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Synoptic drivers of 400years of summer temperature and precipitation variability on Mt. Olympus, Greece

Klesse, Stefan ; Ziehmer, Malin ; Rousakis, Georgios ; Trouet, Valerie ; Frank, David

In: Climate Dynamics, 2015, vol. 45, no. 3-4, p. 807-824

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    Titre
    • Synoptic drivers of 400years of summer temperature and precipitation variability on Mt. Olympus, Greece
    Auteur
    • Klesse, Stefan. Swiss Federal Research Institute WSL, 8903, Birmensdorf, Switzerland
    • Ziehmer, Malin. Physics Institute, University of Bern, 3012, Bern, Switzerland
    • Rousakis, Georgios. Litohoro Forest Service, 602000, Litohoro, Greece
    • Trouet, Valerie. Laboratory of Tree-Ring Research, University of Arizona, 85721, Tucson, AZ, USA
    • Frank, David. Swiss Federal Research Institute WSL, 8903, Birmensdorf, Switzerland
    Type de document
    • Postprint
    Langue
    • Anglais
    Publié dans
    • Climate Dynamics, 2015, vol. 45, no. 3-4, p. 807-824. Springer Berlin Heidelberg
    Autre version électronique
    Identifiant OAI-PMH
    • oai:doc.rero.ch:332098
    Summary
    The Mediterranean region has been identified as a global warming hotspot, where future climate impacts are expected to have significant consequences on societal and ecosystem well-being. To put ongoing trends of summer climate into the context of past natural variability, we reconstructed climate from maximum latewood density (MXD) measurements of Pinus heldreichii (1521-2010) and latewood width (LWW) of Pinus nigra (1617-2010) on Mt. Olympus, Greece. Previous research in the northeastern Mediterranean has primarily focused on inter-annual variability, omitting any low-frequency trends. The present study utilizes methods capable of retaining climatically driven long-term behavior of tree growth. The LWW chronology corresponds closely to early summer moisture variability (May-July, r=0.65, p<0.001, 1950-2010), whereas the MXD-chronology relates mainly to late summer warmth (July-September, r=0.64, p<0.001; 1899-2010). The chronologies show opposing patterns of decadal variability over the twentieth century (r=−0.68, p<0.001) and confirm the importance of the summer North Atlantic Oscillation (sNAO) for summer climate in the northeastern Mediterranean, with positive sNAO phases inducing cold anomalies and enhanced cloudiness and precipitation. The combined reconstructions document the late twentieth—early twenty-first century warming and drying trend, but indicate generally drier early summer and cooler late summer conditions in the period ~1700-1900 CE. Our findings suggest a potential decoupling between twentieth century atmospheric circulation patterns and pre-industrial climate variability. Furthermore, the range of natural climate variability stretches beyond summer moisture availability observed in recent decades and thus lends credibility to the significant drying trends projected for this region in current Earth System Model simulations.