WASHINGTON — America’s national parks are warming up and drying out faster than other U.S. landscapes, threatening iconic ecosystems from the Everglades in Florida to Joshua Tree in California to Denali in Alaska.
That’s the conclusion of a new climate change study published last month, the first to examine rainfall and temperatures in all 417 national parks sites. The study also forecasts the degree that parks could become hotter and more drought-stricken by century’s end, depending on whether nations undertake efforts to reduce greenhouse gas emissions.
“U.S. national parks protect some of the most irreplaceable ecosystems in the world,” said the study, published in Environmental Research Letters, a peer-reviewed scientific journal.
In the Everglades, rising sea levels and saltwater intrusion threaten habitat and wildlife that depend upon fresh flows of water. Catastrophic wildfires threaten Yosemite and other national parks in California. In Montana, there is online debate about whether Glacier National Park should soon rename itself, or face accusations of false advertising.
The new study is the first to analyze how a warming climate affects the entire 85 million-acre national park system.
“A higher fraction of national parks are in extreme environments,” said Patrick Gonzalez, a forest ecologist at the University of California, Berkeley who authored the study with UC Berkeley colleagues and scientists at the University of Wisconsin, Madison.
National parks tend to be relatively high in elevation, where warming occurs more quickly because of the thinner atmosphere, Gonzalez said. In addition, a large proportion of park land is located in the desert Southwest and Alaska — regions feeling the strongest impacts of climate change.
The study found that between 1885 and the year 2010 areas now national parks warmed by 1.8 degrees Fahrenheit, twice the U.S. rate. It also found annual precipitation in national parks declined 12 percent, compared to a 3 percent drop in the United States overall, during that same period.
At current rates of greenhouse gas emissions, temperatures in the most exposed national parks — particularly in Alaska — could rise by as much as 16 degrees Fahrenheit by 2100, according to the study. Arctic permafrost could further melt, trees will replace tundra and wildfires will be more common and damaging. Many rare species would be unable to migrate to more comfortable climes, bringing some to the brink of extinction.
The study, funded partly by the National Park Service, did not analyze all potential impacts of climate change on parks, such as sea level rise. To conduct the research, scientists collected historical rainfall and temperature data, and then created maps for each of the parks and the United States as a whole. One major challenge was taking climate models — generally used to forecast impacts over broad geographic regions — and downscale them to estimate impacts for each of the 417 parks.
The research team then produced estimates for average annual temperature and rainfall changes under four scenarios developed by the Intergovernmental Panel on Climate Change, ranging from “no action” being taken to reducing emissions to various levels of reduction.