Mid-Holocene European climate revisited: New high-resolution regional climate model simulations using pollen-based land-cover

Gustav Strandberg (1) , Johan Lindström , Anneli Poska , Qiong Zhang , Ralph Fyfe , Esther Githumbi (2) , Erik Kjellström (1) , Florence Mazier (3) , Anne Nielsen , Shinya Sugita , Anna-Kari Trondman (2) , Jessie Woodbridge , Marie-José Gaillard (2)

1 SMHI - Swedish Meteorological and Hydrological Institute
2 Linnaeus University
3 GEODE - Géographie de l'environnement

Land-cover changes have a clear impact on local climates via biophysical effects. European land cover has been affected by human activities for at least 6000 years, but possibly longer. It is thus highly probable that humans altered climate before the industrial revolution (AD1750e1850). In this study, climate and vegetation 6000 years (6 ka) ago is investigated using one global climate model, two regional climate models, one dynamical vegetation model, pollen-based reconstruction of past vegetation cover using a model of the pollen-vegetation relationship and a statistical model for spatial interpolation of the reconstructed land cover. This approach enables us to study 6 ka climate with potential natural and reconstructed land cover, and to determine how differences in land cover impact upon simulated climate. The use of two regional climate models enables us to discuss the robustness of the results. This is the first experiment with two regional climate models of simulated palaeo-climate based on regional climate models. Different estimates of 6 ka vegetation are constructed: simulated potential vegetation and recon- structed vegetation. Potential vegetation is the natural climate-induced vegetation as simulated by a dynamical vegetation model driven by climate conditions from a climate model. Bayesian spatial model interpolated point estimates of pollen-based plant abundances combined with estimates of climate- induced potential un-vegetated land cover were used for reconstructed vegetation. The simulated potential vegetation is heavily dominated by forests: evergreen coniferous forests dominate in northern and eastern Europe, while deciduous broadleaved forests dominate central and western Europe. In contrast, the reconstructed vegetation cover has a large component of open land in most of Europe. The simulated 6 ka climate using reconstructed vegetation was 0-5° C warmer than the pre-industrial (PI) climate, depending on season and region. The largest differences are seen in north-eastern Europe in winter with about 4e6 C, and the smallest differences (close to zero) in southwestern Europe in winter. The simulated 6 ka climate had 10-20% more precipitation than PI climate in northern Europe and 10 -20% less precipitation in southern Europe in summer. The results are in reasonable agreement with proxy-based climate reconstructions and previous similar climate modelling studies. As expected, the global model and regional models indicate relatively similar climates albeit with regional differences indicating that, models response to land-cover changes differently.

Mots clés: Paleoclimate; Global climate model; Dynamical vegetation model; Vegetation reconstruction; Spatial statistical models; Land-use and land-cover change; REVEALS; LPJ-GUESS; EC-Earth; RCA4; HCLIM

Domaines: Climatologie

Gustav Strandberg, Johan Lindström, Anneli Poska, Qiong Zhang, Ralph Fyfe, et al.. Mid-Holocene European climate revisited: New high-resolution regional climate model simulations using pollen-based land-cover. Quaternary Science Reviews, 2022, 281, ⟨10.1016/j.quascirev.2022.107431⟩. ⟨hal-03588449⟩