The University of Arizona Press

May 16, 2023

Its monumental rocks, etched by glaciers during the last Ice Age, have made Yosemite National Park a crown jewel of the national park system and a world-celebrated destination. Yet, more and more, fire rather than ice is shaping this storied landscape.

In the last decade, fire has blasted into public attention. California’s blazes have captured national and global media interest with their drama and urgency. Expand the realm of fire to include the burning of fossil fuels, and the fire story also subsumes climate change. Renowned fire historian Stephen J. Pyne argues that the relationship between fire and humans has become a defining feature of our epoch, and he reveals how Yosemite offers a cameo of how we have replaced an ice age with a fire age: the Pyrocene.

Organized around a backcountry trek to a 50-year experiment in restoring fire, Pyrocene Park by Stephen J. Pyne describes the 150-year history of fire suppression and management that has led us, in part, to where the park is today. But there is more. Yosemite’s fire story is America’s, and the Earth’s, as it shifts from an ice-informed world to a fire-informed one. Pyrocene Park distills that epic story into a sharp miniature.

Flush with people, ideas, fires, and controversy, Pyrocene Park is a compelling and accessible window into the American fire scene and the future it promises. Below read an excerpt from the book.

A trek to the Illilouette began as a thought by Jan van Wagtendonk, evolved into a resolve by the park’s upper administration, advanced to a project under the fire management program, and became a reality on September 13–15, 2021. Behind that undertaking lay the massif of the Sierra Nevada Range, California’s Mediterranean climate, a biota built to burn, humanity’s monopoly over fire, America’s halting history from laissez-faire burning to universal suppression to restoring good fires, Yosemite’s status as an emblem of the wild, the Earth’s hastening spiral from ice to fire, and those ineffable moments when planet and people converge.

The Illilouette Valley—hidden in the aesthetic shadow of Half Dome—is not a destination landscape. No John Muir has rhapsodized over its wild splendor. No Ansel Adams has immortalized it in photographs. No guidebooks identify it as one of Yosemite’s many iconic scenes. It boasts no towering granite domes, no Big Trees, no historical markers, no cult of climbing routes. In a place that overflows with the photogenic and the monumental, it projects no special vision or public voice. It is neither in Yosemite Valley nor along the Range of Light that forms the Sierra Crest. Its trees are Jeffrey pine, lodgepole, and aspen patches, not giant sequoias.

Which makes all the more astonishing that the superintendent, deputy superintendent, chief ranger, wilderness policy and recreation planner, chief of resources management and science, chief of ecological restoration, vegetation ecologist, fire ecologist, wilderness manager, park physical scientist, chief of staff, fire management officer, deputy fire management officer, and fuels battalion chief—most of the governing cadre of the park concerned with Yosemite’s natural endowment—along with two academics planned a three-day trek to the basin on September 13–15, 2021. These are the people who must decide how to manage the park’s natural estate.

That domain has been undergoing a slow, now quickening upheaval that makes Yosemite a microcosm of the Earth. Nearly all Yosemite’s fabled sites were shaped by Pleistocene ice as the planet flickered over the past 2.6 million years into and out of long glacial epochs broken by short bouts of warming. That ice was the most visible feature of a makeover that repeatedly recast the Earth’s lands, seas, and air. At Yosemite it widened and deepened valleys, rounded exposed granite, cached moraine and soils, and scoured routes for runoff that became rivers and waterfalls. Over and again, the ice made its mark, departed, and repeated.

The last interglacial, known as the Holocene, began roughly 12,000 years ago. But something new intervened in the rhythm of returning ice. This time a fire-wielding creature, Homo sapiens, interacted with a progressively fire-receptive world. The cooling stalled, then reversed. It was as though the expected ice age had refracted through a pyric prism and re-emerged as a fire age. Fire replaced ice, fire drove off ice. Visible flames reshaped living landscapes of conifers, shrubs, grasses, and peat, while combustion hidden in machines, burning the fossilized residue of formerly living biomes—call them lithic landscapes—began reforging how humans lived on the land. When the effluent from that industrial-scale firing marinated the atmosphere with greenhouse gases, it perturbed the climate, which reconfigured everything it touched. Local fires massed into a globalized fire age.

Even Yosemite, a monument to ice, is being refashioned by the hastening fires. That is what makes the Illilouette, otherwise so mundane, of interest to park management: it is a place informed by fire. It is where the park sought to test the notion, an amalgam of hope and alarm, that good fires might restore the lost fires and help stave off the bad burns, the feral flames, and the megafires that a blowup fire age threatens. It is where a landscape bequeathed by the Pleistocene has morphed into a Pyrocene.