Glacier Change and Paleoclimate Applications of Cosmogenic-Nuclide Exposure Dating

Surface exposure dating using cosmic-ray-produced nuclides has been applied to determine the age of thousands of landforms produced by alpine glaciers in mountain areas worldwide. These data are potentially an extensive, easily accessible, and globally distributed paleoclimate record. In particular, exposure-dated glacier chronologies are commonly applied to study the dynamics of massive, abrupt climate changes characteristic of the transition between the Last Glacial Maximum and the present interglacial climate. This article reviews developments in exposure dating from the perspective of whether this goal is achievable and concludes that (a) individual exposure-dated landforms cannot, in general, be associated with millennial-scale climate events at high confidence, but (b) dating uncertainties appear to be geographically and temporally unbiased, so the data set as a whole can be used to gain valuable insight into regional and global paleoclimate dynamics. Future applications of exposure-age chronologies of glacier change should move away from reliance on individual dated landforms and toward synoptic analysis of the global data set. Mountain glaciers worldwide leave a geologic record of their past advances and retreats, which reflect past climate changes. Geochemical dating methods based on cosmic-ray-produced nuclides have been used to date these deposits at thousands of sites worldwide. This data set is potentially an extensive, accessible, and globally distributed paleoclimate record.