Wildfires in California and Canada generate pyrocumulonimbus clouds

The recent fires in northern California and the resort town of Jasper in Canada have not only burnt vast areas but also produced their own thunderstorms.

As reported by Brian Owens for nature.com, these fires have created ‘pyrocumulonimbus’ clouds, which can trigger lightning and spark additional fires.

Before 2023, the occurrence of such clouds was relatively rare.

However, in recent years, there has been a significant increase in their formation, with Canada alone reporting 140 occurrences in the previous year.

According to Mike Flannigan, a wildfire expert at Thompson Rivers University, this trend is likely to continue unless measures are taken to address climate change.

Rapid spread of fires surprises officials

The Park Fire in northern California and the Jasper Fire in Canada both exhibited faster-than-expected spread.

In California, the Park Fire expanded from a small blaze to more than 140,000 hectares within three days, becoming the fourth-largest fire in the state’s history.

Similarly, the Jasper Fire in Canada reached the town in just two days, half the time predicted by models.

Daniel Swain, a climate scientist at the University of California, Los Angeles, noted: “We’ve seen a lot of fires behave like these ones in recent years, which I don’t think is reassuring at all.”

Climate change and its role in wildfire intensity

Climate change has made conditions more conducive to wildfires, particularly by creating drier fuels.

Extended heatwaves left the forests in both California and Canada tinder-dry, setting the stage for more intense and fast-moving fires.

According to James Gomez, a PhD student studying wildfires at the University of California, Riverside, warmer air, which holds more moisture, draws more water from vegetation, leaving it drier and more flammable.

This results in faster-moving fires with greater thermal output.

Fire management practices and unintended consequences

Fire suppression practices over the past century have contributed to a “fire deficit” across much of the western United States, leading to denser forests that are more susceptible to large fires.

Daniel Swain pointed out that current forest conditions are far from their natural state due to these policies.

In contrast, Canadian forests are naturally denser, and the population density is lower, reducing the impact of these management practices.

Anthony Taylor, a forest-management specialist at the University of New Brunswick, emphasized the importance of addressing climate change to prevent extreme fires in the future.

Wildfires in North America generate thunderstorms as climate change worsens: Summary

Recent wildfires in northern California and Jasper, Canada, have produced pyrocumulonimbus clouds, leading to lightning that sparked additional fires.

These events have become more common, reflecting a trend linked to climate change.

Both fires spread faster than expected, with the Park Fire in California growing from 1–2 hectares to over 140,000 hectares in just three days.

Climate change has increased the likelihood of such intense fires by creating drier fuels and more extreme fire behaviour.

Fire management practices have also contributed to the severity of wildfires, particularly in the United States.