Mount Shasta, Calif. Global warming is shrinking glaciers all over the world, but the seven tongues of ice creeping down Mount Shasta's flanks are a rare exception: They are the only long-established glaciers in the lower 48 states that are growing.
Reaching more than 14,000 feet above sea level, Mount Shasta is one of the state's tallest peaks, dominating the landscape of high plains and conifer forests in far Northern California. Nearby Indian tribes referred to its glaciers as the footsteps made by the creator when he descended to Earth. Hikers flock to Shasta every summer to scale them.
With glaciers retreating in the Sierra Nevada, the Rocky Mountains and elsewhere in the Cascades, those on Mount Shasta - a volcanic peak at the southern end of the Cascade range - are actually benefiting from changing weather patterns over the Pacific Ocean.
"When people look at glaciers around the world, the majority of them are shrinking," said Slawek Tulaczyk, an assistant professor of earth sciences at the University of California, Santa Cruz, who led a team studying Shasta's glaciers. "These glaciers seem to be benefiting from the warming ocean."
Climate change has cut the number of glaciers at Montana's Glacier National Park from 150 to 26 since 1850, and some scientists project there will be none left within a generation. Lonnie Thompson, a glacier expert at Ohio State University, has projected the storied snows at Africa's Mount Kilimanjaro might disappear by 2015.
But for Shasta, about 270 miles north of San Francisco, scientists say a warming Pacific Ocean means more moist air. On the mountain, precipitation falls as snow, adding to the glaciers enough to overcome a 1.8 degree Fahrenheit rise in temperature in the last century, scientists say.
"It's a bit of an anomaly that they are growing, but it's not to be unexpected," said Ed Josberger, a glaciologist at the U.S. Geological Survey in Tacoma, Wash.
By comparison, the glaciers in the Sierra Nevada, more than 500 miles south of Mount Shasta, are exposed to warmer summer temperatures and are retreating.
The Sierra's 498 ice formations - glaciers and ice fields - have shrunk by about half their size over the past 100 years, said Andrew Fountain, a geology professor at Portland State University. He inventoried glaciers in the contiguous U.S. as part of a federal initiative.
He said Shasta's seven glaciers are the only ones scientists have identified as getting larger, with the exception of a small glacier in the shaded crater of Washington state's Mount St. Helens. It formed after the 1980 eruption blasted away slightly more than half the mountain's ice, and scientists believe it will not grow in area once it stretches outside the shade of the crater.
Glaciologists say most glaciers in Alaska and Canada are retreating, too, but there are too many to study them all.
Climate change is causing roughly 90 percent of the world's mountain glaciers to shrink, said Thompson, the Ohio State glacier expert.
"Best that we keep our eye on the big picture," Thompson said in an e-mail about Shasta's unique position. "The picture points unfortunately (to) massive loss of ice on land, which has huge implications for future sea level rise."
Global forecasts show temperatures warming from 2 degrees to 11.5 degrees Fahrenheit by the end of the century if no major efforts are undertaken to reduce greenhouse gas emissions.