California Wildfires Killed 106 People Two Years Ago. Researchers Say the Smoke Killed 3,652

A burnt out boat sits at a marina on Whiskeytown Lake after damage from the Carr Fire near Redding, Calif., on July 30, 2018.  (Mark Ralston/AFP via Getty Images)

According to official numbers, the 2018 California wildfires caused 106 deaths. That was the season the Carr Fire destroyed towns around Whiskeytown Lake in Shasta County, before jumping the Sacramento River and blowing into Redding as a fierce fire tornado. A few months later the Camp Fire in Butte County caused unprecedented destruction in the rural communities of Concow and Paradise. But the damage did not stay in areas directly charred. Those fires also released plumes of toxic wildfire smoke which coated much of the state. And the economic and health damages these flames and plumes caused rippled out beyond counties into the rest of the state and the nation.

Researchers from UC Irvine and around the world now estimate that, when the harm of air pollution is folded in, the 2018 California wildfires led to thousands of additional deaths: 3,652.

“I think a problem historically is that we've been counting what's easiest to count, said Steven Davis, a scientist at UC Irvine.

“[That’s] the numbers of buildings destroyed or the people that were literally killed in a fire, because they were in a building that burned. It's a lot harder to follow the tendrils of literal smoke or the economic damages that permeate throughout the global economy.”

A study published Dec. 7 in Nature Sustainability by Davis and an international team seeks to do just that — convey the comprehensive cost of wildfires. The dangers of wildfire smoke, and the associated death toll, are among the most eye-popping.

“For example, there could be a person with severe respiratory disease and the increased air pollution during one of the wildfires in 2018 could have triggered the event that led to their death,” wrote Colleen Reid, who studies the health impacts of smoke at the University of Colorado Boulder, but was not involved in the current study.

Those deaths, she says, “would be coded as respiratory distress or heart attack [...] and it is possible that death would not have happened if the air pollution had not been elevated.”

Davis and his colleagues used a model developed [PDF] by the Environmental Protection Agency, with input from air sensors to satellite data, to calculate these broad health impacts.

The researchers also tracked how industries — including services, trade and manufacturing — were affected by the fires and how that disrupted the economies of counties, the state, nation and world. They put the financial cost for the 2018 fires at nearly $150 billion. That’s six times the official estimate, which counts only destroyed and damaged property.

Calculating a “disaster footprint” like this is complicated. But Davis says the way we do things now distorts the costs and benefits of recovering from climate-fueled disasters and preparing for future events:

“It's very easy to understand the costs of moving away from fossil fuels. It's a lot harder to understand what are the benefits of that because they're so diffuse.”

Federal and state governments pour lots of money and effort, Davis says, into suppression, but less is put “into actually managing our forests in a way to prevent fires from getting out of hand.”

This approach, he says, can help governments, business and the public better understand the real cost of climate-driven disasters like wildfires, the level of investment needed in recovering from or mitigating future events, and the economic benefits of addressing climate change. Calculating these broader costs has become a priority of institutions such as the World Bank, seeking to get a grasp on how much money is needed for post-disaster support in developing countries or how to better design prevention measures.


“This paper is a really great illustration of how easy it is to underestimate the impact of disasters, if one focuses only on the impact on assets (that is, the value of repairing damages and replacing lost assets), which is what is usually reported in the media and most analyses,” said Stéphane Hallegatte, a lead economist with the Climate Change Group of the World Bank, who was not involved in the current work.

“This type of work is pushing the frontier in terms of disaster analysis, and contributes to building the toolbox we need to understand disasters and manage risk better.”

The paper, Davis says, is garnering some reaction, even amid a busy news cycle.

“I think it resonates very strongly with a lot of people who are concerned about the effects of these fires on the state and on the region in particular, I think people are alarmed that this is being driven by climate change and wondering what it portends for the future.”

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