Sea surface temperature variability in the central-western Mediterranean Sea during the last 2700 years: a multi-proxy and multi-record approach

Abstract

Abstract. This study analyses the evolution of sea surface conditions during the last 2700 years in the central-western Mediterranean Sea based on six records as measured on five short sediment cores from two sites north of Minorca (cores MINMC06 and HER-MC-MR3). Sea Surface Temperatures (SSTs) were obtained from alkenones and Globigerina bulloides-Mg/Ca ratios combined with δ18O measurements to reconstruct changes in the regional Evaporation–Precipitation (E–P) balance. We reviewed the G. bulloides Mg/Ca-SST calibration and re-adjusted it based on a set of core top measurements from the western Mediterranean Sea. According to the regional oceanographic data, the estimated Mg/Ca-SSTs are interpreted to reflect spring seasonal conditions mainly related to the April–May primary productivity bloom. In contrast, the Alkenone-SSTs signal likely integrates the averaged annual signal. A combination of chronological tools allowed synchronizing the records in a common age model. Subsequently a single anomaly stack record was constructed for each proxy, thus easing to identify the most significant and robust patterns. The warmest SSTs occurred during the Roman Period (RP), which was followed by a general cooling trend interrupted by several centennial-scale oscillations. This general cooling trend could be controlled by changes in the annual mean insolation. Whereas some particularly warm SST intervals took place during the Medieval Climate Anomaly (MCA) the Little Ice Age (LIA) was markedly unstable with some very cold SST events mostly during its second half. The records of the last centuries suggest that relatively low E–P ratios and cold SSTs dominated during negative North Atlantic Oscillation (NAO) phases, although SST records seem to present a close positive connection with the Atlantic Multidecadal Oscillation index (AMO).

Deltaic and Coastal Sediments as Recorders of Mediterranean Regional Climate and Human Impact Over the Past Three Millennia

“…but decreased in the Ligurian Sea (Figures a and b). A warmer MCA was also found in the Balearic Sea (Cisneros et al, ) and Alboran Sea (Nieto‐Moreno et al, ). Skliris et al () show a negative correlation between NAO and year mean SSTs in the Ligurian Sea and no correlation in the GoL.…”

Amplified environmental change: Evidence from land‐use and climate change in medieval Minorca

“…The age‐depth model showed a fit of 9.55 and the 95% confidence ranges spanned from 39 to 184 years (average of 114 years), with a time resolution of 38 years every 1 cm between 342 and 301 cm bgl, 4 years every 1 cm between 301 and 237 cm bgl, and 2–3 years every 1 cm between 237 and 0 cm bgl (Figure S2). We defined the onset and end of the MCA ( ad 950–1300) and the LIA ( ad 1330–1850) in the model output following the chronology given by Cisneros et al () for Minorca and by Moreno et al () for the Iberian Peninsula.…”

“…Summary of the main physico‐chemical analyses carried out on the Algendar sequence covering the last approximately 2300 years. Results are shown against the AMS dates ( 14 C dates plus standard error), the age‐depth model, the layers identified in the cores, and the datasets used as temperature and precipitation proxies for the Western Mediterranean and Minorca (Cisneros et al, ; Sabatier et al, ). Elemental ratios are log‐ratios.…”

“…We then assessed the extent to which the increase in sedimentation rate and grain size after approximately ad 1300 could be explained by climatic factors. To do so, we compared the Zr/Rb values from Algendar with the storm activity and the sea surface temperatures (SST) datasets by Sabatier et al () and Cisneros et al () by means of linear models. For each dataset, we built the linear models using those observations that shared the same best‐estimated year with our age depth model (15 observations from the Sabatier et al dataset, spanning ad 1017–1847; nine observations from the Cisneros et al dataset, spanning ad 1328–1748).…”

Historical Climate off the Atlantic Iberian Peninsula

“…4H), reveals that the two warming steps referred above 10 do indeed occur during warming transitions in the AMO index, supporting the influence of the N Atlantic SST pattern on the Atlantic IP and its southern area in particular. A connection also defended by (Cisneros et al, 2016) to explain the last 400 yr SST reconstruction of the central-western Mediterranean Sea.…”