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Iceberg production at Ilulissat (Isfjord), where the Jakobshavns ice stream meets the ocean. The 150-km-long ice stream drains a large part of southern Greenland. Between 1996 and 2005, the front receded ten km (six miles) — added onto 25 km of recession since the first recorded observations in the 1850s. Meanwhile the glacier's speed doubled from six to twelve km per year (more than four feet per hour)! It now discharges some 23 cubic km of ice each year. Recent observations and calculations suggest that such discharges could accelerate still more, bringing grave sea-level rise and climate changes.

Photo ©2005 Spencer Weart.  Numbers from Rignot and Kanagratnam, Science 311 (2006): 986.