Some of America’s greatest ecological and cultural treasures—our national parks—may be disproportionately threatened by climate change, according to recent research. The effects could be so dire that some parks, including Glacier National Park and Joshua Tree National Park, could lose their signature sights entirely.
In a study published in September 2018 in Environmental Research Letters, researchers at UC Berkeley and the University of Wisconsin-Madison analyzed temperature and precipitation data for all 417 U.S. national parks from 1895 to 2010, comparing them with data for the country as a whole. They also looked at climate projections through the year 2100 for all the studied areas under different emissions scenarios (continued high emission of greenhouse gases vs. reduced emissions).
The authors found that climate change is affecting national park areas more than the U.S. as a whole, largely because much national parkland is in areas especially sensitive to changes in temperature and rainfall, including the Arctic (northern Alaska), the arid U.S. Southwest, and various areas at high elevations. The atmosphere is thinner at higher altitudes, which results in the earth warming up more quickly. In the Arctic, melting snow reduces the ratio of lighter surfaces to darker surfaces, which are able to absorb more heat.
Higher temperatures, less rainfall
In national parks, the average temperature increased by a little more than 1 degree Celsius from 1895 to 2010, about double what the rest of the U.S. experienced. Meanwhile, annual precipitation declined significantly in 12 percent of national park areas during that period, compared to 3 percent decline in the country overall. The researchers point out that higher temperatures due to climate change have coincided with low precipitation in the Southwest, intensifying droughts in the region.
Even if substantial reductions in carbon emissions consistent with the upper goal of the international Paris Agreement were to be reached, temperatures are still likely to increase by up to 2 degrees Celsius over 58 percent of national park areas by 2100, versus 22 percent of the nation as a whole. Under the highest emissions scenario the researchers looked at—representing no change from current emissions—park temperatures could increase by as much as 9 degrees Celsius by 2100, with devastating consequences to many plant and animal species.
“The human-caused climate changes would tend to alter natural ecosystems by increasing wildfire and invasive plant species and shifting natural habitats,” said Patrick Gonzalez, PhD, an associate adjunct professor at UC Berkeley and the study’s lead author.
As possible examples of the adverse effects of projected rainfall and temperature changes, the paper cites the elimination of the namesake tree in Joshua Tree National Park in southern California; dramatic thinning of the once-dense forests in Yellowstone National Park in Idaho, Montana, and Wyoming; and the extinction of the American pika, a signature small mammal found in northern California’s Lassen Volcanic National Park.
In Alaska, which accounts for almost two-thirds of national park area, the paper notes that some dramatic changes are already underway: For example, from 1948 to 2000, the lower section of the striking Muir Glacier in Alaska’s Glacier Bay National Park lost almost 2,100 feet of width to melting.
Bottom line: The future of our national parks will rest largely on whether the U.S. and other countries can curb carbon emissions to adequate levels by the year 2100.
Also see Climate Change: Where Are We Now?