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A U.S. scientist studying the "dramatic change" in ice conditions in British Columbia, Canada's Coast Mountains has discovered freshly exposed and perfectly preserved tree stumps that are about 7,000 years old -- an "astonishing" sign of how fast and far the glaciers of Western Canada are retreating in the age of climate change.

The stumps -- found at the foot of a melting glacier in Garibaldi Provincial Park, about 60 kilometres north of Vancouver -- were "still rooted to their original soil" and in such pristine condition that some had retained their bark, says geologist Johannes Koch, a former Simon Fraser University researcher now with Ohio's College of Wooster.

The stumps are relics of an ancient forest that was growing when humans were still relatively new arrivals in the Americas.

At the time, Garibaldi's advancing Overlord Glacier overran the trees and encased their dead remains in an icy tomb that eventually reached hundreds of metres in depth.

The glacier would have advanced and retreated many times during the ensuing 7,000 years. But never, notes Mr. Koch, had historical warming cycles ever shrunk Overlord enough to release these trunks from their primeval deep-freeze -- until now.

"The appearance of this wood indicates that glaciers are becoming much smaller," Mr. Koch said, adding that the stumps' exposure is a strong indicator that "the climate we observe these days is rather unique -- especially considering the pace of change in the past 150 to 200 years is astonishing."

The age of the stumps was measured using radiocarbon dating of samples from the exposed wood. The findings, presented at a Denver conference of the Geological Society of America, echo similar studies of glacial retreat in the Yukon, Europe, South America and New Zealand, said Mr. Koch.

"It seems like an unprecedented change in a short amount of time," Mr. Koch said. He said his stump discovery adds to the growing number of findings that point to human-made causes of what he called the "dramatic change" in global climate over the past 150 years.

He added in an e-mail that the vanishing glaciers are not only worrisome as heralds of climate change.

"In many areas we depend on meltwater coming off glaciers for irrigation, hydropower, drinking water, transportation," he said. "As these glaciers become smaller and some disappear, summer months -- during which we rely on glacier melt to provide run-off in the rivers -- will become even more problematic in regard to water shortages."