Glaciologists have shown that previous studies have largely overestimated mass loss from Alaskan glaciers over the past 40 years. Recent data from the SPOT 5 and ASTER satellites have enabled researchers to extensively map mass loss in these glaciers, which contributed 0.12 mm/year to sea-level rise between 1962 and 2006, rather than 0.17 mm/year as previously estimated. However, the spectacular acceleration in mass loss since the mid-1990s, corresponding to a contribution of 0.25 to 0.30 mm/year to sea-level rise, is not in question and proves to be a worrying indication of future sea-level rise....