Thawing permafrost prompts Denali National Park to reimagine its future
A single, mostly gravel road connects 600,000 visitors a year with the 6 million acres of Alaska’s Denali National Park and Preserve. Most visitors ride park buses to marvel at grizzly and black bears, wolves, caribou, moose, and Dall sheep—the “Big Five” wildlife species—and hope for a peek at North America’s tallest mountain—20,310-foot Denali—which is often shrouded by clouds.
But in recent years, the 92-mile-long Denali Park Road that provides park access has experienced slumps and slides—which require considerable maintenance and occasionally block the road—and scientists believe climate change is likely to blame. Road maintenance challenges are just one of the many effects that warming temperatures are having on Alaska’s national parks.
Like much of Alaska, many parts of Denali National Park are underlain with permafrost, meaning ground that remains at or below freezing for two or more years in a row. As climate change warms the planet, much of the shallow permafrost is thawing. In the 1950s, 75 percent of Denali had near-surface permafrost, which is located just below the active layer that freezes and thaws seasonally. The figure dropped to around 50 percent in the 2000s and is projected to drop to 6 percent by the 2050s. In areas where the near-surface permafrost is thawing, deeper permafrost may still exist, since permafrost can be hundreds of feet thick, and even over 2,000 feet thick in some northern locations in Alaska.
Recently, three National Park Service researchers, including David Swanson, an ecologist, and Pam Sousanes and Ken Hill, both physical scientists, published a study in the journal Arctic, Antarctic, and Alpine Research analyzing air and ground temperatures in Alaska’s eight northernmost national parks. They found the mean annual air temperature increased by at least 1.8 degrees Fahrenheit (1 degree Celsius) from 2014 to 2019 in the study area when compared with the previous 30-year period, with a near 3.6°F (2°C) increase in Denali and most Arctic parks. The increase rose to around 5.4°F (3°C) in certain western coastal park areas. Mean annual ground temperatures were also on the rise.
https://www.nationalgeographic.com/environment/article/thawing-permafrost-forces-denali-national-park-to-reimagine-its-future
