MOUNT SHASTA ­— Ever since Eric White first climbed to the top of 14,162-foot Mount Shasta 22 years ago, he has kept an eye on the mountain.

MOUNT SHASTA ­— Ever since Eric White first climbed to the top of 14,162-foot Mount Shasta 22 years ago, he has kept an eye on the mountain.

He has watched its blanket of snow rise and fall with each passing season. And he has studied the changes on Shasta's seven glaciers.

"One of the things I've really noticed is that some of the glaciers have moved a bit lower since I first saw them back in the '80s," said the 42-year-old lead climbing ranger and avalanche specialist for the U.S. Forest Service's Mount Shasta Ranger Station.

What he has noticed is what appears to be a rare phenomenon of growing glaciers, an aberration in an era when many of the Earth's leading scientists report global warming is shrinking glaciers worldwide.

Indeed, Mount Shasta's glaciers have continued to expand in the past half-century, according to a research paper published last year by Ian M. Howat, then a doctoral student in the Department of Earth Sciences at the University of California-Santa Cruz. Four other scientists assisted him in the project.

The study focused on the Whitney and Hotlum glaciers, the two largest on the mountain. The mountain's glaciers are on the southernmost tip of the Cascade Mountain range.

Using historic records stretching back 110 years to create numerical models and comparing photographs taken over the years, the scientists concluded the glaciers have grown at least 30 percent.

The glaciers on the mountain are responding more to increased precipitation in the past half-century than to increased temperatures, they theorized. The precipitation now falls in the form of snow in the higher elevations, they noted.

However, given the predicted global warming trend, increased temperatures will ultimately outpace the increased precipitation, decreasing snowfall and resulting in a near total loss of the Shasta glaciers by the end of the 21st century, the research concluded.

That means the high mountain snowpack, a source of water for municipalities throughout the West when it melts during the summer, could someday be history.

"In the short term, the glaciers on Mount Shasta are growing," explained glaciologist Slawek Tulaczyk, associate professor of Earth & Planetary Sciences at UC-Santa Cruz who worked with Howat on the project.

"But in the long term, based on global warming predictions, our data indicate they will be shrinking," he added.

Tulaczyk has studied glaciers around the world, from Shasta to Iceland. He left Thursday morning for the Antarctic to resume studying glaciers in that region through mid-December.

"With Shasta, when you get warmer air off the Pacific, there is higher evaporation with the warmer air holding more moisture," he said. "As the storms travel inland, you get more precipitation. In a perverse effect, you get an increase in snow."

He and other scientists involved in the study believe the Shasta glaciers benefit from the El Nino effect of Pacific Ocean warming, which historically sends more winter precipitation to the Southwest while decreasing winter rain and snow in the Northwest. The mountain is on the northern cusp of that weather pattern.

But that trend will reverse itself as warmer temperatures climb the mountain in the future, Tulaczyk said of global warming. The scientists say it takes about a 20 percent increase in snowfall to counter a 1-degree temperature increase.

If the Shasta glaciers are growing as the research indicates, that is contrary to the shrinking trend of glaciers in the United States during the last century, observed Andrew Fountain, a professor of geology and geography at Portland State University.

"That's unique compared to other glaciers in America," said Fountain, who is currently studying 10 glaciers in the Antarctic and some 8,300 in the United States.

For instance, the glaciers in Oregon have decreased about 30 percent since 1900, he said.

The glaciers in Glacier National Park in Montana have decreased 66 percent, the same amount as glaciers in the Sierra Nevada range during the same time frame, he added.

On Mount Rainier in Washington state, the glaciers have decreased 24 percent since 1900, he said.

"Different glaciers are retreating at different rates," Fountain said. "It all depends on their regional setting and climate. None of them are in lock step. Some are retreating faster than others."

The Mount Shasta glaciers notwithstanding, there is little doubt among scientists that global warming is now occurring, said Phil Mote, a research scientist at the University of Washington and leader of the university's Climate Impacts Group. He was the lead author of the International Panel on Climate Change's report focusing on snow, ice and frozen ground.

"Warming of the climate is unequivocal — there is no doubt whatsoever that the Earth is warming," he said during a conference on climate change Saturday at Southern Oregon University.

The report concludes there is less than a 10 percent chance the warming is purely natural, he said.

White, who has been working as a ranger on Mount Shasta for 10 years, plans to keep watching its glaciers.

"With this job, you spend a lot of time out in the field making observations," he said. "Glaciers are the history of climate and climate change. They are kind of like the canaries in a coal mine."

Reach reporter Paul Fattig at 776-4496 or e-mail him at