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Abstract: Dansgaard–Oeschger (D–O) cycles were the most prominent, abrupt climate events of the last glacial period whose impact was most strongly felt in the high latitudes of the North Atlantic region. The climate links between the North Atlantic, the Asian and American tropics, and Antarctica during these cycles are well documented. However, the potential role of the Indo-Pacific Warm Pool and Australasian monsoon system in propagating climate impacts across the hemispheres is still unclear. Here, we use tandem measurements of oxygen isotopes in calcite and fluid inclusions, as well as carbon-isotope ratios, from multiple stalagmites from Liang Luar Cave, Flores (southern Indonesia) to examine the monsoon response to D–O event number 21 (~87,000–84,000 years ago), the longest and warmest event recorded in Greenland ice cores. The record shows that there was a rapid decline in monsoon rainfall in Indonesia during D–O21 warming in Greenland and cooling in Antarctica. At around the same time, the East Asian monsoon was intensified, indicating that the intertropical convergence zone (ITCZ) shifted abruptly to the north during this event. Our record also shows that there was a 2–3°C increase in local air temperature, which would have acted to increase primary productivity and promote the generation of soil carbon for methanogenesis. Therefore, our findings indicate that ITCZ positioning in tropical Australasia—through its influence on large-scale oceanic–atmospheric circulation—played a key role in transmitting the abrupt climate signal between the hemispheres, thereby facilitating the rapid rise of atmospheric CO2 and CH4 concentrations during D–O21 that ultimately led to global warming and the demise of the MIS5b stadial. [Copyright &y& Elsevier]

We present stable carbon (δ13C) and oxygen (δ18O) isotope records from two partially coeval speleothems from Manita peć Cave, Croatia. The cave is located close to the Adriatic coast (3.7 km) at an elevation of 570 m a.s.l. The site experienced competing Mediterranean and continental climate influences throughout the last glacial cycle and was situated close to the ice limit during the glacial phases. U-Th dating constrains the growth history from Marine Isotope Stage (MIS) 5 to MIS 3 and the transition from MIS 2 to MIS 1. 14C dating was used to estimate the age of the youngest part of one stalagmite found to be rich in detrital thorium and thus undatable by U-Th. On a millennial scale, δ18O variations partly mimic the Dansgaard–Oeschger interstadials recorded in Greenland ice cores (Greenland Interstadials, GI) from GI 22 to GI 13. We interpret our δ18O record as a proxy for variations in precipitation amount and/or moisture sources, and the δ13C record is interpreted as a proxy for changes in soil bioproductivity. The latter indicates a generally reduced vegetation cover towards MIS 3–MIS 4, with shifts of ~8‰ and approaching values close to those of the host rock. However, even during the coldest phases, when a periglacial setting and enhanced aridity sustained long-residence-time groundwater, carbonic-acid dissolution remains the driving force of the karstification processes. Speleothem morphology follows changes in environmental conditions and complements regional results of submerged speleothems findings. Specifically, narrow sections of light porous spelaean calcite precipitated during the glacial/stadial sea-level lowstands, while the warmer and wetter conditions were marked with compact calcite and hiatuses in submerged speleothems due to sea-level highstands. Presumably, the transformation of this littoral site to a continental one with somewhat higher amounts of orographic precipitation was a site-specific effect that masked regional environmental changes. [ABSTRACT FROM AUTHOR]

The timing, duration and evolution of sea level during the Marine Isotope Stage 5e (MIS 5e) highstand is a subject of intense debate. A major problem in resolving this debate is the difficulty of chronologically constraining the sea level fall that followed the peak of the highstand. This was mainly controlled by ice-sheet dynamics, the understanding of which is relevant for assessing future sea-level behavior due to global warming. Here we use stratigraphical and geochoronological (U/Th dating and tephra fingerprinting) evidence from the Infreschi archaeological cave (Marina di Camerota, Southern Italy) to constrain relative sea level (RSL) evolution during the MIS 5e highstand and younger stages. Uranium-thorium dating of speleothem deposition phases places the maximum highstand RSL at 8.90 ± 0.6 m a.s.l., as indicated by the near-horizontal upper limit of Lithophaga boreholes measured for along a ∼3.5 km coastal cliff section. Geochronological data show that RSL fell more than 6 m before ∼120 ka, suggesting a duration of the Last Interglacial highstand significantly shorter than proposed in some previous studies. Modelling shows that the RSL trend predicted by the ICE-5G and ICE-6G ice-sheet simulations is consistent with our data, but requires an additional significant reduction of both Greenland and Antarctic ice sheets to match the height of the local maximum highstand if no correction for tectonics is applied. Reconciling field data and models requires an earlier and likely shorter duration of the MIS 5e highstand. This suggests that our new data can constrain global ice-volume variations during the penultimate deglaciation, as well as glacial inception at the end of the Last Interglacial. According to our chronology, there is no local evidence of higher-than-present-day sea levels after 120 ka. • Infreschi cave data indicate that maximum highstand during MIS5e was ca. 8 m asl. • Infreschi cave data indicate RSL dropped of more than 6 m before 120 ka. • Infreschi cave data indicate that there is no evidence of RSL higher than present after 120 ka. [ABSTRACT FROM AUTHOR]

Present climate conditions impede the formation of calcite speleothems in the gypsum caves of the semi-arid region of Sorbas (Southern Spain). However, U-Th dating reveals the uninterrupted deposition of a 46 mm-thick carbonate flowstone in the Sorbas caves from ∼78 to ∼71 ka, during Marine Isotope Stage (MIS) 5a. This indicates that the area was vegetated during this period, producing biogenic CO 2 in soils necessary for the underground deposition of the speleothem, which contrasts with the current unvegetated landscape. During MIS 5a, rainfall recharged the karst aquifer, leading to cave seepage. The development of soils and persistent water infiltration suggests a higher precipitation/evapotranspiration ratio with respect to the present, which was likely favored by lower regional temperatures and a different annual rainfall regime. δ18O and δ13C analyses testify that the speleothem recorded climate pulses synchronous, and structurally similar, with Greenland interstadial and stadial periods, with relatively wetter conditions recorded during interstadials 21.1, 20 and 19.2, and drier periods during stadials 21.1 and 20. This demonstrates that the climate in the desert-like environment of Sorbas is sensitive to inter- and intra- hemispherical triggers, such as the extent of Northern ice sheets and the Atlantic meridional overturning circulation. Interstadials (stadials) were also characterized by a higher (lower) Atlantic/Mediterranean moisture source ratio. For the first time, we show that carbonate speleothems formed in arid gypsum caves can record reliable palaeoenvironmental information spanning multiple millennia, procuring proxies for detailed palaeoclimate reconstructions. Such speleothems are thus excellent candidates for understanding past climate dynamics and patterns in desert-like gypsum terrains. • A rare calcite speleothem from Sorbas arid region recorded MIS5a palaeoclimate. • MIS 5a climate in Sorbas was more humid than today. • Greenland stadials/interstadials impacted MIS5a rainfall dynamics. [ABSTRACT FROM AUTHOR]