Solving the paradox of the end of the Little Ice Age in the Alps

The causes and timing of the Little Ice Age (fifteenth to nineteenth centuries) are still unclear (Crowley, 2000; Bond et al., 2001; Shindell et al., 2001). During the last part of this event (1760–1830), the advance of glaciers in the Alps conflicts with the summer temperature signal (Intergovernmental Panel on Climate Change, 2001). This paper attempts to solve this paradox. From glacier fluctuations and monthly temperature data, we show that mean winter precipitation was higher by at least 25% during this final phase compared to the twentieth century average and that glacier recession after 1830 clearly resulted from a winter precipitation decrease and not a temperature increase. Conversely, since the beginning of the twentieth century, glacier changes have been driven mainly by temperature change.