Knowra Glacier retreat Glacier retreat Glacier retreat is the sustained loss of a glacier’s mass and extent, often causing its terminus to move uphill. It occurs when melting and other losses exceed snowfall and ice accumulation.
Glacier mass balance : The difference between a glacier’s mass gains, mainly from snowfall, and its losses, mainly from melting, sublimation, and calving. Retreat begins when losses persistently exceed accumulation.
Sea-level rise : A long-term increase in the average level of the oceans. Meltwater from land glaciers adds water to the oceans.
Hubbard Glacier : A large tidewater glacier in Alaska that has advanced during periods when many nearby glaciers retreated. Its advance shows that regional warming does not force every glacier to retreat continuously.
Glacier advance : The seaward or downhill movement of a glacier’s terminus over time. It is the opposite terminus trend, though it can occur briefly during an overall period of mass loss.
Glacier terminus : The lower end or margin of a glacier. Its position is the visible measure most often used to describe retreat.
Glacial lake outburst flood : A sudden flood caused by the failure of a dam holding back a glacial lake. Retreat can create or enlarge lakes that threaten downstream communities.
Muir Glacier : An Alaskan glacier that underwent dramatic retreat during the twentieth century. Its changing terminus became a well-documented example of rapid landscape transformation.
Glacier surge : A temporary episode of unusually rapid glacier flow, often followed by a quiescent period. A surge can push a terminus forward without indicating a lasting mass gain.
Ablation : The removal of snow and ice from a glacier through melting, sublimation, wind erosion, or calving. Ablation supplies the losses that can drive retreat.
Water resources : Water available for human use, ecosystems, and other needs. Retreat can first increase meltwater flows and later reduce dry-season supply.
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