Mean July temperatures during the Younger Dryas in northwestern and central Europe as inferred from climate indicator plant species

We estimated minimum mean July temperatures in northwestern and central Europe during the Younger Dryas (10,950-10,150 C-14 yr B.P.) from distributions of climate indicator plant species, which were reconstructed from 140 pollen and plant macrofossil diagrams. Paleobotanical records, mainly from the central and eastern part of the study area, show that the coldest conditions occurred early in the Younger Dryas (before similar to 10,550 C-14 yr B.P.). For this phase, mean July temperatures at sea level of around 10 degrees C are suggested for the northern part of the British Isles and for ice-free Scandinavia. We estimated a mean July temperature of 12 degrees C for central England, The Netherlands, and northern Germany. The 13 degrees C mean July isotherm-largely based on the modern distribution of Typha latifolia-was most probably located in southern England, Belgium, central Germany, and Poland. The reappearance of thermophilous elements in the records after similar to 10,550 C-14 yr B.P. suggests a summer warming, at least temporarily, of 1 degrees to 2 degrees C in the study area. The reconstructed temperatures are comparable with temperature estimates based on beetle data. However, they appear rather high when compared with estimates based on glaciological evidence. (C) 1999 University of Washington.