Rapid climate change during the early Holocene in western Europe and Greenland

Based on microfacies analyses of seasonally laminated varved sediments from lake Holzmaar, Germany, we report evidence of decadal- to century-scale climate variability during the early Holocene. The shifts in climate are documented in the thickness variations and changes in the composition of the varves in response to subtle shifts in limnological conditions. The close similarity between the Holzinaar varve record and the GRIP oxygen isotope record during 7.4-9.0 calendar (cal.) ka suggests that the high frequency climatic variations in both regions were controlled by the same mechanism. Our more detailed studies covering the central 409-yr period (similar to 7.846-8.255 cal. ka, encompassing the 8.2 ka event) document for the first time, on a seasonal scale, the changing precipitation regimes in western Europe during these climate shifts. We show (i) that winters were drier and summers shorter and cooler in western Europe during colder periods in Greenland, (ii) in contrast to the present-day climate in the Holzmaar region, summer rains were clearly reduced during the early Holocene, and (iii) the climate not only changed rapidly (< 5 years) but recurring drier events were common during the studied period. In the Holzmaar record, the 8.2 ka event is the most prominent and longest of a series of short-term climatic oscillations.