Might warming wilt the mountain way of life?
In summer, the hillsides above Crested Butte look like a painting by Claude Monet. Reds, yellows and blues are brilliantly dabbed everywhere on a canvas of green. This is the wildflower capital of Colorado. But on a small plot of land several miles from Crested Butte, at the old mining hamlet of Gothic, is a peek into a less colorful future. There, on a knoll within the grounds of the Rocky Mountain Biological Laboratory, an experiment is being conducted that attempts to predict how global warming will change mountain meadows during the next 50 to 100 years. The experiment is far from complete. But John Harte, a professor from the University of California at Berkeley, says it’s already evident that these meadows and probably many others near mountain towns will probably lose a few hues in coming decades. “One thing we can project from this experiment is that in under 50 to 100 years of warming, we are likely to see our meadows looking differently,” says Harte, who has been supervising the experiment for 14 years. “They will be less flower-laden, less colorful and replaced by plants that you associate more with lower elevations, sagebrush in particular.” In other words, the hills around Crested Butte will become more like those around Gunnison. Ski towns will look more like ranch towns. Upvalley will look more like downvalley. Harte’s experiment near Crested Butte is but one small part of the big picture that is now being assembled about how higher temperatures will affect mountains. Mountains, because they are so sensitive to changes in temperature, offer early indications of what may come to pass around the world.”Sometimes, trying to get the details right on global warming is like trying to paint the Mona Lisa with a 4-inch house brush,” says Dr. Jerry Mahlman, a climate scientist from Boulder who spent more than 30 years in climate modeling at Princeton University. How long before good computer models for regions will be developed? A decade, replies Mahlman, “although the guys down the hall would probably yell at me.” Warmer temperatures are the only odds-on favorite. Far less certain is how much precipitation will change. Some models predict that Sun Valley and Jackson Hole will likely receive more precipitation, while the Colorado Rockies will get less.
But even if Colorado’s rain and snowfall don’t decline as temperatures rise, higher evaporation rates could impact moisture levels. Less snow on the ground means less solar radiation reflected back into the atmosphere. Instead, the sun’s heat would be absorbed by the darker soil and plants.In turn, more heat on the Earth’s surface will further raise temperatures and melt more snow.Evidence in hand Already, anecdotal evidence of weather that could be a symptom of climate change is found almost every season. The temperature dipped below zero only seven times last winter – part of at least a short-term trend of warmer winter nights.Aspen’s environmental affairs office reports that the frost-free season has expanded by 22 days since reliable record-keeping began at the city’s water treatment plant in 1949. Most of the gain in warmth has come in the spring. Elsewhere in the Rockies, marmots are emerging from hibernation an average 23 days earlier than they did in the late 1970s. That coincides with an increase in average May temperatures of nearly 2 degrees Fahrenheit over the same time period, according to a National Academy of Sciences report. Some evidence suggests the higher the elevation, the greater the change. Support for this theory has been found in an atrophying glacier in Wyoming’s Wind River Range. Near the summit of 13,745-foot Frémont Peak, ice cores taken from a glacier show alpine temperatures have risen more than 6 degrees in the past 40 years, a rate of change far greater than what’s found at lower elevations. This disproportionate increase might also explain the disappearance of pikas from several mountain ranges in the Great Basin. Pushed higher by increased temperatures, some ecologists theorize these small mammals have no place to go. Vegetation is also marching higher. In Yellowstone National Park, the whitebark pine is moving up toward the summits of mountains. That changes the scenery, but also affects animals. Grizzly bears feed heavily upon the seeds of the whitebarks.
Changes in vegetation will produce changes in animals in many ways, according to a recent study published in Yale’s Journal of the School of Forestry and Environmental Studies. The study focused on projected changes at eight parks in the United States, including Glacier, Yellowstone, and Yosemite National Parks.Warmer temperatures, says Oswald Schmitz, professor of population and community ecology, will cause an influx of new species into the parks. Schmitz likened the migration caused by this changing climate to the human migration during the Great Depression, when waves of people fled to cities, putting pressure on social services, housing and jobs. “There’s no guarantee the ecosystem won’t simply collapse,” Schmitz said.While plants and animals have adapted to climate change before, the problem is the rate of change being forced by the spewing of greenhouse gases into the atmosphere. “Animal and plant species don’t have enough evolutionary time to adapt,” Schmitz said. These changes are illustrated in a study projecting effects of global warming in Rocky Mountain National Park. Elk populations might actually expand if global warming produces more summer rains. But white-tailed ptarmigan, an above-treeline species that is already struggling, will probably die off, according to the study by scientists from Colorado State University. Warmer summers depress the success of nesting, as well as survival of adults of this species with an affinity for cold climes.Tundra will also shrink. It would take centuries, but the scientists envision the vast expanses eventually being replaced by trees.
As for the merchants in the gateway community of Estes Park, hotter and longer summers will mean more customers – to a point. A too-hot summer becomes a bust for merchants. Scientists say there will be both winners and loser in the early stages of global warming. In the long term, they say, everybody will lose. A big dealBack in the meadows of Crested Butte, John Harte’s heat lamps are strung five feet above the ground, gently warming the plants and soil, day and night, winter and summer.The lamps increase the soil temperature about 4 degrees Fahrenheit – a relatively modest estimate for the global warming expected later this century. A 4-degree change doesn’t sound like much, Harte says, until you consider that the last time ice sheets spilled into New York and Wisconsin, the temperature was only 15 degrees colder. Harte’s study suggests that computer models very likely understate the warming that could be ahead. Because, just as the climate affects the ecosystem, the ecosystem can affect the climate. The sagebrush creeping in absorbs less carbon than the wildflowers, leaving more carbon dioxide in the air. More carbon dioxide in the air traps more heat.This discovery about feedback, Harte said, “is the most exciting thing that is going on scientifically” at his experiment near Crested Butte.Scientifically exciting, yes, but not a happy discovery for people who love summer’s gaudy show of wildflowers.
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