Skip to main content Skip to secondary navigation
Main content start

The science behind the West Coast fires

A collection of research and insights from Stanford experts on wildfires' links to climate change, the health impacts of smoke, and promising strategies for preventing huge blazes and mitigating risks.

Thomas Fire, 2017

Wildfires torched more than five million acres in California, Oregon and Washington in 2020. They killed dozens of people, prompted evacuation orders for hundreds of thousands more and spewed enough toxin-laden smoke to make air conditions hazardous for millions. 

In 2021, wildfires in California alone burned more than 1.7 million acres before the end of August, destroying thousands of structures and forcing mass evacuations.

Tendrils of smoke from fires in the western United States have drifted as far as Europe. As environmental economist Marshall Burke put it in a virtual panel discussion hosted in September 2020 by Stanford’s Woods Institute for the Environment, “This is not just a U.S. West Coast issue, this is a nationwide issue.”

As the fires burn, they are unlocking huge amounts of carbon dioxide from soils and plants and launching it into the atmosphere. 

Six of the seven largest fires on the modern record in California ignited in 2020 or 2021, and most of the largest fires in the state’s history have occurred in the past two decades. Scientists say global warming and decades of fire suppression have helped lay the groundwork for the devastating blazes. One study by Stanford researchers estimated as much as 20 million acres in California would benefit from vegetation thinning or prescribed burns. Another found that the risk of extreme wildfire conditions during autumn has more than doubled across California over the past four decades, and human-caused global warming has made the changes more likely.

This collection covers how scientists are unraveling the factors that contribute to wildfire risk, understanding their impacts and developing solutions. Scroll down for wildfire research news and insights related to climate change, health impacts, prevention and mitigation, prediction and modeling and more.

Last updated: August 31, 2021

Climate change

Back to top

Longer, more extreme fire seasons

Cedar Fire, Sequoia National Forest

A study led by Stanford scientists shows autumn days with extreme fire weather have more than doubled in California since the early 1980s due to climate change.

What to expect from future wildfire seasons

The new normal for Western wildfires is abnormal, with increasingly bigger and more destructive blazes.

Wildfire weather

Woodward Fire

Stanford climate and wildfire experts discuss extreme weather’s role in current and future wildfires, as well as ways to combat the trend toward bigger, more intense conflagrations.

Climate change has its ‘thumb on the scale’ of extreme fire

Chehalem Mountain Fire in Oregon
Media Mention | September 2020

“Humans are ingenious at managing climate risk, but our systems are built around the historical climate,” climate scientist Noah Diffenbaugh told The Washington Post“Systems that were built for the old climate are being stressed in a new way.”

(Image credit: Sheila Sund / Flickr)

Morraine Fire

Wildfire emissions

San Francisco Chronicle | December 2020

“The forests are alive. They’re growing and dying and regrowing,” says Michael Wara, director of the climate and energy policy program at the Woods Institute for the Environment. “That’s really different than carbon that was buried 50 million years ago under the earth that we are unearthing and burning. I think it’s not helpful to compare the two. It’s a misdirection.”

Wildfire smoke worse for kids' health than smoke from controlled burns


Immune markers and pollutant levels in the blood indicate wildfire smoke may be more harmful to children’s health than smoke from a controlled burn.

California wildfires bring questions about health and climate

Wildfire smoke

What does smoke inhalation do to my health? What’s the evidence that these are caused by climate change? Here is how some Stanford experts answer and continue to tackle these complex concerns.

Wildfires' health impacts

Wildfire smoke over Sunnyvale

California’s massive wildfires bring a host of health concerns for vulnerable populations, firefighters and others. Kari Nadeau and Mary Prunicki of Stanford’s Sean N. Parker Center for Allergy and Asthma Research discuss related threats, preparedness and ongoing research.

Mask confusion

Covid mask

"Only certain masks are effective during wildfires, while a range of face coverings may help prevent coronavirus transmission," Stanford researchers write in Environmental Research Letters. Drawing on human behavior studies and past responses to epidemics and wildfire smoke, the scientists recommend ways to communicate mask-use guidance more effectively.

An unexpectedly huge toll on America's lungs

Smoke over San Francisco

As wildfires become more frequent due to climate change, the increasing amounts of smoke may harm Americans nearly as much as rising temperatures, according to a working paper by Stanford environmental economist Marshall Burke and colleagues. “We hadn’t even thought of that as a key part of the climate impact in this country,” Burke told Bloomberg.

Wildfire smoke is poisoning California's kids. Some pay a higher price.

Children biking

Marshall Burke, an economist at Stanford, has found that, across California, as the number of smoke days has risen over the past 15 years, it has begun to reverse some of the gains that the state had made in cleaning up its air from conventional sources of pollution.

The shifting burden of wildfires in the United States

Wildfire and smoke

Wildfire smoke will be one of the most widely felt health impacts of climate change throughout the country, but U.S. clean air regulations are not equipped to deal with it. Stanford experts discuss the causes and impacts of wildfire activity and its rapid acceleration in the American West.

Tips to protect against wildfire smoke

East Troublesome Fire, Colorado

Warnings of another severe wildfire season abound, as do efforts to reduce the risk of ignition. Yet few are taking precautions against the smoke. Stanford experts advise on contending with hazardous air quality.

Wildfire smoke can increase hazardous toxic metals in air, study finds

Dixie fire (Image credit: Cal Fire)

Smoke from wildfires – particularly those that burn manmade structures – can significantly increase the amount of hazardous toxic metals present in the air, sending up plumes that can travel for miles, a new study from the California Air Resources Board has suggested. "No one is protected," said Mary Prunicki of Stanford’s Sean N. Parker Center for Allergy and Asthma Research.

Caldor fire smoke

How do people respond to wildfire smoke?

August 2021

Interviews with Northern California residents reveal that social norms and social support are essential for understanding protective health behaviors during wildfire smoke events – information that could be leveraged to improve public health outcomes.

Wildfire smoke exposure during pregnancy increases preterm birth risk

August 2021

Smoke from wildfires may have contributed to thousands of additional premature births in California between 2007 and 2012. The findings underscore the value of reducing the risk of big, extreme wildfires and suggest pregnant people should avoid very smoky air.

Setting fires to avoid fires

Prescribed burn

Analysis by Stanford researchers suggests California needs fuel treatments – whether prescribed burns or vegetation thinning – on about 20 million acres or nearly 20 percent of the state’s land area.


A new treatment to prevent wildfires


Scientists and engineers worked with state and local agencies to develop and test a long-lasting, environmentally benign fire-retarding material. If used on high-risk areas, the treatment could dramatically cut the number of fires that occur each year.

Wildfire preparedness


Experts with Stanford's Woods Institute for the Environment discuss strategies for managing wildfire risks, including incentive structures, regulations, partnerships and financing.

Mitigating risks with law and environmental policy

Forest fire

"In talking about risks and policy prescriptions, we need to separate out wildfires at the wildland-urban interface – those that put people and communities at most risk – from fires that historically have burned through our remote forestlands," said Deborah Sivas, Director of Stanford’s Environmental Law Clinic. 

Concrete steps California can take to prevent massive fire devastation

Fire damage

"Successful wildfire preparedness begins with a clear strategy and accountability for outcomes," writes Michael Wara, director of the Climate and Energy Policy Program at Stanford's Woods Institute for the Environment.

Are forest managers robbing the future to pay for present-day fires?

Nuns Fire 2017

"As fires burn with greater magnitude and frequency, the cost of fighting them is increasingly borne by money earmarked for prevention," writes Bill Lane Center for the American West writer in residence Felicity Barringer.

San Francisco Bay smoke

Policy brief

Managing the growing cost of wildfire

October 2020

Stanford experts review recent trends in wildfire activity, quantify how the smoke from these wildfires is affecting air quality and health across the U.S. and discuss what policymakers can do to help reduce wildfire risk.

California burning

Essay | September 2020

Heat waves that could melt the fat in uncooked meat until it would “run away in spontaneous gravy.” Forests that turned abruptly into “great sheets of flame.” These are some of the realities of life in California noted by the botanist William Brewer in 1860, and surfaced in an essay for The New Yorker by Stanford Classics professor Ian Morris about being evacuated from his home in the Santa Cruz mountains.


According to Morris, "Before Europeans came, Native Californians had found ways to cope with this reality. Many moved seasonally, partly to avoid forest fires. As much as one-sixth of the state was deliberately burned each year." Not many people lived in places like the Santa Cruz Mountains until the 1870s. Since then, Morris wrote, the "quiet migration of hundreds of thousands of nature lovers has created one of the most unnatural landscapes on Earth."


Preparing together

Coffey Park October 2017
Media Mention | September 2020

"We need programs that emphasize and support herd immunity from fires," Rebecca Miller, a PhD student in the Emmet Interdisciplinary Program in Environment and Resources, told Mic. Rebuilding efforts after a fire, she added, ought to recognize that once-burned neighborhoods are likely to burn again.

Fire burned the Coffey Park neighborhood of Santa Rosa, Calif. in October 2017. (Image credit: Sgt. 1st Class Benjamin Cosse / California National Guard)

Mapping dry wildfire fuels with AI and new satellite data

Forest fire

Stanford researchers have developed a deep-learning model that maps fuel moisture levels in fine detail across 12 western states, opening a door for better fire predictions.


Predicting wildfires with CAT scans

Wildfire and smoke

Engineers at Stanford have used X-ray CT scans, more common in hospital labs, to study how wood catches fire. They’ve now turned that knowledge into a computer simulation to predict where fires will strike and spread.

Satellite imagery shows hot spots and thick smoke plumes from wildfires burning in Oregon and northern California on Sept. 8, 2020. (Video credit: NOAA)

Bobcat fire, 2020

Learn more

Stanford Wildfire Research

Stanford Woods Institute for the Environment

Find experts, events, information about ongoing research projects and more.

Media Contacts

Josie Garthwaite
School of Earth, Energy & Environmental Sciences
(650) 497-0947;

Explore More