Articles | Volume 11, issue 3
Research article
24 Mar 2015
Research article |  | 24 Mar 2015

A high-resolution δ18O record and Mediterranean climate variability

C. Taricco, G. Vivaldo, S. Alessio, S. Rubinetti, and S. Mancuso

Abstract. A high-resolution, well-dated foraminiferal δ18O record from a shallow-water core drilled from the Gallipoli Terrace in the Gulf of Taranto (Ionian Sea), previously measured over the last two millennia, has been extended to cover 707 BC–AD 1979. Spectral analysis of this series, performed using singular-spectrum analysis (SSA) and other classical and advanced methods, strengthens the results obtained analysing the shorter δ18O profile, detecting the same highly significant oscillations of about 600, 380, 170, 130 and 11 years, respectively explaining about 12, 7, 5, 2 and 2% of the time series total variance, plus a millennial trend (18% of the variance). The comparison with the results of multi-channel singular-spectrum analysis (MSSA) applied to a data set of 26 Northern Hemisphere (NH) temperature-proxy records shows that NH temperature anomalies share with our local record a~long-term trend and a bicentennial (170-year period) cycle. These two variability modes, previously identified as temperature-driven, are the most powerful modes in the NH temperature data set. Both the long-term trends and the bicentennial oscillations, when reconstructed locally and hemispherically, show coherent phases. Furthermore, the corresponding local and hemispheric amplitudes are comparable if changes in the precipitation–evaporation balance of the Ionian sea, presumably associated with temperature changes, are taken into account.

Short summary
The key to gaining information on climate over the last millennia is the study of proxy records in ice and sediment cores, trees, etc. We measured the oxygen isotopic ratio in planktonic foraminifera of a high-resolution, well-dated central Mediterranean core. The comparison between the variability detected in this core and that characterizing the Northern Hemisphere allows for local and global (hemispheric) climate variations to be distinguished.