Your children’s Yellowstone will be radically different
Researchers say climate change is dramatically altering park
On a recent fall afternoon in the Lamar Valley, visitors watched a wolf pack lope along a thinly forested riverbank, 10 or so black and gray figures shadowy against the snow. A little farther along the road, a herd of bison swung their great heads as they rooted for food in the sagebrush steppe, their deep rumbles clear in the quiet, cold air.
In the United States, Yellowstone National Park is the only place bison and wolves can be seen in great numbers. Because of the park, these animals survive. Yellowstone was crucial to bringing back bison, reintroducing gray wolves, and restoring trumpeter swans, elk and grizzly bears — all five species driven toward extinction found refuge here.
But the Yellowstone of charismatic megafauna and of stunning geysers that 4 million visitors a year travel to see is changing before the eyes of those who know it best. Researchers who have spent years studying, managing and exploring its roughly 3,400 square miles say that soon the landscape may look dramatically different.
During the next few decades of climate change, the country’s first national park will quite likely see increased fire; less forest; expanding grasslands; more invasive plants; and shallower, warmer waterways — all of which may alter how, and how many, animals move through the landscape. Ecosystems are always in flux, but climate change is transforming habitats so quickly that many plants and animals might not be able to adapt well or at all.
Yellowstone National Park, established in 1872, is one of the UNESCO World Heritage sites threatened by climate change. It is home to some of the country’s oldest weather stations, including one at Mammoth Hot Springs. Data from the park and surrounding area has helped scientists understand and track climate change in the Western United States.
Since 1948, the average annual temperature in the Greater Yellowstone Ecosystem — an area of 34,375 square miles that includes the park, national forests and Grand Teton National Park — has risen about 2 degrees Fahrenheit. Researchers report that winter is, on balance, 10 days shorter and less cold.
“For the Northern Rockies, snowpack has fallen to its lowest level in eight centuries,” said Patrick Gonzalez, a forest and climate change scientist at the University of California, Berkeley.
Because snow is a cornerstone of the park’s ecology, the decline is alarming to some ecologists.
Summers in the park have become warmer, drier and increasingly prone to fire. Even if rainfall increases in the future, it will evaporate more quickly, said Michael Tercek, an ecologist who has worked in Yellowstone for 28 years.
“By the time my daughter is an old woman, the climate will be as different for her as the last ice age seems to us,” Tercek said. Yellowstone’s unusual landscape — of snow and steam, of cold streams and hot springs — is volcanic. Magma gives rise to boiling water and multihued thermophiles, bacteria that thrive at high temperatures. In 1883, the New York Times described the park as an “almost mystical wonderland.”
For many visitors, Yellowstone represents the American wilderness: a place with big, open skies where antelope and bison still roam.
“You run into visitors and they thank you for the place,” said Ann Rodman, a park scientist. “They are seeing elk and antelope for the first time in their lives.”
Rodman has seen vast changes near the town of Gardiner, Montana, at the north entrance to Yellowstone. Some nonnutritious invasive plants such as cheatgrass and desert madwort have replaced nutritious native plants. Those changes worry Rodman and others: Give invasive species an inch, and they take miles.
Cheatgrass has already spread into the Lamar Valley. “This is what we don’t want — to turn into what it looks like in Gardiner,” Rodman said. “The seeds come in on people’s cars and on people’s boots.”
Cheatgrass can thrive in disturbed soils and can ignite “like tissue paper,” she said. It takes hold after fires, preventing native plants from regrowing.
If cheatgrass and its ilk spread, bison and elk could be affected. Cheatgrass, for instance, grows quickly in the spring. “It can suck the moisture out of the ground early,” Rodman said. “Then it is gone, so it doesn’t sustain animals throughout the summer the way native grasses would.”
Forests shade waterways, and those too are experiencing climate-related changes. “We can very definitely see warming trends during the summer and fall,” said Daniel Isaak of the U.S. Forest Service. “Stream and river flows are declining as snowpack declines.” As fish become concentrated in smaller areas, Isaak said, disease can increase in a population because transmission is easier.
In 2016, the Yellowstone River — famous for its fly fishing and its cutthroat trout, which thrive in colder waters — was closed to anglers for 183 miles downstream from the park after an outbreak of kidney disease killed thousands of fish. “The feeling was that this was a canary in the coal mine,” said Dan Vermillion of Sweetwater Travel Co., a fly-fishing operation in Livingston, Montana.
Lower flows and warmer water are one consequence of spring arriving earlier. Quickly melting snow unleashing torrents is another. Flooding has affected the nesting of water birds such as common loons, American white pelicans and double-crested cormorants. “All their nesting is on lakes and ponds, and water levels are fluctuating wildly, as it does with climate change,” said Douglas W. Smith, a park biologist.