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Denali National Park and Preserve in Alaska faces a growing climate change problem: part of the Denali Park Road is sliding down a hillside, faster and faster. The account is by Kaylin Thomas of the Park Service's Climate Change Response Program, written in 2025.
The Denali Park Road parallels the Alaska Range for 92 miles through wild country. It is the only road in the park. NPS photo / Kent Miller.
A road on frozen ground
| Length | 92 miles |
| Crosses | Six million acres of wilderness — the only road through it |
| Runs beside | The Alaska Range, a 600-mile-long mountain range |
| Connects | Visitor centers, campgrounds, staff facilities and businesses, across deep valleys and high passes |
| Built on | Permafrost — permanently frozen ground, now thawing as temperatures rise |
The road is a vital route for staff and visitors alike. With the ground beneath it thawing, the park has turned to the resist–accept–direct (RAD) framework to guide its decisions.
The RAD framework
Climate change, combined with land-use change, more visitors, pollution and non-native species, is pushing park ecosystems and infrastructure beyond anything in their historical range. RAD is a simple, flexible tool that helps managers make informed, deliberate, strategic choices:
| Strategy | What it means |
|---|---|
| Resist | Keep existing conditions, or slow the rate of change, based on historical or acceptable current conditions — often through direct intervention |
| Accept | Let the system change without intervening |
| Direct | Actively steer change toward desired outcomes, which may mean redesigning or repurposing a system to work under new conditions |
An uphill battle at Pretty Rocks
The road crosses steep, unstable ground such as the Polychrome Area, where it passes over several active landslides. One of them, the Pretty Rocks Landslide, meets the road near its midpoint and has been carrying that stretch downhill at an accelerating rate.
- Since at least the 1960s it was a slow-moving nuisance that regularly cracked the road surface.
- By 2021 it had become a substantial threat, moving 0.65 inches an hour. Road crews kept adding gravel to hold the slumping road together, but the park saw that this could not keep up with the landslide's acceleration.
- August 2021. The park closed the road there, cutting off more than half of the park's road access and raising the cost and difficulty of running its facilities and operations. Between July 21 and August 25, 2021, the road moved about 21 feet.
- 2022. That section of road collapsed entirely.
The acceleration is a consequence of permafrost thaw driven by climate change: as average annual temperatures rise to 32 °F, ice-rich permafrost soils subside, collapse and thaw into an unstable slurry.
Resisting change: the Pretty Rocks bridge
One option was to avoid the landslide by rerouting the road out of it and into the valley below. In RAD terms, keeping the road in its existing corridor is resisting change; moving it would be directing change. But rerouting needed more money and time than were available, and might have exposed the new stretch in the valley to flooding.
Instead, the park is resisting: keeping the historic road corridor and building a bridge over the landslide to restore access. The bridge is expected to be finished in 2026, with the road officially reopening in 2027, and has an anticipated lifetime of 50 years — a sustainable near-term solution that keeps the park's interior reachable without endless repairs to unstable road.
The Pretty Rocks construction site in winter, November 11, 2024. Credit: National Park Service.
How the decision was made
- The NPS, with an environmental consulting firm, prepared an Environmental Assessment before committing to construction. After analysing the effects on resources, reviewing comments from stakeholders and the public, and consulting federally recognised tribes, Alaska Native corporations, state and local governments and the State Historic Preservation Office, it began planning to restore reliable road access west of Pretty Rocks.
- The Federal Highway Administration, assisted by the NPS, drew up the Polychrome Area Improvements Plan to do so.
- Funding came from the Bipartisan Infrastructure Law, additional Federal Lands Transportation Fund money and 2023 Disaster Relief Supplement funding. The park posts construction updates on its Pretty Rocks Construction blog.
A model for adapting
Warming will continue, quickening permafrost thaw and eventually bringing down the bridge too, so the park treats it as a near-term solution and knows a longer-term approach will be needed. As climate change goes on, decisions at Denali will keep balancing capacity, time and values. RAD lets the park's stewards explore every option and make forward-looking decisions — thinking strategically and communicating clearly amid uncertainty, while limiting the effects on infrastructure and operations, the visitor experience, and natural and cultural resources.
Two cyclists wait while a caribou crosses the Denali Park Road. NPS photo / Kent Miller.
Sources
- Kaylin Thomas, Climate Change Response Program, "Denali National Park and Preserve: Resisting Permafrost Thaw Impacts on the Denali Park Road," National Park Service, with information from Dave Schirokauer (Denali National Park and Preserve) and Alan Ellsworth (Climate Change Response Program). https://www.nps.gov/articles/000/dena-rad.htm
- The sections from "An uphill battle" on, and two of the photographs, were missing from the imported page and are taken from the article as published.
- Rewritten in hubnx's own words.
En estas publicacionesDenali National Park & Preserve
Licencia: CC0 1.0 (dominio público) · Adaptado de www.nps.gov
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