for National Geographic News
For nearly three decades scientists have carefully watched a Rocky Mountain meadow spring to life.
The meadow is nestled at about 9,500 feet (2,900 meters) above sea level between towering, snowcapped peaks a few miles outside the resort town of Crested Butte, Colorado. The field has been home to the Rocky Mountain Biological Laboratory (RMBL, pronounced "rumble") for 75 years.
Until about 2000, the high-altitude meadow seemed to be resisting the pull of global warming, even though spring seemed to be blooming earlier at lower reaches. Due to heavier-than-usual snowfalls, the meadow was remaining blanketed in white even after the ever warmer spring temperatures arrived.
Since 2000, however, the meadow seems to be catching up with the lower altitudes. It is bursting back to life earlier too now, due to an ongoing drought that has reduced snowfall in the area. It could be the start of a new long-term pattern that sees the meadow more in sync, seasonally speaking, with down-mountain areas. That pattern may be more than just a symptom of global warming. It could even help accelerate climate change, some scientists say.
Regardless of which trends hold true for the future, RMBL researchers agree that their meadow isn't what it used to be.
Out of Synch
David Inouye is a biologist at the University of Maryland in College Park. Based on his observations in the meadow between 1975 and 1999, he published a scientific paper in the Proceedings of the National Academy of Sciences four years ago. His study showed global climate change had forced out of sync low- and high-altitude growing seasons in the study area.
"On average we were getting more and more snow at altitude during that period, and spring was arriving earlier and earlier at lower altitude," Inouye said.
At high altitudes, snow pack governs growing seasons: Nothing sprouts until the snow melts. During the study period before 2000, migratory birds arrived at RMBL hoping to forage on insects and worms. Instead, they found a thick blanket of snowwarming temperatures couldn't keep up with increasing snowfall.
Warmer temperatures also lured marmots out of their winter hibernation. The rodents emerged, only to find their food sources still blanketed with snow.
Winter snowfall in the Rocky Mountains has dropped since 1998. The cause has been a shift in a sea-surface temperature phenomenon known as the North Pacific Oscillation. Similar to El Niño and La Niña, the oscillation affects precipitation patterns in wide areas of the continental U.S.
Inouye believes that climate data he collected from the Rocky Mountain meadow between 1975 and 1999 synced up with the wetter phase of the North Pacific Oscillation. The higher snowfalls fit with scientific models that show global warming will cause increased mountain precipitation due to more moisture-laden storms rolling off the Pacific Ocean.