June 2022 in Alaska was a remarkable month for wildfire. An incredible 1.84 million acres burned, nearly tying the all-time record for June. Notably, 1.2 million acres burned in southwestern Alaska, more than doubling the area burned in that region since the 1950s in a single year. Smoke impacts over the region impacted health and transportation, with air quality reaching 700 ppm PM2.5 at the Nome hospital at one point. Intense drought, followed by massive lightning storms, were two of the major drivers of 2022’s fire season. This year was part of a larger trend occurring for the past few decades in Alaska, a trend of larger and more frequent wildfires as well as the expansion of large wildfires into new areas.
A burning tundra
Changes in climate have altered the tundra landscapes of Alaska. Thanks to recent decades of warmer springs and summers, there is more vegetation (and more fuel). This year southwestern Alaska experienced the two largest tundra wildfires on record for the Yukon Kukoskowim Delta region. Burning primarily in June, the East Fork fire and the nearby Apoon Pass fire burned a combined 257,000 acres. Almost all wildfire activity in this region has occurred in the past seven years. Similarly, in the far north of Alaska large wildfires have become a new phenomenon. In 2007, the largest ever tundra fire in the North Slope region of Alaska, the Anaktuvuk River Fire, burned over 250,000 acres, more than doubling the total area that has burned in the region since the 1950s. Unlike the boreal forest, wildfire in arctic tundra has been a rare occurrence over the past 11,000 years, and increasing fire frequency has the potential to induce shifts in vegetation (and wildfire fuel) cover — especially by promoting shrub growth. Tundra fires are also a factor in adding to climate-induced permafrost thawing and ground subsidence.
A release of carbon
Wildfires in the far north have the potential to release extreme amounts of carbon into the atmosphere because of surface fuels and permafrost. Boreal forest floor contains large amounts of biomass in compacted layers of undecomposed moss and litter (known as duff), which can be hundreds of years old. Estimates of forest floor biomass in the range of 180 tons per acre for black spruce forest are comparable to combined slash/duff loadings for mixed conifer stands in the intermountain west. Even upland tundra contains 30-60 tons per acre of biomass.
The record setting Anaktuvuk River fire was estimated to have released over 2.3 million tons of carbon into the atmosphere. Not only do the deep layers of duff contain huge amounts of carbon, but they also insulate the soils and permafrost below. Subsequent warming of the burned area can double the carbon emission release from a fire as frozen layers thaw and decompose. Arctic and sub-arctic biomes worldwide are estimated to contain 30 to 40 percent of all soil carbon on earth, and permafrost is estimated to contain more than twice the amount of carbon currently in the atmosphere.
Intensifying wildfire environment
The intensity of the Alaska fire season this year and increasing trend over the past few decades coincide with a rapidly changing climate. From 2001 to 2020 wildfires in Alaska burned 31.4 million acres, which is more than 2.5 times as many acres as burned from 1961-1980 or 1981-2000. Changes in environmental factors such as lightning, temperature and precipitation are contributing to more fire on the landscape in Alaska.
Since the 1970s, summer temperatures in Alaska have risen over four degrees Fahrenheit in regions where wildfire is prevalent. As the air temperature rises, the air holds more moisture, leading to more convective storms. Lightning-ignited fires make up the vast majority of burned acres in Alaska and are reaching into places where they have rarely occurred before. Average summer lightning strikes have increased statewide by 17 percent over the past three decades, but several regions have more than doubled in the time. When weather conditions over the state are suitable for convection, the magnitude of storms and lightning ignitions can be overwhelming for fire response. For example, an incredible 18,000 lightning strikes were recorded in two days in interior Alaska this July.
In addition to lightning, drought played a large role in the record setting fire year. In June, nearly 18 percent of the state was classified as having moderate or severe drought, and another 25 percent was classified as abnormally dry. Fortunately, the 2022 fire season rapidly simmered down as precipitation began across the state in mid-July. Before this large rain event occurred, 269 wildfires were burning across the state, and 2.8 million acres had already been burned. The 2022 season wrapped with a total of 3.08 million acres burned, the seventh largest season ever recorded in the state.
Alaska faces many unique challenges when it comes to managing wildfires. The vast majority of wildfires in Alaska are far from the very limited road system. That means fire suppression resources needed to be flown or boated in. Even where road systems exist they are often unmaintained and unsuitable for fire operations. The terrain is so rugged that fire-containment strategies used in the continental United States often do not work well. In remote areas, point protection strategies are often used to protect individual homes and critical infrastructure while allowing fire to play its natural ecological role in undeveloped areas.
Wildfire in Alaska occurs predominantly in the boreal forest of the state’s interior, between the Alaska Range to the south and the Brooks Range to the north. Fairbanks is situated in the middle of this region and is the location of the Alaska Interagency Fire Coordination Center. Management of wildfires in the state of 365 million acres requires incredible planning and cooperation among land management agencies, including the Bureau of Land Management Alaska Fire Service, State of Alaska Division of Forestry and Fire Protection and the U.S. Forest Service.
As the wildfire environment in Alaska becomes more extreme and the wildland urban interface continues to expand, wildfire management in Alaska will require more resources and increased implementation of community protection strategies and fuel treatments such as fuel breaks and prescribed fire. Managers and research cooperators are also working together on better predictive tools and forecasts, advancement in the remote detection and monitoring of wildfire and studies on the effectiveness of management and mitigation strategies.
Special thanks to Alison York and Randi Jandt of the Alaska Fire Science Consortium for assisting in the review of this article.
This article was original published in Western Forester.