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Glaciers directly respond to changes in climate through
changes in their mass balance. Since the end of the Little Ice Age in the mid 19th
century, glaciers all over the world have been receding dramatically, with accelerating rates since about 1985
(fig. 1). For the Alps, total ice volumes in 1850, the 1970s and 2000 are estimated to be about 200 km3,
100 km3 and 75 km3, respectively. In the extraordinarily warm year of 2003 additional 5-10 per cent of the remaining ice
volume were lost (table 1).
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Table 1 - Decline in ice volume (109 m3) in European alpine and Swiss glaciers during the last 150 years (from Schädler & Weingartner 2010)
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| |
Europe |
Switzerland |
| 1850 |
200 |
110 |
| 1973 |
100 |
75 |
| 2000 |
75 |
55 |
| 2006 |
67 |
49 |
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1 - Cummulative global mean specific mass balance
Source: World Glacier Monitoring Service, Zurich, Switzerland
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While changes in mass balance also affect the area covered by a glacier this relationship is also dependent on ice thickness, altitude and steepness of the terrain, resulting in large differences between single glaciers. Overall, Alpine glaciers had lost about 50% of their 1850 area by the year 2000 (fig. 2).
Given the present climate scenarios, glacier recession will continue and may lead to deglaciation of many mountain regions by the end of the 21st century. This will affect landscape appearance and have large implications on seasonal freshwater availability. In addition, there is an increased risk of natural hazards. For example, existing glacier lakes have partly increased and new lakes have formed at a rapid rate during the last decades, especially in the tropical Andes and Himalayas, increasing the risk of outburst floods. |
2 - Glacier front variations in the European Alps. Large Alpine glaciers have retreated continuously since the mid 19th century, whereas steep mid-sized glaciers reacted with re-advances in the 1890s, 1920s and between the 1970s and1980s due to somewhat cooler and wetter periods. Small glaciers feature a high annual variability, but with a clear shrinking trend.
Source: http://glaciology.ethz.ch/swiss-glaciers/ |
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