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Alaska is aflame and enduring one of its biggest fire seasons in decades. So far this year, 2.5 million acres of Alaskan forest—an area more than three times the size of Rhode Island—have burned, continuing a trend of more frequent fires charging through at least one million acres.

After fires burn, the region's conifer forests aren't always growing back like they used to, undermining the foundation of Alaska's boreal ecosystem. Swaths of spruce-dominated forest are being replaced by grasslands and leafy deciduous trees, which grow more quickly than evergreen spruces and readily establish in post-fire landscapes. “It could be 100 years before spruce trees get to regenerate,” says John Morton, fish and wildlife biologist at Kenai National Wildlife Refuge.

The overall picture is that of a landscape transformed by wildfire, where Alaska’s boreal forests give way to other ecosystems. These changes will inevitably alter the food available to wildlife species, experts say, including boreal birds, and in turn their ability to raise their young. One poor breeding year here and there doesn’t typically hurt bird populations, but too many in a row can put a population or species on the decline.

The fire season has also harmed human communities through forced evacuations and smoke pollution. “When fires burn in Alaska in the wilderness, we just let them burn, and a lot of times you don’t even realise they’re happening because the state is so big and sparsely populated,” says Melanie Smith, program director of the Migratory Bird Information Platform at the ���Ϲ��� who is based in Anchorage. “But this year just about everybody living in south-central or interior Alaska is noticing and being affected by the fires.”

While fires are a natural part of the boreal forest ecosystem, the frequency of Alaska’s million-acre fire seasons these past few decades is unprecedented. Since 1990, 12 fire seasons have exceeded 1 million acres, according to from the Alaska Interagency Coordination Center. In the same period prior to 1990, there were five. 

“This year’s wildfire season is not happening in isolation,” says Rick Thoman, climate specialist at the Alaska Center for Climate Assessment and Policy.

The 2004 fire season, Alaska’s largest to date, burned more than 6.6 million acres. Since then, four seasons have exceeded 2 million acres, including this year’s. In all of those years, communities were impacted by fire or severe air quality, and fire-fighting help was sent up from the Lower 48 after the state’s fire suppression resources maxed out. 

“I don’t like the phrase ‘the new normal,’” says Scott Rupp, deputy director at the International Arctic Research Center, “but for the past 15 to 20 years now, that’s sort of been the playbook for these big fire years.”

This increase in big fire seasons is tied to Alaska’s changing weather patterns, Thoman says. Spring lightning is more frequent; at the same time warmer, drier weather is making vegetation more flammable. This combination makes it more likely for fires to start, and provides more fuel for fires to continue burning.

Timing is another issue. Fires have been starting earlier than usual due to warmer, drier weather in the spring and earlier melting of snow cover. August rain that typically squelches fires has also been lacking some years, allowing the burning to continue into September.

These changing weather patterns are all symptoms of the Arctic’s rapidly warming climate, Smith says. Temperatures in the region have increased by more than 2 degrees Celsius (3.6 degrees Fahrenheit) since 1950, double the global average, according to from the Goddard Institute for Space Studies.

Fires have not only been occurring more frequently and for longer periods, but they are also burning in areas that are not supposed to burn, like southwest Alaska and the alpine tundra, says Dawn Magness, landscape ecologist at the Kenai National Wildlife Refuge.

The Kenai Peninsula, located in southern Alaska, is currently trying to contain its 140,000-acre Swan Lake Fire. Ignited on June 5, the fire continued to burn into the alpine tundra, which should have acted as a natural fire break. 

Due to sustained drought conditions and strong winds, the fire spread past containment areas last weekend, forcing the closure of the Sterling Highway—the only connecting road to Anchorage—and threatening the community of Cooper Landing. “The strange thing about this fire is that it’s in a habitat that normally isn’t extreme in fire behavior,” Magness says. “The Swan Lake Fire behavior has been pretty extreme and just been relentless.”

Ultimately, Alaska’s fires are transforming the state’s spruce-dominated landscape into grasslands and deciduous vegetation. “It used to be if you cut a forest, you get a forest,” Morton says, “but now if you cut a forest, you get a grassland, because the system is drying out so much.”

This change affects birds and other wildlife species that rely on conifers for food and shelter. Caribou have already been moving away from their usual habitat, Rupp says. The lichen that the reindeer depend on as their primary food source is incinerated in fires, so they tend to stay out of areas that have burned in the last 50 years, Rupp says. 

Jeff Wells, vice president of boreal conservation at ���Ϲ���, says boreal birds like the Canada Jay, Boreal Chickadee, and Spruce Grouse are likely to move north to find habitats more conducive to their survival if Alaska’s landscape continues to change. “It would be a generational shift as a result of the changing habitat and climate,” Wells says. 

Following the northward trend, many warbler species that currently range in southern parts of the boreal forest, where there is a mixture of coniferous and deciduous trees, are as the landscape changes.

One of the concerns is that Alaska’s more frequent megafires will not allow coniferous trees to repopulate. They take much longer to grow than grass and deciduous trees like aspen; if fires burn through the same areas repeatedly, the seedlings are killed before they can establish. “It’s still a big unknown, but if climate change causes the fires to become just too frequent and too intense, it might be hard for coniferous-dominated species to maintain themselves,” Wells says.

Even Black-backed Woodpeckers, which are known to thrive in post-fire landscapes and benefit from the boom of wood-boring beetles, may not benefit from the trend of wildfires in Alaska, he says. indicate that the bird thrives in areas which contain a mosaic of habitats, some burned lightly, some burned intensely, and some regenerating from past burns—a patchwork known as pyrodiversity. A fully scorched landscape would not meet their needs.

“As a scientist who’s fascinated by wildfire and interactions with landscape and climate, to some degree I find it very interesting to watch things unfold,” Rupp says. “But as a resident and citizen here in Fairbanks, it’s concerning in terms of what sort of impact it will have on species distribution of wildlife, but also on people and communities here.”

The increasing frequency of big fire seasons is also a heavy contributor to carbon dioxide emissions, creating a positive feedback loop wherein global warming begets more warming. Boreal forests and Arctic tundra cover one-third of the global land area, yet they store a disproportionate amount of the world’s soil carbon—an estimated 50 percent. Wildfires release this stored carbon into the atmosphere, where it traps heat, in time creating conditions for even bigger wildfires.

This year’s Arctic fires have released more than 150 megatons of carbon dioxide as of August 18, according to the . That’s more than Venezuela’s total carbon dioxide emissions in 2017.

Smoke pollution from the fires is already threatening the health of local Alaskans. In Fairbanks, air respite centers have opened to provide people with respiratory conditions a place free from smoke. The Fairbanks International Airport has reported more than 20 days of restricted visibility due to smoke from the fires, which has become relatively common since 2004, Thoman says.

“People acclimate pretty quickly to what’s happening around them and think, this is the way it’s always been,” Thoman says. “But prior to 2004 that only happened one year going all the way back to the 1950s.”

Alaskans have also been experiencing unusually high temperatures this year. The state had its second hottest June on record, as well as its in July. In Anchorage, during a week-long heat wave, temperatures reached an all-time-high of 90 degrees Fahrenheit, five degrees higher than the previous record. Juneau, Kenai, King Salmon, and Kodiak are other Alaskan cities that have experienced historically high temperatures this year. 

“Around here people don’t argue about climate change,” Smith says. “They just understand that it’s a reality.”

Correction (August 26, 2019): The original version of this story incorrectly stated that Melanie Smith is the director of conservation science at ���Ϲ��� Alaska; this month she began a new position as program director of the Migratory Bird Information Platform at the ���Ϲ���. The original story also stated that Anchorage temperatures reached 95 degrees Fahrenheit, not 90 degrees. ���Ϲ��� regrets the errors.

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