LEAVENWORTH – The South Cascade Glacier has been shrinking at such a rapid pace in the last three decades that scientists predict it could melt away completely within a century.
South Cascade is one of only a few ice fields in the world being studied for longterm effects of climate changes, The Wenatchee World reported Sunday.
Scientists have been studying it since 1959 in order to better understand connections between glaciers and global warming, weather and water supply, nature and humans.
The glacier is located at the head of the Cascade River, which drains into the Skagit River and Puget Sound.
Glaciers make up three-quarters of the “permanent” ice in the lower 48 states, and drain into area rivers to provide water for people, fish, industry and recreation.
Nearly all of the state’s 700 glaciers are receding rapidly, and many have disappeared in the past few decades.
Since 1983, students from Nichols College in Dudley, Mass., have been studying glaciers in the North Cascades, nearly all of which drain into the Columbia River system. To the west, near Mount Stuart, the college recorded 15 glaciers in 1969. Now there are 12, four of them dwindling rapidly.
Deprived of sufficient snowfall and melted by warming temperatures, the receding glaciers could one day mean less fresh water for river systems.
“The whole way we manage water may one day have to change,” said Mark Savoca, chief of physical hydrology for the U.S. Geological Survey’s Washington Water Science Center in Tacoma, which monitors the South Cascade Glacier.
“Instead of ice and snow being a natural storage system for the gradual release of water during the middle to late summer, we may have to manage storage using a different system altogether.”
Seasonal snowmelt and ground water runoff contribute in the spring and early summer, but the systems are fed almost entirely by glaciers in the late summer and fall, said Bill Bidlake, a USGS hydrologist studying the South Cascade Glacier.
In Eastern Washington, the glaciers provide critical water during the dry months.
“If these glaciers continue to decrease in size, and if some disappear altogether, it’s going to have a significant impact on the mountain ecosystems as we know them,” Bidlake said.
The South Cascade Glacier is ideal for study because it melts completely into one river basin, so scientists can more easily gauge how much of it melts away each summer, Savoca said.
The glacier has been alternately advancing and shrinking since the last Ice Age, he said. Since its last major advance in the late 1500s, the glacier has retreated more than three-quarters of a mile. About a third of that retreat – about one-third of a mile – has occurred since 1959.
“We are concerned that the rate of decrease in the glacial size and mass seems to have gotten a lot more rapid in the last 25 to 30 years,” Savoca said.
Scientists visit the remote site in the Glacier Peak Wilderness about six times a year, measuring winter snowfall and summer melt, ice thickness and water quantity, and collecting weather readings.
Research suggests the glacier made a significant advance starting around 3,000 B.C. Then in the late 16th century, it began to retreat. A smaller advance ended in the late 19th century, and it has been retreating ever since.
Research shows it has “been much larger than it is now,” Savoca said. “It’s questionable whether it’s ever been smaller.”
Similar retreats are being noted at ice fields around the world.
That “tells us that the climate is too warm and dry to sustain them,” Bidlake said.
Some experts believe that industry and the burning of fossil fuels are contributing to the problem. In the past century, some glaciers and ice shelves have melted completely.
But Savoca said scientists really don’t know how much, if any, of the melting is caused by humans and how much by natural climate fluctuations.
“If there is a human cause, it’s has only been a recent one,” he said. “There are thousands and thousands of years before that where glacial receding was caused by something else.”
Researchers are starting to see a natural consequence of the shrinking South Cascade Glacier: less spring runoff in the Cascade River.
Runoff corresponds directly to the size of a glacier, Savoca said. If a glacier loses half its mass, the river would likely lose half its runoff. Water may need to be collected and stored earlier in the spring and summer, he said.
People will likely adapt to the shrinking of glaciers by changing the way they use water, Savoca said.
“For me, the idea of not being able to put on crampons and climb around on the snow and ice, the prospect that future generations might not have that chance, is very sad,” he said. “For some people it won’t really matter.”
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