Sunday, 09/19/2021 | 2 a.m
The Pleistocene era, which began 2.6 million years ago, sent ice in waves through Yosemite.
Glaciers excavated large valleys along the Merced and Tuolumne rivers, ice sheets rounded off granite domes, and basins formed the High Sierra. John Muir traced virtually every feature of the Yosemite landscape back to its ice legacy.
Now the leftover ice is melting, the streams and waterfalls are drying and the living landscape is on fire. In 1990, the A-Rock fire closed the park for the only time in its history. The 2013 Rim Fire burned around Hetch Hetchy Reservoir; The 2018 Ferguson Fire burned along the park’s Wawona Road. Where the fires did not spread, their smoke spread.
Add to this the industrial burning of fossil fuels with its climatic effects, and virtually every management problem facing Yosemite today is due to fire.
People have always used fire: it’s our ecological signature.
The end of the last ice age allowed us, a fire-wielding species, to interact with an increasingly fire-receptive planet. Our pact with fire was mutual. Fire made us prosper; in return, we took fire everywhere, even in Antarctica.
The pact had to operate within the boundaries set by living landscapes. After all, fire was a creation of life that provided its oxygen and fuel and erected ecological barriers. Then we discovered a huge reservoir of combustible materials that was buried in geological time. It was as if we had found a new world – a petrified, “lithic” landscape – we could work the way we made living landscapes. The only restrictions were those that were self-imposed.
Adding up all of the burns people are doing in life now, it seems like we’re reshaping the earth with the fire-informed equivalent of an ice age, complete with climate change, rising sea levels, mass extinction, major changes in the world’s biogeography and clouds of smoke. Little on earth is untouched by it.
Fire drives away the last remnants of the Pleistocene, from ice to its mammoths. We’ve created a Pyrozene for millennia, but burning fossil fuels puts the process on afterburners.
Fifty years ago, Yosemite realized that the scene of the fire was out of whack. The problem then wasn’t too much of the wrong kind of fire, but too little of the right kind. The park tried to restore the pre-settlement fire regime. Target areas included Illilouette Creek, an elevated basin southeast of Glacier Point.
The park realized that fire suppression had stored fuels from the foothills to the ridge, inundating the Yosemite Valley and Mariposa Grove with invasive conifers blocking the view and preventing the fabled sequoias from regenerating. The park introduced mandatory fires and learned to manage forest fires easily. The Illilouette Basin was moving in the direction of its previous fire regime.
No place has the desired fire program, but Yosemite appears to be better positioned than the national forests and private lands around it. It is no longer about restoring natural fires, but rather finding the right mix of suppressed and prescribed fires and conquered wildfires to ward off the mega-fires that are raging everywhere else.
Yosemite deals with fires that can threaten small and not-so-small villages. His specialty is working with forest fires.
As of August 20 of this year, the park had dealt 54 fires, 43 from lightning and 11 from people. Some were kicked out. Some were locked within natural barriers. And a few burns in the Illilouette Basin were tweaked as nature’s invisible hand massaged them in five decades of stratified burns. The legacy of past fires had altered the conditions for the fires that followed, easing the shock of tougher, meaner burns.
Yosemite has long been known to distill the grandeur of the western landscape into a near crystalline state. As it moves from ice to fire, it shows that it can also serve as a proxy for some of what the earth must do to survive our increasing age of fire. There is no way we can’t handle fire.
Steve Pyne is a contributor to Writers on the Range, authorsontherange.org, a nonprofit dedicated to stimulating a lively debate on the West. He is the author of the new book The Pyrocene: How We Created an Age of Fire, and What Happens Next.