Spasm Geyser is one of hundreds at Yellowstone -- including Old Faithful… (Anne Cusack / Los Angeles…)
Reporting from Yellowstone National Park — Roy Renkin is a biologist by training but a detective by inclination, and something about the willows was nagging him.
The shrubs flanking a creek in Yellowstone's Blacktail drainage had never grown so tall and lush. But why?
Many of the park's scientists theorized it was related to the successful reintroduction of wolves, which might have pushed elk out of the area, putting an end to the constant nibbling that stunted willows' growth.
But this summer, Renkin and a colleague arrived at their own theory: climate change.
Warmer temperatures have extended the park's growing season for plants by up to 30%. Renkin found that given the additional growing time, willows produced powerful defensive compounds that made them unpalatable to wildlife, enabling some to grow more than twice as high.
The tentative findings are a small piece of a much larger climate puzzle whose effects are making themselves known at national parks across the country. In some cases, the changes are imperiling the very features that define some of the nation's most-beloved parks.
The ice fields at Glacier National Park in Montana are quickly fading and may be gone by the end of the decade. In California, the namesake plants at Joshua Tree National Park are disappearing, as are the big trees at Redwood. Increasing hurricane frequency and intensity is destroying the Everglades in Florida.
But, because of a number of unique factors, all eyes are on Yellowstone to lead the way in understanding climate change.
Yellowstone's 2.2-million carefully managed acres are among the few places left in North America to retain a virtually intact ecosystem, in a landscape where the hand of man remains light. The park's strict federal protections have maintained a refugium -- a kind of Noah's Ark of plants and animals whose lives are largely unmolested by localized industrial pollution.
"We are fortunate here to have a natural laboratory that is mostly in its original state," said Kerry Murphy, a Yellowstone wildlife biologist. "It's one of the few places in the United States where natural processes are allowed to operate."
That approach has support in Washington from newly installed park service Director Jon Jarvis. "Climate change is going to be the most significant challenge to the fundamental premise and foundational management of our national parks that we have ever faced," he said.
As more and more climate research originates in the park, subtle changes are coming into focus. Yellowstone officials are quick to say that not all of the unexplained transformations here have a direct link with climate change. Scores of effects have yet to be extensively studied, they say. But park managers point to a host of worrisome changes.
With food sources and hospitable weather lingering well into fall, Yellowstone's grizzly bears are retiring to their dens later than ever before. In September, a federal judge ordered the region’s grizzlies back on the endangered species list, in part because of climate change.
Aided by warmer weather and the easy pickings of drought-stricken trees, beetles are ravaging the park's pines; a 50% mortality rate among mature trees is destroying grizzlies' most important food source.
The population crash of pikas, small rabbit-like mammals that have historically lived in the park's rocky alpine slopes, has led to their being considered for inclusion on the endangered species list, the first animal in the lower 48 states whose extinction threat is pegged to climate change.
The number of heat-loving invasive plants and weeds has doubled in the last two decades, out-competing native flora that are crucial to overall ecosystem health.
Yellowstone's complex water network also shows signs it has been thrown out of kilter, initiating a host of concerns about rippling effects as the course of the park's lifeblood is altered. Many of the park's dwindling creeks and rivers are no longer draining into Yellowstone Lake, cutting off native fish from their spawning grounds.
Yellowstone's kettle ponds, formed by retreating glaciers, have been shrinking at an alarming rate. This has reduced the population of trumpeter swans, which rely on the bodies of water not just for nesting but also as a refuge from predators.
The park's iconic Old Faithful is also at risk. Park officials worry that receding groundwater levels -- which regulate Old Faithful and hundreds of Yellowstone's other geysers -- could soon diminish their dramatic displays.
Not long ago it was impolitic for scientists in the National Park Service to consider climate change in their analysis of park problems.
"We were advised not to use 'climate' and 'change' in the same sentence," said Tom Olliff, chief of the Yellowstone Center for Resources. But the Obama administration has made climate-change science a priority, Olliff said, so now the issue is at the forefront of staff discussions about resource protection.