The climate and vegetation of Europe, North Africa and the Middle East during the Last Glacial Maximum (21,000 years BP) based on pollen data

Abstract

Abstract. Pollen data represents one of the most widely available and spatially-resolved sources of information about the past land cover and climate of the Last Glacial Maximum (21,000 years BP). Previous pollen data compilations for Europe, the Mediterranean and the Middle East however have been limited by small numbers of sites and poor dating control. Here we present a new compilation of pollen data from the region that improves on both the number of sites (63) and the quality of the chronological control. Data has been sourced from both public data archives and published (digitized) diagrams. Analysis is presented based on a standardized pollen taxonomy and sum, with maps shown for the major pollen taxa, biomes and total arboreal pollen, as well as quantitative reconstructions of forest cover and winter, summer and annual temperatures and precipitation. The reconstructions are based on the modern analogue technique (MAT) with a modern calibration dataset taken from the latest Eurasian Modern Pollen Database (~8000 samples). A site-by-site comparison of MAT and Inverse Modelling methods shows little or no significant difference between the methods for the LGM, indicating that no-modern-analogue and low CO2 conditions during the LGM do not appear to have had a major effect on MAT transfer function performance. Previous pollen-based climate reconstructions based on MAT show a much colder and drier climate for the LGM than both Inverse Modelling and climate model simulations, but our new results suggest much greater agreement. Differences between our latest MAT reconstruction and those in earlier studies can be largely attributed to bias in the small modern calibration dataset previously used. We also find that quantitative forest cover reconstructions show more forest than that previously suggested by biome reconstructions, but less forest than that suggested by simple percentage arboreal pollen, although uncertainties remain large. Overall, we find that LGM climatic cooling/drying was significantly greater in winter than in summer, but with large site to site variance that emphasizes the importance of topography and other local factors in controlling the climate and vegetation of the LGM.

The demographic history of the wild crop relativeBrachypodium distachyonis shaped by distinct past and present ecological niches

“…The climate, vegetation and landscape of Northern Eurasia (north of ca. 40°N and from 10°W to 180°E) underwent massive changes during the last glacial period (Binney et al 2017; Davis et al 2022). Under the cooler and dryer conditions faced during the LGM specifically, forests retreated to glacial refugia in Spain, Italy or the Balkans (for review Feliner 2011; Nieto Feliner 2014) and land remained mostly covered by steppe and tundra (Binney et al 2017).…”

Holocene vegetation dynamics of the Eastern Mediterranean region: Old controversies addressed by a new analysis

“…Quantitative reconstructions of Last Glacial Maximum climates (Davis et al, 2022) indicate somewhat moderate cooling in regions to the west and south of the Black Sea accompanied by increased growing season precipitation, which could favour the persistence of moisture-demanding broad-leaved trees along with conifers.…”

“…This is consistent with the fact that Abies was the dominant taxon at this site (Figure S4), though Ulmus is also present in relatively high abundance (3.5%). Quantitative reconstructions of Last Glacial Maximum climates (Davis et al., 2022) indicate somewhat moderate cooling in regions to the west and south of the Black Sea accompanied by increased growing season precipitation, which could favour the persistence of moisture‐demanding broad‐leaved trees along with conifers.…”

The demographic history of the wild crop relative Brachypodium distachyon is shaped by distinct past and present ecological niches

“…The climate, vegetation and landscape of Northern Eurasia (north of ca. 40°N and from 10°W to 180°E) underwent massive changes during the last glacial period (Binney et al 2017;Davis et al 2022). Under the cooler and dryer conditions faced during the LGM specifically, forests retreated to glacial refugia in Spain, Italy or the Balkans (for review Feliner 2011;Nieto Feliner 2014) and land remained mostly covered by steppe and tundra (Binney et al 2017).…”