European summer temperature response to annually dated volcanic eruptions over the past nine centuries

The drop in temperature following large volcanic eruptions has been identified as an important component of natural climate variability. However, due to the limited number of large eruptions that occurred during the period of instrumental observations, the precise amplitude of post-volcanic cooling is not well constrained. Here we present new evidence on summer temperature cooling over Europe in years following volcanic eruptions. We compile and analyze an updated network of tree-ring maximum latewood density chronologies, spanning the past nine centuries, and compare cooling signatures in this network with exceptionally long instrumental station records and state-of-the-art general circulation models. Results indicate post-volcanic June–August cooling is strongest in Northern Europe 2 years after an eruption (−0.52±0.05 °C), whereas in Central Europe the temperature response is smaller and occurs 1 year after an eruption (−0.18±0.07 °C). We validate these estimates by comparisonwith the shorter instrumental network and evaluate the statistical significance of post-volcanic summer temperature cooling in the context of natural climate variability over the past nine centuries. Finding no significant post-volcanic temperature cooling lasting longer than 2 years, our results question the ability of large eruptions to initiate long-term temperature changes through feedback mechanisms in the climate system. We discuss the implications of these findings with respect to the response seen in general circulation models and emphasize the importance of considering welldocumented, annually dated eruptions when assessing the Editorial responsibility: C. Oppenheimer Electronic supplementary material The online version of this article (doi:10.1007/s00445-013-0736-z) contains supplementary material, which is available to authorized users. J. Esper (*) : L. Schneider Department of Geography, Johannes Gutenberg University, Mainz 55099, Germany e-mail: [email protected] P. J. Krusic Department of Physical Geography and Quaternary Geology, Stockholm University, Stockholm 10691, Sweden J. Luterbacher Department of Geography, Climatology, Climate Dynamics and Climate Change, Justus-Liebig University, Giessen 35390, Germany U. Büntgen Swiss Federal Research Institute WSL, Birmensdorf 8903, Switzerland M. Timonen Finnish Forest Research Institute, Rovaniemi Research Unit, Rovaniemi 96301, Finland F. Sirocko Institute for Geoscience, Johannes Gutenberg University, Mainz 55099, Germany E. Zorita Institute for Coastal Research, HZG Research Centre, Geesthacht 21494, Germany U. Büntgen Oeschger Centre for Climate Change Research (OCCR), Bern 3012, Switzerland U. Büntgen Global Change Research Centre AS CR, v.v.i., Bělidla 986/4a, Brno CZ-60300, Czech Republic Bull Volcanol (2013) 75:736 DOI 10.1007/s00445-013-0736-z