Introduction
Mendenhall Glacier flows approximately 21 kilometers from the Juneau Icefield to Mendenhall Lake, terminating just 19 kilometers from downtown Juneau, the capital of Alaska. This remarkable proximity to a state capital makes it one of the most visited glaciers in the world.
The glacier and its surrounding landscape tell a vivid story of climate change. Mendenhall has been retreating since the mid-1700s, and the rate of retreat has accelerated dramatically in recent decades. A visitor center operated by the U.S. Forest Service within the Tongass National Forest provides educational exhibits and panoramic views of the ice.
Geography & Dimensions
- Length: ~21 km
- Width: ~2.4 km at widest
- Ice Face Height: ~30 m above lake
- Source: Juneau Icefield (3,900 km²)
- Terminus Elevation: ~25 m above sea level
Mendenhall Glacier descends from the vast Juneau Icefield, one of the largest non-polar ice fields in the world at 3,900 km². The glacier winds through a U-shaped valley flanked by steep peaks before reaching Mendenhall Lake, which formed as the glacier retreated from its Little Ice Age maximum.
The lake, which did not exist before about 1930, now stretches roughly 2.5 km between the glacier terminus and the visitor center. Icebergs calved from the glacier float in the turquoise water, and Nugget Falls, a 115-meter waterfall, cascades into the lake near the ice face.
Formation & Movement
- Source Ice Field: Juneau Icefield, 3,900 km²
- Ice Flow Rate: ~60 cm per day
- Accumulation Zone: Above ~1,200 m on the icefield
- Annual Snowfall: Icefield receives 8-30 m of snow per year
The Juneau Icefield receives enormous amounts of snowfall from moisture-laden storms rolling in from the Gulf of Alaska. Snow accumulates at higher elevations, compresses into ice, and flows downhill through multiple outlet glaciers, of which Mendenhall is one of the most prominent.
Mendenhall moves at roughly 60 centimeters per day, moderate by glacial standards. The ice at the terminus is estimated to be several hundred years old. As the glacier flows over bedrock irregularities, it cracks and fractures, creating the crevasses and seracs that give the surface its rugged texture.
Climate Impact & Retreat
- Retreat Since 1958: ~2.8 km
- Retreat Since Little Ice Age: ~5 km total
- Recent Retreat Rate: ~50-60 m per year
- Lake Formation: Mendenhall Lake formed as glacier retreated after ~1930
Mendenhall Glacier has been one of the most closely monitored examples of glacial retreat in North America. Since the U.S. Forest Service began detailed measurements in 1942, the glacier has retreated significantly, with the pace accelerating since the 1990s.
The retreat has been particularly stark in recent years, with the glacier pulling back roughly 50-60 meters per year. Scientists warn that within a few decades, the glacier could retreat entirely behind a rock outcrop, disappearing from view of the visitor center. The retreat also threatens the famous ice caves, which may become less stable and accessible.
Surrounding Ecology
- Forest: Tongass National Forest (largest in the U.S.)
- Vegetation: Sitka spruce, western hemlock, moss, blueberry
- Wildlife: Black bear, mountain goat, bald eagle, salmon
- Salmon Streams: Steep Creek (sockeye and coho salmon)
Mendenhall Glacier sits within the Tongass National Forest, the largest national forest in the United States at 68,000 km². The forest surrounding the glacier is temperate rainforest dominated by Sitka spruce and western hemlock draped in moss.
Steep Creek, which runs near the visitor center, hosts spawning runs of sockeye and coho salmon in late summer and fall. Black bears gather along the creek to feed on the salmon, creating wildlife viewing opportunities within sight of the glacier. Bald eagles perch in the surrounding spruce trees.
Exploration & Tourism
- Visitor Center: USFS Mendenhall Glacier Visitor Center
- Activities: Hiking trails, kayaking, ice cave tours, helicopter tours
- Distance from Juneau: ~19 km from downtown
- Photo Point Trail: 1 km easy trail to glacier viewpoint
The Mendenhall Glacier Visitor Center offers exhibits on glaciology, climate change, and the Tlingit people who have inhabited the region for thousands of years. Multiple hiking trails radiate from the center, including the short Photo Point Trail and the more challenging West Glacier Trail.
Ice cave exploration has become hugely popular in recent years. Visitors can access crystal-blue caverns either by kayaking across the lake and hiking, or via helicopter tours that land on the glacier. However, ice caves are inherently unstable and their availability varies year to year. Kayaking among icebergs on Mendenhall Lake is another popular activity.
Key Facts
- Mendenhall Glacier is just 19 km from downtown Juneau, Alaska's capital.
- The glacier has retreated approximately 2.8 km since 1958.
- Mendenhall Lake did not exist before approximately 1930.
- The Juneau Icefield feeding Mendenhall is one of the largest non-polar ice fields in the world.
- Spawning salmon runs occur in streams within sight of the glacier.
Fun Facts
- The Tlingit people call Mendenhall Glacier "Aak'wtaaksit" meaning "glacier behind the little lake."
- A forest of tree stumps over 1,000 years old has been exposed by the glacier's retreat, showing it overran ancient forest during the Little Ice Age.
- The blue color of Mendenhall's ice caves comes from dense ice absorbing all colors of light except blue.
- Mendenhall is one of the few glaciers in the world where you can see bears fishing for salmon with icebergs floating in the background.
Final Thoughts
Mendenhall Glacier offers an unparalleled window into glacial processes and climate change, all within a short drive of Alaska's capital city. Its retreat is a tangible, visible reminder of warming temperatures, while its ice caves, wildlife, and surrounding rainforest make it one of the most rewarding glacier experiences in North America.