The following essay is reprinted with permission Conversationan online publication covering the latest research.
Alaska is on track for another historic wildfire year, with the fastest start to the fire season on record. By mid-June 2022. more than 1 million hectares burned down Until the beginning of July, this number was good more than 2 million acres, which is more than twice the area of a a typical fire season in Alaska.
Rick Thoman, climate expert at the International Arctic Research Center in Fairbanks explains why there are so many large, intense fires in Alaska this year and how the region’s fire season is changing.
Why are there so many fires in Alaska this year?
There isn’t one simple answer.
Early in the season, Southwest Alaska was one of the few areas in the state with below normal snow cover. Then we had a warm spring and Southwest Alaska dried out. Thunderstorms that erupted there in late May and early June provided the spark.
Global warming has also increased the amount of fuel – plants and trees – that can be burned. So, more fuel more intense fires.
Yes, in combination with weather factors – a warm spring, low snow cover and unusual thunderstorm activity multidecadal warming which allowed vegetation to grow in southwest Alaska, together contribute to an active fire season.
A significant part of the territory was in the interior of Alaska abnormally dry since the end of April. So, because of the thunderstorms, it’s not surprising that we’re seeing a lot of fires in the region right now. The interior had about 18,000 strokes over two days in early July.
Are such storms becoming more frequent?
That’s the million dollar question.
The question has two parts: Are thunderstorms more common in places where they were rare before? I think the answer is definitely yes. Are the total number of strikes increasing? We don’t know because the networks that track lightning strikes are much more sensitive today than in the past.
Thunderstorms in Alaska differ from thunderstorms in most of the lower 48 in that they tend not to be associated with weather fronts. They are called meteorologists air mass or impulse thunderstorms. They are caused by two factors: the available moisture in the lower atmosphere and the temperature difference between the lower and middle atmosphere.
In a warming world, the air can hold more moisture, so you can get a strong storm. Thunderstorms are more common in interior Alaska. For example, the number of days with thunderstorms recorded at Fairbanks Airport show obvious growth. Older indigenous people also agree that they see thunderstorms more often.
You mentioned hotter fires. How are forest fires changing?
Wildfires are part of the natural ecosystem of the Boreal North, but the fires we experience now are not the same as the fires that burned 150 years ago.
More fuel, more lightning strikes, higher temperatures, less humidity – these combine to start fires that burn stronger and burn deeper into the ground, so instead of just burning trees and undergrowth, they consume everything and you’re left with this moonscape made of ashes.
Fir trees what rely on fire burst, their cones cannot regenerate as the fire reduces those cones to ash. People who spent decades fighting the fire say they are amazed at the amount of destruction they are seeing now.
So, while fire has been natural here for tens of thousands of years, the fire situation has changed. Fire frequency on million acres in Alaska doubled compared to 1990.
What effect do these fires have on the population?
The most common human exposure is smoke.
Most wildfires in Alaska do not burn in densely populated areas, although they do happen. When you burn 2 million acres, you’re burning a lot of trees, and so you’re putting a lot of smoke into the air that travels long distances.
In early July, we saw explosives forest fires north of Lake Iliamna in southwest Alaska. The winds were blowing from the southeast at the time, and thick smoke was billowing for hundreds of miles. In Nome, 400 miles away, the air quality index for the hospital exceeded 600 parts per million for PM2.5, fine particulate matter which can trigger asthma and harms the lungs. Anything more than 150 ppm is harmful to healthand more than 400 ppm is considered dangerous.
There are other risks. When wildfires threaten rural Alaska, as they did near St. Mary’s in June 2022, evacuation may mean the departure of people.
Worsening fire seasons are also putting a strain on firefighting resources everywhere. Fighting fires is expensive, and Alaska relies on fire crews, aircraft and equipment from the lower 48 states and other countries. In the past, when Alaska had a big fire season, crews would come up from the lower 48 because their fire season was usually much later. Now, the wildfire season lasts all year, and there are fewer mobile resources available.