Abrupt termination of the Little Ice Age in the Alps in the mid-19^th century: lessons from a multi-proxy tree-ring reconstruction of glacier mass balance

Abstract. Glacier mass-balance reconstructions provide a means of placing relatively short observational records into a longer-term context. Here, we use multiple proxies from Pinus cembra trees from God da Tamangur combining tree-ring anatomy and stable isotope chronologies to reconstruct seasonal glacier mass balance (i.e. winter, summer and annual mass balance) for the nearby Silvrettagletscher over the last two centuries. The combination of tree-ring width, radial cell wall thickness and δ¹³C isotope records provide a highly significant reconstruction for summer mass balance, whereas, for winter mass balance, the correlation was less significant but still robust when radial cell lumen was combined with δ¹⁸O and δ¹³C records. Combination of the reconstructed winter and summer mass balances allows quantification of the annual mass balance of Silvrettagletscher, for which in-situ measurements date back to 1919. Our reconstruction indicates a substantial increase in glacier mass during the first half of the 19^th century and an abrupt termination of this phase after the end of the Little Ice Age. Since the 1860s, negative glacier mass balances have been dominant and mass losses accelerate as anthropogenic warming picks up in the Alps. This abrupt termination of the Little Ice Age cannot be found if the mass balance reconstruction is obtained from the gridded temperature and precipitation fields (1 × 1 km) available for Switzerland since 1763.