A new paper published in The Cryosphere reconstructs Alpine glacier fluctuations over the past 1600 years and finds glacier lengths of 7 Alpine glaciers were similar during the Medieval Warm Period and the end of the 20th century.
The paper uses a combination of observations shown as the black dots in Fig 1 below and modeled glacier lengths shown as the red lines. Lengths of the seven modeled glaciers are approximately the same or slightly less during the Medieval Warm Period 1000 years ago as compared to the end of the 20th century:
The author also finds a link between the Atlantic Multidecadal Oscillation [AMO] and reconstructed Alpine summer temperatures and glacier lengths. The AMO, in turn, has been linked to solar activity variation.
The Cryosphere, 8, 639-650, 2014