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Maritime glaciers have the greatest sensitivity to climatic changes, because they occur in high-precipitation environments. This high sensitivity, combined with short response times compared to ice sheets, means that maritime glaciers will make a significant contribution to sea-level rise in the coming decades, as the climate warms. Calculations of glacier sensitivity and volume change are common for individual glaciers, but have rarely been undertaken on a regional basis. The relationship between mass balance sensitivity and precipitation is hence derived from glaciers in very different climatic settings. The Southern Alps of New Zealand, with its extremely high precipitation gradients, provides an opportunity to test how mass balance sensitivity varies in a single mountain range which experiences annual precipitation totals in the range 2 to 12 m.
We use a energy balance model on a regional scale to calculate the mass balance sensitivity of the ice mass in the central portion of the Southern Alps. Using a thirty-year dataset of gridded climatology, the changes in mass balance in this area are calculated. The model is tuned against mass balance measurements on a few glaciers, and evaluated against annual snowline measurements on many glaciers over the thirty-year period. The gradients of precipitation and mass balance sensitivity across the Southern Alps are then assessed.
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