Mont Blanc may still be Europe's highest mountain, but it is not quite as high as it was last year. Glaciologists say the dimensions of the mountain, drilled into French schoolchildren, have shrunk: 50cm have gone over the year, making it 4,807.5m (15,772ft) high. More frustrating still, particularly for expeditions, there is uncertainty about where the precise summit now lies, and a serious risk that the recognised peak may be soon be overshadowed by a second, rockier tip 500m to the west. If you judge according to the rock formation, this western tip is the tallest point at 4,792m, with...