Wildfire smoke drifted into the U.S. from Canada frequently during the 2023 growing season. Will this become common in the future?

Concern over wildfire smoke led Mark Jeschke to investigate the phenomenon thoroughly. Jeschke, agronomy manager for Pioneer, Johnston, Iowa, presented information about wildfires during recent meetings. While there is no way to determine if smoke will reoccur in 2024, several factors point toward more wildfires in both the U.S. and Canada in the future, Jeschke says.

“It’s also not clear if it will affect crop yields or harm plants, although there is the potential that those things could happen,” he says. “Corn yields probably have not been impacted so far, and plants likely haven’t been harmed by toxic substances associated with wildfire smoke.”

That doesn’t mean smoke is healthy for growing crops, however, he notes. Several factors determine both why wildfires could be more prevalent and what future impacts might be.

Why more wildfires?

“There is some indication of more acres burned in Canada over time during the past 40 years,” Jeschke begins. “Even so, the area burned in 2023 was unprecedented, with over twice as many acres burned as in any other single year. Meanwhile, the area burned annually in the U.S. has quadrupled over the past 40 years.”

Experts track increases in wildfires to poor forest management and climate change. “Fire is a natural part of forest ecosystems,” Jeschke says. However, he notes that sometimes human-based activities, including government policies, get in the way.

Wildfires in the U.S. are not new. One of the most destructive wildfires ever, known as the Big Burn, occurred in 1910, burning over 3 million acres in northern Idaho and western Montana. The aftermath shaped forest management policy in the U.S. for decades. Yet even that knowledge doesn’t always overcome obstacles, leading to a buildup of fuel inside forests.

“An entrenched legacy of suppression-based management, lack of funding and personnel to carry out prescribed burns, liability risks, and lack of coordinated interagency cooperation likely contribute,” Jeschke says.

What causes wildfires?

“Some sources insist climate change contributes to more wildfires, with increased temperatures and lower rainfall during fire season, a longer fire season, earlier snowmelt and reduced river flows,” Jeschke says, “Experts believe these factors help make fuel loads in forests drier and more combustible.”

The impact of climate change is most evident in California. Jeschke discovered that average fire season temperatures in California exceeded the 20th century average every year since 2004. The worst wildfire years in California, where over 1 million acres burned, all featured above-average temperatures and below-average precipitation.

Nationwide, most wildfires are caused by humans. However, the leading cause of western U.S. wildfires that burn the most acres is lightning.

“Lightning was a major cause in the 2023 Canadian wildfires and in the 2020 California wildfires,” Jeschke reports. There is also evidence that frequency of lightning rises as global temperatures rise.

The bottom line is that buildups of combustible material, drought in California, increased lightning and multiple climate change factors set the stage for more wildfires in the future. “Wildfire smoke is likely to be an ongoing and even worsening issue,” Jeschke concludes.