Large Wildfires in California: A Multi-Dimensional Fire Challenge

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This is the second part of a story about fires in California. Read part 1 here.

Accumulating fuels and rising populations are contributing to California’s large, destructive fires.

Climate change has helped fuel California’s surge of unusually large and destructive fires by exacerbating heat waves and droughts, but climate is not the only factor contributing to the surge. More than a century of fire suppression has caused excessive amounts of dead trees, leaf litter, and dried brush to build up in forests. Meanwhile, California’s increasing population means that many more people now live and work in areas that are prone to fire.

The consequences of all the fires are remarkable, even from space. The false-color image at the top of the page shows burn scars left by large fires that burned in recent years, including the two largest incidents on record in California: the August fire complex and the Dixie fire. The image was captured by the Moderate Resolution Imaging Spectroradiometer (MODIS) on ’s Terra satellite on September 21, 2021.

“During the past few years, much of the activity has been in forested parts of the northern two-thirds of California,” said John Abatzoglou, a climate scientist at the University of California, Merced. “Many of these forests have built-up a large amount of biomass due to a century of successful fire suppression. Now the bill is coming due.”

Before firefighters started intervening and stopping fires in the early 20th Century, low-intensity blazes were periodically ignited by lightning or by Tribal Nations in Northern California. Those fires would periodically burn along the surface and clear out leaf litter, brush, and saplings, thereby reducing the risk of severe fires.

“Low-intensity fires that stay close to the surface don’t cause much ecological damage and can even help forests thrive,” explained University of California climatologist Daniel Swain. “But for the better part of a century, we have followed a policy of total fire suppression with few prescribed fires. That has left California with many unnaturally dense and overgrown forest stands.”

The overabundance of “ladder fuels” makes it much easier for flames to move up tree trunks and turn what might have been low-intensity surface fires into fires that spread along the treetops. These “crown” fires are the hottest, most intense, and most destructive type. “They burn so hot that they consume the majority of the biomass and essentially sterilize the soil,” Swain said. “Unfortunately, there is no list from Cal Fire that… Brinkwire News Summary.

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