Climate changes with phases of glacier advance and retreat alternated at irregular intervals during the post-glacial period (over the last 11,700 years). Phases of glacier recession such as the present one are nothing unusual in this respect. However, the continued and now accelerated shrinkage of the Alpine glaciers since the last glacial high around 1850 / 1860 is cause for concern. The rise in temperature observed since the middle of the 20th century can no longer be explained without the increase in greenhouse gases (especially CO2 and methane) caused by humans.
What consequences does global warming have for Alpine glaciers and the glaciers in the UNESCO-World Heritage property in particular? From 1850 to 2000, Alpine glaciers lost around 50 per cent of their area, Swiss glaciers 40 per cent. In the same period, the Alpine glaciers lost almost two thirds of their ice volume. In an extreme summer like 2003, 3.5 percent of the Swiss ice mass is lost. In the UNESCO World Heritage property Swiss Alps Jungfrau-Aletsch, about 125 glaciers are smaller than one square kilometre. It is highly probable that the majority of these will have disappeared by 2050. The largest glaciers, on the other hand, are unlikely to disappear from the map in the next few decades. By the end of the 21st century, a temperature increase of 1.1 to 6.4°C is expected, with the average and realistic value being around 3°C. If this average value is correct, then the glaciers will have to be replaced. If this average value is correct, 80 per cent of the glaciated area of the Alps will disappear in relation to today. With a temperature increase of 5° C, the Alps would be ice-free.