Contrasting patterns of climatic changes during the Holocene in the Central Mediterranean (Italy) reconstructed from pollen data
1UMR6249 – Chrono-Environnement, Université de Franche-Comté, Besançon, France
2Department of Geography, Univ. of Wisconsin-Madison, Wisconsin, USA
3UMR5276 – LGLTPE, Université Lyon 1, France
4UMR7263 – IMBE, Université Paul Cézanne, Aix-en-Provence, France
5D. di Agricoltura, Ambiente e Alimenti, Univ. degli Studi del Molise, Campobasso, Italy
6Dipartimento di Biologia Ambientale, Università di Roma "La Sapienza", Roma, Italy
7CNR – Istituto di Genetica Vegetale – Corso Calatafimi, Palermo, Italy
8Dept. of Hist. Geology, University of Athens, Greece
9Institute of Geology and Mineral Exploration, Olympic Village, Greece
10UMR1572 LSCE – Gif-sur-Yvette, France
Abstract. Lake-level records from Italy suggest a north–south climatic partition in the Central Mediterranean during the Holocene with respect to precipitation, but the scarcity of reliable palaeoclimatic records in the North and Central-Southern Mediterranean means new evidence is needed to validate this hypothesis. Here, we provide robust quantitative estimates of Holocene climate in the Mediterranean region based on four high-resolution pollen records from Northern (Lakes Ledro and Accesa) and Southern (Lakes Trifoglietti and Pergusa) Italy. Multiple methods are used to provide an improved assessment of the paleoclimatic reconstruction uncertainty. The multi-method approach uses the pollen-based Weighted Averaging, Weighted-Average-Partial-Least-Squares regression, Modern Analogues Technique, and the Non-Metric-Multidimensional Scaling/Generalized-Additive-Model methods. The precipitation seasonality reconstructions are validated by independent lake-level data, obtained from the same records.
A climatic partition between the north and the south during the Holocene confirms the hypothesis of opposing mid-Holocene summer precipitation regimes in the Mediterranean. During the early-to-mid-Holocene the northern sites (Ledro, Accesa) are characterized by minima for summer precipitation and lake-levels while the southern sites (Trifoglietti, Pergusa) are marked by maxima for precipitation and lake-levels. During the late Holocene, both pollen-inferred precipitation and lake-levels indicate the opposite pattern, a maximum in North Italy and a minimum in Southern Italy/Sicily. Summer temperatures also show partitioning, with warm conditions in Northern Italy and cool conditions in Sicily during the early/mid-Holocene, and a reversal during the Late-Holocene.
Comparison with marine cores from the Aegean Sea suggests that climate trends and gradients observed in Italy shows strong similarities with those recognized from the Aegean Sea, and more generally speaking in the Eastern Mediterranean.