Climate change fuels wildfires, but it's been a quiet season in the West. Here's why.
Due in part to a wet winter in California, this year's wildfire season across the mainland U.S. is turning out to be the quietest in 25 years, in terms of acres burned.
In fact, so far in 2023, wildfires have scorched 2.5 million acres across the U.S. While that may seem like a lot, it's actually the fewest acres burned as of this date since 1998, according to data from the National Interagency Fire Center (NIFC) in Boise, Idaho.
It's also only about one-third of the average, despite the horrific Maui wildfires and the smoky air this past summer.
Why was it such a quiet year for fires in the Lower 48 states?
The fire season in the West typically determines the severity of the fire season across the country, as the majority of acreage burned in the contiguous 48 states is found in the West, UCLA geography professor Glen MacDonald told Paste BN.
He said that much of the western U.S., including California, had above-normal rain and snow coming into the fire season and states such as California, Nevada, Utah and Wyoming had relatively cool temperatures from June to September.
"The cool and moist conditions in California kept vegetative fuel flammability and fire spread potential low," MacDonald added.
NIFC meteorologist Jim Wallmann agreed, telling Paste BN that "the wet winter in California delayed the fire season there." California endured a series of atmospheric river storms throughout the winter, which dumped record amounts of snow and rain across the state.
Wallmann also said that in August, Hurricane Hilary "dumped a lot of rain onto the Sierra and the Rockies," helping to douse and prevent fires in those mountain ranges.
What happened in Canada? Why were the fires so bad there?
In stark contrast to the U.S., it was the worst wildfire season ever recorded in Canada, with a whopping 45.7 million acres burned, according to the Canadian Interagency Forest Fire Centre. Smoke from the fires spread across the border into the U.S. in the summer, creating hazy, surreal skies across the nation in cities from Chicago to New York.
The reason for the disastrous fire season there, MacDonald told Paste BN, is that western Canada and large stretches of the boreal forest (in northern Canada) experienced very dry and hot conditions coming into the wildfire season. "That is the time when you saw the really huge areas of Canada experiencing fires," he said.
MacDonald added that the contrast between California and western Canada was particularly striking in June, when "you saw large areas of western Canada experiencing moderate to severe drought and most of California experiencing non-drought conditions and large persistent snowpacks in the mountains."
Wallmann said that lightning storms helped spark wildfires across Canada, also noting that it was extremely warm and dry early in the season nationwide.
What happened in Maui?
The 2023 wildfire season in the U.S. will be most remembered for the catastrophic, deadly wildfires in Maui, Hawaii, in August, which killed at least 99 people.
The fires in Maui and the resulting destruction of much of Lahaina were due to several factors, MacDonald said. The first cause was the abundance of fuel that was present in the form of flammable, fast-growing, invasive grasses around Lahaina.
Then in May, Maui began to experience a flash drought, which is a rapidly developing and intense drought. That flash drought dried out the vegetation and provided particularly dangerous fuel conditions.
Finally, in August, when Hurricane Dora passed to the south of Maui, despite being some 500 miles distant, it produced downslope winds towards Lahaina with gusts up to 60 mph. "Unfortunately, the fire ignited in the worst of all conditions in terms of fuel and weather, and in a location that led to its spread into Lahaina itself," MacDonald said.
What does next fire season look like?
The severity of next year's fire season in the West and in Canada will be determined by the amount of winter precipitation and resulting snowpack, and the spring and summer temperatures. "A large snowpack with a slow melt and cool summer temperatures will dampen down fuel flammability, fire spread and intensity," he said.
How does climate change impact wildfires? Was this season an outlier?
The amount of acres burned due to wildfires annually in California and the western United States can vary wildly from year to year. For example in 2020 California saw 4 million acres burned, while this year’s total thus far is only about 319,000 acres, according to MacDonald.
"The variability reflects a number of factors including the seasonal conditions of temperature and precipitation, the timing and location of ignition events, and the weather and winds associated with a fire," he said.
"However, if we take a long view and look at the overall statistics from 1980 to the present, there is a significant upward trend in annual areas burned," he said. Studies show that much of this overall trend in increasing annual area burned is related to higher temperatures and drier air, and the majority of these changes in climate are attributable to increasing greenhouse gasses due to human activities.
"So yes, climate change is increasing wildfire risk," MacDonald concluded.