Abstract

The transition from the late glacial interval to the early Holocene was characterized by abrupt warming in the northern hemisphere middle and high latitudes broadly associated with a peak in orbitally-forced summer insolation. However, palaeotemperature reconstructions from marine and terrestrial archives as well as modeling investigations indicate that there were marked geographical variations in the timing of peak warmth associated with the so-called Holocene Thermal Maximum (HTM). Remnant Laurentide and Fennoscandian ice sheets, which persisted into the mid Holocene, delayed the HTM until around 8 – 7.5 ka BP in some regions as a result of albedo-sea ice feedbacks, changes in atmospheric circulation, and the slowing of North Atlantic convection by meltwater. However, despite previous attempts to characterize the nature of early to mid Holocene climate, palaeoclimate data and modeling experiments do not always agree and the relative importance of changes in temperature versus precipitation and the extent of shifts in atmospheric circulation, remain unclear. Oxygen-isotope values of precipitation are valuable tracers of past climate. We compiled published and unpublished oxygen-isotope records from lacustrine and speleothem carbonates from across western and central Europe as a proxy for the isotope composition of past precipitation, in order to investigate early to mid Holocene climate. We compare the geological data with results of experiments with the isotope-enabled GCM HadCM3. Temporal and geographical patterns show poor agreement with previous palaeotemperature reconstructions, but are consistent with a change in atmospheric conditions in the early to mid Holocene, associated with a weakening of the westerly circulation.