U.S. national parks are in danger from climate change, and people need to take action to protect them, said Brendan Cummings, conservation director for the Center for Biological Diversity, a nonprofit organization working to protect endangered species.
From coast to coast, in 63 iconic parks, visitors can see soaring waterfalls, colorful hot springs and giant sequoia trees in landscapes that vary from wetlands to desert.
The landscapes are under stress, and climate change is making it worse, Garrett Dickman, a Yosemite National Park forest ecologist, told VOA.
Scientists are warning that if the warming continues at its current rate, much of the wildlife and vegetation in the parks is in danger of disappearing by the end of the century.
"Climate change is the greatest threat the national parks have ever faced, … [ they] are warming at twice the rate as the rest of the country," the National Parks Conservation Association said on its website.
Across the country, one of the biggest problems is water, sometimes too much, causing flooding, or too little, triggering drought and fires.
Yellowstone National Park in the western U.S. is known for its wildlife, vibrant hot springs and beautiful mountain ranges.
It has also experienced devastation from climate change.
Over four days in June, the park had record rainfall. Along with an already rapidly melting snowpack, the rain caused disastrous flooding and rockslides that eroded riverbanks and tore apart bridges.
"Yellowstone historically did not have a lot of floods," and there was no warning that this level of flooding was coming, said Cam Sholly, the park superintendent.
Cathy Whitlock, a Yellowstone climate change expert, explained, "There was a lot of snowfall late in the season, with excessive rain on top of the snowpack, and instead of getting soaked into the ground, it was flowing into the rivers."
As the park continues to get warmer, she said, "we get more precipitation in the winter and then very dry summers, which leads to more frequent forest wildfires."
The loss of the trees is affecting the ecosystem.
"We don't get the same trees that were burned coming back, and some areas that were once forested are becoming shrublands or grasslands," Whitlock said.
The changing climate is also affecting wildlife.
"Cold water fish are going to colder streams in higher elevations, and grizzly bears are looking for additional food sources," Whitlock said.
Yosemite National Park in California features granite cliffs, tall waterfalls and old-growth trees.
In recent years, an increasing number of tree and shrub species have been dying from extreme heat.
"This summer there's been more days over 100 degrees (37 Celsius) than there used to be in the past," Dickman said. "The trees can't get enough moisture to survive, and so they get weakened and become more vulnerable to insects and disease."
The dead vegetation is adding fuel to the fires.
“We're having these huge fires that burn hotter than ever before and we have areas that have converted to invasive grasses," Dickman said. "Within the lower elevations, we've lost at least 2.4 million trees."
Climate change is also having an impact on the giant sequoia trees in the park, which can live some 3,000 years.
They're very resilient, but they haven't adapted to the fires of today, said Dickman. Although none of the trees in the park have died, he continued, they are showing stress from the drought.
Joshua trees at Joshua Tree National Park in the California desert are also having trouble surviving due to increasing temperatures.
"I see lots of dead Joshua trees that look like they died from drought or heat stress," said Cummings, who lives near the park. The trees are also dying because rodents have stripped their bark for food when there's nothing else to eat because it's been so dry.
The slow-growing trees do not bounce back quickly.
"It takes about 30 years before the trees produce seeds, and very few of them grow to become a Joshua tree, maybe one in a thousand," Cummings explained. Today, it is even more difficult for the seedlings to survive the harsh desert climate.
“We may need a plan to grow the seedlings in higher, cooler elevations,” he said.
The awe-inspiring Grand Canyon in Arizona was carved by the 446-kilometer-long Colorado River.
"There are reduced flows in the river due to the changing weather patterns," said Mark Nebel, the parks geosciences program manager. He said, "This impacts the groundwater, which feeds our springs" that the wildlife relies on, as well as the vegetation, causing massive die-offs of junipers, small trees that are relatively drought tolerant.
The river is also used for agriculture and drinking water for millions of people in the Southwest.
“We're taking too much water out of the river,” he told VOA, "and we need to find ways to use less of it.”
In the southeastern U.S., the Florida Everglades is a vast subtropical wetland ecosystem.
Rising sea levels that have caused coastal erosion and flooding in south Florida have also changed the Everglades.
"We're seeing changes in the water chemistry, specifically salt, and the soil elevation is sinking," said John Kominoski, an Everglades researcher and associate professor at Florida International University.
“Freshwater areas are becoming more salty and saltwater wetlands are getting freshwater,” he said, "and that can affect the trees, mangroves and wildlife."
Kominoski said he is hopeful the Everglades will remain intact in the future, but that water management is key.
"It's a reality that we can't ever go back to how things were before," he said, "so we have to find ways to go forward in a new way."