Stalagmite luminescence and peat humification records of palaeomoisture for the last 2500 years

Abstract

Recent research has suggested that both raised and blanket bogs can provide proxy climate signals from variations in peat humification. In particular, oceanic margin sites have provided sensitive records that demonstrate century scale variations in humification. However, previous research has not compared records of peat humification with other terrestrial palaeoclimate proxies. Here, two records of climate change from an oceanic marginal site in NW Scotland are analysed. One, from a blanket bog, is derived from peat humification and covers the period 2100–100 BP. A second, from two stalagmites in a cave overlain by the bog, is derived from stalagmite luminescence wavelength variations for the samples deposited over 2500–0 BP. Both peat humification and stalagmite luminescence records demonstrate 90–100 year oscillations in bog wetness, that are attributed to variations in rainfall intensity or totals over this time period. It is argued that this is probably generated by a southward shift of the path of northern hemisphere depression tracks, possibly linked to variations in solar output.