Climate and Fire
As summer rolls in each year in the western United States, inevitably, wildfires break out. On average each year, over 5 million acres are burned in the US by wildfire. Some are the result of human negligence or arson, but most are sparked naturally by lightning. But, climate change has created conditions that are primed for bigger, more destructive fires each year. Factors like increasing heat, changes in rain and snow patters, and other climate-related issues are all contributing to more frequent, more widespread, and longer burning fires each year.

There are other anthropocentric factors contributing to worsening fire seasons as well, such as forest management decisions that allow the buildup of dry brush which becomes wildfire fuel, as well as the encroachment of housing into burn areas. Once this occurs, human-triggered fires become a much higher risk, whether its through a carelessly managed bonfire, a cigarette butt flicked from a moving vehicle, or the spark of a trailer chain on a mountain highway.

But, wildfires are not always a bad thing. Many of the forests in the American west depend upon wildfires to maintain a healthy ecosystem. There are several species of evergreen trees that only germinate in the presence of fire, species like the lodgepole pine and even the giant sequoia. Fire’s role in the reproductive cycles of sequoia wasn’t fully understood until well into the 20th century.

The Mariposa Grove of sequoias in what is now Yosemite National Park was the first federally protected wilderness in the world. It was set aside and declared protected by Abraham Lincoln during the height of the Civil War, a testament to the size and beauty of the giant sequoia. For decades, the grove was protected from fire, as best as its stewards could manage. Yet, it was only after decades of no new baby sequoia trees that biologists began to see there was a correlation between fire and the seed cones of the giant sequoia. The trees depend upon low-intensity fire to release the seeds from their waxy cones.

So, you may be thinking, this is all counterintuitive. Wildfires are good, so how is it that more fires aren’t making healthier forests? The answer to that is fire intensity. A healthy fire burns up dried undergrowth, weak and diseased trees, fertilizes the soil, and clears the way for sunlight to reach that soil leading to new, healthy growth. This process not only can destroy disease in trees, but it can eradicate parasites such as the infamous bark beetle that has destroyed so much of Colorado’s evergreen forests.

But, a bad fire burns too hot. It scorches the soil, preventing any new growth. It cuts right through the fire-retardant bark of healthy trees, and leaves a barren wasteland where nothing can grow until decades later. And, this is why climate change has become such a factor in these fires. As drier, hotter conditions become the mainstay of a western summer, dried vegetation becomes more abundant, providing more fuel for the fire. Add to that the intense, dry winds, and the stage is set for disaster. Additionally, as fires burn hotter and longer, they pose a greater risk to humans and their homes and businesses.