Elevation
The summit of Mont Blanc is a thick, perennial ice and snow dome whose thickness varies. No exact and permanent summit elevation can therefore be determined, though accurate measurements have been made on specific dates. For a long time its official elevation was 4,807 m (15,771 ft). Then in 2002, the IGN and expert surveyors, with the aid of GPS technology, measured it to be 4,810.40 m (15,782 ft 2 in).
After the 2003 heatwave in Europe, a team of scientists re-measured the height on 6 and 7 September. The team was made up of the glaciologist Luc Moreau, two surveyors from the GPS Company, three people from the IGN, seven expert surveyors, four mountain guides from Chamonix and Saint-Gervais and four students from various institutes in France. This team noted that the elevation was 4,808.45 m (15,775 ft 9 in), and the peak was 75 centimetres (30 in) away from where it had been in 2002.
After these results were published, more than 500 points were measured, to assess the effects of climate change and the fluctuations in the height of the mountain at different points. From then on the elevation of the mountain has been measured every two years.
The interpretation that the heatwave had caused this fluctuation is disputed because the heatwave is known not to have significantly affected the glaciers above 4,000 m (13,000 ft). The height and position of the summit could have been moved by general glacial forces. At this elevation, the temperatures rarely rise above 0 °C (32 °F). During the summer of 2003, the temperature rose to 2 °C (36 °F), and even 3 °C (37 °F), but this would not have been enough for the ice, which stayed at −15 °C (5 °F), to melt.
The summit was measured again in 2005, and the results were published on 16 December 2005. The height was found to be 4,808.75 m (15,776 ft 9 in), 30 cm (12 in) more than the previous recorded height. The actual rock summit was found to be at 4,792 m (15,722 ft), some 40 m (130 ft) away from the ice-covered summit.
In 2007 the summit was measured at 4,810.9 m (15,784 ft) and in 2009 at 4,810.45 m (15,782 ft).
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