What was done
The authors determined the age of subfossil wood and peat samples from six glacier forelands in the Central Swiss Alps in an attempt to identify and quantify glacier recessions that occurred over the past 10,000 years.

What was learned
Observational records indicate that since the 19th century, the glaciers under study have retreated with two readvance periods around 1920 and 1980.  Radiocarbon dating of the wood and peat samples revealed several periods of glacier recession during the Holocene beyond present glacier locations: from 9910-9550, 9010-7980, 7250-6500, 6170-5950, 5290-3870, 3640-3360, 2740-2620 and 1530-1170 years before present.

What it means
It is important to note that shorter-term glacial fluctuations on the order of decades are not likely to be resolved by the methods used in this study, as it can take decades for trees and peat to become fully established in areas vacated by receding glacial ice.  Thus, the periods of glacial recession noted in this study are more indicative of prolonged and/or large magnitude climatic fluctuations.  That said, it is obvious that the current terminus positions of the Central Swiss Alps glaciers examined in this study fall well within their range of natural Holocene variability.  It therefore follows that current values of the climatic factors influencing these glaciers' mass balances, including temperature and precipitation, are also likely to be well within their range of natural Holocene variability.  Thus, there is nothing unprecedented about the current glacial recession that has occurred in this region since 1991, other than perhaps its lack of duration and magnitude when compared with previous Holocene glacial recessions.