USA TODAY International Edition
Alteration a given for Yellowstone
Climate change seen as a ‘when,’ not an ‘if,’ in park
YELLOWSTONE NATIONAL PARK, Wyo. – Warmer temperatures, longer and more volatile fire seasons, shorter winters, less snowfall and significant changes in the dominant species of plants: The iconic park you see here today will be fundamentally altered by global warming in the coming decades.
“That conclusion is pretty much inescapable,” said John Gross, an ecologist with the National Park Service’s Climate Change response program. “It’s really more a question of the when and how it occurs than if.”
Scientists have already documented dozens of changes in the park in the past 50 years, including 30 fewer days with snow on the ground per year, 80 more days above freezing per year at the northeast entrance and higher average temperatures overall, especially at night.
The ramifications are significant, but what that means for the park in the future is hard to pinpoint.
“We’re kind of in the middle of it, and we’re now thinking of those historic trends as more of an indicator for us about where we’re going into the future,” said Ann Rodman, director of geographic information system operations for the park.
Extreme weather
A hotter, drier climate in Yellowstone means extreme weather events, and the frequency and severity of fires could become more common, Rodman said. Snow melting faster in the spring increases the potential for flooding.
A lower snowpack means less water to last through the summer, causing plants to potentially die out sooner and reducing the vegetation that animals feed on. A longer growing season, where winter starts later and ends earlier, makes drought more likely in the middle of the summer.
“Things are becoming a problem now that weren’t a problem in the past,”
Gross said
Those events are difficult to predict because of the variables that must come into play each year and each season.
Yellowstone and other ecosystems have undergone changes due to natural climate cycles in the past. What makes it different now is the timescale on which these changes are happening. Big temperature shifts used to take 5,000 to 10,000 years. Now, they’re happening in decades, Rodman said.
“One of the things about climate change that I’m beginning to appreciate is the rate and speed at which this is happening, which is kind of the unprecedented part in all of this,” she said.
The implications for the park’s animals and plants are immense, but because the changes are occurring far more rapidly than in the past, scientists don’t have a model to predict what Yellowstone will look like 50 or 100 years from now.
“We don’t have a past we can look back on and say if something happens this fast, this is how things are going to react,” Rodman said. “You really don’t know, if the vegetation changes, how the animals are going to react to it, but they certainly will.”
The park is already changing due to warmer temperatures. Parts of the park have been invaded by plants that take advantage of the newer climate conditions and can out-compete the native vegetation for moisture.
“At the lowest elevations of the park, we’ve seen a huge change in vegetation in the last 10 years,” Rodman said.
Add in the fire threat, and you’ll see the problem: What happens when plant species that have survived in an area for thousands of years can’t come back after a large chunk of land is burned? Plants that didn’t previously grow in that area may spring up because they can survive the hotter, drier climate now in place.
“With climate change, it’s going to be really difficult to figure out in some cases what an invasive species is,” Gross said. “The park will be really changed.”
The highest elevations in Yellowstone, where trees give way to alpine meadows, could be some of the most affected by climate change, said Tom Olliff, head of landscape conservation and climate change for the National Park Service’s Intermountain Region, which covers more than 80 different parks, including Yellowstone, where he’s worked for more than 30 years.
“In some scenarios, we’ve projected that those would disappear and you’d have all forests, and clearly that’s going to hurt things,” including animal species such as the American pipit, marmot and pika, Olliff said.
Invasive plants could be OK
Yellowstone and other ecosystems around the U.S. and the world have evolved to handle wildfires and natural changes that occur slowly over time.
But with climate change, the old vegetation might not grow back after a fire and instead a different species, one more tolerant to warmer and drier conditions, might take its place – and that’s new.
That could mean letting plants move into the park even though they are technically invasive but are native to areas outside its borders. Rodman’s fear i that change in mindset won’t happen quickly enough.
“National parks have been all about preservation and really managing things with a look to the past. And we have to switch over and be more forward looking and managing for change as opposed to preservation,” she said. “I worry about our ability to make that switch in time to be effective.”