Oslo joint seminar in atmospheric, ocean and climate science, Nov. 14

Title: Eastern Mediterranean summer temperatures since 730 CE from Mt. Smolikas tree-ring density data

Speaker: Jan Esper, Johannes Gutenberg University, Mainz

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Jan Esper, Johannes Gutenberg University


The Mediterranean has been identified as particularly vulnerable to climate change, yet a high-resolution temperature reconstruction extending back into the Medieval Warm Period is still missing. I will present such a record from a high-elevation site on Mt. Smolikas in northern Greece hosting some of the oldest trees in Europe and providing estimates of warm season temperature variability back to 730 CE. 

The reconstruction is derived from 192, annually resolved, latewood density series from ancient living and relict Pinus heldreichii trees calibrating at r1911-2015 = 0.73 against regional July-September (JAS) temperatures. Considering the reconstruction mean, 1985-2014 was the warmest 30-year period (JAS Twrt.1961-90 = +0.71°C) since the 11th century. However, temperatures during the 9-10th centuries, including the warmest reconstructed 30-year period from 876-905 (+0.78°C), were even warmer. Several distinct cold episodes are reconstructed throughout the Little Ice Age, yet the coldest 30-year period is centered during high medieval times from 997-1026 (-1.63°C). Comparison with reconstructions from the Alps and Scandinavia shows that a similar cold episode occurred in central Europe but is absent in northern Europe. The reconstructions also reveal different millennial-scale temperature trends (NEur = -0.73°C/1000 years, CEur = -0.13 °C, SEur = +0.23°C) potentially triggered by a latitudinal change in summer insolation due to orbital forcing. These features, the varying millennial-scale temperature trend and the medieval multi-decadal cooling evolving from northern Europe towards the Mediterranean, are not well captured in state-of-the-art climate model simulations.


What is the Joint Oslo Seminar (JOS):

Atmospheric and climate sciences have a stronghold in Oslo among the four institutions University of Oslo, the Meteorological Institute, CICERO and NILU. This joint seminar invites renowned international experts to contribute to an informal series of lectures, meant to create interaction with the Oslo atmospheric and climate science community on recent highlights and analysis in the field. All seminars will be held on Thursdays (Noon -1pm) and lunch (sandwiches) will be served on a “first-come-first-served”-basis.

Published June 19, 2019 11:26 AM - Last modified Nov. 11, 2019 8:45 AM