Climate change will increase lightning-induced wildfires, which already account for nearly half of all wildfires in Canada.
As vegetation and lightning strikes rise, more extensive burnt areas are expected.
This can overwhelm fire management efforts.
The trend is mirrored in the US and Europe, where lightning also triggers significant wildfires.
Lightning-induced fires contribute to almost half of all the wildfires and over 90 per cent of the burnt area in Canadian forests, scientists have found.
The effects of climate change, they warned in a study conducted from 2000 through 2020, will result in increased frequency of such instances, as vegetation cover and lightning strikes are expected to rise.
In 2024, Environment and Climate Change Canada’s global atmospheric model estimated that increases in lightning in northern mid-latitudes will result in greater area burnt by the end of the century, according to the study published in May 2025.
Each year, an average of 1.96 million hectares of land in Canada is burnt by forest fires. The study said that between 1959 and 2015, lightning played a role in about 50 per cent of wildfires, while the other half was caused due to anthropogenic factors.
Fires ignited by lightning led to a more extensive burnt area because they happened in isolated regions, unlike those caused due to anthropogenic triggers, because they were closer to human habitations and could be contained quickly.
Moreover, the lightning-induced forest fires were spatially distributed in clusters, overwhelming the fire management agencies to address them in multiple and remote areas.
Another study published in August pointed out cloud-to-ground (CG) lightning is a major source of summer wildfire ignition in the western United States (WUS). These fires are responsible for wiping out over two-thirds of the total burnt area in the region.
“Smoke from these fires has detrimental effects on air quality and public health and has partially reversed air quality improvements stemming from the Clean Air Act. As the climate continues to warm in the WUS, the risk of wildfires — including those sparked by lightning — is projected to grow due to drier vegetation,” the study said.
It was also observed that climate change has led to alterations in surface heating, moisture fluctuations and circulation changes, which contribute to cloud-to-ground lightning occurrences and precipitation. This increases the risk of flash floods and slope failures due to heavy rain-producing thunderstorms, especially impacting recently burnt areas.
The risks in these areas may not necessarily be from lightning-induced wildfire but rather hydrologic hazards.
The researchers factored in Fine Fuel Moisture Code, Duff Moisture Code and Drought Code from the Canadian Forest Fire Weather Index (FWI) System to understand and estimate fire ignition possibility due to lightning.
The study predicted coincidence in cloud-to-ground lightning days with FWI by 2031 and 2060, particularly in the interior northwestern US.
Apart from the US, wildfires have wiped out over 1 million hectares of forests in Europe this year, releasing volumes of carbon dioxide equivalent to the annual emissions of Sweden or Portugal.
Lightning was found to be responsible for triggering wildfires in Portugal and Spain.