Climate change has already brought irreversible changes to the national parks. And more are imminent, without major reductions in pollution from cars, power plants and deforestation. Here’s a sampling.
MELTING GLACIERS
The elevation of Muir Glacier in Alaska’s Glacier Bay National Park and Preserve has dropped in places by 2,100 feet since 1948. This is one of many glaciers in southeast Alaska that have shrunk astoundingly in recent decades, dramatically changing what visitors see and contributing to sea-level rise. Scientists estimate that over the latter half of the 20th century, melting ice masses in Alaska and neighboring Canada have increased global sea level even more than the Greenland ice sheet has. Muir Glacier offers a great example of how the rich data from national parks has contributed to the global understanding of climate change. It’s among 168,000 glaciers used by the Intergovernmental Panel on Climate Change to determine that human-created climate change is melting glaciers globally.
SHIFTING BIOMES
Since 1880, lodgepole and other pine trees have moved uphill into what once were subalpine meadows in Yosemite National Park. The thirsty trees have helped dry up a wetland ecosystem important for small mammals like marmots as well as high-elevation frogs and salamanders. Yosemite now is working on a restoration project to restore the meadows’ hydrological functioning. “You want them to remain wetlands,” says Linda Mazzu, Yosemite’s resource manager. “When trees invade, it’s like a biome shift.” A biome is the community of plants and animals in a particular region, and this was one of 23 biome shifts worldwide documented by the Intergovernmental Panel on Climate Change. Other biome shifts are underway — boreal conifer forests moving into tundra and alpine biomes in the Kenai Mountains-Turnagain Arm Natural Heritage Area and in Noatak National Preserve.
VORACIOUS BEETLES
Climate change is causing extensive bark beetle outbreaks across the West, because winters have been too mild to kill the insects and trees are stressed by drought. Rocky Mountain National Park has been hit especially hard, with 90 percent of the park’s forested areas affected. Hundreds of thousands of lodgepole, ponderosa, Engelmann spruce and other evergreens have died. Park staff remove standing dead trees at campsites and other heavily visited areas so they don’t fall on people or property. They also spray insecticide on thousands of tree trunks in non-wilderness areas. But 95 percent of the park is designated wilderness, and the beetles, which are native, have free rein there. The park has planted a small number of trees, but leaves most areas for natural regeneration.
LOOMING DIE-OFFS OF DESERT PLANTS
The exquisite desert plants of Arizona’s Saguaro National Park are adapted for dry conditions, but climate change may make their Sonoran Desert home too hot even for them. Scientists project major die-offs of saguaro, palo verde, ocotillo and creosote bush. And even if the planet’s people manage to modestly reduce their greenhouse gas emissions, scientists project that 90 percent of Joshua Tree National Park could become too dry for Joshua trees by 2100.
SHRINKING WILDLIFE HABITAT
In Mount Rainier, North Cascades and Olympic national parks, scientists predict that climate change will dramatically shrink habitats for high-elevation mammals. As temperatures warm and snowpack decreases, hoary marmot, wolverine, mountain goat, American pika, American marten, snowshoe hare and Canada lynx will probably lose most of their current turf. Small patches of mountaintop habitat in national parks will become increasingly important for the conservation of these species, because other suitable homes for them are likely to be gone.
SNOW AND SNOWMOBILES
Across the West, snowpacks have plummeted because of human-caused climate change. That trend is likely to continue, disrupting Yellowstone’s $60 million winter tourism industry, among other things, according to a paper published this month in PLOS One by Michael Tercek and Anne Rodman, the park’s acting branch chief for physical science. By the end of this century, they predict that, during 70 percent of the winter season, there won’t be enough snow for snowmobiles and snow coaches to drive into Yellowstone from its West entrance. The agency might eventually have to plow its roads for cars, they say, if it wants to maintain high levels of year-round tourism.
This part of a special report on the state of the national parks.
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