The Extreme Ice Survey was the first to document the retreat of the massive Columbia Glacier, Alaska, above.
Photograph by Chris Johns, National Geographic

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  • On June 22, 2006, Extreme Ice Survey (EIS) photos were taken of the Columbia Glacier, Alaska, the first in a series documenting changes in the extent of glacial ice, year after year. The EIS is a large-scale study of glaciers using real-time photography. EIS uses time-lapse photography to show seasonal and multi-year changes in glacial ice in Greenland, Iceland, Alaska, and the Rocky Mountains.


    The time-lapse photography shows the natural process of glacial accumulation and ablation. Accumulation is when a glacier grows—usually in the winter, when snowfall and other precipitation build up (accumulate). Ablation is when a glacier retreats or shrinks—usually in the summer, due to icemelt. Long-term trends, including those documented by EIS, show that Earth’s glaciers are retreating more than they are growing.

  • Term Part of Speech Definition Encyclopedic Entry
    ablation Noun

    removal of material from the surface of an object, including melting, evaporation, or erosion.

    accumulation Noun

    a buildup of something.

    glacier Noun

    mass of ice that moves slowly over land.

    Encyclopedic Entry: glacier
    precipitation Noun

    all forms in which water falls to Earth from the atmosphere.

    Encyclopedic Entry: precipitation
    time-lapse photography Noun

    photographing of a slow and continuous process at regular intervals, for projection at a higher speed.