Pollen-based Holocene temperature and precipitation pattern of the Northern Hemisphere regions in the light of the global temperature trend

Mismatch in model- and proxy-based Holocene climate change, known as the Holocene Conundrum, may partially originate from the poor spatial coverage of climate reconstructions e.g. in Asia, limiting the number of grid cells for model-data comparison. Here we investigate pollen-based reconstructions of mean annual, mean July temperature, and annual precipitation from 2594 sites in  the northern hemisphere extratropics that were set up with a harmonized calibration method and were presented with revised chronologies. Temperature trends show strong latitudinal pattern and differ between (sub-)continents. While Europe and eastern North America show a pronounced mid-Holocene temperature maximum, western North America shows only weak changes and Asia a continuous Holocene temperature increase but with strong latitudinal differences. While on hemisphere scale, temperature and precipitation show similar trends (i.e. a Holocene toward the late mid-Holocene increase until followed by a slight decline until present), on continental and regional scale positive, negative and non-correlation are found. Particularly in Asia strong latitudinal pattern of precipitation is found.  Finally, we merged our data with the data of Kaufman et al 2020 doubling the number of records in this data base and presented a revised global temperature curve.