What is the threat of climate change in national parks?

US national parks are warming up and drying up faster than other US landscapes, threatening iconic Florida Everglades ecosystems in Joshua Tree California and Denali, Alaska.

This is the conclusion of a new climate change study released on Monday, the first to examine precipitation and temperatures in the 417 national parks. The study also looks at the extent to which parks could become warmer and more affected by drought by the century, as countries strive to reduce their greenhouse gas emissions or continue their normal activities. .

"US 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.Emergency emission reductions could "dramatically reduce greenhouse gas emissions." 39 "magnitude" of the expected impacts, adds the study, "offering hope for the future of US national parks".

This is hardly news that climate change is challenging many national parks. In the Everglades, sea level rise and salt water intrusion threaten habitat and wildlife that depend on fresh water flows. Catastrophic fires threaten Yosemite and other national parks in California. In Montana, there is an online debate about whether Glacier National Park should soon be renamed or face false advertising charges.

Yet Monday's study is the first to analyze how global warming affects the entire 85 million-acre national park system, a collection of particularly dynamic landscapes.

"A higher fraction of national parks are in extreme environments," said Patrick Gonzalez, a forest ecologist at the University of California at Berkeley, author of the study with colleagues at UC Berkeley and University scientists from Wisconsin to Madison.

National parks tend to be relatively high in altitude, where warming occurs more quickly due to thinning of the atmosphere. In addition, much of the park's land is located in the Southwest Desert and Alaska – regions that are experiencing the greatest impacts of climate change.

The study found that between 1885 and 2010, areas that are now national parks have warmed 1.8 degrees Fahrenheit, twice the US rate. He also found that annual precipitation in national parks decreased by 12%, compared with 3% in the United States during the same period.

At the current rate of greenhouse gas emissions, temperatures in the most-exposed national parks – particularly in Alaska – could increase by 16 degrees Fahrenheit by 2100, according to the study.

With this level of increase, Arctic permafrost could melt further, trees would replace tundra and forest fires would be more frequent and more damaging. Many rare species would be unable to migrate to more comfortable climates, leading to the brink of extinction.

Individual parks face various threats, according to Monday's study and other research cited:

• In Yellowstone National Park, beetle epidemics due to climate change have killed half of the park's white-bark pines in areas that have increased by 3.4 degrees since the 1950s.
• In Joshua Tree National Park, officials fear that climate change will make the park too hot for Joshua trees in the park. This form of yucca was widespread in the southwest in the lazy giant manure that disappeared 13,000 years ago and adapted to certain altitudes and temperatures. Although it is possible to survive at higher altitudes outside the park, this would require human intervention to disperse the seeds as did the lazy extinct.
• In Glacier National Park, mean temperatures have risen nearly 4 degrees Fahrenheit since 1950, one of the causes of the decline in the park's ice fields. According to Monday's study, temperatures in the park could increase to 9 degrees by 2100. "At this point, it is likely that glaciers in Glacier National Park will disappear," he said. said John Williams, a professor of geography at the University of Wisconsin. contributed to the study.

National parks face the largest increases in temperatures expected in northern Alaska, which, like other Arctic regions, are warming faster than in the rest of the world. Yet, according to the study's authors, efforts to reduce global emissions could prevent some of these impacts. They predict that temperatures in the Noatak National Reserve, which protects the Noatak River in Alaska, over the Arctic Circle, could increase by 15 degrees in the century without climate action, but only by 2.7 degrees if global emissions were reduced.

"It's the message of hope here," Gonzalez said. "Reducing greenhouse gas emissions can save our parks from the most extreme heat."

Monday's study, funded in part by the National Parks Service, did not analyze all of the potential impacts of climate change on the parks, such as sea level rise. But an important calculation time was necessary to provide projections of temperature and precipitation.

To conduct the research, scientists collected historical data on rainfall and temperature, and then created maps for each of the parks and for the entire United States. A major challenge was to take climate models – typically used to predict impacts over large geographic areas – and reduce them to estimate impacts for each of the 417 parks.

The research team then produced estimates of average annual variations in temperature and precipitation in four scenarios developed by the Intergovernmental Panel on Climate Change, ranging from "no action" to reducing emissions.

The authors hope that these maps will help national park managers reduce the risk of fire and better protect parks, the species that live there, and the people who visit them. "All of this data is meant to be practical and help park officials prepare for the future," Gonzalez said.

Stuart Leavenworth: 202-383-6070, @sleavenworth