Millennial-scale variability during the last glacial in vegetation records from Europe

This paper evaluates the evidence for millennial-scale variability in pollen records of the last glacial (Marine Isotope Stages 4, 3, and 2; 73.5–14.7 calendar ka BP) from the European continent, taking into account information derived from long, continuous terrestrial records, the fragmentary northern European terrestrial record, and marine pollen records of the European continental margins. Pollen records from these numerous European sites provide evidence for multiple intervals of relatively warm and humid conditions during the last glacial, which promoted the establishment of grassland and shrub tundra in northwestern Europe, shrub- and forest-tundra in northeastern Europe, open boreal forest in central western Europe and the Alpine region, and open temperate forest in southern Europe. The northern limit for temperate forest development during these intervals was at ∼45°N, with a subsequent northward transition to tundra across a latitudinal band of ∼15° in western and central Europe, and a greater northward extension of boreal forest in eastern Europe, with boreal forest elements detected close to their present-day limits at ∼70°N. A much smaller number of sites with sufficiently high temporal resolution provide evidence that warming intervals correspond to millennial-scale variability as recorded in Greenland ice cores. A synthesis of sites providing high-resolution terrestrial and marine records from Europe is undertaken in order to examine geographical and temporal patterns in the expression of Dansgaard–Oeschger (D–O) cycles in the European vegetation. Detailed comparison of temperate forest development at these sites during four specific D–O cycles (D–O 16–17, 14, 12 and 8) reveals contrasts between vegetation response at southernmost European latitudes (below 40°N) and at latitudes above 40°N. At southernmost latitudes, marked forest development occurred during all four D–O cycles including D–O 16–17 and 8, while at latitudes above 40°N, forest development was stronger during D–O 14 and 12 than either D–O 16–17 or 8.