YOSEMITE NATIONAL PARK, Calif.—Wake up on an autumn morning at the Yosemite Lodge and you see a glorious sight: tumbling, foaming water cascading down the raw granite cliffs of Yosemite Falls.

It is a stunning experience. But it may not be forever. The issue is climate change. Most scientists now agree that the earth is warming more than previously and some scientists, along with park officials, say waterfalls, foliage, animals and other striking features here and at other national parks are likely to suffer.

Less snow and ice are anticipated, the experts say. At the same time, rainfall is likely to be heavier at times and flooding may result. Decreased snow and ice are expected to diminish the spectacular flows of Yosemite Falls and other waterfalls in the park. “Our ecosystem is in a delicate balance,” said National Park Ranger Yenyen Chan in an interview.

Yosemite is among two dozen national parks regarded as most threatened by climate change, according to studies by the Natural Resources Defense Council and the Rocky Mountain Climate Organizations, two private environmental groups. The federal government says it is setting aside additional funds to help the parks cope. As temperatures rise over many decades, the environmental groups say, the parks may lose plants and wildlife and their landscapes may begin to show signs of strain.

Some impact is already being noted. Snowmelt is beginning up to 20 days earlier and so is the blossoming of many plants that park animals rely upon, experts say. A speeded-up life cycle for plants means that some food may wither before hibernating animals awake and begin foraging. Bears and other creatures could end up going without some foods. Not good. More over, early blooming plants can be wiped out by late spring cold snaps, scientists say. 

The park’s two glaciers were formed about 700 years ago. The glaciers, on Mount Maclure and Mount Lyell, have been shrinking. It has been a long, slow process. Scientists at the United States Geological Survey in Reston, Va., and at the University of California in San Diego say that over nearly 70 years the Lyell Glacier has lost 35 percent of its west portion and 70 percent from its east side.

Bridal Veil Falls in the spring. Photo by Kenny Karst / DNCParks and Resorts at Yosemite, Inc.

“It is melting at a rate that makes it very easy to see it shrink from year to year,” said Pete Devine, a naturalist at Yosemite, in an email to me.

Jim Roche, a hydrologist at Yosemite, says in a park video that with less snow, Yosemite will have less water. The total amount of usable water will decline, he said, even with an expected increase in rainfall.

Ranger Chan, who was born in California to parents who had moved from Hong Kong, said she has seen supporting evidence: “Rainfall doesn’t stay long on the landscape.” The decrease in water in Yosemite may intensify shortages already being experienced in California, the California Climate Change Center says in its study.

Scientists say climate change is taking place over many decades. The impact can be striking. In one example here, some experts say that in 90 years, the snowline in Yosemite may be at 9,000 feet, 3,000 feet higher than now.

Ranger Chan said that at least one animal in Yosemite, the tiny American pika, was already feeling the pressure of climate change. The pika is a fury creature that is related to the rabbit, but looks a bit like a thick-coated mouse. Pikas often weight in at four to six ounces.

Talking with me one morning at Yosemite, Ranger Chan pulled out a toy, stuffed pika from her backpack and put it on the conference table before us. “The pika is the cutest animal,” she said.

But some scientists say the pika is in danger of becoming extinct.  The pika overheats when the air around it gets warmer than 78 degrees Fahrenheit. Sometimes that relatively mild temperature is enough to kill the animal. Even so, the Federal government recently declined appeals from environmentalists to provide pikas special protection as an endangered species.

Ranger Chan said pikas in Yosemite have begun making adaptive changes. “Warming temperatures,” she said, “are forcing pikas to climb higher” up the mountains in search of comfortable, cool places. #