Preboreal climate oscillations in Europe: Wiggle-match dating and synthesis of Dutch high-resolution multi-proxy records

In order to compare environmental and inferred climatic change during the Preboreal in The Netherlands, five terrestrial records were analysed. Detailed multi-proxy analyses including microfossils (e.g., pollen, spores, algae, and fungal spores), macroremains (e.g., seeds, fruits, wood, mosses, etc.), and loss on ignition measurements were carried out with high temporal resolution. To link the five Preboreal records, accurate chronologies were produced by AMS 14C wiggle-match dating. The Dutch records show that following the Lateglacial/Holocene climate warming, birch woodlands expanded between 11,530 and 11,500 cal BP during the Friesland Phase of the Preboreal. After the Friesland Phase, two distinct climatic shifts could be inferred: (1) around 11,430–11,350 cal BP the expansion of birch forests was interrupted by a dry continental phase with open grassland vegetation, the Rammelbeek Phase. This phase was coeval with the coldest part of the Preboreal oscillation (PBO) as observed in the δ18O record of the Greenland ice-core records and has been attributed to a large meltwater flux that resulted in a temporary decrease of the thermohaline circulation in the North Atlantic. (2) At the start of the Late Preboreal, between 11,270 and 11,210 cal BP, a sudden shift to a more humid climate occurred and birch forests expanded again. A simultaneous increase in the cosmogenic nuclides 14C and 10Be suggests that these changes in climate and vegetation were forced by a sudden decline in solar activity. Expansion of pine occurred during the later part of the Late Preboreal. At the onset of the Boreal, between 10,770 and 10,700 cal BP, dense woodlands with hazel, oak, elm and pine started to develop in The Netherlands.