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We are in the midst of another long and intense wildfire season, and the worst may still lie ahead. Human-caused climate change is intensifying the heat that drives wildfire.
On Friday, July 22, 2022, SciLine interviewed Dr. Patrick Gonzalez, a forest ecologist and climate change scientist at the University of California, Berkeley. He discussed topics including: climate change effects on wildfire across the western U.S. and globally; how wildfire is a natural part of many forest ecosystems but rare or absent in others—and how these patterns are being disrupted; current and future wildfire risks due to climate change and deforestation; strategies to improve our resilience to wildfire; and ways to reduce wildfire and climate change.
PATRICK GONZALEZ: Hello. I’m Patrick Gonzalez. I’m a forest ecologist and climate change scientist and an associate adjunct professor at the University of California, Berkeley.
Interview with SciLine
What does wildfire look like in forests where it’s a natural part of the ecosystem versus forests where it’s not? How is this changing?
PATRICK GONZALEZ: In much of the western U.S., like the giant sequoia groves in Yosemite National Park, forests naturally experience low-severity fires, ignited by lightning, every 10 to 20 years. In a natural situation, the fire burns at a low severity along the ground, in the deadwood, and large, old trees with thick bark survive and thrive. You know, ground-level fires clear the understory.
In contrast, wildfires in unburned areas can burn up into the tree canopy, become catastrophic, completely burning stands of trees at high severity. In ecosystems where fire is absent or rare, including the boreal forests of the far north and tropical rainforests of the Amazon and the Congo, the vegetation isn’t adapted to fire, and it burns and dies. And forests can become grasslands, and grasslands can become deserts.
How is climate change currently affecting wildfire patterns across the western U.S.?
PATRICK GONZALEZ: Human-caused climate change is intensifying the heat that drives wildfires. At the same time, outdated policies of stopping all fires—even natural ones—have generated unnatural accumulations of small trees and dead woody debris in the western U.S. forests. This combination of climate change and wood accumulation has increased burned area 10 times since 1984. Climate change alone has doubled the area burned by wildfire over natural levels across the western U.S.
How will ongoing climate change affect future wildfire risks?
PATRICK GONZALEZ: Continued climate change could increase wildfire frequency in western U.S. forests as much as 14 times historical levels by the end of the century. That could—continued climate change could push fires farther north in Alaska and exacerbate fire risks in moister regions, including Hawaii and the eastern United States. In Yellowstone, continued climate change could increase burned area 4 to 6 times. And in the Sierra Nevada of California, climate change under the worst scenario could triple burned area.
But if we meet the Paris Agreement goals and cut our carbon pollution, fire in the Sierra Nevada would only slightly increase. So cutting carbon pollution reduces fire risk. In tundra and boreal forests, the combination of climate change and ignitions from oil and gas drilling could cause so much fire it could thaw permafrost and generate the equivalent of 15 years of global carbon emissions. In tropical rainforests, the combination of climate change and intentional deforestation for cattle pastures could double burned area and convert half of Amazon rainforest to grassland.
What strategies can be used to increase human resilience to wildfire?
PATRICK GONZALEZ: More people have been moving into fire-prone areas—fire-prone forests—in the U.S., putting themselves at risk. Since 1990, more than 13 million more houses have been built, and 25 million more people have moved into fire-prone areas. A common sense solution will be to encourage people to build outside of fire areas, and the state of California is examining legislation and regulations to encourage such common sense solutions.
What strategies can be used to increase ecosystem resilience to wildfire?
PATRICK GONZALEZ: Scientific research in field practice have shown that two actions in particular can reduce small trees and deadwood and effectively restore natural fire regimes. No. 1, managed wildland fire—that’s allowing remote natural fires to burn. And No. 2—prescribed burning—pre-emptively setting low-severity fires during cooler weather. These two practices—prescribed burning and managed natural fire—can store more carbon in the long term in large trees than is lost in the short term from small trees. For ecosystems where fire has been absent or rare, like boreal forests, tundra and tropical rainforests, halting intentional burning is the most effective action. Halting tropical deforestation would cut carbon emissions 15% and protect globally important biodiversity. Most importantly, the fundamental solution to prevent catastrophic wildfires is cutting the carbon pollution from cars, power plants and other human sources that causes climate change.
What individual actions can people take to mitigate the climate change that is worsening wildfire?
PATRICK GONZALEZ: Transportation generates more carbon pollution than any other sector in the United States and the world. So you can take action on climate change by walking, biking or taking public transit. And by doing that, you can cut your transportation carbon pollution by up to 99%.
In addition, livestock—cows, sheep and goats—produce a lot of carbon pollution because they generate a lot of methane, which is a very potent greenhouse gas, in their guts. And also, raising the feed to feed them produces a lot of carbon pollution. So global adoption of a plant-rich diet could cut carbon pollution enough to get us halfway to the Paris Agreement goal of limiting heating to 1.5 degrees, which is how we avoid the most dangerous impacts of climate change.
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