Retreating glaciers - changes in mass balance 1950-2010 for six mountain glaciers around the Arctic

Changes in the size of hundreds of Arctic mountain glaciers and ice caps have been measured. Nearly all have retreated over the past 100 years and the rate of loss has increased during the last decade across most regions. The overall mass of ice held in mountain glaciers has fallen since recording began about 60 years ago. Over half of the ice loss has taken place in southern Alaska and the Canadian Arctic and the rate of mass loss in Icelandic glaciers has strongly increased. In the Canadian Arctic, the average net loss of ice has increased three times since 2005. When considered together, the total loss of ice from mountain glaciers and ice caps in the Arctic probably exceeded 150 Gt/y since 2000. This is not far off the estimated amount being lost from the Greenland Ice Sheet each year (~200 Gt/y), although the ice sheet is almost twelve times larger. The mountain glaciers shown in the graph are those with the longest continuous record of ice mass for each Arctic region. These numbers are calculated using the mass budget approach. All six glaciers show a net loss of ice over time, and more rapid thinning after about 1990. The recorded periods of ice loss match increases in the length of the summer melt period and higher air temperatures.