The grizzly giant is estimated to be more than 2,000 years old, and over 60m (200ft) tall. However, at some points this week it appeared that its end could be approaching.
Grizzly giant is a large sequoia tree. It is the best-known of its type in Mariposa grove in Yosemite National Park in California. Both the tree and the grove appeared to be in peril for a time in recent days as the latest big wildfire hit the region.
The fire spread across 800 hectares (2,000 acres), threatening the grove which is home some of the longest-living and tallest trees in the world. At one point, there were 600 firefighters and a dozen helicopters fighting the blaze.
The effect of the fire was so intense that some 300km away in the bay area near San Francisco, authorities issued an air quality alert. They warned if the smell of smoke was present residents should protect their health by avoiding exposure. If possible, and if temperatures permitted, they were urged to stay inside with windows and doors closed until smoke levels subsided.
A mandatory evacuation order was put in place for the grove itself while dozens of campers and holidaymakers in the area had to leave.
TV news crews broadcast, sometimes on an hourly basis, about the track of the fire across the Sierra Nevada mountains and the dangers posed to grizzly giant and the other sequoias.
“We have to go to the ends of the earth to protect this tree,” Garrett Dickman, a forest ecologist with Yosemite National Park, who was helping to manage the efforts to protect the Mariposa grove of giant sequoias, told the New York Times. “The past couple years have been a real wake-up,” he added. “We never thought the giant sequoias would really burn.”
Climate change
California has been hit hard by climate change both in terms of drought and the increasing incidence of wildfires. Californians have been asked to reduce their water use amid increasingly dry conditions and falling levels in key reservoirs.
Last year, the US space agency Nasa warned that the American west was not only experiencing more frequent wildfires, but that they were bigger, more severe and faster than ever before.
In a report, it said a changing climate was producing warmer and drier conditions. Dry vegetation and trees were providing more fuel for wildfires and increasing numbers of storms meant more lightning, which could ignite a blaze.
While damaging fires and storms have become more common, authorities in California have been determined to protect Mariposa grove.
The grove and grizzly giant are of huge importance both from a heritage and historical perspective. Reportedly, it was camping overnight beneath the tree more than a century ago that led former US president Theodore Roosevelt to establish more national parks across the country. In 1905, he created the US Forest Service.
Special measures have been introduced to protect the grove. Sprinkler systems have been introduced surrounding the large sequoia trees to keep the area moist while vegetation and dead trees that provided fuel for the fire were bulldozed away.
The US National Park Service says the giant sequoias have coexisted with fire for thousands of years. But things are changing. Up to recently it was considered that the thick bark insulated most trees from the impact of heat from fires.
Evolving threat
The branches of large sequoias also grow high enough to avoid the flames in most cases. In fact, the park service maintains that fires in some ways can be beneficial for this particular type of tree. The heat releases large numbers of seeds, which fall on ground left vacant after a fire has cleared away existing trees and vegetation. This can provide space for young sequoias to take root.
However, the park service warns that the nature of the fires affecting the Sierra Nevada range is evolving. The blazes are more intense, and this is posing a much greater threat to the famous sequoias.
“Starting in 2015, higher-severity fires have killed large giant sequoias (those four feet or greater in diameter) in much greater numbers than has ever been recorded. We have reached a tipping point – lack of frequent fire for the past century in most groves, combined with the impacts of a warming climate – have made some wildfires much more deadly for sequoias,” the park service says.
It says that even before the current blaze, six fires, which broke out between 2015 and 2021, had killed many large sequoias in numerous groves across the Sierra Nevada.
It says that one blaze, known as the Castle fire, which raged between August and December 2020, burned 70,000 hectares, including over 3,800 hectares of giant sequoia groves on US Forest Service, National Park Service, state of California, Tulare County and private lands.
“This represents one-third of all sequoia grove area across the Sierra Nevada, the only area in the world where giant sequoias occur naturally,” the park service says. The Castle Fire, it says, killed an estimated 7,500-10,600 large sequoias – those with trunk diameters of 1.2m (4ft) or more.
Yosemite National Park is a big tourist attraction in the American west. As the week progressed, the imminent threat to the famous Mariposa grove appeared to diminish. However, future wildfires and further risk of damage would appear inevitable in the years ahead.