Climatic variability over the last 3000 years in the central-western Mediterranean Sea

Abstract The climate evolution of the last 2700 years in the central - western Mediterranean Sea has been reconstructed from marine sediment records by integrating planktonic foraminifera and geochemical signals. The results provide the characterization of six climatic phases: Balearic Bronze Age (BA), Roman Period (RP), Dark Age (DA), Medieval Climate Anomaly (MCA), Little Ice Age (LIA) and Industrial Period (IP). Paleoclimatic curve inferred from planktonic foraminifera associated with heavy values in δ18O Globigerinoides ruber during the BA document two cold intervals (spanning ca. 200 years) related to the Homeric and Greek solar minima. The dominance of Turborotalita quinqueloba –Globigerinita glutinata gr. and Globigerina bulloides during the RP suggest high fertility surface waters condition probably triggered by the increase in precipitation. During the DA, changes in the foraminiferal paleoclimate curve and oxygen isotope values display a cold –dry phase from 700 CE to the end of the DA (ca. 850 CE). This phase corresponds to the cold Roman IV solar minimum and marks the beginning of a long - term cooling interval that terminates during the LIA. The MCA is characterized by mild climatic conditions, interrupted at ca. 1050 CE by a cold - dry event. The gradually increase in abundance of G. ruber white characterize the IP warm period. The reconstructed climate evolution in the Balearic Basin results almost time - equivalent with the Mediterranean climate variability over the last 2700 years.


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The study of last three millennia climate variability are crucial to distinguish anthropogenic from 38 natural forcing and to provide information for medium and long -term prediction models. These 39 reconstructions can be obtained using high-quality datasets of proxies measured from different natural  The planktonic foraminiferal specimens are abundant and well preserved. G. bulloides and G. 171 ruber white variety are continuously present (mean values ca. 15 %) in the whole study interval; only 172 from ca. 1700 CE they show a drastic reduction in percentages (Fig. 2). G. inflata, G. truncatulinoides 173 and Orbulina spp. exhibit from ca. 50 CE upwards a decreasing trends followed by peaks in 174 abundance from ca. 800 CE to top core (Fig. 2). Conversely, T. quinqueloba and G. glutinata increase 175 from ca. 50 CE upwards reaching higher values from ca. 1750 CE to top core (Fig. 2).

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G. quadrilobatus shows low abundance from base core to ca. 50 CE and becames relevant (about 9 177 %) at ca. 600 CE (Fig. 2). This species shows a progressive upward decreasing trend from 9% to 2% 178 (Fig. 2). G. ruber pink variety shows a similar distribution pattern observed for G. quadrilobatus gr. 179 (Fig. 2). G. siphonifera is constantly present (mean values of ca. 5 %) in the study record with an

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During these two cooling events, δ 18 OG. bulloides signal does not show heavier values (Fig. 2), this may 238 suggest that the intense winter mixing could be more episodic.

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The paleoclimatic curve documents warm climate condition, at ca. 150 CE, between Roman I and II trends to higher values have been observed at the end of the period (Fig. 2). 256 The first one occurs between ca. 500 and ~ 700 CE and is characterized by δ 18 OG.ruber light values and 257 the increase in abundance of G. quadrilobatus gr., G. ruber and Orbulina spp. (Fig. 2). These species

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The second climate phase chronologically corresponds to the cold Roman IV solar minimum (Fig.   265 2). This interval is characterized by high percentages of G. inflata and Neogloboquadrinids spp.,  (1995) the Orbulina species prevail only in the summer mixed layers. In addition, the antithetic 314 response between δ 18 OG. ruber and δ 18 OG. bulloides signals during the Maunder (Fig. 2), could suggest a 315 possible seasonal contrast, due to strong temperature/salinity difference respectively in winter/spring 316 and summer/autumn (Pujol and Vergnaud-Grazzini et al., 1995).

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The increase in abundance of T. quinqueloba -G. glutinata gr. (Fig. 2), at the end of these solar 318 minima events, just before the following warms phases, and the antithetic distribution of G. inflata associated with a decrease in percentage of G. truncatulinoides and G. bulloides (Fig. 2).

Correlation between Mediterranean records
For the first time we provide the correlation among different regions of the Mediterranean Sea 340 during the last 2700 years. This effort permits to verify the synchronicity of climate events in land 341 and ocean in order to better understand global forcing within the Mediterranean region (Fig. 3).

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The comparison between the marine records of Menorca basin (this study), central and south  The cooling phase at ca. 250 -300 BCE corresponding to the Greek solar minimum is widely 351 recognised in all the investigated Mediterranean records by δ 18 OG.ruber signatures (Fig. 3), excluding 352 the Taranto Gulf as probably due to a regional overprint. The cooling event recorded by δ 18 OG.ruber 353 heavy values at ca. -600 BCE in the study core (Menorca area) has been correlated to the Homeric 354 solar minimum (Fig. 3).

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Between 220 and 800 BCE, the cold events Roman II, III and IV are well documented by δ 18 OG.ruber 356 signals of the western basins (Fig. 3)   In the upper part of the DA, the prominent cooling event corresponding to the Roman IV solar 362 minimum, marks the beginning of a progressive cooling trend that culminates during the LIA (Fig.   363 3). Trends to cool temperatures during the DA have been also reconstructed in the north Europe  (Fig. 3).   The results allow us to identify and characterize six intervals related to known cultural / climatic  This interval predates the long -term cooling trend upwards documented by planktonic foraminiferal curve. The RP was generally dominated by the of cold winter condition with high productivity in the habitats using stable isotope data: a case history for Mediterranean Sapropel S5. Marine  The black arrows with ages represent the ages when this areas becomes part of the Roman Empire.