It’s “official” – Mont Blanc, the highest point in the Alps and in western Europe, is 4,810m tall. Well, the Chamonix newspaper Le Dauphiné says so, and so does Wikipedia, if that makes it official. This is more than two metres higher than the 4,807m that was generally agreed a few years ago.
Le Dauphiné’s report came after a group of French scientists repeated in September an exercise that they do every second year: they climbed the mountain with sophisticated GPS equipment to measure its height. Using two GPS receivers at the summit linked to two more in the valley communicating with the Teria satellite network, their precise measurement was 4,810.44m.
This agrees very closely with the 4,810.45m they measured in 2009, and the 4,810.90m in 2007.
But these are very precise figures. Is it really possibly to measure the height of a mountain that accurately?
Great Britain’s Ordnance Survey blog explains how mountains are generally measured, and say this gives accuracy to a few centimetres.
And what about the fact that Mont Blanc is covered in snow? If there is an extra metre of snow on top, is the mountain effectively a metre higher?
There is no easy answer to this, and lots of debate surrounding it. The Nepalese are currently remeasuring Everest, whose height is now widely recorded as 8850m instead of the previously generally accepted 8848m, although the Himalaya are still growing at a reported rate of around 6cm a year, so not all of this will be down to differences in the measurement techniques.
When it comes down to it, one of the Mont Blanc-measuring scientists, Philippe Borel, said that the main object of the two-yearly exercise for them was really as much about testing the accuracy of their measuring equipment and the reliability of GPS, as actually arguing about a few centimetres here and there. And all of the volunteers agree, it’s a lovely walk up, so why not?
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