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Warming in the Arctic during the past several decades has caused Greenland’s ice sheet and outlet glaciers to thin and retreat. The lost ice mass makes a growing contribution to global sea-level rise.
Sebastian Mernild of the Laboratory’s Computational Physics and Methods group, William Lipscomb of the Lab’s Fluid Dynamics and Solid Mechanics group, and collaborators have investigated ice-mass loss for the Mittivakkat Gletscher, the only glacier in Greenland with long-term observations of both the surface mass balance (the difference between ice mass gained by snow accumulation and that lost to various processes) and glacier front fluctuations.
The glacier terminus (the end of a glacier at any given time) has retreated 1,600 meters since 1900. Researchers used the mass-balance record to estimate present-day and future equilibrium accumulation-area ratios (ratio of the
accumulation area to the area of the entire glacier) for the Mittivakkat Gletscher. Their calculations indicate that the glacier could lose at least 70 percent of its area and 80 percent of its volume over the next 60 to 70 years, even in the absence of further climate changes.
Temperature records suggest that recent Mittivakkat Gletscher mass losses are indicative of glacier changes in the broader region. Mean temperatures in East Greenland have experienced early twentieth century warming from 1900 until the 1930s and late twentieth-century warming from 1970 to the present, interrupted by several decades of mid-century cooling. Higher temperatures have generally been associated with lower precipitation, and vice versa.
To the extent that the recent warming is anthropogenic (resulting from human activity) in origin, the scientists conclude that the temperatures in the Mittivakkat region will likely continue to increase, leading to larger glacier area and volume losses than are projected based on the current average accumulation-area ratio.