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The circum-Mediterranean region is the cradle of ancient civilizations that had their roots in the Holocene. Climate change has been considered a key element that contributed to their rise or fall. The Roman Warm Period (RWP), 200 B.C. to 400 A.D., was the warmest period in Europe during the last two thousand years. Hydroclimatic change at the end of the RWP has been suggested as a possible influence on the stability of the Roman political regime and the eventual collapse of the Roman Empire in 476 A.D. A lack of precise proxy records hampers our understanding of hydroclimatic variability over the RWP. Here we present a stalagmite-based climate record from 550 ± 10 B.C. to 950 ± 7 A.D. (2σ) from northern Italy, which reveals a climatic trend of warming and increased humidity throughout the RWP. By comparison with other proxy records in Europe and the circum-Mediterranean region, we argue that the warm, humid climate in southern Europe could be linked to the multi-centennial warming of the Mediterranean Sea. Our record further suggests a century-long rapid drying trend from the early-4th to early-5th century, followed by a 100-year-long drought event, which could have influenced the fall of the Roman Empire. [ABSTRACT FROM AUTHOR]

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Studies on the last interglacial (LIG) can provide information on how our environment behaved in a period of slightly higher global temperatures at about 125 ± 4 ka, even if it is not the best analogue for the Holocene. The available LIG climate proxy records are usually better preserved and can be studied at a higher resolution than those of the preceding interglacials, allowing detailed comparisons. This paper presents complex stable hydrogen, carbon and oxygen isotope records obtained for carbonate (δ 13 C and δ 18 O carb ) and fluid inclusion hosted water (δD and δ 18 O w ) of a stalagmite from the Baradla Cave system in Central Europe that covers most of the LIG, as proven by U-Th dates. Comparing its C and O isotope data with records reported for other speleothem (cave-hosted carbonate) deposits from Europe revealed the complex behavior of these climate proxies, with a concerted relative increase in 18 O of carbonates from 128 to 120 ka and synchronized shifts in the opposite direction after 119 ka. The hydrogen isotope analyses of inclusion-hosted water extracted from the BAR-II stalagmite also correspond to the regional climate proxy records, with meaningful deviations from global temperature trends. Beside following the general paleotemperature pattern from the climate optimum (high δD values up to −64‰ around 120 ka) to the subsequent cooling starting at about 119 ka (low δD values down to −90‰ at about 109 ka), a period between 126.5 and 123 ka with low δD values (down to −81‰) is detected in the BAR-II stalagmite. Although the isotope shifts are muted in the C-O isotope data of carbonate due to competitive fractionation processes, the δ 13 C data show a positive relationship with the δD pattern, indicating humidity – and possibly temperature – variations. The periods with low δD values fit well to temperature and humidity changes inferred from proxy records from western Europe to the eastern Mediterranean. Spatial distributions of these variables show, that at about 125 ± 2 ka the Mediterranean region was characterized by warm, humid conditions and enhanced seasonality with elevated winter precipitation. The combined interpretation of stable isotope data revealed that the Alpine and Mediterranean regions behaved differently during Greenland Stadial 26 (GS26, ∼119 to 116.2 ka). While the Alpine records fluctuated in close agreement with the Central Greenland ice core δ 18 O data, the BAR-II stalagmite show a positive δ 18 O carb anomaly. The Baradla data indicate enhanced aridity and seasonality for a part of GS26, with the relative dominance of summer precipitation and Mediterranean moisture contribution. Following the GS26 event, the effect of long-term global cooling becomes dominant in the Baradla isotope records and leads to glacial inception at about 109 ka. [ABSTRACT FROM AUTHOR]

The Weichselian glaciation is characterized by significant ocean circulation variations starting from ∼115 thousand years ago (ka) and terminating at ∼11.5 ka. The early Weichselian (115–74 ka), especially marine isotope stage (MIS) 5a at 85–74 ka, provides a window for understanding the linkage between the European westerlies and Mediterranean climate. However, lack of highly-resolved paleoclimate records with absolute chronologies hampers our knowledge of decadal-to-centennial-scale climate changes and forcings in the circum-Mediterranean realm. Here, we present 230Th-dated stalagmite-inferred hydroclimate records from Observatoire cave (43°44′ N, 7°25' E), Monaco, for the period between 88.7 ± 0.4 and 80.3 ± 0.1 ka, covering portions of MIS 5b and 5a. Agreement between Observatoire and circum-Mediterranean stalagmite records confirm large-scale warming over the Atlantic-Europe territory during the transition from MIS 5b to 5a. Subdecadally-resolved Observatoire δ18O and δ13C records express four multi-centennial arid intervals in southern Europe at 84–80 ka in the first-half of MIS 5a, suggesting centennial westerly drifts, a finding supported by a model simulation. Westerly changes and associated arid events can be attributed to slowdowns of the Atlantic meridional overturning circulation, North Atlantic Oscillation states, and solar activity. • Stalagmite δ18O and δ13C records from Monaco show precipitation changes in southern Europe from 89 to 80 ka at MIS 5b-5a. • Multi-centennial arid events at 84-80 ka during MIS 5a could be linked to AMOC slowdowns, NAO states, and solar activity. • Models suggest that centennial-scale AMOC slowdowns at MIS 5a could induce reduced precipitation over western Europe. [ABSTRACT FROM AUTHOR]

The front section of marine isotope stage (MIS) 5a, 84.5-76.0 ka, after an abrupt globaltemperature rise from MIS 5b, 95.0-84.5 ka, has been considered as a good analoguefor understanding the anthropogenic impact of current global warming on Earth.However, lack of well-calendared paleoclimate records hampers our understandingof regional climatic change and global links on centennial-to-millennial scales.Here, we present a 230Th-dated stalagmite δ18O-inferred precipitation time seriesduring 83.7-80.2 ka from Observatoire Cave (43∘44’N, 7∘25’E), Monaco, southernEurope. It shows a millennial decreasing precipitation trend from 83.7 to 82.5 kawith an abrupt 200-yr wet event at 82.7 ka and a rapid shift from aridity to wetnessduring 82.5-82.4 ka, followed by a relatively stable condition at 82.4-80.2 ka insouthern Europe. This hydroclimatic variability concurs with the decrease sea surfacetemperature in the Mediterranean and an ice rafted debris event in Nordic Sea onmulti-centennial-to-millennial scales. Coupled with published global proxy records, theresults show that southern Europe hydroclimate is dominantly influenced by high latitude inthe northern hemisphere and westerlies. The results suggest that southern Europe is sensitiveto the climate change and ice sheet variability in high-latitude northern Eurasia. [ABSTRACT FROM AUTHOR]

The variability of the northern westerlies has been considered as one of the key elements for modern and past climate evolution. Their multiscale behavior and underlying control mechanisms, however, are incompletely understood, owing to the complex dynamics of Atlantic sea-level pressures. Here, we present a multi-annually resolved record of the westerly drift over the past 6,500 years from northern Italy. In combination with more than 20 other westerly-sensitive records, our results depict the non-stationary westerly-affected regions over mainland Europe on multi-decadal to multi-centennial time scales, showing that the direction of the westerlies has changed with respect to the migrations of the North Atlantic centers of action since the middle Holocene. Our findings suggest the crucial role of the migrations of the North Atlantic dipole in modulating the westerly-affected domain over Europe, possibly modulated by Atlantic Ocean variability., (© 2022. The Author(s).)

The Little Ice Age (LIA; ca. 1450-1850 C.E.) is the best documented cold period of the past millennium, characterized by high-frequency volcanism, low solar activity, and high variability of Arctic sea-ice cover. Past studies of LIA Atlantic circulation changes have referenced the North Atlantic Oscillation (NAO), but recent studies have noted that LIA climate patterns appear to possess complexity not captured by an NAO analogue. Here, we present a new precipitation-sensitive stalagmite record from northern Italy that covers the past 800 years. We show that in the early LIA (1470-1610 C.E.), increased atmospheric ridging over northern Europe split the climatological westerlies away from central and northern Europe, possibly caused by concurrent Artic sea-ice reduction. With ongoing ice melting in the northern high latitudes and decreasing solar irradiance in the coming years, the early LIA may potentially serve as an analogue for European hydroclimatic conditions in the coming decades., (© 2022. The Author(s).)