Glaciers and Climate Change

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Researcher taking GPS readings on Blue Glacier

Researcher taking GPS measurements on upper Blue Glacier

Courtesy T.J. Fudge, Univ. of Washington

What can be 900 feet thick, move several feet a day, and carve out any solid rock in its way? The Blue Glacier, a 2.6-mile long glacier that descends from 7,980-foot Mount Olympus, the highest peak in the Olympic Mountains. The last inventory compiled in 1982 tallied 266 glaciers and permanent icefields in the Olympic Mountains, covering 18 square miles (46 km2). Blue Glacier is one of the largest. Varying from 500 to 1000 feet thick, one researcher calculated it would be equivalent to 20 trillion ice cubes!

The glaciers of the Olympic Mountains and the neighboring Cascades helped sculpt the wild and beautiful landscape that attracts millions of visitors to Olympic, North Cascades and Mount Rainier National Parks. They comprise the most glaciated area of the United States outside of Alaska. Their meltwater combines with annual snowpack to feed rivers, forests and lowland communities en route to the sea, and nurture cold-water-loving fish like salmon and bull trout. The yawning crevasses challenge climbers who use ropes, crampons and ice axes to ascend the high peaks. They have had a powerful role in the past but also offer insights into our future.


Continental ice sheet at its maximum extent, approximately 15,000 years ago.

Glaciers of the Past

Over thousands of years glaciers have carved away at Olympic rock, leaving behind smoothed rocks, sharp ridges and lake-filled basins. Gravel embedded in the moving ice grinds away at underlying land as a glacier flows downhill. In the fastest sections, the Blue Glacier is moving about 3 feet a day. At the top, glacial ice eats away at the mountain embracing it, eventually carving a bowl-like cirque. Jewel-like cirque lakes reveal where past glaciers sculpted the range.

Continental Glaciers
Continental glaciers are huge ice sheets that spread from the north during the last ice age. The westernmost ice sheet split when it hit the Olympic Mountains, one lobe flowing out what is now the Strait of Juan de Fuca, the other lobe through what is now Puget Sound. At its thickest the continental ice sheet was more than 3,500 feet (1,100 m) thick. By about 13,000 years ago the ice sheet retreated, leaving behind a landscape of rounded foothills, a rugged mountainous core and an isolated peninsula with saltwater on three sides.

Blue Glacier 1899-2008 pair

Comparison photographs show thinning and retreat of the Blue Glacier on Mount Olympus.

1899: Olympic National Park archives
2008: Jim Patterson, ONP

Glaciers in the Present and Future

The Olympic Mountains are tall enough and far enough north (48° latitude) that much of the moisture they rake from storms born in the Pacific Ocean falls as snow. Each year 50-70 feet (15-22 m) of snow can fall on Mount Olympus, feeding the Blue, White, Hoh, and Humes glaciers and others on its flanks. The Blue Glacier is one of the most studied glaciers in the world. For decades researchers have been observing, photographing, drilling and measuring the glacier to read the stories written on its icy pages.

The Climate Story Told in Ice

Because they grow or shrink in response to snowfall and snowmelt, glaciers are sensitive indicators of changes in regional and global climate. To grow, a glacier must receive more snow in winter than melts or evaporates the following summer. If more melts than accumulates, a glacier will shrink.

As Earth’s climate warms, the rapid loss of glacial ice is being documented around the world. Olympic is no different; in fact temperatures at higher elevations and latitudes are warming the fastest. Using data from weather balloons released near Forks, Washington, glacier researchers at the University of Washington discovered that average January through March temperatures at 4,700 feet (1,450m) increased about 6° F (3.3° C) from 1948 to 1996, a rate five times faster than the global average. As a result, more of the precipitation that used to fall as snow, blanketing the mountains’ flanks and feeding the glaciers, is now falling as rain. Summer temperatures are also rising, but not as fast as the winters are warming.

Lillian Glacier 1905-2010 pair

Comparison photographs illustrate that the Lillian Glacier disappeared completely between 1905 and 2010.

Olympic National Park

Disappearing Glaciers

What does that mean for Olympic’s glaciers? Comparison photographs clearly show glaciers in retreat. The terminus (bottom end) of the Blue Glacier retreated about 325 feet (100 m) in the 20 years from 1995-2006. But length is only a small part of the story; the glaciers are also getting thinner. Surface measurements taken on the Blue Glacier in 2009 compared with 1987 data revealed the glacier lost 178 feet (55 m) of thickness at the terminus. Even the snowier upper glacier lost 32-48 feet (10-15 m).

Since these rivers of ice tell such a critical story, Olympic National Park is conducting a new glacier inventory and measuring the surface area and elevation of larger glaciers to calculate the volume of ice loss and impacts on the park’s glacial-fed rivers. In an area famous for its rainfall, summers are actually quite dry in the Pacific Northwest. Glacier melt is an important part of maintaining summer flows for the aquatic life that depends on these lifelines.

Preliminary results are sobering. In comparing aerial photos from the late 1970s to 2009, researchers detected over 30% loss of glacier surface area in only 30 years. For the two glaciers on Mount Anderson, a rugged peak in the southeastern part of the park, the findings are even more stark. Since 1920, the north-facing Eel Glacier has shrunk by about 50%. Between 1927 and 2009, the south-facing Anderson Glacier, familiar to hikers as one of the few glaciers in the park accessible by trail, receded to less than 10% of its former size! Early results to determine the volume of ice loss show at least a 15% loss in total ice volume in the 22 years from 1987-2009.

These critical and beautiful rivers of ice have shaped and adorned the Olympic Mountains for millennia, but have rapidly shrunk in just decades, stark evidence of the ongoing impact of human-driven climate change. Their ice is an essential resource for creatures from the tiny ice worms found only on glacial ice, or the steelhead and salmon returning up snow and ice-fed rivers, and even for humans living downstream or climbing to the icy heights. The data and photographs are clear. What’s unclear is if humans will to make the changes necessary to help these icons of the Pacific Northwest summits persist.

Anderson Glacier 1936-2004 pair

Comparison photographs show the dramatic retreat of Anderson Glacier.

1936: Asahel Curtis
2004: Matt Hoffman, Portland State Univ.

Links for more Information

See links below for how you can help or to learn more about glacier and climate change studies. - This site integrates federal research on climate and global change. - Site for the National Snow and Ice Data Center. - National Park Service Climate Change Response Program page. See /athome for ideas on things to do at home to reduce your carbon footprint. projects/blue_glac/blue.html - University of Washington site for Blue Glacier research. - Glaciers of the American West site, a project at Portland State University with funding from the National Science Foundation, NASA, the US Geological Survey, and the National Park Service.

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