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We present a hydroclimate synthesis of the southern Great Basin over the last two glacial-interglacial cycles focused on paleolakes in Death Valley (core DV93-1), Searles Valley (core SLAPP-SRLS17), Owens Valley (core OL92), and the Devils Hole cave. There is close agreement between the occurrence of lakes in Death Valley and the height of the water table in the Devils Hole (50 km east of Death Valley) during the last 200 kyr. Death Valley and Devils Hole have adjacent, partly overlapping, drainage areas and most likely did over the last 200 kyr. When the water table in the Devils Hole was above the threshold level of ∼5 m higher than the modern, permanent lakes existed in Death Valley. At water table elevations less than 5 m above the modern, ephemeral lakes, saline pans, and mudflats occurred in Death Valley. The close temporal agreement between inferred paleoenvironments from the sediments in the Death Valley core and the paleowater table elevation in Devils Hole suggests a common forcing and provides insight into climate variability in the southwestern United States over the last 200 kyr. Owens Valley and Searles Valley, which derived inflow waters from the Sierra Nevada via the Owens River, contain paleohydrologic records which match those from Death Valley and the Devils Hole in terms of timing and direction of water availability over the last 200 kyr, indicating a similar paleohydrologic history for the entire southern Great Basin region. Near the end of Marine Oxygen Isotope Stage 6 (MIS 6), 140 ka - 130 ka, Lake Manly in Death Valley became shallow and hypersaline, and ultimately dried up at 127.1 ka ±4.3 ka. The transition from glacial to interglacial vegetation, which involved the loss of Juniperus pollen and an increase in Quercus (oak) pollen, occurred in Death Valley core DV93-1 at 131.3 ka ±4.0 ka. Following the glacial to interglacial pollen shift, a large alkaline lake formed in Death Valley. Similar conditions (freshwater, high productivity, and a mixed, deeply oxygenated water column indicated by biomarkers) existed in Searles Lake between 135.3 +2.7/ -2.9 ka and 130.1+2.7/ -2.6 ka, also following the juniper-oak pollen transition. Sr isotopes in calcite and sulfate minerals (gypsum, glauberite, thenardite), and the rare occurrence of the sodium carbonate mineral northupite with a low 87Sr/86Sr ratio in core DV93-1, together with organic geochemical proxies from Searles core SLAPP-SRLS17, all suggest that at this time, late MIS 6 Lake Manly in Death Valley received alkaline water via spillover from Searles Valley into Death Valley through Panamint Valley. The hydrologic connection between Searles Valley, Panamint Valley, and Death Valley at Termination II (130 ka) is documented here for this system of pluvial lakes for the first time. The Devils Hole water table decreased to +6.5 m at 140.8 ka ±3.2 ka, rose briefly to +8 m at 137.6 ka ±0.5 ka, and then dropped 8 m by 120.36 ka ±0.45 ka, when it reached an elevation similar to the modern. The pluvial lakes in Death Valley and Searles Valley may have coincided with the rise of the Devils Hole water table at ∼137.6 ka ±0.5 ka years ago, although the age models for core DV93-1 and core SLAPP-SLRS17 during the end of MIS 6 carry large uncertainties. • 200,000 year paleohydrologic synthesis of southern Great Basin: Death Valley, Searles Valley, Owens Valley, Devils Hole cave. • New data from Death Valley: U-Th dates (halite) and 87Sr/86Sr ratios (carbonates and sulfates). • Close agreement between Death Valley paleoenvironments and water table elevations in Devils Hole. • Searles Lake overflowed into Death Valley via Panamint Valley near the end of MIS 6. [ABSTRACT FROM AUTHOR]

Long-term hydroclimate records provide an opportunity to understand potential drivers of the past, and give context to modern and future climate warming. A wide variety of proxy data now allow for reconstruction of climate variables that were not previously possible. Here we present a multi-proxy dataset including n -alkane δ2H (δ2H n-alk) values from an open-basin lake in Estonia to reconstruct past hydroclimate conditions for the eastern Baltic region. We complement our sedimentary δ2H n-alk data with existing carbonate-based oxygen stable isotope (δ18O) data to derive deuterium (d -) excess. We present multiple isotopic records and reconstructed relative humidity (ΔRH) values over the Holocene, and link these with modern precipitation δ2H and δ18O values to guide the interpretation of the paleo-proxies. Fossil pollen and chironomid-based temperature reconstructions, as well as biogeochemical data provide additional information for inferring past environmental changes. Our results indicate that the middle Holocene in Estonia had on average 6 ± 3% higher RH values than the late Holocene. The δ18O and δ2H values were also higher during the middle Holocene, which we interpret as increased warm season precipitation. Our reconstructed d -excess values were relatively higher during the middle Holocene, indicating a more northerly or cold source water origin, in comparison to the late Holocene. In addition to the paleoclimatic significance, our results show how multiple quantitative proxies can be combined to characterize hydroclimate sensitivity to changes in relative humidity, temperature and moisture source. • Combined H and O isotope proxies permit d -excess and RH reconstructions. • Sedimentary biomarkers in the eastern Baltic region reflect Holocene hydroclimate. • Higher relative humidity and d-excess values recorded during the middle Holocene. • Relative humidity changes were modeled and quantified using n-alkane proxy. • Northerly moisture sources were dominant in Estonia during the late Holocene. [ABSTRACT FROM AUTHOR]

Understanding the Indian summer monsoon (ISM) variabilities under different climatic constraints on various timescales is crucial for socio-economic stabilization within the ongoing warming globe. However, aside from stalagmite records, very few terrestrial paleoclimate archives have been used to explore the last glacial ISM characteristic, which limits our understanding of the ISM natural behaviors and their underlying mechanisms on longer timescales. Here, we present a grain size end-member analysis for Tengchongbeihai wetland sediments from southwestern China to investigate the paleo-hydroclimate changes since the late MIS3. The overall low fine silt content before ∼19 cal ka BP resulted from weak catchment erosion indicating weak ISM during cold glacial while the increasing trend thereafter indicates the ISM strengthened during the last deglaciation and Holocene. Such an orbital ISM evolution resembles to the insolation gradient between 25°N and 25°S during the boreal summer periods, which implies that the transequatorial insolation difference could be an alternative explanation for the orbital scale low latitude hydroclimate changes. The remarkable peaks of coarse component around ∼9, 12, 19, 26, 32, 37 and 42 cal ka BP were related to significant water level descending indicating the millennial ISM collapse corresponding to the YD and Heinrich events. However, the absence of sawtooth feature as the NGRIP δ18O and the well correspondence to the Indian Ocean sea surface temperatures (SSTs) of the ISM collapses evidence the modulation of low latitude forcing on the North Atlantic climate effects on the millennial scale hydroclimate variabilities. • Millennial to orbital ISM changes over 46 ka was studied using a wetland sediment. • The trans-equatorial insolation gradient controlled orbital ISM evolution. • The millennial ISM fluctuations tele-connected to the North Atlantic instabilities. • Indian Ocean SSTs modulated the relation between ISM and North Atlantic climate. [ABSTRACT FROM AUTHOR]

Bat guano is an emergent paleoenvironmental archive and isotopic compositions of bat guano have been tied to climate, vegetation, and trophic processing in isolated studies. However, a comprehensive, multi-isotope assessment of bat guano has not been established, hindering the proliferation of guano-based paleoenvironmental research. In this study, we comprehensively examine isotopic compositions of a 12,000-year long bat guano core from Cave Springs Cave, Alabama as well as relevant isotopic data from other sources to improve our understanding of each isotope system (δ13C, δ15N, and δ2H), the source-to-sink components of guano isotope pathways, and the fractionation occurring along each multi-step isotopic pathway from sources (i.e., soil, atmosphere, rainfall) to guano formation. We find the δ13C values of guano from Cave Springs Cave primarily reflect local vegetation with a large shift that coincides with the onset of the Anthropocene (after 1950 C.E.). We also determine that the δ15N values of Cave Springs Cave guano were not associated with precipitation or any other climatic variable but instead reflect a change in bat diet and agricultural intensification during the past 600 years. Overall, this study adds to the existing body of bat guano research and supports bat guano as a reliable archive for paleoenvironmental reconstructions. [ABSTRACT FROM AUTHOR]

Reconstructing past climate seasonality is fundamental to understanding the nature of past climate changes. This is especially true in the Arctic, where climate is intensely seasonal and proxies that can distinguish climate conditions of multiple seasons in a single year are relatively rare. We propose that submerged aquatic mosses, which are abundant subfossils in some Arctic lake sediments and have distinctive seasonal growth morphologies, can be used to estimate past lake water oxygen isotope composition (δ18O lw) across multiple seasons. Aquatic mosses are abundant, well preserved, and grow continuously in Arctic lakes whenever light is available, with some species displaying unique seasonal morphologies influenced by water temperature. Although Greenland paleorecords suggest that aquatic moss oxygen isotope values (δ18O om) reflect the δ18O values of lake water, no modern calibration between δ18O om and δ18O lw exists in Greenland. We present a modern δ18O om vs. δ18O lw calibration using multiple moss species or morphotypes from eight lakes and ponds near Pituffik (Thule), northwest Greenland. We find strong linear relationships (r2 = 0.76-0.85) between the δ18O om and δ18O lw values of multiple species or morphotypes across the range of relatively low δ18O lw values at Pituffik, and our results indicate isotopic fractionations are similar to those found previously at lower latitudes. To assess the potential of mosses as archives of seasonal δ18O lw values, we analyzed δ18O om in season-specific segments of moss strands, with seasons identified based upon growth morphology. Moss inferred lake water δ18O values (δ18O lwom) are higher in autumn than spring or summer, likely due to increasing contributions of 18O enriched precipitation and the cumulative effects of lake water evaporation throughout the ice-free season. For moss subsampled throughout summer, δ18O lwom values generally increased through the season in parallel with observed δ18O lw values. Potential temperature dependent fractionation effects during biosynthesis, however, remain unconstrained and should be further addressed with future research. Overall, these findings suggest that aquatic mosses from lake sediments could be used to directly resolve climate seasonality of the past. • Aquatic moss strand δ18O values reflect lake water values through multiple seasons. • Summer subsampled moss strands show weekly to monthly evolution of lake water δ18O. • Aquatic moss vs. lake water δ18O calibrations are similar for species tested here. • Aquatic moss δ18O needs testing down core to evaluate past seasonal signals. • Temperature-dependent fractionation and pre-treatment effects need more research. [ABSTRACT FROM AUTHOR]

Holocene paleotemperature records from ice-free margins of Greenland suggest spatiotemporal heterogeneity in the timing of key climate transitions following retreat of the Greenland Ice Sheet. However, the paucity of high-resolution climate records from this region limits our understanding of the timing, spatial variation, and drivers of Holocene climate variability. Here, we present a middle to late Holocene climate reconstruction based on δ18O of aquatic invertebrate (chironomid and cladoceran) remains and sediment geochemistry from lake sediments to elucidate millennial to submillennial-scale drivers of climate in southwestern Greenland. We establish that our site, Arrowhead Lake, is a through-flowing basin with an integrated signal of annual meteoric water with no evidence of significant evaporative enrichment. Core sediment geochemistry captures the transition from minerogenic-dominated to organic-rich sediments ∼8 cal ka BP. Chitin-based δ18O measurements of both chironomid head capsules and ephippia exhibit similar temporal variability through the record, broadly decreasing from 8.2 cal ka BP to present, concurrent with decreasing summer insolation and regional Neoglacial cooling. A simplified assumption that temperature is the sole driver of changes in isotopes of precipitation yields an estimated average temperature change from the middle to late Holocene at Arrowhead Lake of 2.1–3.0 °C, comparable to existing estimates of middle to late Holocene temperature decline in western Greenland. Depleted δ18O values after 3.3 cal ka BP correspond to the onset of Neoglacial cooling and independent evidence for a slowdown of the West Greenland Current, and suggests that both temperature and sea-ice variability were important controls on isotopic variability at this site. Highly depleted isotopic values at 8.2 cal ka BP followed by high isotopic variability in the early part of the middle Holocene suggests that our record may capture regional 8.2 ka cooling. This new isotope record provides insight into climate influences during the middle and late Holocene along the western Greenland margin that are important for understanding how ongoing melt of the Greenland Ice Sheet and amplified warming in the Arctic may impact the climate system. • A new δ18O record offers insight into 8200 years of climate change in SW Greenland. • Data suggest ∼2.1–3.0 °C Neoglacial cooling, consistent with regional records. • Decreasing magnitude of temperature from north to south in western Greenland. • Highly depleted isotopic values are consistent with the 8.2 ka cooling. [ABSTRACT FROM AUTHOR]

In the piedmont of uplifting mountains, alluvial fan rivers undergo significant aggradation-degradation processes, which are usually attributed to climate change. An ongoing debate is whether this process requests the participation of glaciation. To address this debate, we need the knowledge of the quantitative relationship between the ratio of water to sediment flux (q w / q s) with the aggradation/degradation process. This study examined the aggradation and degradation processes in three alluvial rivers at the piedmont of the Qilian Shan (Shan referes to Mountain) and simulated the river processes by a one-dimensional numerical model based on the transport-limited principle. Along the studied piedmont rivers, field measurements show a magnitude of 120–200 m degradation and aggradation in the Late Pleistocene. Through simulation analysis, we explored how factors like the ratio of water to sediment flux (q w / q s), channel width, and sediment grain size influence river processes and longitudinal profiles, and found distinct morphologies in different processes, where aggradation is characterized by concave-up profiles, while degradation is characterized by convex-down profiles. Additionally, the water flux is inversely proportional to the time required for the river to reach a new equilibrium profile. The simulated degradation amplitude aligns closely with the measured data in the Qilian Shan, indicating that precipitation during the Last Glacial Maximum in the region amounted to approximately ∼32% of the Holocene precipitation. This supports the notion that changes in water flux or precipitation alone can induce significant piedmont deepening without the necessity of glaciation. • Built a model to quantify the link between water-sediment fluxes and river processes. • Simulated Qilian Shan piedmont river incision: ∼32% LGM precipitation vs. Holocene. • Precipitation alone can create deep canyons without requiring glaciation. [ABSTRACT FROM AUTHOR]

Mainland Southeast Asia experiences complex and variable hydroclimatic conditions, mainly due to its location at the intersection of Asian monsoon subsystems. Predicting future changes requires an in-depth understanding of paleoclimatic conditions that is currently hindered by a paucity of records in some regions. In this paper, we present the first speleothem stable isotope records from western Thailand detailing the Bølling-Allerød interstadial, Younger Dryas termination, and early- to mid-Holocene period. We find evidence of higher precipitation during the Bølling-Allerød (14,321–12,824 years before present (1950: BP)) compared to a Younger Dryas termination that starts 11,702–11,674 BP, has a rapid shift centered on 11,660–11,641 BP, and ends 11,603–11,589 BP. In addition, our records show Holocene monsoon intensity peaking at 8250 BP or before, a multi-millennia delay from the Northern Hemisphere summer insolation peak, followed by a trend to drier conditions until at least 750 BP. Assessment of the timing of the Younger Dryas termination in paleoclimate records across Southeast Asia reveals an earlier shift of the Indian Summer Monsoon to global climate shifts when compared to East Asian Summer Monsoon records. The causes of this are currently unknown. Some potentially important aspects include: an Indian Summer Monsoon influence on East Asian Summer Monsoon strength via the Indian Ocean Dipole climate pattern, the role of the Tibetan Plateau in monsoon dynamics, and exposure of the Sundaland shoreline. More high-resolution paleoclimate records, especially on the pathway of Indian Summer Monsoon to East Asian Summer Monsoon, are required for further discussion on the mechanisms controlling the differences between climate regimes. • We present two new speleothem stable isotope records from western Thailand. • Conditions trend wetter during the Bølling-Allerød. • Early and abrupt termination of the Younger Dryas (11,675–11,600 BP, ±73 years). • Change Point Analysis of records finds earlier rapid shift in Indian Summer Monsoon. • Distinct trend of increasing δ18O and δ13C values throughout Holocene. [ABSTRACT FROM AUTHOR]

The Southern Hemisphere Westerlies (SHW) are a vital part of the Southern Hemisphere's coupled ocean-atmosphere system and play an important role in the global climate system. The SHW affect the upwelling of carbon-rich deep water and exchange of CO 2 from the ocean to the atmosphere by driving the Antarctic Circumpolar Current. On seasonal to millennial timescales, changes in the strength and position of the SHW are associated with temperature and precipitation changes throughout the extratropical Southern Hemisphere. Understanding the behaviour of the SHW under different background climate states is important for anticipating its future behaviour and remains a subject of ongoing research. Terrestrial paleoclimate records from lake sediments are valuable for reconstructing past atmospheric change and records from the handful of sub-Antarctic islands provide the opportunity to develop datasets to document spatio-temporal patterns of long-term SHW behaviour. Here, we generate palynological, microcharcoal, and sedimentological reconstructions (including CT imagery, μXRF analysis, magnetic susceptibility, and loss-on-ignition) on lake sediments from the Kerguelen Islands (49°S) to constrain variability in Holocene vegetation, climate, and atmospheric circulation (SHW position). Due to the influence of the SHW on the Kerguelen Islands, the influx of long-distance transported (LDT) pollen and microcharcoal from southern Africa serve as proxies for the meridional position of the SHW. In contrast with the stable conditions that prevailed on the Kerguelen Islands over the past 8,600 cal yr BP, our findings reveal a highly dynamic Early Holocene period. Consistent with local palynological evidence of warmer conditions, a high influx of LDT pollen and charcoal from southern Africa suggest that the SHW core belt was located further south of the Kerguelen Islands during this time. Comparison against paleoclimate records from the surrounding region and beyond suggests that the inferred changes might be explained by changes to our planet's interhemispheric thermal gradient, triggered by North Atlantic cooling in response to melting of the last remnants of the Laurentide Ice Sheet. • We study Holocene vegetation and atmospheric circulation on the Kerguelen Islands. • Southern Hemisphere Westerlies position is based on long-distance pollen transport. • Wind belt shifts coincide with changes in local temperature and precipitation. • Durin the Early Holocene the core wind belt was positioned south of the Kerguelen. • From 8,600 cal yr BP the core wind belt shifted northward of the Kerguelen Islands. [ABSTRACT FROM AUTHOR]

Branched glycerol dialkyl glycerol tetraethers (brGDGTs) are a type of bacterial membrane lipid that are ubiquitous and robust for inferring paleoclimate evolution in continental settings, especially for paleotemperature. They can be engineered to show differential responses to ambient conditions under different settings, making setting-specific brGDGTs-based calibrations, mostly being linear models, preferable for paleoclimate reconstructions. However, even such a cautious approach is challenging given the allochthonous inputs and changing sedimentary settings that were inevitable in the geological past. In this study, a method called Locally Weighted Weighted Average-Partial Least Squares Regression (LWWA-PLS) commonly used in pollen-based reconstructions was introduced to address this challenge. In the latest modern global brGDGTs dataset from all archives known to host brGDGTs (n = 3068), we found that the LWWA-PLS model had high credibility in predicting environmental parameters (temperature, precipitation and pH) and that the average accuracy in estimating the contribution of brGDGTs in a sample from different environments (soil, peat, and subaqueous) reached 81%. Based on brGDGTs in two lacustrine sediment cores exhibiting multiple deposition settings since 90 and 70 cal ka BP, the LWWA-PLS model was able to generate results comparable to those from pollen-derived paleorecords and better than those derived from linear models. This is especially true for the mean annual air temperature reconstruction. Moreover, the LWWA-PLS model successfully estimated the contribution of brGDGTs from different sources, which was generally consistent with the sedimentary facies of the two sequences. Overall, the LWWA-PLS model based on the global brGDGTs dataset is expected to advance the applicability of brGDGTs to complicated terrestrial environments. • Confirm the efficacy of LWWA-PLS model in the modern brGDGTs dataset. • Generate records comparable to the pollen derived-paleoclimate parameters. • Reduce the influence from the lithology transition on paleotemperatures. [ABSTRACT FROM AUTHOR]

The Mid Piacenzian Warm Interval (MPWI) has been identified as an analogue for future global warming because it had warmer temperatures and higher atmospheric CO 2 levels than today, while subsequent early Pleistocene cooling is more similar to modern climate. However, reconstructions of these intervals lack seasonal-scale temperature reconstructions. Seasonal sea surface temperature (SST) reconstructions from deep-time archives can potentially provide insight into the nature of the climate system on sub-annual scales during critical climate states. Here we compared seasonal variability in growth temperatures during the MPWI and subsequent early Pleistocene cooling to modern climate reconstructed from oxygen isotope ratios recorded by the bivalve Mercenaria. Modern shells were collected from the University of North Carolina's Marine Sanctuary. Fossil shells from the Mid-Atlantic Coastal Plain (North Carolina) were collected from the Duplin Formation (MPWI) and the Waccamaw Formation (early Pleistocene). Oxygen isotope ratios range from −1 to 2.4 ‰ during the MPWI, −1–2.4 ‰ during the early Pleistocene, and −2.2 to 2.3 ‰ in modern shells. Stable carbon isotope ratios ranged from −0.91 to 1.67 ‰ during the MPWI, 0.19–1.87 ‰ during the early Pleistocene, and −2.46 to 0.60 ‰ in modern shells. Average seasonal growth temperature variations for the MPWI (∼11 ± 3 °C) are reduced compared to modern instrument records (∼16 ± 3 °C), while the early Pleistocene (∼14 ± 2 °C) was more similar to today. Modern Mercenaria record dark increment formation during the summer while fossil Mercenaria record dark increment formation during the winter. We hypothesize that this difference is timing of dark increment formation may be due in part to differences in water depth (∼1m for modern shells and ∼20m for fossil shells) or a shift in the location of the boundary between biogeographic zones. A −1.6 ‰ shift in mean stable carbon isotope ratios between fossil (0.92 ± 0.66 ‰) and modern (−0.65 ± 0.44 ‰) shells has been observed and may be a result of the "Suess Effect" and/or influences of estuarine/freshwater relative to marine settings. • Growth temperatures derived from oxygen isotope ratios show the MPWI had warmer winters and reduced seasonal amplitude compared to the early Pleistocene and today. • Mercenaria from the early Pleistocene recorded cooler summers and winter growth temperatures compared to modern Mercenaria. • Modern and fossil Mercenaria shells exhibit differences in the seasonal timing of dark increment formation. [ABSTRACT FROM AUTHOR]

Paleoclimatic records of sub-annual to interannual resolution are valuable for the study of climatic forcing mechanisms but these records are rare in terrestrial settings. Here, we show that high-resolution stable carbon isotope data within shells of land snails (δ13C shell) living in a C 3 plant-dominated community can be an indicator of growing season precipitation (GSP) amount. We collected modern land snails along two wet-dry climate gradients from northern Iran and the Chinese Loess Plateau (CLP), where the precipitation is mainly distributed in the boreal winter and boreal summer seasons, respectively. Our results indicate a common pattern of δ13C shell values increasing with aridity, driven by water stress in the local plant community. In contrast, temperature has a weak and inverse effect on δ13C shell values in these two regions, suggesting that rainfall amount is the primary control on δ13C shell for this modern comparison. Furthermore, we present a δ13C shell record covering the middle Holocene to the middle Pleistocene from the CLP. This record suggests that most of the average δ13C shell values from interglacial paleosol layers are lower than those from the adjacent glacial loess strata, suggesting higher GSP. However, the reconstructed glacial-interglacial difference in GSP is smaller than that estimated by other proxy indicators. This is likely due to the dietary preference of land snails and/or the sparse nature of this dataset, which might not be sufficient to capture the glacial-interglacial history of rainfall on the CLP. Large datasets with good taxonomic control and high stratigraphic resolution will be required to better describe the glacial-interglacial differences. • We report δ13C shell values from Westerlies Asia and Monsoonal Asia. • δ13C shell in C 3 plant communities is an indicator of growth season rainfall. • Reconstructed GSP are higher during interglacial periods than glacial periods. • Large dataset with high stratigraphic resolution will be required in future work. [ABSTRACT FROM AUTHOR]

This study offers a new record of laminated ooze for paleoclimate, paleoceanography and paleoecology interpretation in the deep ocean, promoting search for other similar records in the West Pacific Ocean to improve understanding of Ethmodiscus rex ooze formation and relative paleoenvironmental change. The laminated diatomaceous ooze includes large quantities of fragmented E. rex in a box core retrieved from the Challenger Deep, Southern Mariana Trench. Radiocarbon dating of the ooze revealed the studied sediment to originate during an interval of ca. 23 400 to ca. 6620 cal. yr. BP, inserting a hiatus during ca. 19 800 - 16 800 cal. yr. BP. This is the first geochronology data to constrain the E. rex ooze time span across the Pleistocene/Holocene boundary, compared to previous studies in this West Pacific Ocean trench. In this study, the laminated diatomaceous E. rex ooze type, with increased abundance of fragmented E. rex valves is mainly documented during ca. 23 400 - 19 800 cal. yr. BP. within the Last Glacial Maximum stage, at ca. 12 900 - 11 500 cal. yr. BP. in the Younger Dryas stadial, and around 9000–7700 cal. yr. BP. in the Postglacial. These data show a response to the paleoclimatic conditions with late Pleistocene cold periods that triggered E. rex diatom bloom that strongly competed for nutrients in this principally oligotrophic region. These phenomena are likely to be linked with terrestrial nutrients input through the aeolian dust transfer by winter Monsoon and the silicon supply from Southern Ocean via thermohaline circulation. In the Postglacial, the E. rex bloom generated a high ooze accumulation rate in terms of higher flux deposition with a complicated formation mechanism. • Laminated diatomaceous ooze with fragmented E. rex described from Mariana Trench. • First geochronology data shows E. rex ooze also occurred in Holocene in this Trench. • Diatomaceous ooze was not only driven by glacial stage but also created in warm period. • High E. rex flux responses to the LGM, YD event, and early-mid Holocene transition. • This offers a new record of ooze for paleoclimate, -oceanography, -ecology in this Trench. [ABSTRACT FROM AUTHOR]

Glacial-marine sediments from the Antarctic continental margin provide a record of depositional environment, oceanographic variability and ice dynamics that is tapped with scientific ocean drilling. This study focuses on Ocean Drilling Program Core 693A-2R, a 9.7 m sediment core retrieved from near the continental margin of the Archean Grunehogna Craton in Dronning Maud Land (DML), East Antarctica. The results contribute to a better understanding of ice-shelf behavior in DML during the mid-Pleistocene transition (MPT), a well-known transition from 40-kyr to 100-kyr cycle periods. The age model, constructed based on Sr isotope stratigraphy and geomagnetic reversals, indicates that the core spans 1.20 to 0.65 Ma. The dynamic behavior of DML ice shelves with periodic iceberg calving is revealed by the glacial–interglacial variation in sedimentation patterns, with interglacials characterized by higher concentrations of ice-rafted debris (IRD) associated with enhanced paleoproductivity than glacial intervals. The responses of DML ice shelves to warm climates are represented by a prolonged interglacial period at 1.0–1.1 Ma (MIS 31–27) and significant interglacial expressions during MIS 19 and 17. The 40Ar/39Ar ages of individual ice-rafted hornblende grains are compared with the on-land geology of DML and neighboring regions to determine the provenances of IRD. Specifically, 40Ar/39Ar results record primarily late Neoproterozoic to Cambrian ages (600–400 Ma) with a predominant peak of 520–480 Ma. This Pan-African/Ross orogeny signature is very common in East Antarctica but is not found in the most proximal margin of the Grunehogna Craton, and is instead associated with the region of DML several hundred kilometers east of the deposition site. This indicates that significant discharges of icebergs occurred in the remote DML, which were then transported by the westward-flowing Antarctic Coastal Current to deposit IRD at the studied site during the MPT. This study establishes a confirmed MPT sedimentary sequence off DML, against which future MPT proxy records from the Weddell Sea embayment and other sectors in Antarctica can be compared and correlated, and provides a basis for more detailed analyses of the response of DML ice sheet to Pleistocene climate variations. • Records from ODP Core 693A-2R indicate DML ice shelf instability during the MPT. • An age model constructed by Sr isotope stratigraphy and geomagnetic reversals. • A multi-proxy study to identify and characterize glacial-interglacial sedimentation. • Ice-rafted debris has a predominantly distal source instead of a local origin. • DML ice responses to climate changes align with global glacial cycles. [ABSTRACT FROM AUTHOR]

Peat-core records have a long history of being used for paleoclimate reconstructions in northern high-latitude regions but are less common in the southern tropical zone. In this study, we present a synthesis of published peat-core reconstructions and basal ages from high-elevation (>3000 m a.s.l.) sites in the northern and central Andes of South America. We complement this database by providing a new multi-proxy peat-core-based paleoecological reconstruction from the Alta Murmurani peatland, Cordillera Vilcanota, Peru. This record, with a peat inception age of 8980 cal. yr BP, was analyzed for plant macrofossils and stable isotopes (carbon, oxygen). This review (1) assesses the timing of peat initiation and development across the tropical high-elevation region of South America (8°N to 27°S); (2) assesses the reliability of peat-core paleoclimate reconstructions by comparing the peat-core inferences across sites and against other independent archives (e.g., lake sediments, ice cores, speleothems); and (3) determines which hydroclimatic conditions are favorable for peat formation and expansion across the study area. Our results show that peat initiation occurred throughout the Holocene, progressing from the northern Andes to central Andes, with highest initiation frequencies clustered at ca. 10,700 cal. yr BP and 8300 cal. yr BP, respectively. Our synthesis reveals that peat cores can be used to assess regional paleoclimate trends in the central Andes using a multi-proxy approach combining micro- and macrofossils such as pollen, stable isotopes, as well as organic and inorganic elemental analyses. We also identify three optimal peat-forming time periods, all with optimally wet conditions occurring at transitional hydroclimate phases: (1) following deglaciation, with warming temperatures and increased moisture related to glacial runoff (ca. 11,000 cal. yr BP and ∼8000 cal. yr BP), (2) under moderate moisture regimes related to intensifying ENSO and warmer conditions (∼3500 cal. yr BP), and (3) under conditions related to increased precipitation at the beginning of a cold period (Little Ice Age). We show that either regional climate (e.g., changes in precipitation) or local conditions (e.g., changes in glacial runoff) can promote peat formation across the study region. • Peat initiation occurred in the Andes throughout the Holocene with peaks at 10,700 cal. yr BP and 8,300 cal. yr BP. • Peat-based paleoclimate reconstructions are consistent across the central Andes since the mid Holocene. • Holocene peat-forming time periods were characterized by optimal moisture conditions and land availability. [ABSTRACT FROM AUTHOR]

This study investigates how convection over the Indo-Pacific warm pool (IPWP) differed during the mid-Holocene compared to the preindustrial period. The research employs modeling data from the Paleoclimate Modelling Intercomparison Project phases 3 and 4 combined with published hydroclimate records from the Maritime Continent and a new primary productivity reconstruction in the western Celebes Sea. While there is large variability amongst models in terms of simulating precipitation changes, the model AWI-ESM-1-1-LR has the highest agreement with proxy data. This model indicates a dipole pattern consisting of strengthened convection over the eastern equatorial Indian Ocean and Sumatra and weakened convection over the western equatorial Pacific and Borneo-Sulawesi-New Guinea. The reduced convection over the latter region is supported by the primary productivity record illustrating lower precipitation over Borneo and a deepened nutricline in the western Celebes Sea driven by anomalous equatorial easterly winds. This dipole pattern demonstrates an anomalous trans-ocean zonal circulation cell that links the western equatorial Pacific and equatorial Indian Oceans. This cell emerging in summer and peaking in autumn, is proposed to arise from a trans-ocean zonal imbalance of equatorial precipitation change induced by altered summer insolation, and higher equatorial insolation in autumn. The increased precipitation in South Asia during the mid-Holocene is partially attributed to moisture transported from the western equatorial Pacific associated with this anomalous zonal cell. Thus, the dipole pattern of altered IPWP convection is tightly linked to dynamic precipitation changes and can influence regions outside the IPWP. • Proxy-model comparison indicates an east-west dipole pattern of altered IPWP convection under the mid-Holocene condition. • An anomalous divergence occurs in the western equatorial Pacific resulting in lower primary productivity. • An anomalous zonal circulation can transport moisture from the western equatorial Pacific to South Asia in autumn. [ABSTRACT FROM AUTHOR]

Investigations of chronology play a key role in the majority of archaeological research endeavors and are particularly pertinent to examinations of culture-environment relationships, especially during periods characterized by rapid and marked climatic variability and environmental reorganization. Rigorous evaluations of available data and robust methods are required if one wishes to reconstruct reliable chronologies, and this is especially the case when examining periods that are associated with a relatively few radiometric measurements. Such is the case for the Upper Paleolithic archaeological record documented in present-day France from 32,000 to 21,000 calibrated years BP. We take into account critically examined radiocarbon measurements from contextually secure archaeological contexts and employ a recently-developed method of Hierarchical Bayesian Modeling to reconstruct the chronology of archaeological cultures from the Middle Gravettian to the Badegoulian. The calculated chronological intervals for each typo-technologically defined culture phase are compared to the Greenland ice core climatic record and a terrestrial paleoenvironmental record from Bergsee Lake (Southern Germany)—itself expressed in calendar years calculated with the same calibration curve employed in our age model—thereby permitting each archaeological culture to be correlated accurately with documented paleoclimatic variability. • Robust chronologies are needed to correlate past cultures with climate variability. • A recently-developed method of Hierarchical Bayesian Modeling is employed. • Temporal intervals for archaeological cultures are determined with this method. • Arguments are presented as to why this new Bayesian method is preferable. [ABSTRACT FROM AUTHOR]

Alpine glaciers are sensitive indicators of changes in climate, and their ubiquity in mountainous regions make them valuable proxies for terrestrial climate reconstructions worldwide. However, the timing and extent of glacier change across the South American mid-latitudes through the Holocene are still poorly constrained relative to their counterparts in the Northern Hemisphere. Here we report a new 10Be surface exposure-based chronology of moraines recording a series of progressively less-extensive glacier advances of Glaciar Torre (Argentina, 49.3°S/73.0°W) since the Last Glacial Maximum, with expansions culminating at 17,600 ± 900, 13,500 ± 500, 9700 ± 400, 6900 ± 200, 6100 ± 300, 4500 ± 200, and 530 ± 60 yr BP. The declining magnitude of Holocene glacier expansions parallels a gradual rise in local summer insolation intensity during the Holocene, while individual advances occurred during inferred negative Southern Annular Mode (SAM)-like states at centennial to millennial timescales. These observations suggest that (i) summer insolation intensity modulated antiphased trends in glacier extent in the polar hemispheres during the Holocene, and that (ii) centennial-scale 'SAM-like' temperature and precipitation anomalies paced glacier fluctuations throughout Patagonia. Given the persistence of the inferred 'SAM-like' anomalies throughout the Holocene, the modern measured trend towards positive SAM index conditions could mark the onset of a fundamental shift in the climate of the Southern Hemisphere midlatitudes that warrants consideration in projections of future climate. Image 1 • Seven advances of the Torre glacier, Argentina (49°S), are dated using cosmogenic 10Be surface exposure dating. • Progressively less-extensive advances occurred at 17.1 ka, 13.5 ka, 9.7 ka, 6.9 ka, 6.1 ka, 4.5 ka, and 0.5 ka. • Late-glacial advances correspond to the onset of the Last Glacial Termination and the ACR. • Repeated expansions after an early Holocene glacier maximum define a new pattern in Patagonia, reminiscent of New Zealand. • We propose Holocene glaciers in Patagonia were controlled by trends in summer insolation and the Southern Annular Mode. [ABSTRACT FROM AUTHOR]

The Levant region of Israel, located along the Eastern Mediterranean Sea, is characterized by Mediterranean climate, but sixty km eastwards towards the Dead Sea Rift Valley (DSRV), the region rapidly becomes a 'rain shadowʼ desert. Speleothems from the Mediterranean climate zone continuously grew throughout several glacial/interglacial cycles, indicating that water was always available in the unsaturated zone. Their δ18O variations match global and regional climate changes, with the Eastern Mediterranean Sea being the major control on their δ18O values, as evident from the similarity between the speleothems and the planktonic foraminifer G. ruber records. In contrast, speleothems along the central and southern segments of the DSRV grew mainly during last glacial periods coinciding with the higher stands of Lake Lisan, the precursor of the present-day Dead Sea. This paper discusses the newly discovered Zalmon Cave speleothems, located in the northern segment of the DSRV shedding light on the hydrological conditions along the rift during last glacial. Unlike speleothems located further south along the DSRV, Zalmon Cave speleothems grew both during glacial and interglacial periods. However, during last glacial their δ18O values, shifted to lower values by ∼1–2‰ relative to speleothems from central Israel coinciding also with the largest difference in δ18O values between Zalmon Cave speleothems and the marine record. The data suggest that a change of the westerlies' storm tracks occurred during most of the last glacial period, which resulted in increased rainfall in the northern DSRV providing freshwater input during the otherwise relatively 'drierʼ glacial. • Speleothems were deposited almost continuously in the northern Dead Sea Catchment. • Interglacial climatic conditions in the Lower Galilee and central Israel were similar. • Glacial climatic conditions in the Lower Galilee were more humid than central Israel. • The Levant experienced a southern shift in storm tracks during the Last Glacial. • Differences in sea-land isotopic relationships indicate changes in precipitation. [ABSTRACT FROM AUTHOR]

Quaternary interglacials provide key observations of the Earth system's responses to orbital and greenhouse gas forcing. They also inform on the capabilities of Earth system models, used for projecting the polar ice-sheet and sea-level responses to a regional warmth comparable to that expected by 2100 C.E. However, a number of uncertainties remain regarding the processes and feedbacks linking climate, ice-sheet and sea-level changes during past warm intervals. Here, we delineate the major research questions that need to be resolved and future research directions that should be taken by the paleoclimate, sea-level and ice-sheet research communities in order to increase confidence in the use of past interglacial climate, ice-sheet and sea-level reconstructions to constrain future predictions. These questions were formulated during a joint workshop held by the PAGES-INQUA PALSEA (PALeo constraints on SEA level rise) and the PAGES-PMIP QUIGS (QUaternary InterGlacialS) Working Groups in September 2018. [ABSTRACT FROM AUTHOR]

Extensive drillings and 31 new C-14 datings were used to establish the geomorphological evolution of the Turia river delta and coastal barrier-lagoon system of Valencia (Spain) over the last three millennia. Integration of geomorphological, stratigraphic, malacological, sedimentological and geoarchaeological data enables us to relate river Turia avulsions and alluvial episodes to the development of coastal spits and barriers. Geomorphological changes in the study area may also be associated with global climate events, sea-level fluctuations or anthropogenic periods in the Turia catchment. Six phases may be differentiated: (1) a major early alluviation phase during the Iberian period, when the Turia river ran to the north of the coastal plain and sand spits closed the Valencia open lagoon environments, forming a permeable barrier (2800 BP to 2300 BP approximately); (2) an avulsion phase of the Turia river to the south at the end of the Roman period (4th century AD); (3) formation of a more advanced spit just behind the most recent barrier during the Late Antique Little Ice Age (LALIA, Visigothic period); (4) a flood period of high-magnitude with coarser sediments throughout the Medieval Climate Anomaly (MCA, 11th century AD), when La Punta meridional deltaic ridge developed, which can be related to beach ridge closing and marine isolation of the Valencia lagoon around the 12th century; (5) important river alluviation and growth of the recent coastal barrier favoured by Turia channel changes during the Middle Ages, in the early Little Ice Age (LIA); (6) rapid coastal progradation and decline in salinity in the Valencia lagoon between the Maunder sunspot minimum (MM) and the end of LIA. • Mediterranean delta and lagoon evolution has been linked to Turia River's alluvial phases and global climatic episodes. • The Turia River mouth's increasingly meridional advance towards the sea fed successive prograding spits from 2800 BP. • A period of high-magnitude floods throughout the MCA precedes the total marine isolation of the lagoon by the 12th century. • The Turia river channel was overloaded with sediments during the early LIA, contributing to the coastal barrier growth. [ABSTRACT FROM AUTHOR]

This study presents the results of a multi-proxy analysis of a Holocene lacustrine sediment sequence recovered from a small tundra lake in the central Canadian Arctic and links climatic variations there to the North Atlantic. Chironomid and pollen-based reconstructions of mean July air temperature (MJAT) document notable deviations at 9.3 ka and 8.2 ka. Chironomid-inferred July air temperature is depressed by 1.4 °C at 9.3 ka and 1.7 °C at 8.2 ka relative to the long-term chironomid-inferred Holocene average of 9.4 °C. These cooling events also correspond to an increase in Gramineae (Poaceae) and a decrease in Betula pollen, reflecting a decrease in the density of dwarf birch cover. Concurrent, abrupt increases in several diatom taxa, including aerophilic epiphytes, and Sphagnum indicate an expansion of moss habitats as a result of wetter conditions. The expression and timing of the cooling evidenced at TK2 during the early Holocene is consistent with abrupt climate events identified in the North Atlantic and coincides with intervals of North Atlantic cooling and weakened Atlantic Meridional Overturning Circulation (AMOC). This research, which improves our understanding of the spatial extent and magnitude of the 9.3 ka and 8.2 ka events in the central Canadian Arctic, serves as a benchmark for coupled-ocean atmosphere climate models simulating the response of the climate system to abrupt climate events and provides insight in marine-atmosphere teleconnections in the circum-North Atlantic region. • Fluctuation in mean July air temperature (MAAT) evidenced in the Canadian Arctic in the early Holocene. • MAAT depressed by ∼ 1.4 °C at ∼ 9.3 ka and 1.7 °C at ∼ 8.2 ka relative to the Holocene average. • Events coincide with intervals of weakened Atlantic Meridional Overturning Circulation. • Supports role of atmosphere and ocean in transmitting climate signal associated withevents. [ABSTRACT FROM AUTHOR]

Ravine slopes at the recently discovered Nesseltalgraben site in southeastern Germany provide a unique last glacial sediment record for the Northern Calcareous Alps. The 21 m-long profile is dominated by fine-grained lacustrine-palustrine sediments overlain by several metres of glacifluvial gravels and lodgement tills of the Last Glacial Maximum and underlain by a diamicton. The age model includes 29 radiocarbon analyses and one paleomagnetic anomaly (Laschamp event) together providing a modelled age range from c. 59 to 29.6 ka cal BP, i.e. Marine Isotope Stage (MIS) 3. Apart from a description of the lithofacies, X-ray-fluorescence (XRF) scanning and elemental analyses provide high-resolution records of the geochemical composition. Multivariate analyses of XRF data separate Ca from other major elements. Carbonate contents, represented by Ca and total inorganic carbon, reach maxima in repeatedly occurring calcareous silty to sandy layers and are related to glacigenic origin. These indicate repeated inner-alpine local glaciations during stadials of MIS 3. Scanning electron microscopy and XRF data confirm the detrital origin of these layers. In contrast, organic matter and elements more resistant to chemical weathering (Si, Ti, Zr) accumulated during interstadials and concurrently elevated Rb/Sr ratios indicate intensified weathering. The high-frequency proxy variations determined for Nesseltalgraben reflect interstadial-stadial climate variability comparable with oxygen-isotope records from Greenland ice cores and Alpine speleothems. Thus, Nesseltalgraben is among the very few independently dated sediment records from continental Europe covering the entire MIS 3 and reflecting the full Dansgaard-Oeschger climate variability. • A 21 m sediment profile from the northern Alps provides a complete MIS 3 record. • Repeated inner Alpine glaciations are indicated by calcareous silt layers. • Geochemical variations reflect interstadials and stadials. • The Nesseltalgraben record resembles Dansgaard-Oeschger climate variability. [ABSTRACT FROM AUTHOR]

We present a new speleothem trace element and stable isotope record, which extends previous paleoclimate evidence from Cuban speleothems to the last 96 ka. Multiple proxies were used to reconstruct Caribbean hydroclimate and vegetation variability on orbital to millennial timescales. In particular, our proxies indicate a shift to more abundant C4 (compared to C3) vegetation and/or reduced soil activity during the Last Glacial Maximum. Our results confirm the close link of Caribbean precipitation to North Atlantic climate variability, insolation and the strength of the AMOC. The associated variations in Caribbean SSTs and the shift of the ITCZ led to substantial changes of the hydrological cycle. During Heinrich stadials and the Younger Dryas, climatic conditions in Cuba were comparably cool and/or dry. In contrast, warm Dansgaard/Oeschger cycles were accompanied by wetter conditions. This is in agreement with previous evidence for the Holocene, when North Atlantic cold (warm) events coincided with drier (wetter) conditions in Cuba. However, our record suggests that this connection was less dominant during MIS 4 to 2, displayed by a weaker response of Cuban precipitation proxies to North Atlantic climatic shifts than during MIS 5 in particular. We hypothesize that this weaker connection was mediated by the southerly shifted ITCZ inducing a weakening of the northern branch of the Caribbean Low Level Jet which usually transports moisture into the northern Caribbean. This is strikingly evident during the deglacial, when driest and/or coolest conditions prevailed in western Cuba from HS 1 into the Younger Dryas, including the Bølling/Allerød interstadial. • We present a speleothem stable isotope and trace element record from Cuba covering the last 96 ka. • Our results confirm the link of Caribbean precipitation to NA climate, insolation and the AMOC. • Last glacial NA cold (warm) (inter)-stadials coincided with drier (wetter) conditions in Cuba. • During the LGM, our data suggest a shift to more abundant C4 vegetation and/or reduced soil activity. • We observe a weaker sensitivity to NA climate during MIS 4 to 2 compared to MIS5 and the Holocene. [ABSTRACT FROM AUTHOR]

The Maritime Continent, home to widespread tropical rainforest and millions of people, is the primary region of deep atmospheric convection on the Earth. However, debate exists whether the isotopologues of water reflect rainfall amount during the Last Glacial Maximum (LGM), resulting in different interpretations of the LGM climate of the Maritime Continent. Here we present paired leaf wax δ13C and δD records together with pollen data from a sediment core retrieved off East Java dating back to 22,000 years before present. We use three n- alkane homologues (n- C 29 , n- C 31 and n- C 33) in order to reconstruct past changes in vegetation types and seasonal rainfall. Our results suggest that in East Java, evergreen rainforest remained the dominant vegetation type in montane regions since the seasonality there remained relatively unaltered over the entire period. In contrast, the East Javanese lowlands were characterised by C 4 grass expansion and an extended dry season but a wetter rainy season, thus stronger seasonality, during the LGM. • Canopy structure of the montane rainforest of East Java remained relatively closed during the Last Glacial Maximum (LGM). • East Javanese lowlands were more seasonal with a shorter but wetter rainy season during the LGM compared to the Holocene. • Multiple-homologue leaf wax isotopes reflect rainfall regimes of distinct ecosystems. [ABSTRACT FROM AUTHOR]

This study aims to evaluate a reconstruction method of past storminess using aeolian sand influx (ASI) in peat deposits. We use high-resolution records of ASI from four peat bogs along the Estonian coast and compare those with local instrumentally-recorded storminess data since 1920 AD and with historical climatic records around the Baltic Sea over the last two centuries. Potential effects of local changes in forest cover and anthropogenic disturbances on the ASI signals are also evaluated with historical maps available for the study sites. Diameter of all sand grains >65 μm is measured with an image analysis system to detect temporal changes in the grain-size distribution. Our results demonstrate two major periods of high ASI over the last centuries in the region: during the 19th century and since the 1950s with highest values in 1980–2000 AD. Cross-correlations between the changes in ASI and the instrumentally-recorded storm days during the last century are positive and significant. High ASI values recorded during the 19th century correspond to the positive NAO indices and high cyclonic activity reconstructed in southern Sweden. We find that sand grains <250 μm in diameter add additional information for detecting changes in storminess. Temporal shifts in grain-size distribution and median diameter of mineral grains occur in every core, showing changes in the source materials through time. • Validity of aeolian sand influx (ASI) as an index of past storminess is evaluated. • ASI records in peat correspond well to the overall trend of storminess since 1800s. • Sand fractions <250 μm in peat are reliable to depict past storminess trends. • Shifts in grain-size distribution of sands suggest changes in the source material. [ABSTRACT FROM AUTHOR]

Due to the scarcity of natural archives for palaeoenvironmental studies, the climatic evolution of South Africa during the late Quaternary remains the subject of considerable debate. Peat deposits provide excellent archives to investigate past environmental and climate variability. Vankervelsvlei, a fen near the southern Cape coast, located 152 m above mean sea level within the year-round rainfall zone of South Africa, is ideally suited to investigate past environmental changes in this region. A 14.6 m long sediment sequence was retrieved from the fen, from which 8.85 m of sediment have been analysed using a multi-proxy approach. This includes elemental, macrofossil and micropalaeontological analyses. As a novelty in palaeoenvironmental reconstruction in this region, leaf wax n -alkanes and their compound-specific stable carbon and hydrogen isotopes were also investigated. The chronology of the sequence is based on 13 radiocarbon ages and reveals a basal age of 37,430 +1,570/ -1,710 cal BP. The top of the investigated sequence has an age of 1,180 +340/ -170 cal BP. Leaf wax n -alkane abundances and their compound-specific stable carbon and hydrogen isotopes, as well as various (in)organic (bio)geochemical parameters, indicate that the older section of the sequence (37,430 +1,570/ -1,710 - 28,050 +510/ -600 cal BP), which is composed of strongly degraded peat, represents a rather dry phase during MIS 3. This is followed by a hiatus of around 20,000 years (28,050 +510/ -600 to 8,360 +730/ -810 cal BP) reflecting the driest conditions during MIS 2. By comparing to supra-regional archives, this is hypothesised to have resulted from a larger extension of the Antarctic sea ice, which caused an equatorward shift of the Westerlies, blocking the tropical easterlies and resulting in drier conditions along the south coast and the adjacent coastal platform. During the Early Holocene, the input of reworked soil into the depression and subsequently renewed peat formation from 6,820 +305/ -365 cal BP to 1,180 +340/ -170 cal BP in Vankervelsvlei point to moister climatic conditions. Contraction of Antarctic sea ice and a poleward shift of the Westerlies during the Holocene is consistent with this interpretation. Climatic driving forces are suggested to differ between centennial/millennial and orbital time scales. Evapotranspirative enrichment through stronger winds is assumed to be the main driver on centennial to millennial time scale within this hydrological system. However, a combination of evapotranspiration and precipitation amount seems to be the most prominent driver on the orbital time scales. • Multi-proxy approach including compound-specific isotopes from leaf wax n -alkanes. • Westerly movement affects the southern African climate. • MIS 3 dry, MIS 2 even drier, MIS 1 wetter, but variable climatic conditions. • Leaf wax δ2H values are affected by wind-driven evapotranspiration. [ABSTRACT FROM AUTHOR]

From 10Be surface-exposure dating we make the case that classic late-glacial moraines in southwestern Norway, including the iconic Esmark moraine, and in the Southern Hemisphere middle latitudes, including the iconic Birch Hill moraine of the Southern Alps of New Zealand, were constructed coevally within dating uncertainties. This finding of simultaneous glacier resurgence in the two polar hemispheres carries the implication that the millennial-scale climate reversal of the last deglaciation was global and required a change in the energy budget of the earth's climate system. • Construction of Esmark and Lysefjord moraines took place by 12,700 yrs ago. • Glacial recession to Esmark position during Heinrich Stadial 1. • Recession from the Esmark moraine during Younger Dryas time. • Coeval glacier advance in Scandinavia and in Southern Hemisphere during the ACR. [ABSTRACT FROM AUTHOR]

Palynomorphs, including pollen and dinoflagellate cysts from marine sediments, can provide a history of paleoclimate and paleoceanography. We present new palynological profiles based on a core from the Integrated Ocean Drilling Program Site U1430, which was drilled in the Ulleung Plateau East Sea. This core covers the past 2 Ma and spans the Mid-Pleistocene Transition (MPT, 1.2–0.8 Ma) and Mid-Brunhes Event (MBE, ∼0.43 Ma). Terrestrial and marine palynomorph records indicate orbital-scale variations in paleoclimate and paleoceanography, reflecting changes in the interconnections between vegetation, climate, and the ocean. Before the MPT, the high pollen taxa ratio and abundant temperate pollen suggest a relatively warm temperature associated with astronomical forcing-induced insolation changes. At ca. 1.3 Ma, boreal coniferous pollen increased, suggesting intensification of the East Asian winter monsoon (EAWM). The long-term trend of boreal coniferous pollen concentration was similar to that of benthic δ18O. This orbital scale boreal conifer pollen assemblage variation indicates Quaternary EAWM evolution controlled by changes in global ice volume and climatic cooling. The marine palynological data reflect the ocean circulation history of the study area, where sea level fluctuations and tectonic activity played important roles around the marginal sea. The abundance of warm-water dinoflagellate species after ca. 1.9 Ma, including Tuberculodinium vancampoae , indicates Tsushima Warm Current intrusion related to the expansion of the Korea (Tsushima) Strait. Nematosphaeropsis labyrinthus and other cold-water species increased markedly during the MPT, suggesting a low sea surface temperature and weakened vertical mixing of the East Sea due to the cooled climate and sea ice during the MPT. The marked sea level fluctuation associated with the glacial–interglacial cycling after the MBE resulted in an assemblage composition shift from cold to warm water species. Tsuga and Betula thrived during mild winters, primarily influenced by winter insolation. These genera were particularly prosperous in the early Pleistocene, coinciding with a strong intrusion of the Tsushima Warm Current (TWC). Our findings should be considered in developing a comprehensive understanding of the paleoclimate and paleoceanographic history of northern East Asia across the major climate transitions of the Pleistocene. • Palynological records of Site U1430 reflect paleoenvironmental history over the 2 Ma. • Pollen records imply insolation forced paleotemperature changes prior to the MPT. • Boreal conifer pollen records indicate that the EAWM intensified at ca. 1.3 Ma. • Intrusion of the TWC intensified following the expansion of the KS at ca. 1.9 Ma. • Our results allow a direct comparison between climate-vegetation-marine conditions. [ABSTRACT FROM AUTHOR]

The El Mirón Cave site in Spain has one of the most complete archaeological and palaeontological records of the Late Pleistocene in the Iberian Peninsula, encompassing most of the last c. 50,000 years. Among other studies, the fossiliferous record has allowed the development of various interpretations of faunal and climatic changes during this period of time in the northern Atlantic region of the Iberian Peninsula. The addition of more radiocarbon dates from El Mirón Cave make it possible to revise some of the interpretations of the micromammal sequence carried out earlier for this major site. The record of small mammals is one of the most used tools to study the climate of the past, and among them the several Arvicolinae species are of great importance for the study of Quaternary climatic variations, due to their adaptations to a great diversity of habitats. New methodologies such as ancient DNA and geometric morphometric analyses now permit us to conduct a review of the Arvicolinae species previously described at this site and better to differentiate between species with similar morphologies, like Microtus arvalis and M. agrestis. We also identified the presence of a species not recorded before in El Mirón, Terricola pyrenaicus. With the study of the Arvicolinae species associations, we reaffirm the climate variations originally described in this deposit, indicating in detail how the successive changes in temperature and environment took place throughout the course of the late Last Glacial and early Postglacial periods (Marine Isotope Stages 3–1). • Review of the Arvicolinae association in the El Mirón Cave. • Using geometric morphometry to differentiate morphologically similar species. • Using ancient DNA analysis to identify a new specie in this site. • Climatic variations during the Late Pleistocene in the northern Iberian Peninsula. [ABSTRACT FROM AUTHOR]

Paleoclimate records from highland and coastal contexts are synthesized for Peru's north-central coast with a focus on the period from 6000 to 2000 cal yr BP. Around 6000 cal yr BP, both the highlands and coast experienced considerable climatic change. Increased precipitation in the southern tropical Andes ended a long period of aridity, resulting in higher lake levels and renewed glacial activity. Meanwhile, the north and central coasts experienced a major shift in the El Niño-Southern Oscillation that may have accompanied a change in background sea surface temperatures. Between 4000 and 3500 cal yr BP, glaciers began to retreat even as the South American Summer Monsoon strengthened, signaling a shift to warmer temperatures and continued increases in highland precipitation. Around 3000 cal yr BP, El Niño abruptly increased in frequency to near-modern intervals, with more frequent rain events on the coast and greater climate variability in the highlands, including notable periods of drought. This synthesis highlights areas in which more work is needed to improve understanding of paleoclimate change and its effects on water availability, including disentangling the effects of precipitation and temperature on water balance, reconstructing changes in coastal humidity, and investigating the relative influence of coastal and highland climate regimes over the middle elevations of the western Andean slope. • Holocene paleoclimate records are broadly consistent for north-central Peru. • Climate shifts at 6000, 4000, and 3200 cal yr BP affected coast and highland areas. • Changes in coastal and highland climates affected runoff production and river flow. • Basin-wide perspectives of paleoclimate provide insights on coastal culture change. [ABSTRACT FROM AUTHOR]

The difficulty in constraining the large-scale Asian summer monsoon (ASM) variability in the Chinese monsoon region (CMR) during glacial Termination II lies in our limited knowledge of the western part, primarily due to sparse paleoclimate records. To get a better picture of the ASM during Termination II, we examined a precisely dated stalagmite δ18O record between 133.1 and 127.0 kyr B.P. from Wanxiang Cave located at the ASM's northern edge in western China. In combination with published δ18O data from this cave, we have identified the 'Weak Monsoon Interval' (WMI) in the Wanxiang δ18O record and confirmed that the Heinrich 11 cold event in the North Atlantic caused the weakened ASM over the CMR via reorganization of the large-scale ocean-atmospheric circulation. However, the post-WMI change in δ18O is gradual, in contrast with the abrupt shift shown in the other cave records from southern and northeastern China. The rapid northward migration of the westerly jet relative to the Qinghai-Tibet Plateau is probably responsible for this discrepancy. This northward-positioned westerly jet prevented the more 18O-depleted moisture from the Indian Ocean from reaching the study site. Simultaneously, it facilitated the earlier northward movement of the East Asian summer monsoon (EASM) rainband that carries positive precipitation δ18O to obscure the abrupt decrease in our δ18O record. After the onset of the last interglacial, no obvious Younger Dryas (YD)-like event was recorded in Wanxiang Cave. This result is consistent with most stalagmite δ18O records in the CMR and further suggests a minimal impact of the YD-like event on ASM variabilities. The relatively large amplitude of δ18O variations observed in Wanxiang Cave between the late penultimate glacial and the last interglacial corresponds to a dominant control of the Indian summer monsoon (ISM), whereas smaller δ18O amplitudes were recorded in cave sites mainly under the influence of both ISM and EASM. Therefore, we posit that the heterogeneity of the hydroclimate in the CMR during Termination II resulted from a combination of multiple processes, that is, the westerly jet, ISM and EASM, rather than a single one. • A precisely dated stalagmite from the ASM's northern edge in western China reveals ASM variability during Termination II. • Our δ18O records capture the WMI event, which corresponds well to the HS 11 period at northern high latitudes. • Gradually changes in δ18O at the onset of the last interglacial are due to the abrupt northward shift of the westerly jet. • The YD-like event did not have a far-reaching impact on ASM variabilities in the Chinese monsoon region. • Moisture sources cause the amplitude discrepancies in Chinese stalagmite δ18O records during the penultimate deglaciation. [ABSTRACT FROM AUTHOR]

The long-term climate dynamics of the central Andes are part of an ongoing international research effort to reconstruct past climatic variations and sensitivity to different regional and global drivers during the last 50,000 years. The large number of diverse records, however, makes it difficult to compare results without an integrated spatial analysis that considers the nature of the record and whether they are integrating environmental conditions across a large basin (i.e., a lake record) or at a very local scale (such as a rodent midden). We compiled 92 records from the southern sector of the central Andes (SCA, 18°-35°S). Recalibrated records were further compared by converting the original author's interpretation into a scale of relative moisture anomalies (compared to the present) that ranges from −2 (very dry) to very wet (+2). Moisture anomaly maps were generated for intervals at 4, 6, 9.5, 14, 17, 21 and 32 ka BP (103 calibrated 14C years before present) using records within a 5% age uncertainty. Our compilations show a surprising degree of agreement in the extent and magnitude of past climate changes during late Pleistocene, but less spatial agreement during the Holocene. The TRACE21 transient climate model shows similar results, with better agreement during the Pleistocene compared to the Holocene. Our analyses not only reveal discrepancies between proxy record interpretations at sites from the same region but show which regions in the SCA require more study. • We compiled 92 paleorecords from the South-Central Andes and produced paleoclimate maps from 32 to 4 ky. • The wettest period in our maps occurs at 17 ky BP during Heinrich Event 1. • Holocene maps show much less spatial agreement than reconstructions for the Pleistocene. • Proxy-model comparisons using TRACE21 show better agreement in Late Pleistocene maps than for Holocene maps. • The most arid period recorded occurred in the map of 6 ky BP (Northgrippian). [ABSTRACT FROM AUTHOR]

Holocene paleotemperature reconstructions across the western Arctic suggest strong spatial variations in air temperature despite zonally uniform Northern Hemisphere insolation forcing. Although most paleotemperature reconstructions across the Eastern Canadian Arctic place the Holocene thermal maximum >3 kyr after peak summer insolation, other records indicate maximum summer warmth was coincident with peak summer insolation. To address this discrepancy, we use radiocarbon inventories in plants and rocks recently exposed by receding ice caps to reconstruct early Holocene changes in glacier dimensions, a reliable proxy for summer air temperature. Fourteen radiocarbon ages from newly exposed plants in growth position collected at the margins of eight retreating ice caps on Baffin Island indicate ice caps expanded 9.3 ± 0.3 ka, and remained over these sites until recent summer warming, indicating peak early Holocene summer warmth occurred prior to ∼9.3 ka. We test this conclusion using in situ cosmogenic 14C (in situ 14C) inventories in rocks at four sites with dated plants. In situ 14C production simulations using realistic Holocene ice-cover histories constrained by plant 14C ages show that measured in situ 14C concentrations are consistent with centuries to millennia of pre-9.3 ka exposure, followed by continuous ice burial. The combination of plant and in situ 14C data provide firm evidence that the Eastern Canadian Arctic experienced peak Holocene summer warmth prior to ∼9.3 ka, consistent with peak summer insolation, followed by continuously colder summers until modern warming. • 14C inventories in plants and rocks exposed by receding ice reconstruct early Holocene glacier changes on Baffin Island. • Ice caps buried sample sites at 9.3 ± 0.3 ka and remained over these sites summer warming. • Simulations of radiocarbon production in rock surfaces are consistent with centuries to millennia of pre-9.3 ka exposure. • This new evidence suggests that Baffin Island experienced peak Holocene summer warmth prior to ∼9.3 ka. [ABSTRACT FROM AUTHOR]

The Dead Sea sedimentary fill is the basis for interpreting limnological conditions and regional paleohydrology. Such interpretations require an understanding of present-day hydroclimatology to reveal the relative impact of different atmospheric circulation patterns on water and sediment delivery to the Dead Sea. Here we address the most important meteorological conditions governing regional and local rainstorm occurrences, with different discharge characteristics. These meteorological controls over the Dead Sea watershed offer insights into past hydrometeorological processes that could have governed the Dead Sea water budget, seasonal and annual flows, floods, and the resultant sedimentology. Rainfall is typically associated with synoptic-scale circulation patterns forced by an upper-level trough that include Mediterranean cyclones (MCs), active Red Sea troughs (ARSTs), and active subtropical jets (STJs), although other rainstorms and sub-synoptic processes also affect the region. We point to their relative importance in inflow volume, peak discharges, and delivery of sediments from the various environments of the basin. MCs control the annual water amount discharging into the Dead Sea. A change in their frequency, intensity, or latitude can substantially alter the lake water balance. A change in frequency or intensity of ARSTs and STJs affects extreme flood and sediment discharge. Floods reach the lake through (a) the Mediterranean-climate-controlled Lower Jordan River, (b) desert-climate-controlled Nahal HaArava, and (c) the arid wadies draining directly into the Dead Sea, some with wetter headwaters. Floods in the wetter parts of the watershed are mainly controlled by MCs, and characterized by larger frequency, volume, and duration, but lower peak discharges and possibly sediment delivery, than floods in the desert parts, which can be produced by the three synoptic types. ARSTs contribute to heavy rainfall, typically of a spotty nature, in the desert parts of the watershed. STJs are currently rare, but their rainfall accumulation may be greater than the annual mean over a broad area in the southern dry Dead Sea watershed. This article presents a review of recent studies, which is extended with new analyses of meteorological, rainfall and flood data, underlining the importance of the Lower Jordan River in supplying water volume to the Dead Sea, as compared to the high-discharge, low-volume floods of the arid part of the watershed. Our analyses will help interpret paleoenvironmental conditions in the Dead Sea sedimentary record, and cope with the region's changing climate. • Three synoptic systems control rainfall and flood patterns in the Dead Sea watershed. • Winter Mediterranean cyclones control annual rainfall patterns and water budget. • Floods and sedimentology are dominated by rainfall patterns in the watershed. • Paleoenvironmental sedimentary interpretations require present, robust observations. [ABSTRACT FROM AUTHOR]

Millennial-scale Dansgaard Oeschger (DO) variability at northern high latitudes has influenced climatic and environmental conditions in the Mediterranean during the last glacial period. There is evidence that the hemispheric transmission of the DO variability occurred at the end of DO event 25; however, the exact timing and the trigger that activated the environmental response in the Mediterranean remains incompletely understood. Here, we provide evidence that the clear millennial-scale teleconnection between Greenland and the Mediterranean started at ∼111.4 ka BP and was initiated by a sub-millennial scale cooling in Greenland (GI-25b). High-resolution sediment proxies and the pollen record of Lago Grande di Monticchio (MON), Italy, reflect climatic instability during the last millennium of the last interglacial, which was characterised by a first and short cooling episode (MON 1) at 111.44 ± 0.69 ka BP, coinciding with the Greenland cold sub-event GI-25b in duration and timing (within dating uncertainties). MON and Greenland (NorthGRIP ice core) also agree in recording a subsequent warm rebound phase that abruptly culminated in the stadial MON 2/GS-25, marking the transition into the last glacial period. Our results show that the GI-25b triggered an early environmental response at MON to centennial-scale climate change in Greenland as a prelude to the millennial-scale teleconnection that was maintained during the glacial period. • Annual-resolution study of the transition from the Last Interglacial period to the last Glacial period. • Evaluation of the differences in proxy response to sub-millennial-scale climate variability. • Chronological discussion based on comparison of independent chronologies. [ABSTRACT FROM AUTHOR]

Abstract Stalagmite data from Anjohibe Cave in northwest Madagascar suggest six distinct climate periods from 9.1 to 0.94 ka. Periods I and II (9.1–4.9 ka) were wetter and punctuated by a series of prominent droughts. Periods IV-VI (4–0.94 ka) were much drier and less variable. Period III (4.9-4 ka) marks the transition between wetter and drier conditions and consists of two significant droughts: the first (4.8–4.6 ka) coincides approximately with the end of the African Humid Period and the second (4.3–4.0 ka) may be the expression of the Northern Hemisphere 4.2 ka dry event in northwest Madagascar. Strong positive correlations between δ13C and δ18O values in Periods I-IV (r = 0.63–0.91) suggest that both isotopes were influenced by natural climate changes indicating that humans may not have been present in the area. In contrast, during Periods V (r = 0.07) and VI (r = −0.12) the "decoupling" of δ13C and δ18O might signal an impact from human activities starting around 2.5 ka. Rapid changes in climate during the early and middle Holocene, with prominent droughts lasting up to 800 years, did not kill off Madagascar's megafauna, and neither did a human population, present since the early Holocene if evidence from south Madagascar is reliable. However, many extinctions occurred under the more stable climatic conditions of the late Holocene, despite an antiphase climate relationship between northern and southcentral Madagascar. This suggests that initial human colonization, or significant increase in human population, triggered the megafaunal extinctions by hunting and destruction of megafaunal habitats. Highlights • Massive droughts at 4.7 and 4.2 ka were followed by a permanently drier and less variable climate in NW Madagascar after 4 ka • Drought and human deforestation after 1.6 ka, indicated by higher stalagmite δ13C, may have triggered megafaunal extinctions • Decoupling of δ13C and δ18O values at 2.5 ka is the first evidence of humans in the 9-1 ka Anjohibe Cave stalagmite record • Holocene climate changes in NW Madagascar were in phase with N and E Africa but antiphase with S Madagascar and SE Africa [ABSTRACT FROM AUTHOR]

Abstract Investigating controls on past variability of South American hydroclimate is critical to assessing its response to future warming scenarios. δ18O records from South America offer insight into past variability of the South American Monsoon System (SAMS). The controls, however, on precipitation δ18O values can be decoupled from precipitation amount at a given site and, thereby, limit local moisture condition reconstructions. Here we use a principal components analysis to assess the coherence of speleothem and lake core Holocene δ18O records in tropical and subtropical South America to evaluate the extent to which δ18O variability reflects changes in SAMS intensity at different sites across the region. The main mode of variability across Holocene δ18O records (PC1) closely tracks austral summertime insolation, consistent with existing work. Sites towards the periphery of the continent are heavily weighted on PC1, whereas interior sites as not. Further δ18O variability at interior sites bear little similarity to each other and implicate controls, beyond regional monsoon intensity, on these δ18O records. Further, we develop speleothem 87Sr/86Sr records spanning the Holocene from Tamboril Cave (Brazilian Highlands), Paraíso Cave (eastern Amazon Basin), Jaraguá Cave (Mato Grosso do Sul Plateau), and Botuverá Cave (Atlantic coastal plain) to investigate coupling between reconstructed monsoon variability (reflected by PC1) and local moisture conditions (interpreted from 87Sr/86Sr records). We interpret speleothem 87Sr/86Sr variability as a proxy of local moisture conditions, reflecting the degree of water-rock interaction with the cave host rock as driven by variations in water residence time. Speleothem 87Sr/86Sr records from all the sites, except Botuverá cave, do not co-vary with PC1, suggesting that local moisture conditions do not necessarily follow variations in regional monsoon intensity at these interior sites. These speleothem 87Sr/86Sr records generally suggest dry mid-Holocene conditions relative to the early- and late-Holocene, consistent with interpretations of other paleo-moisture records in the region, but timing of wet-dry transitions varies between sites. These results highlight that controls, in addition to SAMS variability, might influence δ18O variability. Further, our results suggest spatially variable local moisture conditions at interior sites that do not uniformly respond to regional monsoon intensity, and stress the need for δ18O-independent reconstructions of moisture conditions. Highlights • The main mode of speleothem δ18O variability follows austral summertime insolation. • Speleothem 87Sr/86Sr values are a feasible proxy of local moisture conditions at our study sites. • Local moisture conditions are largely decoupled from overall monsoon intensity. • Speleothem 87Sr/86Sr values suggest a widespread mid-Holocene drying across study sites. [ABSTRACT FROM AUTHOR]

Abstract We present new sedimentological and environmental magnetic records spanning ∼3.2–2.2 Ma, during the intensification of Northern Hemisphere glaciation, from North Atlantic Integrated Ocean Drilling Program Site U1307 on Eirik Drift. Our new datasets and their high-fidelity age control demonstrate that while inland glaciers – and potentially also at times restricted iceberg-calving margins – have likely existed on southern Greenland since at least ∼3.2 Ma, persistent and extensive iceberg-calving glacial margins were only established in this region at 2.72 Ma, ∼300 kyr later than in northeastern and eastern Greenland. Despite a dramatic increase in Greenland-sourced ice-rafted debris deposition on Eirik Drift at this time, contemporaneous changes in the bulk magnetic properties of Site U1307 sediments, and a reduction in sediment accumulation rates, suggest a decrease in the delivery of Greenland-sourced glaciofluvial silt to our study site. We attribute these changes to a shift in depositional regime from bottom-current-dominated to glacial-IRD-dominated between ∼2.9 and 2.7 Ma, in response to a change in the depth of the flow path of the Western Boundary Undercurrent relative to our study site. Highlights • New high-fidelity RPI-based age model for Site U1307. • Orbital-resolution history of Greenland IRD deposition on Eirik Drift during iNHG. • Persistent marine-terminating margins established in southern Greenland from 2.7 Ma. • Potentially ∼300 ka later than in northeastern and eastern Greenland. • Major reduction in flow speed of bottom currents bathing Site U1307 during iNHG. [ABSTRACT FROM AUTHOR]

Abstract The geologic time scale serves as an essential instrument for reconstructing Earth history. Astrochronology, linking regular sedimentary alternations to theoretical quasi-periodic astronomical rhythms, often provides the highest resolution age models for strata that underlie the time scale. Although various methods for testing astronomically-tuned time scales exist, they often present challenges, such as the problem of circularity. Here, we introduce an approach to extract a reliable obliquity envelope from astronomically tuned data, avoiding the effects of frequency modulations that can artificially introduce astronomical beats. This approach includes (1) the application of a broad obliquity filter followed by (2) a Hilbert transform and (3) a low-pass filter of the amplitude envelope to (4) test the significance of correlation between amplitude envelope and astronomical solution. These data amplitudes provide a robust means to evaluate the climate response to obliquity forcing and, more specifically, to test the significance of correlation with the theoretical astronomical solution, in a manner similar to the phase-randomized surrogate approach previously introduced for the evaluation of precession tuning. Synthetic astronomical/ice-sheet models and several Quaternary climate proxy records – where obliquity can be a dominant component of astronomically driven climate variability – are used to demonstrate the feasibility of the proposed method and yield new insight into climate system evolution. Highlights • We develop a test for time scales based on the obliquity imprint. • We reconstruct robust obliquity amplitude variations from tuned time scales. • Methods are tested and discussed using several Quaternary datasets. [ABSTRACT FROM AUTHOR]

Abstract Early Pleistocene (Calabrian) clays of the Lindos Bay Formation have been uplifted and are exposed today on the eastern coast of Rhodes (Hellenic forearc, Greece). The hemipelagic origin of these sediments and the excellent preservation of the microfossils they contain, make the Lindos Bay Formation a unique element in the eastern Mediterranean, which has the potential to constitute a paleoclimate referential framework of the region for the Early-Middle Pleistocene Transition (EMPT). In this context, 98 samples were collected in the type locality section of the Lindos Bay Formation. Stable isotope (δ18O, δ13C) analyses were carried out on benthic (Uvigerina peregrina) and planktonic (Globigerina bulloides) foraminifera for the interval between ∼1100 ka and ∼858 ka. We identify and continuously reconstruct the climate cycles that occurred between Marine Isotope Stages (MIS) 32 and 21. Counts of planktonic foraminifera were further carried out and allow connecting the conditions occurring locally in the surface waters with the glacial-interglacial cycles during the onset of the EMPT. While (sub)tropical taxa dominate the assemblages, glacials were associated with short-term (<∼10 kyr) influxes of temperate to subpolar species suggesting cooling and/or increasing productivity in the surface waters correlating with the deposition of sapropels in the eastern Mediterranean deep sea. Finally, planktonic/benthic foraminiferal ratios show that the section deposited at upper bathyal depths between ∼450 m and ∼150 m. During the late Early Pleistocene, the eastern coast of Rhodes has locally undergone repeated, transient and possibly very rapid vertical motions which are overprinted on a regional tectonically-forced regressive trend. Highlights • Foraminiferal stable isotopes and counts in the late Early Pleistocene of Rhodes. • A continuous upper bathyal record exposed onshore for the onset of the EMPT. • A climate referential framework for the Calabrian of the eastern Mediterranean. • Rhodes underwent repeated and rapid vertical motions during the Early Pleistocene. [ABSTRACT FROM AUTHOR]

Abstract Interglacial to glacial transitions represent the most drastic turnovers in the Quaternary climate system. Yet, millennial-scaled climate variability and stochastic internal variability that result in (inter)glacial transitions remain poorly understood. Here, three speleothems from two different cave systems in Belgium are investigated to characterize the Eemian to early Weichselian transition. The speleothems show high reproducibility for δ13C, interpreted as a proxy for past vegetation activity, controlled by type of vegetation above the cave. All three speleothems show a drastic increase in δ13C between 118 and 117 ka, reflecting a rapid change in vegetation from last interglacial temperate tree species towards glacial open-grass vegetation. This transition shows a strong affinity with the Late Eemian Aridity Pulse (LEAP) at 118 ± 1 ka, previously identified in pollen records from Western Germany. An age of 117.7 ± 0.5 ka is determined for the start of this transition in the Belgian speleothems. The speleothem records show a distinct transition in the proxies between Eemian optimum conditions and increased variability during the glacial inception and therefore the Eemian-Weichselian transition is set at 117.7 ± 0.5 ka in the speleothem records. High-resolution trace element analysis shows that the transition is initiated by a cooling pulse followed by a decrease in precipitation. Through comparison with other archives, including North-Atlantic sedimentary records, it is proposed that the transition at 117.7 ka constitutes an internal climate response caused by a substantial input of freshwater from degraded ice-sheets by the end of the Eemian (∼120-118 ka). Highlights • A paleoclimate reconstruction of the Eemian-Weichselian transition is presented. • The EWT occurs at 117.7 ± 0.5 ka in the records. • This transition is linked with a larger regional cooling. • There is evidence for a climatic connection with the North Atlantic region. [ABSTRACT FROM AUTHOR]

Abstract The stable isotope composition of key chemical elements for life on Earth (e.g., carbon, hydrogen, nitrogen, oxygen, sulfur) tracks changes in fluxes and turnover of these elements in the biogeosphere. Over the past 15–20 years, the potential to measure these isotopic compositions for individual, source-specific organic molecules (biomarkers) and to link them to a range of environmental conditions and processes has been unlocked and amplified by increasingly sensitive, affordable and wide-spread analytical technology. Paleoenvironmental research has seen enormous step-changes in our understanding of past ecosystem dynamics. Vital to these paradigm shifts is the need for well-constrained modern and recent analogues. Through increased understanding of these environments and their biological pathways we can successfully unravel past climatic changes and associated ecosystem adaption. With this review, we aim to introduce scientists working in the field of Quaternary paleolimnology to the tools that compound-specific isotope analysis (CSIA) provides for the gain of information on biogeochemical conditions in ancient environments. We provide information on fundamental principles and applications of novel and established CSIA applications based on the carbon, hydrogen, nitrogen, oxygen and sulfur isotopic composition of biomarkers. While biosynthesis, sources and associated isotope fractionation patterns of compounds such as n -alkanes are relatively well-constrained, new applications emerge from the increasing use of functionalized alkyl lipids, steroids, hopanoids, isoprenoids, GDGTs, pigments or cellulose. Biosynthesis and fractionation are not always fully understood. However, although analytical challenges remain, the future potential of deeper insights into ecosystem dynamics from the study of these compounds is also emerging. Highlights • Compound-specific isotopes analysis of biomarkers extends paleolimnological toolkit. • Carbon and hydrogen isotopes help identifying the source of a biomarker. • CSIA allows, e.g., the reconstruction of changes in proportion of C3 and C4 plants. • Compound-specific hydrogen isotope values indicate changes in meteoric water source. • Sulfur isotopes provide insights into diagenesis and sulfur cycling in lakes. [ABSTRACT FROM AUTHOR]

Abstract Latitudinal treeline in northwestern Québec, Canada, is a broad band of forest-tundra between 56 and 58°N. Three new pollen records from the forest-tundra zone were combined with ten previously-published records to form a transect of paleoecological data across this treeline. The area was deglaciated ∼6–7 ka, with only a brief period of shrub tundra vegetation in the oldest sediments of all sites. Noticeable values of Populus , Juniperus and Larix pollen percentages were found during this time in the southernmost sites, suggesting they comprised part of the initial plant migration. Maximum Picea pollen percentages were found between 2 and 4 ka across the boreal forest and forest-tundra, with values remaining constant in the boreal forest and decreasing in the forest-tundra in the past 3 ka. Across the entire area, pollen influx decreased in the past 4 ka, and non-arboreal pollen increased in the forest-tundra, suggesting an opening of the forest and decrease in terrestrial production. Charcoal influx also declined, indicating a reduction in fire activity in the past 2–4 ka. Although the treeline has remained in the same average location in the region over the past 6 ka, the strength of the temperature gradient across the frontal zone changed over the course of the Holocene. Highlights • Rapid migration of trees after deglaciation. • Maximum temperatures 5-3ka. • Neoglacial cooling shown by pollen percentages, pollen and charcoal influx. • Climate gradient across treeline changed through time. [ABSTRACT FROM AUTHOR]

Abstract We found strong signals of two cooling events around 9700 and 8200 cal yrs. BP in lakes Store Finnsjøen and Flåfattjønna at Dovre, mid-Norway. Analyses included pollen in both lakes, and C/N-ratio, biomarkers (e.g. alkanes and br-GDGTs), and XRF scanning in Finnsjøen. The positions of these lakes close to ecotones (upper forest-lines of birch and pine, respectively) reduced their resilience to cold events causing vegetation regression at both sites. The global 8.2 event reflects the collapse of the Laurentide Ice Sheet. The 9.7 event with impact restricted to Scandinavia and traced by pollen at Dovre only, reflects the drainage of the Baltic Ancylus Lake. More detailed analysis in Finnsjøen shows that the events also caused increased allochtonous input (K, Ca), increased sedimentation rate, and decreased sediment density and aquatic production. br-GDGT-based temperatures indicate gradual cooling through the early Holocene. In Finnsjøen, ca. 3100 maxima-minima couplets in sediment density along the analysed sequence of ca. 3100 calibrated years show the presence of varves for the first time in Norway. Impact of the 9.7 and 8.2 events lasted ca. 60 and 370 years, respectively. Pine pollen percentages were halved and re-established in less than 60 years, indicating the reduction of pine pollen production and not vegetative growth during the 9.7 event. The local impact of the 8.2 event sensu lato (ca. 8420–8050 cal yrs. BP) divides the event into a precursor, an erosional phase, and a recovery phase. At the onset of the erosional phase, summer temperatures increased. Highlights • Sediments in two alpine Dovre lakes show distinct traces of the 9.7 and 8.2 events. • The ecotonal position of the sites reduced their resilience to climate fluctuations. • Sediment density and elements in Finnsjøen show annually varved sediments. • The local impact of the 9.7 and 8.2 events lasted 60 and 370 years, respectively. • Pine pollen production was severely reduced during the 9.7 cold event. [ABSTRACT FROM AUTHOR]

Abstract Understanding millennial and sub-millennial climate variability during past low eccentricity interglacials similar to the Holocene is important for forecasting the evolution of climate and natural variability. The Ideale section (Montalbano Jonico, Southern Italy) studied here provides one of the best records of MIS 19c, the closest orbital analog to the Holocene. This exposed marine series covers Termination IX to the inception of MIS 18 with very high sedimentation rates (i.e. 90–200 cm/ka). We present 1) benthic δ18O and δ13C records at 90–200 year time-resolution, 2) a new 40Ar/39Ar age of 774.1 ± 0.9 ka for tephra layer V4 (Matuyama-Brunhes transitional period) and 3) new calcareous plankton, palynological and authigenic 10Be/9Be data. Our new Bayesian depth-age model suggests a 11.5 ± 3.4 ka (95% confidence) duration for the climatic optimum. The δ18O series reveals millennial-scale oscillations (with sharp transitions < 200 years) between ∼774.0 and the onset of MIS 18 (∼757.0 ka) with a cyclicity of about 5.4 ka. Spectral analysis and band-pass filtering indicate that these climate oscillations existed throughout the entire MIS 19 period, although they were dampened during MIS 19c, which is chiefly controlled by orbitally-driven insolation. The amplitude of those sub-orbital oscillations increased towards MIS 18 as the climate became drier and cooler. The Ideale section reveals, with unprecedented detail, millennial-scale climatic oscillations of MIS 19b-a that have been observed worldwide. They highlight the response of the central Mediterranean area to North Atlantic climatic variation (i.e. oceanic circulation and atmospheric processes related to ice-sheet dynamics) during this low eccentricity interglacial. Graphical abstract Image 1 Highlights • The 74.2 m IDEAL section (Montalbano-Jonico, Southern Italy) was revised. • New d18O, d13C, calcareous plankton, palynological and authigenic 10Be/9Be records are presented. • A refine age of 774.1 ± 0.9 ka for tephra layer V4 within the Matuyama-Brunhes transitional period is proposed. • The d18O reveals millennial-scale oscillations between 774.0 and 755.0 ka with a cyclicity of about 5.4 ka. • Climate oscillations existed throughout the entire MIS 19 period but hampered during MIS 19c. [ABSTRACT FROM AUTHOR]

Abstract Diatom-based transfer functions for salinity, precipitation and temperature were developed using a training set that included data from 40 sites along central Mexico. These transfer functions showed good performance parameters and were subsequently applied to the previously published diatom record from lake Chalco, southern Basin of Mexico. Heinrich stadials (HS-3 to HS-0) were reconstructed as cold and dry events, with HS-2 representing the coldest and driest conditions, while HS-1 shows a complex bimodal cooling pattern. Orbital scale variability is also recorded. High and variable lake salinities from ∼34 to 29 ka BP (marine isotope stage 3, MIS-3) corresponded with times of maximum summer insolation and evidences of frequent fires. MIS-2 was identified as a cold period, with low lake salinity associated with low evaporation, with two cold intervals during the minima in spring (∼25.5 ka BP) and summer (∼20 ka BP) insolation. The ∼20 ka BP cold event together with HS-2 (24-23 ka BP), defined a bimodal maximum cooling during the last glacial maximum (LGM: 24.5–19.5 ka BP) within the range of pollen-based estimates, further supporting a maximum tropical cooling of 4–5 °C for the LGM. The deglacial (19.5–11.5 ka BP) showed the highest precipitation anomalies with three peaks that closely correlated with glacier advances in the nearby mountains (Iztaccihuatl). The early Holocene marked a change towards high lake salinities and the highest positive temperature anomalies (+3.5 °C) during a peak in summer insolation. Even though at orbital scale Chalco showed a nearly opposite trend to the record from the more southerly lake Peten-Itza (Guatemala), at millennial scale it showed a common pattern of cold and dry conditions during HSs, comparable to other tropical latitude sites in the northern hemisphere and further supporting the idea that there is a strong coupling between tropical and higher latitudes climates, in particular with the North Atlantic. Highlights • Diatom-based transfer functions produced a ∼40 ka BP paleoclimatic reconstruction for central Mexico. • Orbital and millennial scale events were identified in the salinity, precipitation and temperature reconstructions. • Maximum last glacial cooling of ∼5°C is reconstructed, a relatively wet deglacial and a warmer (+3.5°C) early Holocene. • Heinrich stadials (3 to 0) are cold and dry; HS2 was the coldest while HS-1 showed a bimodal cooling. [ABSTRACT FROM AUTHOR]