Two millennia of climate variability in the Central Mediterranean

Abstract

Abstract. This experimental work addresses the need for high-resolution, long and homogeneous climatic time series that facilitate the study of climate variability over time scales of decades to millennia. We present a high-resolution record of foraminiferal δ 18 O from a Central-Mediterranean sediment core that covers the last two millennia. The record was analyzed using advanced spectral methods and shows highly significant oscillatory components with periods of roughly 600, 350, 200, 125 and 11 years. Over the last millennium, our data show several features related to known climatic periods, such as the Medieval Optimum, the Little Ice Age and a recent steep variation since the beginning of the Industrial Era. During the preceding millennium, the δ 18 O series also reveals a surprising maximum at about 0 AD, suggesting low temperatures at that time. This feature contradicts widely held ideas about the Roman Classical Period; it is, therefore, discussed at some length, by reviewing the somewhat contradictory evidence about this period.We compare the δ 18 O record with an alkenone-derived sea surface temperature time series, obtained from cores extracted in the same Central-Mediterranean area (Gallipoli Terrace, Ionian Sea), as well as with Italian and other European temperature reconstructions over the last centuries. Based on this comparison, we show that the long-term trend and the 200-y oscillation in the records are temperature driven and have a dominant role in describing temperature variations over the last two millennia.

A high-resolution δ<sup>18</sup>O record and Mediterranean climate variability

“…Singular-spectrum analysis (SSA) of the series (Fig. 2) allowed for detection of the presence of a long-term trend and of highly significant oscillatory components with periods of roughly 600, 380, 170, 130 and 11 years, thus confirming the results found by Taricco et al (2009), who analysed the previously published time series covering 188 BC-AD 1979 (Figs. 1, 3, and 4).…”

The Impact of the Little Ice Age on Coccolithophores in the Central Mediterranea Sea

“…A temperature drop of 2 • C has been deduced along the northern Sicilian coast by geochemical analysis on Vermetid Reefs (Silenzi et al, 2004). A similar temperature drop, accompanied by concomitant heavier values in δ 18 O of planktonic foraminifera, has been shown in the Gulf of Taranto, western part of the Ionian Sea (Versteegh et al, 2007;Taricco et al, 2009). …”

Recent unprecedented warming and oligotrophy of the eastern Mediterranean Sea within the last millennium

“…This feature was identified in marine, lake, and stalagmite records from the western Mediterranean [Martin-Puertas et al, 2010], suggesting NAO forcing of the western Mediterranean climate during the last millennium. However, clear patterns of NAO forcing over the EM are missing from the few marine records from this region [Roberts et al, 2012;Taricco et al, 2009;Versteegh et al, 2007] and lake records from Turkey, Greece, and the Levant [Roberts et al, 2012]. Instead, the strong correlation (r 2 = 0.76, n = 75, p < 0.001) between our EM-SST composite record and the reconstruction of monsoon winds from Arabian Sea sediment cores [Anderson et al, 2002] (Figure 3b) suggests long-term forcing by monsoon circulation over the EM.…”

“…A limited number of marine records for the last millennium from the Algarian-Balearic Sea (Mg/Ca-based sea surface temperature (SST)) [Moreno et al, 2012] and Ionian Sea (foraminiferal δ 18 O and alkenone-based SST) [Taricco et al, 2009;Versteegh et al, 2007] show inconsistent SST trends during the Medieval Warm Period (MWP) and the Little Ice Age (LIA). Lowresolution foraminiferal δ 18 O and δ 13 C records from the EM Sea show undefined paleo-oceanographic changes during the late Holocene [Schilman et al, 2003[Schilman et al, , 2001.…”