A high-resolution δ18O record and Mediterranean climate variability

A high-resolution, well-dated foraminiferal delta18O 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–1979AD. Spectral analysis of this series, performed by Singular Spectrum Analysis (SSA) and other classical and advanced methods, strengthens the results obtained analyzing the shorter delta18O profile, detecting the same highly significant oscillations of about 600 yr, 380 yr, 170 yr, 130 yr, and 11 yr, 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 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. Also 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.