In the opinion of M. Auguste Bouchayer, scientist and engineer, there were no glaciers in Europe in the Middle Ages. In a recent communication to the Dauphine Scientific Society, he submits the conclusion that since the Middle Ages there has been a considerable fall in the maximum summer temperature. Consequently, winter snows and ice accumulations which were formerly melted in summer are no longer dissipated.
Mont Blanc, he points out, is under 16,000 feet in height, and, as in the thirteenth century the maximum summer temperature was capable of melting snow and ice at a much greater height than that, there could in those times be no eternal snow on its summit. Glaciers, he adds, are dependent for their formation and existence on eternal snows; therefore, there can have been no glaciers on Mont Blanc in the Middle Ages.
Source: Kalgoorlie Miner