Alaska never saw large tundra fires like the East Fork Fire until climate change provided more fuel

The East Fork Fire in Western Alaska is the state’s largest fire at the moment, estimated at more than 150,000 acres Thursday, and it’s burning in a region where, just a couple decades ago, large fires would not have been expected.

And a major contributing factor is our warming climate, says climate specialist Rick Thoman with the Alaska Center for Climate Assessment and Policy at the University of Alaska Fairbanks.

Thoman says hot, dry weather and a lightning strike at the end of May combined to make the East Fork Fire the biggest tundra fire on record, by far, for the Yukon-Kuskokwim Delta region.

Listen:

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The following transcript has been lightly edited for clarity.

Rick Thoman: You know, really prior to about 2015, there were a handful of documented wildfires on the tundra in the Y-K Delta, but very few. There’s been a big uptick. Similarly, in the upper Bristol Bay Area, the Dillingham, King Salmon area, historically there’s been only a relatively few number of fires. Most of them have been documented in the last decade or so. But this year, we’ve had easily the largest wildfires, for instance, anywhere close to Dillingham. So really quite remarkable. And it really is a big change from what we saw even 10 or 15 years ago. We just didn’t think about, or really expect, these kinds of fires on the tundra landscape.

Casey Grove: What even is a tundra fire? What is burning out there?

RT: So tundra comes in many different shapes and sizes and types of vegetation. So Southwest Alaska, their vegetation is much thicker, much denser, the willows and alders growing up, you know, taller than your head, versus on the coastal North Slope, where most of the plants aren’t much above your ankle. So they’re both tundra but very different environments, from a wildfire perspective. Of course, the more plant material you have to burn, the hotter the fire is, potentially. If you’ve got a hotter fire burning deeper into that duff layer, the surface layer, that’s going to be harder to extinguish. In tundra fires, you don’t have the tree mass to burn like you do in the boreal forests. In areas where the tundra is quite thick with vegetation, there’s still plenty to burn from willows and alders and through the the tundra grasses, as well.

CG: So whether it’s tundra, or trees or whatever burning, how is our fire season shaping up this year? And how does that rank in terms of other fire seasons that we’ve seen at this point in the season?

RT: Well, that’s the million dollar question here. As of Wednesday, the total acreage burned is now over 800,000 acres in the state. The only other year that was even approximately this high at this point in the season, on June 15, was back in 2010. Now, 2010 is not one of the big fire years in Alaska. We had burned a lot of acreage in the Interior in May and early June. But then the weather turned cloudier or rainier. And while 2010 did exceed a million acres, it didn’t exceed it by very much. And some of the very biggest wildfire seasons — 2004, 2005, 2015 — they were not really going yet at this point of the season. On the other hand, 2002 — which is now the third largest wildfire season to June 15th — did wind up being a very big season. So the bottom line is: what the rest of the wildfire season brings for the state, as a whole, is going to depend entirely on what the weather does over the coming four weeks or so.

CG: So we’ve talked about the shorter-term implications of the weather changing, but then there’s some longer-term things that are affecting this too, right? So how does the changing climate factor into this?

RT: Well, our changing climate, our changing environment, of course, didn’t cause the thunderstorm on May 31 that sparked the East Fork Fire. But what our warming environment does is it supports, for instance, the increased growth of plants on the tundra in Southwest Alaska. And so as elders from St. Mary’s and really all around Western Alaska had been reporting for years, that vegetation is thicker. It’s growing taller. We see trees, spruce trees, are advancing into places where they didn’t grow or places where trees were just very spindly and few and far between. They’re getting more robust and thicker now. And all of this is the result of this long-term, decades-long warming. Spruce trees, of course, don’t spread because you have one warm week. It’s that sustained, year after year, warmer conditions that are allowing plants to grow more, grow in places they didn’t before. Plants don’t care how we measure anything. They just grow where they can and don’t grow where they can’t.

CG: Is it fair to say that this might be the future that we should expect? That there would be these fires out in that region?

RT: Certainly, that’s been the case so far in the Y-K Delta. Wildfire on the tundra used to be very rare, and when it happened it was pretty darn small. That is clearly not the case. 2015, 2020, now 2022, have featured these very large fires without precedent in this part of the state. Now, of course, in the boreal forest portion of the state, fires this size happen somewhere literally most years. But out on that tundra, where it’s a cooler environment, there’s less fuel to burn, fires this size didn’t used to occur, and they are now. There’s no reason to think that this isn’t going to be a feature going forward. Of course, they won’t occur every year. You have to have all the weather ingredients come together, as well. That is dry conditions and something to spark the fires, like lightning. But when all of those pieces come together, this is the kind of thing that will result. We’re seeing it now.

CG: Rick, speaking of those ingredients, how are we seeing things shape up, you know, either in Western Alaska or elsewhere in Alaska, as far as the dryness, and just the weather going forward? What do you expect to see in terms of potential fire danger?

RT: Well, the big risk right now, Casey, is that most of mainland Alaska has had very little rain since the snow melted in April or May, depending on where exactly you’re at. And that means that there has been drying of the land surface since then. For instance, in Fairbanks, there has been no measurable rain, not enough to completely wet the ground, since the snow was completely melted in mid-May. And this is now the longest dry streak on record in Fairbanks that’s gone into the summer. There’s much longer dry streaks in the spring. That’s not uncommon, but not at this time of year, when the snow is gone. It’s warmer, things are drying out. That kind of dryness covers a large portion of the central and western Interior and Southwest Alaska and really much of Southcentral, as well, although there were those thunderstorms last week. You know, some places got a lot of rain, nearby places got almost nothing. So overall, it’s very dry across much of Alaska right now. And if — big if — we get into a pattern where we get a lot of lightning, we have a lot of land that is primed for wildfire.