Activity 2.2 – Cyrosphere: Eliot Glacier, Mount Hood, Oregon

Above: Eliot Glacier 1901 (Oregon Hikers.Org, 2013)

Above: Eliot Glacier 2012 (Oregon Hikers.Org, 2013)

Above: Eliot Glacier 2023 (Google Earth, 2023)

  Problem: 

    In my photo set, the Eliot Glacier on Mount Hood looks very different in 1901, 2012, and 2023. In the 1901 image, the ice fills more of the valley and its front edge sits much farther downslope. By 2012, the front has pulled back and more bare rock and valley floor are exposed. The 2023 Google Earth view shows even more retreat and visible thinning. So, the problem is pretty clear, and that is the glacier is retreating over time.

Explanation:

    The explanation comes from how glaciers gain and lose ice. Each year the glacier adds ice through accumulation (snowfall that gets compacted) and loses ice through ablation (mainly melting and or evaporation, sublimation, and calving). In warmer years, the part of the glacier where loss happens, the ablation zone, gets larger. At the same time, the high-elevation accumulation zone doesn’t grow as much, so less new ice is added. When this pattern repeats for many years, the glacier shrinks overall (National Snow and Ice Data Center).

Surface brightness also plays a factor. Clean snow and fresh ice have high albedo, which means they reflect a lot of sunlight. As the glacier shrinks, darker rock and old ice cover more area and absorb more heat. That speeds up the melting process for the glacier (UCAR Center for Science Education).

This change affects more than one valley. Meltwater from Eliot Glacier on Mt. Hood feeds local streams that are part of the hydrologic cycle and the surrounding watershed. As the glacier retreats, the timing and amount of runoff can shift, which matters for late-summer water supply, ecosystems, and people downstream. Exposed loose sediment can also be carried into creeks during storms, which can increase erosion and flood risks (Hood River Watershed Group).

Overall, the problem is a century of visible glacial retreat at Eliot Glacier on Mt. Hood in Oregon. The explanation is repeated years of more loss than gain in larger ablation zones, smaller accumulation zones, and surface changes that lower albedo. The three images in 1901, 2012, and 2023 make that process easy to determine.

References

Hood River Watershed Group. Obtained 2025. https://hoodriverwatershed.org/our-watershed/

NSIDC National Snow and Ice Data Center. Obtained 2025. https://nsidc.org/learn/parts-cryosphere/glaciers/science-glaciers

UCAR Center for Science Education. Obtained 2025. https://scied.ucar.edu/learning-zone/how-climate-works/albedo-and-climate