‘The changes aren’t just coming — they’re already here’
Climate change fuels wildfires in Alaska
Climate change is transforming landscapes in Alaska, where seemingly immutable scenes of dense glaciers, frozen tundra, and trackless spruce forests define public perception. These changes make conservation initiatives more complex and threaten wildlife, ecosystems, and societies.
While it’s clear the long-term driver is climate change, a subsidiary effect — wildfire — is enforcing immediate and dramatic effects on the environment and its wildlife.
“It’s a complex situation with regional differences,” said Lisa Saperstein, the regional fire ecologist with the U.S. Fish and Wildlife Service’s National Wildlife Refuge System in Alaska. “There are significant unknowns — for one, trends in available water are difficult to predict. But all the computer models show we should expect increased wildfire occurrence. We’re already experiencing it.”
Over the past six decades, the average temperature across the state has increased by about four degrees Fahrenheit — more than twice that of the Lower 48. That’s causing profound changes to some Alaskan ecosystems and wildfire behavior.
Wildfires naturally occur, but climate change makes the Alaska fire season hotter and longer, creating environmental conditions for more frequent and intense fires. Wildfire weather also becomes more severe, allowing fires to burn through the environment more quickly.
While wildfires can be a tool for regeneration and regrowth, extreme fires can be devastating for some species. For example, Alaska’s black spruce — which is highly susceptible to fire — needs the heat for regeneration. However, if the fires are too frequent and/or intense, reproduction becomes difficult.
“Black spruce cones are serotinous— they need heat to open their cones and reseed,” said Saperstein. “In that sense, wildfire is essential to black spruce forest regeneration. But, when fires are too frequent, intense, or both, you can lose your mature seed trees and reproduction can become difficult or impossible.”
The state’s boreal forests — vast, interior woodlands dominated by black spruce — are also undergoing changes.
Black spruce is being replaced in some areas by deciduous trees and shrubs. Current research predicts there will be more deciduous vegetation on the landscape as fire occurrence increases. Charcoal records taken from lakes in Alaska’s Yukon Flats area confirm that the current burning rate in the area exceeds that of any wildfire regime in the past 10,000 years.
“The past few decades have been particularly intense,” said Jimmy Fox, the manager for the Yukon Flats National Wildlife Refuge. “As a manager, it can be difficult just to get your hands around the enormity of it.”
In some areas, increased wildfires are also accelerating the thaw of permafrost — ground that remains at or below freezing for at least two consecutive years. Permafrost is not only a stabilizing element for Alaskan landscapes and ecosystems but also functions as a carbon sink.
Frozen permafrost holds an estimated 1,400 gigatons of carbon. As permafrost thaws, it releases more methane and carbon dioxide into the atmosphere, accelerating climate warming. Thawing results in widespread impacts to wildlife habitats across Alaska’s sprawling wetland and muskeg landscapes.
“Fire impacts can change hydrology over very large areas. In some cases thawing permafrost can expand the margins of a wetland, but it can also have the opposite effect,” said Fox. “It’s not a straight line from a warming climate to more fires to fewer wetlands. It’s more complicated than that. But it’s evident the impacts are profound.”
While climate change impacts are clear, it’s unclear what wildlife species can make use of the new ecosystem and hydrology shifts.
“Moose are browsers, so they may respond positively to an increased food supply that results from more fires,” said Fox. “On the other hand, the warmer summers that are driving these fires are causing ticks to expand in range and numbers. Moose are vulnerable to tick infestations, so warmer weather, more fires, and a shift in boreal forest vegetation may not be a boon for moose.”
Farther south, moose are the primary herbivore on the Kenai Peninsula, browsing the tender shoots of shrubs. Intense fires may increase deciduous cover and benefit moose. However, seedlings may also face conditions where they cannot establish and grow, which would reduce vegetation. Similar to Yukon Flats, the Kenai National Wildlife Refuge manager anticipates variability in post-fire landscapes that will cause species to respond to these ecosystem changes.
“There are clearly going to be surprises in terms of species changes and assemblages,” said Andy Loranger, the manager for the Kenai National Wildlife Refuge. “More than anything else, I think this shows that ecological transitions can happen quickly, and we need to incorporate that fact into our thinking.”
One species of particular concern is Alaska’s iconic caribou, a critical source of food for subsistence hunters and a major draw for sport hunters and wildlife enthusiasts. Approximately 750,000 caribou forage in migratory circuits across the state, but their numbers could be reduced drastically by the changes induced by wildfires.
“In the winter, caribou subsist on lichens, which can grow abundantly in mature black spruce,” said Saperstein. “There’s good research indicating it takes 50 to 100 years post-fire for lichens preferred by caribou to regrow to grazable levels. So, when you have increased fire in lichen-rich sites in shorter and shorter cycles, it could have a negative effect on caribou herds.”
These impacts continue to add challenge and complexity to wildfire management. Today, the U.S. Fish and Wildlife Service Alaska Region focuses on preparation, mitigation, and suppression of future wildfires across the state.
Fire managers work closely with other with federal, state, local, and Tribal partners to keep communities, wildlife, and ecosystems safe from the impacts of wildfire. By crafting plans together, sharing resources, and working alongside one another, the response to these fires can be more rapid and effective in a changing climate.
“As ecosystems transition due to fire, we have to determine our response,” said Saperstein. “Which species will benefit? Which will decrease? How do we manage for either — or do we? Do we introduce certain species in emerging habitats, or do we step away completely? We need to really think about these things, because the changes aren’t just coming — they’re already here.”
In Alaska we are shared stewards of world renowned natural resources and our nation’s last true wild places. Our hope is that each generation has the opportunity to live with, live from, discover and enjoy the wildness of this awe-inspiring land and the people who love and depend on it.
Story compiled by Grace Rodgers, Climate Communications Specialist with the USFWS Alaska Region, External Affairs and Science Applications.