Very high-elevation Mont Blanc glaciated areas not affected by the 20th century climate change

International audienceThis paper analyses the impact of climate change over the last 100 years on high-elevation glaciated areas of the Mont Blanc range, comprising ice fields covering the top of the Mont Blanc (4808 m) and Dôme du Goûter (4300 m) areas. Surface ablation is negligible for these high-elevation areas and the surface mass balance is mainly controlled by snow accumulation. At Dôme du Goûter, ice fluxes have been calculated through two transversal sections by two independent methods in order to assess long-term surface accumulation. A comparison between these results and recent accumulation observations, together with the strong relationship between valley precipitation and snow accumulation, suggests that surface accumulation rates did not change significantly over the entire 20th century. Moreover, the small ice thickness changes, less than 3 m on the average, observed at Mont Blanc and Dôme du Goûter between 1905 and 2005 clearly reveal that these high-elevation glaciated areas have not been significantly affected by climate change over the last 100 years