A single, devastating California fire season wiped out years of efforts to cut emissions

A firefighter sprays water water in a burning forest.
A firefighter battles the 2020 Creek Fire in Madera County, Calif.
(Associated Press)

A nearly two-decade effort by Californians to cut their emissions of planet-warming carbon dioxide may have been erased by a single, devastating year of wildfires, according to UCLA and University of Chicago researchers.

The state’s record-breaking 2020 fire season, which saw more than 4 million acres burn, spewed almost twice the tonnage of greenhouse gases as the total amount of carbon dioxide reductions made since 2003, according to a study published recently in the journal Environmental Pollution.

Researchers estimated that about 127 million metric tons of carbon dioxide equivalent were released by the fires, compared with about 65 million metric tons of reductions achieved in the previous 18 years.

“When we look at the contribution of the 2020 wildfires, it becomes almost like a new sector of emissions in the economy,” said Michael Jerrett, a professor of environmental health sciences at the UCLA Fielding School of Public Health and a lead author of the research. “Really, we’re about double the reductions.”

As wildfires become more extreme, some worry California will near a tipping point in which its forests emit more carbon dioxide than they absorb.

Aug. 29, 2022


The findings challenge the notion that wildfire emissions should be considered differently than the emissions of tailpipes, industry and other sources because forests eventually grow back, Jerrett said. In fact, the study found that wildfires were second only to transportation as the state’s primary source of planet-warming gases in 2020, ahead of industry and electrical power generation.

He said that’s the essence of the study’s title, “Up In Smoke,” because “a lot of the hard-earned gains to fight climate change could be wiped out if we don’t start changing the way that we manage the forests, manage the interface between human activity and the wildland-urban interface, and really start tracking these emissions more carefully and comparing them with other major sources so that we don’t unwittingly think that we’re meeting our climate goals when we’re not.”

Dave Clegern, a spokesman for the California Air Resources Board, said the agency does not consider wildfire emissions when assessing its progress toward greenhouse gas targets because the targets are specific to human-caused emissions. The approach is aligned with legislative direction, he said, and was designed to ensure that the state’s targets and emissions reductions are comparable with other national inventories.

However, that will soon change, because new guidance from the Intergovernmental Panel on Climate Change has clarified that to achieve carbon neutrality, “we must consider all emissions sources and sinks,” Clegern said.

He said the Air Resources Board is starting a process to include wildfire emissions in its 2022 “scoping plan,” which focused on achieving carbon neutrality by 2045.

“Our efforts have been concentrated on reducing the use of fossil fuels because that is the direct cause of climate change. Wildfires on the other hand, are part of the natural carbon cycle,” Clegern said. “However, we are concerned about both the climate and public health impacts from wildfires and that climate change will only exacerbate these impacts in the future. That’s why we’re addressing it in the draft scoping plan and the state is advancing action to both reduce wildfire emissions and improve forest health.”

Nationally, 29 of the top 30 counties with the highest level of particulate pollution in 2020 were in California, researchers say.

June 17, 2022


This year, a Times report on the 2020 wildfire season found that it not only offset decades of antipollution efforts, but also contributed to more than $19 billion in economic losses. Jerrett said that’s all the more reason to consider wildfires as part of the big picture.

“I think the only way that we’re going to effectively deal with this is to start tracking these emission very carefully, understanding the magnitude of their impacts in terms of the economic costs and also the potential warming they could cause, and putting them in comparison with other sectors so that we can begin to make societal decisions that are much better informed than what we’ve made so far,” he said.

The study’s findings could have implications for global warming. According to the Intergovernmental Panel on Climate Change, it is critically important to avoid a 1.5-degree Celsius rise in global average temperature, as increases above that would have dire implications for extreme weather events, infectious diseases, economies, agriculture and many other sectors.

Forests have long played a role in that system, with large trees sequestering carbon and helping to alleviate some emissions. But California’s new breed of climate-change-fueled fires are burning hotter and faster than those of the past, sometimes slowing the regrowth process and even converting some areas from coniferous trees into grasslands, shrubs and chaparral, the researchers said.

“Although wildfires are a natural feature of many ecosystems in California, the increase in severe and frequent wildfire events has raised the possibility of transformed post-fire ecosystems,” said Miriam Marlier, a Fielding School professor and co-author of the study. “Even if long-term regrowth occurs, however, the carbon emissions occurring in the next 15 [to] 20 years will make it difficult to reach emission reduction targets needed to avert the increases in mean global temperature advocated by the Intergovernmental Panel on Climate Change.”

As California struggles with an increase in extreme wildfires, researchers are studying exactly what a healthy or fire-resistant forest looks like.

Oct. 4, 2022

Rajinder Sahota, deputy executive officer of the Air Resources Board, discussed the study’s findings on KPCC’s “AirTalk” on Wednesday. She said California’s 2020 greenhouse gas targets, set in 2006, were “focused on the root cause of climate change, which is energy and combustion of fossil fuels in the state.”

“What we didn’t know then, and what we’ve learned now, is that the climate impacts have accelerated,” Sahota said, noting that the combustion of fossil fuels has contributed to the intensification of wildfires in the last decade. (Fourteen of the state’s 20 largest wildfires on record have occurred since 2010, according to the California Department of Forestry and Fire Protection.)

“So not only do we need to think about the evolution of how we set our targets past 2020 ... but we also have to acknowledge that we’re planning for energy and our forestry sector in a changing landscape,” Sahota said.

The state is taking steps to achieve carbon neutrality in the coming decades, including banning the sale of new gas-powered cars by 2035. In August, Gov. Gavin Newsom also called for more aggressive targets for greenhouse gas emissions, including expanding the current goal of a 40% reduction by 2030 to 55%.

But forest management will also play a significant role, especially because a century of wildfire suppression has allowed for an unnatural buildup of carbon inside forests that is getting released almost instantaneously during massive wildfires. The state has allocated billions in funding toward wildfires, including investments in forest management, fuel breaks and community hardening.

Managing forests through mechanical thinning, prescribed burns and other methods will make a difference, Jerrett said, especially as researchers and state agencies learn more about the role of wildfires in greenhouse gas emissions.

“That conventional wisdom of the wildfires as carbon neutral is something we have to rethink in the context of a climate crisis,” he said, especially “when we have so little time to meet critical goals.”