Surveyors in Haute-Savoie, the French region that includes the mountain, report that Mont Blanc's measured summit height is now 4,807.47 metres — down 1.29 metres from last year's measurement, according to the Guardian.
It's worth being precise about what that number is. Mont Blanc's rock does not lose a metre of height in a year. What moves, year to year, is the snow and ice cap sitting on top of the bedrock summit — and it is that cap, not the mountain itself, that surveyors are measuring when they report a new height. A bad snow year, a warm summer, a shift in how the ice compacts: all of these can move the number up or down before the next survey. This isn't a new practice. Surveyors have remeasured the summit periodically for decades, precisely because the cap is known to vary.