fire had scorched over 3,700 acres by Wednesday morning since it erupted on 7 July. Firefighters are continuing to battle the fire with the perimeter around 17 per contained.

Evacuation orders are still in place for the small community of Wawona, near the blaze. Most of the popular California park — including the iconic Yosemite Valley — remained open.

Officials predicted that weather conditions would spur more fire growth in the next few days.

The fire prompted evacuations of hundreds of people from Yosemite, and swept dangerously close to the Mariposa Grove area of giant sequoias.

Yet despite starting near the grove the blaze appears to have spared the towering trees, Yosemite firefighter and ecologist Garrett Dickman told SFGate.

While some of the trees had been licked by flames they would probably survive, he added.

The fact that severe damage was avoided from the Washburn fire could be due to previous intentionally-lit fires, Dickman told the Associated Press.

So-called prescribed burns help to clear vegetation and fallen wood, which acts like fuel if a fire ignites, fire officials explain, and can lead to super-hot, out of control blazes. These fuels are also becoming increasingly dry due to rising temperatures linked to the climate crisis.

“We’ve been preparing for the Washburn Fire for decades,” Dickman told AP.

Some of the Mariposa sequoias had additional help to protect them from fire. The famous “Grizzly Giant”, once visited by the late President Teddy Roosevelt, had sprinkler systems placed around it over the weekend.

Giant sequoias are among the world’s largest trees and native only to the Sierra Nevada mountains. The species is adapted to fire, a natural part of the Western landscape for thousands of years.

But in the past decade, the climate crisis has driven wildfires in California to new extremes.

In 2020, the Castle Fire decimated sequoia groves in Sequoia National Forest along the southern Sierra Nevada, killing thousands of individual trees – which are classified as “Endangered” by the International Union for Conservation of Nature.

The National Parks Service also reports that the Castle Fire, and others, have intensified due to the decision to suppress natural burns over the past century.

This has allowed tons of potential fuel to build up in the mountains — creating dangerous conditions when blazes do strike. Hotter temperatures and drier conditions, caused by the climate crisis, have only made that danger more apparent.

The majority of wildfires are caused by lightning strikes. However, Yosemite park superintendent Cicely Muldoon told a community meeting on Monday that while an official cause for the Washburn Fire is yet to be determined, it was due to human activity.

“As you all know, there was no lightning on that day. So it’s a human-start fire and it’s under investigation,” Muldoon said.

The US wildfire season has gotten off to an explosive start with over 5 million acres burned since January, according to the National Interagency Fire Center, around double the ten-year average for this time of year.

Wildfires are expected to get worse in the US west as the climate crisis accelerates. A study last year found that under a worst-case scenario for global emissions, the amount of land burned in the Sierra Nevadas could increase around 60 per cent by the 2040s.