Ninety per cent of forest fires in the boreal forests of northern Canada and Alaska are triggered by lightning with research showing weather conditions play a huge role in determining which strikes are fire-starters. As the climate warms, these weather conditions are expected to become more prevalent, significantly increasing the ignition efficiency of lightning strikes.
For every 10,000 lightning strikes in northern North America, between two and five will trigger a forest fire. But what causes one lightning strike to be a damp squib and another to spark a blaze? Researchers looked at forest fire outbreaks in the boreal forests between 2001 and 2018 and assessed the influence of weather conditions, tree type and landscape features on the probability of lightning triggering a fire. Their results, published in Environmental Research Letters, suggest weather conditions were a key driver with higher temperatures, lower rainfall and low humidity all greatly increasing the chances of a lightning-induced blaze.
As global climate warms, fire-friendly weather conditions are to become more common in this region, and the researchers estimate that when the projected doubling in lightning strikes is taken into account, there could be up to 65% more lightning-generated fires in the region for every 1C temperature rise.
