When the Sierra Started Burning Differently

In August of twenty thirteen, a fire started near the community of Groveland on the western approach to Yosemite and burned for two months. By the time rain and crews finally contained it in mid-October, the Rim Fire had consumed two hundred fifty-seven thousand three hundred fourteen acres, making it the third-largest wildfire in California history at that point in time. The fire burned through the Stanislaus National Forest and into Yosemite National Park, where it moved through stands of trees that had not burned in more than a century.

That last detail is the important one. Fire suppression policy, the systematic extinguishing of every wildfire in the Sierra Nevada from roughly nineteen twenty onward, had allowed fuel loads to accumulate over multiple decades. The forests were not more fire-resistant than they had been before suppression. They were the opposite: loaded with dead wood and ladder fuels that meant any fire that did start would burn hotter and higher than the low-intensity fires that had periodically moved through the forest for thousands of years.

Parts of the Rim Fire burned at intensities that ecologists describe as stand-replacing: so hot that the soil was sterilized, the seed bank destroyed, and the regeneration pathway for coniferous forest interrupted. Some of those areas around Hetch Hetchy may not return to conifer woodland within any human lifespan. That is the judgment of researchers who study these burns, not hyperbole.

The Rim Fire was followed by the Creek Fire in twenty twenty, the Caldor Fire in twenty twenty-one, and the Washburn Fire in twenty twenty-two, which pushed to the edge of the Mariposa Grove. The Sierra Nevada is recalibrating to a fire regime that the park boundaries were not designed to accommodate.

The landscape outside your window has been burning its way toward a new baseline for a decade. What it looks like on the other side of that process is not known.