Climate in northern Eurasia 6000 years ago reconstructed from pollen data

摘要

Using a climatic calibration based on the scores of the plant function types (PFTs) calculated for 1245 surface pollen spectra, the climate at 6 ka BP has been reconstructed for a set of 116 pollen spectra from the former Soviet Union and Mongolia. The results are presented as maps of climatic anomalies and maps of probability classes showing the significance of these differences from the modern climate. The reconstructed patterns are spatially coherent, but have confidence levels that vary from region to region, due to the often-large error ranges. At 6 ka, the winters were more than 2 deg C warmer than today north of 50 deg N, with a high significance east of the Urals. Summers were also more than 2 deg C warmer than today with a high level of confidence north of the Polar Circle and in central Mongolia. In the mid-latitudes of Siberia, in northern Kazakhstan and around the Black and the Caspian seas, 6 ka summers were significantly cooler than today. The reconstructed moisture availability (ratio of actual to equilibrium evapotranspiration) was more than 10% higher than today in the Ukraine, southern Russia and northern Mongolia, and more than 10% lower than today in central Mongolia. This pattern corresponds partly with that of the water budget (annual precipitation minus evaporation) reconstructed f