Warming blamed for Yosemite glacier retreat

Written by Chris Caskey, The Union Democrat February 06, 2013 10:20 am

The Lyell Glacier (upper right in photo) at Yosemite National Park has stopped moving and could lose its status as a glacier due to a warming climate. File photo / Union Democrat, Copyright 2013.
One of two remaining glaciers in Yosemite National Park has stopped moving, as both continue to shrink with a warming climate, the park announced this week.

A study by scientists with the National Park Service and University of Colorado have found that no movement has occurred at the Lyell Glacier in the past several years, likely within the past decade though possibly as far back as the 1930s. 

The park’s second glacier, the nearby Maclure glacier, is still moving at its historical rate of one inch per day. 

Researchers have connected the glacier’s stagnation to the fact that it has shrunk 60 percent since 1900, which the Park Service said is likely due to a warming climate. 

The development suggests the formation could lose its status as a glacier altogether, as the term refers to a moving river of ice.

“The lack of movement suggests that the term ‘glacier’ no longer accurately describes this feature,” said Yosemite National Park geologist Greg Stock, who co-led the investigation with Robert Anderson of the University of Colorado.

The Lyell has long been considered the second-largest glacier in the Sierra Nevada, and is located deep in the high country of the park above 12,000 feet along with the Maclure. 

Studied by famed naturalist John Muir, the research continues in much the same manner with scientists using stakes placed in the ice fields to track their movement.

Glaciers form through long-term accumulation of snow and ice, and their slow but powerful movements millions of years ago shaped Yosemite Valley with its sheer walls and iconic granite formations. 

The health of a glacier, according to the park service, is determined by a balance between winter snowfall and summer melt and its movement is based on its thickness and steepness.

While the Lyell and Maclure glaciers both have experienced significant shrinkage, the Maclure continues to move likely due to its thickness, park officials said.

The research was funded by the Yosemite Conservancy. It will continue with scientists collecting data on snowpack, temperatures and ice melting rates.

The study is one of about 120 research projects for which the park issues permits per year. Research in the national park focuses on issues like old-growth forest, amphibious species decline and snowpack levels.

The Conness Glacier is also nearby, though it is situated just outside the park on the north slope of Mount Conness.