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Southern Ocean (SO) climate is rapidly changing because of global warming and regional climate feedback loops like shifts of the Southern Hemisphere (SH) westerly winds (SHW) and related Southern Annular Mode (SAM). Over the past decades, the former has been persistently positive, shifting the latter southwards: the ensuing changes in temperature and precipitation are linked to the rapid retreat of mid-latitude mountain glaciers. Beyond the short instrumental period, the long-term impact of this coupled SHW-SAM system on regional glaciers remains poorly constrained. To help close this gap, we reconstruct glacier advances from an outlet glacier on the sub-Antarctic Kerguelen (49°S, 69°E), an archipelago that is strategically located in an under-investigated region of the SHW core belt. Based on alternations between relatively organic and minerogenic mud detected using a multiproxy approach on a 1200-year-long sediment record from a glacial threshold basin, we document glacier advances between 1150 and 850, 820–620, 500–250 and 160–90 cal yr BP. Coincident glacier advances in adjacent regions like sub-Antarctic South Georgia and southern Patagonia, suggest that SO glaciers responded symmetrically to climate forcings during the past 1200 years. We attribute this synchronicity to shifting SAM-like conditions and associated temperature changes. We suggest that cold and negative SAM-like conditions, favourable for glacier growth on the Kerguelen and other SO land masses, dominated during much of this period. Furthermore, the findings presented here support the growing consensus for a two-phased regional expression of the Little Ice Age (LIA). • Outlet glacier on the sub-Antarctic Kerguelen (49°S) islands is reconstructed using glacial threshold lake sediments. • The glacier advanced between 1150 and 850, 820–620, 500–250 and 160–90 cal yr BP. • First lake sediment-based glacier reconstruction from Kerguelen. • Glacier advances on Kerguelen are synchronous with other mid-latitude mountain glaciers. [ABSTRACT FROM AUTHOR]

The Pleistocene sediments of the Nihewan Basin in northern China preserve a detailed terrestrial sediment archive for reconstructing the palaeoenvironment and palaeoclimate changes during early times of hominin occupation in E Asia, following the earliest locations outside of Africa. In this study, we investigate the composite 86.2-m long NH-T section of Dachangliang which was formed with an astronomically tuned age between ca. 1.66 and 0.78 Ma. Parameterized grain size end-member modelling analysis is applied for the first time in the Nihewan Basin to unravel the characteristics of sediment sources, transportation dynamics, and climatic signals in the region. The grain-size distributions of the NH-T sediment samples are attributed to a mixture of four distinct end members (EMs 1-4). EM 1 represents a global atmospheric fine silt component (mode at 7.9 μm) which probably resulted from high-altitude westerly transport from distal sources. EM 2, a medium silt component (mode at 27.6 μm) was probably transported by the low-level westerly winds during the spring from a relatively proximal source in comparison to EM 1. EM 3, a coarse silt component (mode at 59.9 μm), represents short distance suspended materials that were blown out by N or NW winds of the East Asian winter monsoon (EAWM). EM 4 is a fine sand component (mode at 221.1 μm), probably representing fluvial deposits carried by overland flow. Therefore, the temporal fluctuations in the abundances of EMs 1-3 are used to infer the history of the East Asian summer monsoon (EASM) (EM 1), of dust-storm outbreaks during springtime (EM 2), and of the EAWM (EM 3). The NH-T climate record shows an overall increase in EM 3 peaks, accompanied by a decrease in EM 1 minima from ca. 1.45 to 0.82 Ma, indicating a long-term aridification and cooling trend in the Nihewan Basin. At ca. 1.25 Ma, the EM patterns transition from short-frequency to longer fluctuations, apparently coinciding with the onset of the Mid-Pleistocene transition (MPT). Periods of stronger EASM with more frequently warm and wet conditions probably occurred in the basin between ca. 1.66-1.62, 1.52-1.25 and after 0.82 Ma. Intensified EAWM conditions probably prevailed in the basin during the intervening periods from ca. 1.62-1.52 and the MPT 1.25-0.82 Ma. The inferred warmer and wetter conditions likely supported hominin activities in the Nihewan Basin, in contrast to mostly colder and drier conditions. Nevertheless, the higher number of discovered Palaeolithic sites and recorded lithic artifacts from the first half of the MPT apparently reflects the successful adaptability of hominins to the prevailing cold climate. The relatively consistent patterns observed between the variations of a median grain-size stack of the Chinese Loess Plateau (CLP MD) and EM 3, and of the magnetic susceptibility stack of the CLP (CLP MS) and EM 1, indicate the climatic sensitivity of these EMs in response to the long-term glacial/interglacial oscillations previously inferred from the CLP. However, significant differences in the CLP MD and CLP MS on the one hand side and in the trends of the EMs 3 and 1 on the other suggest that regional climate conditions varied between the CLP and the Nihewan Basin. Further research is required to explore such regional climate differences and their possibly underlying factors in the Early Pleistocene. • The first application of end-member modelling analysis of the Nihewan sediments produces four grain-size end members (EMs). • EMs 1-3 are proxies for East Asian summer winter /summer monsoons (EAWM/EASM). • The EM patterns shifted from short-to long-frequency fluctuations at ca. 1.25 Ma. This shift coincided with the onset of the mid-Pleistocene transition (MPT). • EASM conditions dominated at ca. 1.66-1.62 Ma, 1.52-1.25 Ma, and after 0.82 Ma, and likely supported hominin activities. [ABSTRACT FROM AUTHOR]

Holocene climate change between different geographic units of the Asian continent exhibits spatiotemporal heterogeneity under the control of different atmospheric circulation systems. Precipitation/moisture variations between the northeastern and southeastern Tibetan Plateau show an out-of-phase pattern on decadal, centennial, and millennial time scales during the Holocene, influenced by interactions between the summer monsoon system and the westerlies. However, conflicting proxies exist in some regions on millennial time scale, and it is vital to detect and evaluate the detailed processes responsible for such a dipolar pattern. Here, we select and summarize well-dated Holocene records of pollen-based vegetation, oxygen isotope composition (δ18O) of authigenic carbonates and cellulose, hydrogen isotope composition (δD) of long-chain n -alkanes from leaf wax, and chronology of aeolian activity and soil development from various geological archives, including lake sediments, peat bogs, aeolian deposits, cave speleothems, and tree rings from the eastern margin of the Tibetan Plateau. We find a long-term decreasing trend in summer monsoon precipitation across the eastern Tibetan Plateau during the Holocene, indicated by declining arboreal pollen percentages, enhanced values of δ18O from lakes in the southeastern Tibetan Plateau (SETP), speleothems, and tree-ring cellulose, as well as enhanced δD values across the entire eastern margin of the plateau. A summary of the chronology of aeolian sand and paleosol on the northeastern Tibetan Plateau (NETP) reveals enhanced aeolian activity during the early Holocene and increased soil development from the middle Holocene onwards. These data, combined with those indicating increased lake levels and decreased lake-water δ18O values in the region, suggest that the effective moisture on the NETP increased throughout the Holocene. Our findings indicate that increased non-monsoon-season precipitation with the strengthening intensity of the westerlies, against a background of possible decreasing summer evaporation, provided increased moisture to the NETP, ultimately resulting in a Holocene dipolar pattern of humidity variations between the northern and southern parts of the eastern margin of the Tibetan Plateau. The inference that the seasonality of precipitation controlled moisture variation in the study region is supported by high-resolution climate proxies and meteorological data on centennial and decadal time scales during the last millennium. Additionally, we propose a conceptual framework of hydroclimatic processes in a land–lake system to reconcile contradictions between different indicators. The present study not only clearly summarizes the Holocene climate change on the eastern margin of the Tibetan Plateau, but it also highlights the critical importance of distinguishing terrestrial and lacustrine signals in paleolimnological studies, and of noting associated differences that may potentially result from proxy sensitivity to seasonal climate changes. • There is an out-of-phase pattern of Holocene effective moisture variations between the NETP and SETP. • Non-monsoon-season precipitation contributed to the Holocene wetting trend in the NETP. • A conceptual framework of hydroclimatic processes in a land–lake system is proposed. • It is important to distinguish terrestrial and lacustrine signals in paleolimnological studies. [ABSTRACT FROM AUTHOR]

Reconstructing mid-latitude glacier variations is a prerequisite for unveiling the interhemispheric climate linkages and atmospheric-ocean forcings that triggered those changes during the last glacial cycle. Nonetheless, the timing, magnitude, and structure of glacier fluctuations in the southern mid-latitudes remain incomplete. Here, we present a new 10Be chronology of the Universidad Glacier in the Andes of central Chile (34° S, 70° W; ∼2500 m a.s.l.) based on 21 cosmogenic-exposure ages of boulders on discrete moraine ridges defining former ice margins. Our findings include the mapping and dating of three moraines, UNI I, UNI II, and UNI III, located ∼20 km, 15 km, and 10 km down-valley from the present-day glacier front, respectively. The 10Be exposure ages of the UNI I moraine range from 135.9 ± 7.1 to 51.4 ± 2.7 ka (n = 3). The UNI II moraine gave a mean age of 18.0 ± 0.9 (n = 15) and the UNI III moraine yielded a mean age of 13.9 ± 0.8 ka (n = 3). The UNI I moraine implies the largest ice extent during a pre-Last Glacial Maximum (pre-LGM) period, including the penultimate glaciation. The UNI II is a moraine complex that represents cold and humid conditions in central Chile at the end of the LGM, which we attribute to the northward-shift of the Southern Westerly Winds (SWW). The UNI III moraine represents a return to glacial conditions interrupting the Termination, evidencing both a double-step deglacial trend observed through the southern middle and high latitudes at the end of the last ice age. The Andes at this subtropical latitude record a global signal of glacial and climate change. • We constructed a new 10Be chronology of the Universidad Glacier for the last glaciation. • Universidad Glacier reached full glacial conditions during the LGM culminating by 18.0 ± 0.9 ka. • A glacier readvance occurred by 13.9 ± 0.8 ka interrupting the Termination. • The subtropical latitude of the glacier records a global signal of climate change. • Shifts of the Southern Westerly Winds ultimately forced the observed glacier fluctuations. [ABSTRACT FROM AUTHOR]

We examine the vegetation and environmental evolution of central Isla Grande de Chiloé (IGC), northwestern Patagonia (NWP), spanning the two climatic endmembers of the last glacial-interglacial cycle: the Last Glacial Maximum (LGM) and the Early Holocene (EH). Our results from Lago Auquilda show Evergreen Subantarctic forests interspersed with Magellanic Moorland during the early LGM (∼30.9-26.1 ka), followed by species-poor closed-canopy Nothofagus forests with low conifer abundance and absence of Magellanic Moorland during the late LGM (∼18.9-17.9 ka). Initial canopy fragmentation at ∼17.9 ka gave way to rapid densification and diversification of trees, herbs, and vines characteristic of North Patagonian rainforests (NPRF), marking the onset of the Last Glacial Termination (T1). Closed-canopy NPRF established between ∼15.5-14.8 ka, followed by mixed forests with shade- and cold-tolerant hygrophilous NPRF conifers until abrupt increases in shade-intolerant trees favored by local fires between ∼12.6-11.4 ka. NPRF conifers disappeared as thermophilous species of the Valdivian rainforest and fire activity increased between ∼11.4-8.7 ka. We interpret that temperate rainforest inhabited the periphery of the Patagonian Ice Sheet in NWP under cold and hyperhumid conditions during the LGM. Precipitation was highest in the early LGM, declined during the late LGM, diminished to an early T1 minimum between ∼17.1-16.4 ka, and then increased steadily to a maximum between ∼14.8-12.6 ka, overlapping with the Antarctic Cold Reversal (ACR). Subsequent declines at ∼12.6 ka and ∼11.4 ka led to extreme warm-dry conditions during the EH with intense fire activity. Hyperhumid conditions during the LGM and ACR imply equatorward-shifted Southern Westerly Winds (SWW), minimum precipitation during the early portion of T1 relates to poleward-shifted SWW, and the EH warm-dry phase reflects a zonally symmetric decline in SWW intensity. Our Lago Auquilda record replicates the timing and structure of changes revealed by multiple paleoclimate studies throughout western Patagonia which, in turn, are synchronous/coherent with key southern mid- and high-latitude records. • We studied sediment cores from Lago Auquilda, central Isla Grande de Chiloé (∼42°S). • We report fine-resolution sedimentary, pollen, and charcoal records between ∼31-9 ka. • Extreme cold and strong southern westerly wind (SWW) influence characterize the LGM. • The SWW were strongest during the early LGM and weakest during the early Holocene. • Evergreen rainforests thrived against the Patagonian ice sheet margin during the LGM. [ABSTRACT FROM AUTHOR]

The Tibetan Plateau (TP) is currently experiencing rapid warming, which has been associated with an increase in atmospheric water vapor, contributing to the replenishment of the Asian Water Tower. The climate of the TP is influenced by the interplay between the Asian summer monsoon (including both the East Asian summer monsoon and the Indian summer monsoon) and the westerlies. However, the specific changes in monsoon-driven vapor transport, the behavior of the westerlies, and their interactions with ongoing climate change remain unclear. In this study, we adopt a comprehensive approach that integrates luminescence chronology and climate modelling to reconstruct and simulate the paleoclimate changes during Marine Isotope Stage (MIS) 5, i.e., the last interglacial period. Luminescence dating of K-feldspar, using both multiple and single grain techniques, was applied to establish reliable chronologies for three sedimentary sequences from two catchments, Qinghai Lake in the northern TP and Selin Co in the central-southern TP. Our findings reveal a striking discrepancy in the timing of lake highstands, occurring during the late MIS 5 in Qinghai Lake but during the early MIS 5 in Selin Co, respectively. Model simulations indicate that a strengthened Indian summer monsoon was the primary driver of increased precipitation and elevated lake-levels in the central-southern plateau, while enhanced westerlies and their southward shift led to wetter conditions in the northern TP. Despite ensemble models predicting a substantial long-term trend towards increased precipitation across the entire TP in the future, with a shift from dipole to monopole precipitation pattern, our study suggests that an out-of-phase precipitation pattern over the TP is likely to persist. • OSL-dated highstands from Qinghai Lake and Selin Co used to investigate hydroclimate on TP. • Striking difference in timing of highstands was observed between these two large lakes. • MIS 5 highstand was late in Qinghai Lake but early in Selin Co. • Asynchronous hydroclimate pattern persisted throughout MIS 5 over the TP. • Enhanced Indian summer monsoon and westerlies jet drove this pattern. [ABSTRACT FROM AUTHOR]

The evolution of aridity and its forcing mechanisms in the Arabian Peninsula are of significance for better understanding the environmental response of the region to global change and the impact of past climate shifts in human evolution. Paleoclimatic reconstructions for the region are predominantly derived from fragmentary terrestrial records. Here, we present a detailed environmental magnetic record for marine sediments from the western equatorial Indian Ocean, which constitute the terminal sink for eolian material originated from the Arabian Peninsula. The dominant magnetic minerals identified in the studied sediments include magnetite, maghemite, and hematite. The hard isothermal remanent magnetization (HIRM), widely used as a proxy for the abundances of the high coercivity mineral hematite, has been used to track variations in the concentration of Arabian dust over the last 200 kyr. Dust concentrations are lowest during interglacial periods of maximum boreal summer isolation, and coincide with intervals during which lake and fluvial systems developed and speleothems formed across most of southern and central Arabia. Our results point to a sharp decrease in the production of dust due to the expansion of vegetation cover up to 30°N during these periods. West African Monsoon appears to be the major source of increased rainfall across Arabia, while the Indian Summer monsoon likely contributed to enhance rainfall in the south and southeastern parts of the peninsula. Variation in the supply of Arabian dust were also driven by changes in high-latitude ice volume and atmospheric CO 2 , as indicated by highest dust concentration found during glacial periods. We interpret that the expansion of high-latitude ice sheets increased the global meridional temperature gradient, weakened the monsoon system, and resulted in a more southerly, colder and descending subtropical westerly jet, leading to the retreat of vegetation cover and the enhanced production of dust from the Arabian deserts. Our results highlight a link between the production of Arabian dust and orbital-scale climate variability, including both monsoon and northern hemisphere ice sheets dynamics. • A 200-ka record of Arabian dust supply into the equatorial Indian Ocean was reconstructed based on hematite content. • Dust concentrations are lowest at the peak of the interglacial periods, and highest during glacial periods. • The aridity in Arabia was controlled by summer monsoon variability and northern hemisphere ice-sheet dynamics. [ABSTRACT FROM AUTHOR]

The Pacific sector of Northwestern Patagonia (NWP, 40°-44°S) is key for examining the interaction between climate variability, explosive volcanism, and human influences on southern mid-latitude ecosystems. A limited number of studies in this region, however, have focused on aquatic ecosystem and hydrologic balance (HB) changes throughout the Holocene. Here we report a fossil diatom record from Lago Pichilaguna, a small closed-basin lake located in the lowlands of the Chilean Lake District, that reveals prominent changes in species composition and functional groups since ∼12.6 cal ka BP. We interpret positive HB between ∼12.6–11.4 cal ka BP and from ∼5.7 cal ka BP until recent that alternate with negative HB between ∼11.4–6.9 cal ka BP. We observe centennial-scale fluctuations since ∼5.7 cal ka BP that culminate with a negative HB phase over the past ∼270 years. Coherent responses in terrestrial and aquatic ecosystems recorded in the Lago Pichilaguna sediments underscore the influence of variations in the Southern Westerly Winds in NWP from multimillennial to centennial timescales since ∼12.6 cal ka BP. These inferences replicate the timing and direction of changes from previous studies at regional, pan-Patagonian, and zonal scales. The magnitude and rapidity of changes in diatom assemblages that started at ∼0.2 cal ka BP exceeds the ranges of local natural variability since ∼12.6 cal ka BP. This abrupt change is associated with a negative HB phase at centennial timescale, deposition of a tephra layer, and large-scale disturbance by Chilean/European settlers. • A diatom record from Lago Pichilaguna tracks southern westerly wind (SWW) activity since ∼12.6 cal ka BP. • Positive hydrologic balance prevailed between ∼12.6–11.4 cal ka BP and ∼5.7-0 cal ka BP under strong SWW. • A distinct negative hydrologic balance occurred between ∼11.4–6.9 cal ka BP under a SWW minimum. • Centennial-scale variability in SWW influence started at ∼5.7 cal ka BP and lingers until the present. • Terrestrial and aquatic ecosystems covaried in response to SWW variations since ∼12.6 cal ka BP. [ABSTRACT FROM AUTHOR]

Sub-Antarctic glacier chronologies can provide valuable information about the past variability of climate dynamics in the Southern Ocean region. The Kerguelen Archipelago (49°S) is advantageously located under the influence of the Southern Hemisphere's westerly wind belt, thus fluctuations of climate-sensitive glaciers on Kerguelen can provide a baseline for understanding the behavior of this atmospheric regime in response to climatic forcings. We present 17 36Cl exposure ages of moraine and erratic boulders to provide chronological constraints to paleoglacier extents of the Guynemer cirque glacier, located just north of the Cook Ice Cap. Erratic boulders show ice thinning in the Guynemer region started to occur in the Late Glacial by 13.5 ka and continued past 12.4 ka. Ice retreat was punctuated by the formation of two moraine stages, the outermost at 11.5 ± 0.4 ka followed by another at 10.4 ± 1.2 ka, which are indicative of Early Holocene glacier advances/standstills. A glacial advance occurred at 1.4 ± 0.3 ka, which corroborates other Late Holocene re-advances elsewhere on the archipelago. Finally, three undated moraine stages are found between 1.4 ka and the 1960s. The lack of moraines after 10.4 ka and through the Mid-Holocene suggests that the Guynemer glacier was significantly smaller during this extended period of the Holocene compared to its Early Holocene as well as its Late Holocene limits. The Guynemer glacier history provides unique evidence of Early Holocene moraines on Kerguelen, which have not been discovered thus far on the archipelago. Similar to glaciers in Patagonia, New Zealand and South Georgia, the Guynemer glacier was at its largest Holocene extent in the Early Holocene. However, while other southern mid-latitude glacier chronologies show progressively smaller glacial extents throughout the Mid- to Late Holocene, the Late Holocene re-advance of the Guynemer glacier, like other Kerguelen glaciers, likely exceeded its Mid-Holocene extent. • We present 17 new 36Cl surface exposure ages from the Kerguelen Archipelago. • 36Cl ages range from 13.5 ± 0.3 ka to 1.2 ± 0.2 ka. • First early Holocene-dated moraines on Kerguelen. • Glacial readvance occurred in late Holocene. • Holocene glacial evolution on Kerguelen differs from other sub-Antarctic glaciers. [ABSTRACT FROM AUTHOR]

Understanding the role of disturbance regimes on terrestrial ecosystems is often compounded by the paucity of time series sufficiently long and detailed to capture triggering events and the sequence of changes in species composition, community structure and dynamics along a time continuum until the present. Adding complexity to this problem, disturbance regimes and the distribution/competitive interactions of participating species may vary in time with shifts in mean climatic conditions and variability. Here we present results from sediment cores we collected from small closed-basin lakes near the Pacific coast of central Isla Grande de Chiloé, a sector with the lowest seasonality and recurrence of explosive volcanic events in Northwestern Patagonia (NWP). Our aim is examining vegetation development since the last glaciation and exploring potential climatic and disturbance impacts. We found rapid establishment of closed-canopy rainforests, which have persisted with little variation in terms of physiognomy until the present. Significant changes in species composition, structure, dynamics, and rates of change are evident over the last ∼18,000 years, along with fire maxima at ∼16.7 ka, ∼12.7 ka, between ∼11.7-9 ka, from ∼2 ka to the present, and minima in the interim. Fires precede major increases in disturbance favored taxa, which correspond in timing with fire activity maxima at NWP scale. The most recent ∼2000 years coincide with the highest number and ubiquity of human occupations at central-west and NWP scale, raising the possibility that fires were driven by human activities near our study sites. We detect a conspicuous increase in disturbance-favored trees ∼150 years after deposition of the Puma Verde Tephra (∼8.3 ka) and interpret their subsequent maintenance by frequent blowdown events after ∼7.5 ka in exposed sectors of the Coastal Range. We posit that enhanced storminess driven by stronger Southern Westerly Winds since ∼7.5 ka has favored early successional opportunistic trees in detriment of old-growth forests dominated by shade-tolerant species, generating a spatial mosaic of forest patches or gaps in different stages of recovery. • We studied two sites ∼11 km apart in central Isla Grande de Chiloé (IGC), NW Patagonia. • Volcanic, tectonic, and fire disturbance are lowest in this maritime sector of IGC. • Our fossil pollen records replicate the regional climate signal since ∼18 ka. • Fires and tephra layers precede major increases in disturbance favored trees (DFT). • DFT persist after ∼7.5 ka despite low fire and absence of tephra by blowdown events. [ABSTRACT FROM AUTHOR]

Few studies along the western slopes of the Andes in Northwestern Patagonia (NWP: 40°-44°S) allow examining vegetation development through environmental gradients in latitude and elevation along a time continuum since the Last Glacial Termination (T1, ∼18-11 ka). This complete biostratigraphic context is necessary for assessing the sequence, timing, rates, and direction of compositional/structural changes of the former vegetation, and for deciphering their environmental drivers. Here we report palynological results from two NWP sites spaced ∼22 km apart on the western Andean slopes, Caleta Puelche roadside section located near sea level and Lago Reflejos at mid elevations (∼800 m a.s.l.) and assess their continuous records since local ice-free conditions against other NWP sites. We find that cold-tolerant early successional trees dominated the initial stages of vegetation development in the Seno Reloncaví lowlands (∼18-17 ka), followed by thermophilous shade-tolerant North Patagonian rainforest (NPRF) trees, which achieved their maxima between ∼17 and 15 ka at low-elevations. A spread of cold- and shade-tolerant hygrophilous NPRF conifers ensued (∼14.8-13 ka) reaching similar magnitude at low- and mid-elevations, interrupted by increases in trees favored by canopy fragmentation linked to fire and explosive volcanism (∼13-11 ka). Thermophilous, shade-intolerant, summer-drought tolerant Valdivian rainforest (VRF) trees increased and achieved maxima between ∼10 and 8 ka, most notably in the lowlands, coeval with peak abundance of the NPRF conifers Fitzroya/Pilgerodendron and Podocarpus nubigena in mid-elevation Lago Reflejos, contemporaneous with their virtual disappearance near sea level. Widespread increases in cold-tolerant hygrophilous NPRF trees occurred after ∼8 ka, followed by mixing of NPRF and VRF elements in the lowlands after ∼6.3 ka with centennial-scale alternations. Inter-site and regional coherences of our findings suggest that variations in Southern Westerly Wind influence, along with disturbance regimes of natural and human origin, have driven the composition, structure, dynamics, and zonation of temperate rainforests in NWP since T1. We observe that Lago Reflejos features the highest abundance of Fitzroya cupressoides at regional scale since ∼12 ka, attesting to the importance of mid-elevation Andean environments for the persistence of these highly valued trees in the context of postglacial climate evolution, shifts in fire regimes, volcanic, and human disturbance in NWP. • We studied two sites ∼22 km apart on the Northwestern Patagonian Andes (∼42°S). • We detect differences in vegetation, fire, and tephra recurrence at low and mid elevations. • Warm and summer-drought tolerant trees were most abundant in lowland sites after ∼13 ka. • Cold-wet tolerant conifers persisted in high abundance at mid elevations since ∼14.8 ka. • This contrast accentuated during the early Holocene westerly minimum (∼12-8 ka). [ABSTRACT FROM AUTHOR]

We studied a multisequal soil succession (MSS) just south of Torres del Paine National Park (51°S), at the present-day core of the Southern Westerly Winds (SWW). The Río Serrano Section comprises paleosol horizons with associated intervening loess and sandy loess beds formed during the Holocene. Our record suggests strong and stable aeolian activity between ∼9.3–7.2 ka followed by a decline with centennial-scale variations until ∼5 ka. A strengthening commenced at ∼5 ka and culminated in a maximum between ∼2.2–0.5 ka with millennial-scale variations. Subsequent weakening of aeolian activity between ∼0.5 and 0 ka was coeval with the deposition of a ∼40 cm-thick paleosol, after which aeolian activity increased abruptly and reached an unprecedented maximum starting in the mid-20th century. The inferred wind intensity variations from our data bear partial agreement with competing hypotheses of SWW evolution, which postulate minimum SWW influence in SW Patagonia during the early Holocene and maximum influence during the Late Holocene, or vice versa. When analyzed through the lens of vegetation physiognomy/distribution and associated hydrological balance inferences from neighboring sites, our results suggest a primary control by precipitation and wind speeds associated to SWW strength at regional scale, modulated by the position of the forest/steppe ecotone east of the austral Andes. Human activities during the mid-20th century (deforestation, fire-regime shifts, livestock grazing, land use changes) caused an unprecedented increase in aeolian activity through decreased vegetation cover that increased sediment availability for aeolian transport, marking a striking difference with the magnitude of natural processes before the Anthropocene. Our results highlight the importance of climate change and natural/human-driven changes in vegetation cover for deciphering wind intensity histories, particularly in the transition from humid to semiarid environments along the eastern slope of the southern Patagonian Andes. • The Southern Westerly Winds (SWW) play a key role on global climate. • SWW Holocene changes in Southern South America (SSA) are still matter of debate. • Most of SWW reconstructions in SSA are based on indirect proxies of wind intensity. • Vegetation cover is a key factor on wind transport affecting sediment availability. • This is particularly significant in the transition from humid to arid environments. [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]

Last Glacial Maximum (LGM) proxy evidence of surface wind direction across eastern and midcontinental North America comes primarily from loess and dune deposits, and overwhelmingly suggests surface winds had a strong westerly component. However, the season of sediment deposition and the temporal scale of wind information preserved in these deposits remains uncertain. Furthermore, paleoclimate model simulations over the last several decades have indicated a predominance of easterly winds across this region, due to the presence of an anticyclone over the Laurentide Ice Sheet as well as katabatic winds flowing off the ice sheet and over the adjacent land surface. Here we reassess model-data near-surface wind direction agreement using nine general circulation models participating in the LGM experiment of the third Paleoclimate Model Intercomparison Project (PMIP3) and a compilation of previously published paleowind directions from loess and dune deposits dating to the LGM. We find the highest overall model-proxy data agreement in winter (December–February), indicating predominantly westerly winds across the region in the LGM model simulations. We also find high zonal and meridional wind direction agreement in spring (March–May) and fall (September–November) in many models. Winter, spring and fall also have faster mean daily near-surface wind speeds in the LGM simulations relative to pre-industrial control simulations. Thus, this model-data assessment suggests LGM aeolian deposition in the study region likely occurred dominantly in these three seasons, at times when local conditions favorable for aeolian deflation coincided with high wind speed events. Models that agree best with the proxy data have strengthened Aleutian and Icelandic Low pressure systems and a weakened Laurentide High pressure system, which constrains the spatial footprint of the Laurentide High to the ice sheet, reducing northeasterly winds near the ice sheet margin. A weaker Laurentide High in turn coincides with warmer surface temperatures over the ice sheet and the North Atlantic. The strength and location of semi-permanent pressure systems were thus key controls on surface wind direction across midcontinental and eastern North America during the LGM. • Wind direction in Last Glacial Maximum model simulations and proxies agree. • Winter, spring, and fall are likely seasons of aeolian activity in region. • The strength and position of the Laurentide High influences surface wind direction. [ABSTRACT FROM AUTHOR]

The history and dynamics of deciduous Nothofagus forests along the eastern slopes of the central Patagonian Andes (44°-49°S) remain insufficiently studied and understood, particularly at timescales ranging from centuries to millennia. Available fossil pollen records point to time-transgressive responses of the arboreal vegetation to climatic changes during the Last Glacial Termination (T1) and early Holocene, and spatial heterogeneity since then along north-south, east-west, and elevation transects. The degree to which these results represent biogeographic and climatic trends, varying environmental gradients, or site-specific phenomena has not been assessed in detail. Here we present a fossil pollen and macroscopic charcoal record from Lago Churrasco (45°41′S, 71°49′W), a small closed-basin lake located in the deciduous Nothofagus forest zone of the central-east Andes of Chilean Patagonia. Our results suggest that Nothofagus trees colonized newly deglaciated terrains at ∼16,000 cal yr BP and formed scrublands/woodlands several millennia earlier than reported by previous studies east of the Andes. This suggests expansion and local densification of tree populations sourced from the eastern margin of the Patagonian Ice Sheet during the Last Glacial Maximum, with the additional implication that temperature and precipitation conditions favorable for tree survival and reproduction developed early during T1. We posit that the amount of moisture delivered by the Southern Westerly Winds was not a limiting factor for arboreal expansion during T1 in this sector of the central Patagonian Andes. Closed-canopy Nothofagus forests established at ∼10,000 cal yr BP and have remained essentially invariant despite climate change and natural disturbance regimes. This resilience was challenged and exceeded by human disturbance during the 20th century through the use of fire, leading to deforestation and spread of invasive exotic species in an extraordinarily rapid event. Our record suggests a permanent influence of the Southern Westerly Winds over the last 10,000 years, with relatively modest variations at centennial and millennial timescales. • We studied lake-sediment records from the eastern slopes of central Andean Patagonia. • Deglaciation started at 17,800 cal yr BP and led to the formation of a glacial lake. • Colonization and densification of Nothofagus trees started at ∼16,000 cal yr BP. • Closed-canopy forests have persisted essentially unaltered since ∼10,000 cal yr BP. • Chilean/European disturbance drove the largest-magnitude vegetation changes on record. [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]

Understanding responses by penguins to climate change in Antarctica is often complicated by other factors including microclimate and landscape effects. Here, we analyze an ornithogenic sediment profile to reconstruct penguin occupation history on the eastern side of Ardley Island, west Antarctic Peninsula, and synthesize the results from various studies on Ardley Island in the past 20 years. Penguins have inhabited the eastern side of this island since about 900 yr BP, with populations significantly increasing from ∼500 yr BP. On the western side, delineated by the Ardley Ridge Line , penguins began to abandon nest or molt sites at ∼1000 yr BP. By the time of 500 yr BP, the abandonment and population decline became a common tendency on the west side. This shift in occupation areas was likely driven by local microclimate and a change in wind patterns causing more snow to accumulate on the west side of the island. We found a linkage between this penguin movement and the Southern Westerly Winds, which became stronger at ∼1000 yr BP and impacted local conditions at Ardley Island, likely induced by more positive Southern Annular Mode (SAM). These results indicate that island topography, wind and snow patterns, combined with large-scale climate forcing can be just as important in determining penguin distribution as temperature and other environmental factors. This study provides a new perspective for investigating the possible impact of microclimate and site topography on penguin behavior. • Penguins moved from the western to the eastern side of Ardley Island from 1000 yr BP. • Enhanced westerlies impacted local microclimate conditions and drove penguins to move. • A new perspective is proposed for investigating the impacts of climate forcing and site topography on penguin distribution. [ABSTRACT FROM AUTHOR]

Paleoclimate reconstructions suggest that the complex variability within the Greenland stadial 1 (GS-1) over western Europe was governed by coupled ocean and atmospheric changes. However, few works from the North Atlantic mid-latitudes document both the GS-1 onset and its termination, which are often considered as single abrupt transition events. Here, we present a direct comparison between marine (alkenone-based sea surface temperatures) and terrestrial (pollen) data, at very high resolution (28 years mean), from the southwestern Iberian shelf record D13882. Our results reveal a rather complex climatic period with internally changing conditions. The GS-1 onset (GS-1a: 12890-12720 yr BP) is marked by a progressive cooling and drying; GS-1b (12720-12390 yr BP) is the coldest and driest phase; GS-1c (12390-12030 yr BP) is marked by a progressive warming and increase in moisture conditions; GS-1 termination (GS-1d: 12030-11770 yr BP) is marked by rapid switches between cool wet, cold dry and cool wet conditions. Although hydroclimate response was very unsteady throughout the GS-1 and in particular during its termination phase, the persistence of an open temperate and Mediterranean forest in southwestern Iberia during the entire episode suggests that at least some moisture was delivered via the Westerlies. We propose coupled ocean and atmospheric mechanisms to reproduce these scenaria. Changes in the strength of the Atlantic Meridional Overturning Circulation (AMOC) as well as variations in the North Atlantic sea-ice growth have favoured the displacement of the polar jet stream's latitudinal position and contributed to a complex spatial pattern and strength of the Westerlies across western Europe. • Highlights of the Quaternary Science Reviews paper by Naughton et al.. • GS-1 in SW Iberia is a complex climatic period with four main phases. • Hydroclimate was very unsteady throughout the GS-1 event and in particular during its termination phase. • Ocean and atmospheric changes contributed to a complex spatial pattern of the Westerlies across Western Europe. [ABSTRACT FROM AUTHOR]

The coast of the Great Australian Bight contains perhaps the largest concentrations of clifftop dunes in the world. It consists of 1350 km of calcarenite and limestone cliffs of which 508 km are capped by clifftop dunes covering an area of 958 km2. To develop a preliminary chronology of dune emplacement and an assessment of triggering mechanisms, 89 OSL dates were obtained from clifftop dunes spread around the Bight. Starting in the east, dunes were sampled for dating on Kangaroo Island, southern Yorke Peninsula, western Eyre Peninsula, Bunda (Nullarbor) Cliffs, Hampton Bluffs, Twilight Cove, Baxter Cliffs and the Wylie Scarp. In addition, the large Roe Plain dune complex that merge with the Baxter-Hampton clifftop dunes were also dated. The dunes are carbonate-rich in the east and center, to grading to quartz-rich to the west. Examining the entire Bight dune systems in a chronological order, the oldest dunes (>164 ka) were located on Kangaroo Island in the far east and are quartz-rich, but overlain by subsequent carbonate deposits, which also date >136 ka. Next were dunes deposited during sea-level highstands along the Baxter Cliffs during Marine Isotope Stage (MIS) 5a (∼80 ka) and MIS3 with dates between 60 and 40 ka, followed by reactivation during the Last Glacial Maximum (LGM) by strong westerly winds between 26–16 ka, particularly across the Roe Plain and on some Eyre Peninsula headlands. Initial Holocene clifftop emplacement accompanied the sea level transgression and stillstand between 10–6 ka. Most beaches and sand ramps that supplied the dunes have since been eroded, though ongoing reactivation on top of the cliffs has occurred at scattered sites throughout the late Holocene, a fact exacerbated by the general aridity, with some sites showing evidence to two to three reactivations. More dating is required to determine if the reactivation is periodic or more random together with a more complete chronology of the dune systems, including their initial emplacement. • Clifftop dunes along the 2000 km long Great Australian Bight. • Dune OSL ages spans early Pleistocene to present. • Multiple episodes of dune emplacement and reactivation. • Last Glacial Maximum dunes extend over 100 km inland. [ABSTRACT FROM AUTHOR]

The variations of atmospheric Δ14C over the past two millennia are classically attributed to changes in its production rate in the upper atmosphere, which in turn is related to changes in solar activity and the Earth's magnetic field. However, the potential contribution of atmospheric and oceanic circulation changes during this period has not been precisely quantified. This has been achieved here using a coupled climate model simulating explicitly the evolution of the different carbon isotopes, driven by a new estimate of 14C production derived from 10Be measurements, and using different production rates for each hemisphere. Our results confirm that changes in global and hemispheric atmospheric Δ14C are primarily driven by changes in production rate. The very good agreement between our results and observed atmospheric Δ14C also highlights the strong consistency of current interpretations of 10Be and 14C measurements. By contrast, the interhemispheric difference in atmospheric Δ14C is controlled by changes in the intensity of southern hemisphere westerly winds (SHWW) that impact atmosphere-ocean exchange and the upwelling of 14C depleted water masses in the Southern Ocean. Changes in deep water formation in both hemispheres or open ocean polynyas in the Southern Ocean only have a small impact on atmospheric Δ14C over that period. When driven by changes in the SHWW proportional to three existing reconstructions of the Southern Annular Mode (SAM) index, the model reproduces some key characteristics of the observed interhemispheric Δ14C gradient. These include the low values in the 15th century and the peak in the 16th century, but there are also clear differences between the experiments and Δ14C observations. This suggests that while SAM reconstructions capture some robust features in the centennial variability, large uncertainties remain. • The model skillfully reproduces variations of atmospheric Δ14C over the past two millennia. • Atmospheric Δ14C is mainly driven by changes in the 14C production rate. • Interhemispheric atmospheric Δ14C gradient is controlled by southern hemisphere westerly winds. • Δ14C provides constraints on the centennial variability of the Southern Annular Mode. [ABSTRACT FROM AUTHOR]

It is increasingly apparent that local and regional factors, including geographic location, topography and climatic variability, strongly influence the timing and extent of glaciations across the Southern Hemisphere. Glacial chronologies of sub-Antarctic islands can provide valuable insights into the nature of regional climatic variability and the localised response(s) of glacial systems during periods of climatic change. With new cosmogenic 36Cl exposure ages from Marion Island in the southern Indian Ocean, we provide the oldest dated terrestrial moraine sequences for the sub-Antarctic islands. Results confirm that a local Last Glacial Maximum was reached prior to ∼56 ka when ice retreated with localised stand still events at ∼43 ka and between ∼38 and 33 ka. Evidence of ice re-advances throughout MIS 2 are limited and particularly absent for the cooling periods at ∼32 and ∼21 ka, and retreat continued until ∼17 ka ago. Any MIS 1 readvances on the island would be confined to altitudes above 900 m a.s.l. but the Holocene exposure ages remains to be documented. We compare Marion Island's glacial chronology with other sub-Antarctic islands (e.g., the Kerguelen archipelago, Auckland and Campbell islands and South Georgia) and review the evidence for a Southern Hemisphere glacial maximum in late MIS 3 (∼41 ka). At a regional scale we recognize sea surface temperatures, sea ice extent and the latitudinal position of the Southern Westerly Wind belt as key controls on equilibrium-line altitudes and ice accumulation due to their influence on air temperature and precipitation regimes. At an island scale, geomorphological mapping shows that deglaciation of individual glacier lobes was a-synchronous due to local physiographical and topographical factors controlling the island's micro-climate. We suggest that variability in deglaciation chronologies at smaller scales (particularly at the sub-Antarctic Islands) are important to consider when untangling climatic drivers across the Southern Ocean. • Chlorine-36 exposure ages of glacial features from across on Marion Island. • Local last glacial maxima terminated before ∼56 ka ago, in MIS 3. • Retreat continued throughout MIS 2 with localised stand stills at ∼43 ka and ∼38-33 ka. • Island scale deglaciation was a-synchronous. • Sea-ice, sea level and the Southern Westerly winds are key climatic drivers. [ABSTRACT FROM AUTHOR]

The influences on climate in the Northwest Tibetan Plateau (NwTP) have changed on millennial to precessional timescales and have been dependent on the size of the Northern Hemisphere ice sheets, Northern Hemisphere summer insolation, and the migration of the Intertropical Convergence Zone (ITCZ). All these influences control the position and intensity of the westerlies over Central Asia and the Tibetan Plateau and of the Asian Monsoon over South Asia. The top 187.4 m of a 309.7-m ice core (2015GP) drilled on the plateau of the Guliya ice cap contains a 41-kyr climate history of the NwTP, a region where information on past climate and environment is limited. The oxygen isotope ratio (δ18O), and ammonium (NH 4 +) and dust concentration records from 2015GP show that during the glacial (41–17.5 ka BP) temperature and precipitation in the NwTP were primarily influenced on the precessional timescale by summer insolation, while at millennial resolution the climate was linked to the North Atlantic temperature via the westerlies. During the deglaciation (17.5–12 ka BP) summer insolation remained an important temperature forcing, but the influence of the North Atlantic climate on the NwTP climate weakened as the westerlies shifted northward. The Guliya Holocene δ18O record shows that NwTP climate was no longer in phase with decreasing summer insolation or with North Atlantic climate, perhaps as the moisture source and pathways were more determinative factors in isotopic fractionation than temperature, and/or incoming solar radiation (insolation) forcing was replaced by rising greenhouse gas concentrations as the primary driver of warming in NwTP. • An ice core from the western Kunlun Mts shows orbital to millennial climate changes. • Summer insolation and westerlies influenced glacial stage climate in western Kunlun. • Ice core δ18O variations in NW Tibet and Greenland were similar in last glacial. • Ice core δ18O variations in NW Tibet and Greenland were opposite after 17.5 ka BP. • Mechanisms influencing δ18O in NW Tibet may vary with changing climatic conditions. [ABSTRACT FROM AUTHOR]

Variations in mid-latitude westerlies have an important influence on climate change, but their impact on the Tibetan Plateau (TP) since the Last Glacial Maximum is still debated, due to shortage of direct proxies reflecting the variations in the westerlies. Here we present an exotic (Cedrus) pollen record from the interior of the TP since 26.5 cal ka BP to reconstruct the changes in westerlies. Combined with its modern distribution, the Cedrus pollen in our record is considered to reflect the change in the intensity and position of the westerlies. Increased Cedrus pollen inputs are consistent with cooling phases during the Heinrich Stadial (HS) 2, HS 1a, HS 1c and Younger Dryas, suggesting that the westerlies were abruptly enhanced and southward-shifted, which can be attributed to the increased equator-to-pole temperature gradients and sea ice advance. Our record over the TP is in agreement with other reconstructions from the lower altitudes suggests a synchronous change in the westerlies at different levels. • A direct proxy for variations in the westerlies over the Tibetan Plateau was presented. • We reconstructed the variations in the westerlies since the LGM. • The Cedrus pollen record was a direct evidence for variations in the mid-upper westerlies. [ABSTRACT FROM AUTHOR]

Abstract This paper constitutes a review of the last (Otiran) glaciation in New Zealand, spanning marine isotope stages (MIS) 4-2. We highlight the nature of glaciation, which is characterised by exceptional sedimentation, relatively mild maritime climatic conditions and the widespread presence of water associated with proglacial settings. These conditions produce glacial systems characterised by extensive outwash fans and relatively small terminal moraines. Extensive recent geochronological work allows us to recognise at least eight glacial advances during the Otiran. These occurred at 65 ± 3.25ka, 47.5 ± 3 ka, 38.5 ± 2 ka, 31.5 ± 3 ka, 26.5 ± 2 ka, 20.5 ± 2 ka, 17 ± 2 ka and 13 ± 1 ka, which we term the Otira 1 to 8 advances, respectively. Though the analytical uncertainty ranges for some of these advances overlap, all are independently distinguished through moraine morphologic relationships and/or stratigraphic relationships in outcrop. Major advances appear to be associated with climate influences such as periods of Southern Hemisphere insolation minima (65ka, and 31.5 ka advances), the last glacial maximum cooling (LGM) (20.5 ka) and periods of Antarctic cooling (13ka). The timing of greatest glacial extent in the last glacial cycle is not simultaneous across New Zealand. The MIS 4 advance was the greatest in the southern South Island, while the MIS 3/2 advances (26.5 ka) were greatest in the central South Island. In the northern South Island and the North Island, MIS 4, MIS 3/2, and the last glacial maximum appear to be equivalent in extent. We attribute these spatio-temporal variations in the timing of maximum glaciation to precipitation changes related to a northward shift in the track of the westerlies. Highlights • Temperate style of New Zealand glaciation is described. • Eight significant glacial events are recognised in the last (Otiran) Ice age. • Multiple glacial drivers are recognised. • Evidence for possible northward movement of surface westerly winds in late MIS 3 is summarised. [ABSTRACT FROM AUTHOR]

Abstract This study derives a new function describing the relationship of channel bankfull discharge (Q bf) to channel width in modern rivers of the Murray-Darling Basin (MDB) of southeastern Australia and applies this to dated palaeochannels of seven rivers to quantify late Quaternary discharge history in this important basin. All rivers show high MIS3 and MIS2 Q bf , declining in the Holocene. The Q bf of modern MDB rivers is correlated with total catchment precipitation but comparison with palaeochannel Q bf estimates shows that while enhanced runoff efficiency is necessary to account for much larger late Pleistocene palaeochannels, either lower or higher precipitation rates could have prevailed. A strong association between relative palaeo- Q bf enhancement and temperature suggests a temperature-mediated mechanism controlling river discharge, such as the fraction of precipitation stored as snow and thawing in spring, the enhancement of orographic rainfall, or CO 2 feedbacks with vegetation cover. Significantly enhanced MIS3 Q bf requires an additional mechanism, such as increased rainfall. These findings are consistent with others that increased moisture availability was associated with past colder climates, although this was not necessarily the result of enhanced precipitation. Highlights • Dated palaeochannels of the Murray-Darling basin, Australia, reveal late Quaternary hydrological history. • A regime equation based on modern rivers is used to predict palaeo-discharge. • Discharge of MIS2 and MIS3 palaeochannels was 3–270 times equivalent modern rivers. • MDB palaeochannel discharge follows Antarctic temperature, which determines catchment runoff. • Relatively larger MIS3 MDB palaeochannels require additional moisture sources. [ABSTRACT FROM AUTHOR]

Abstract The influence of the mid-latitude westerlies (MLW) competing with the Asian summer monsoons (ASM) over the Tibetan Plateau (TP) remains a matter of discussion on how and to which extent both atmospheric systems have been controlling hydro-climate during the Holocene. Depleted oxygen isotopes in lake deposits were commonly interpreted in terms of enhanced summer monsoon moisture supply, implying a migration of the ASM deep into the interior of the plateau during Holocene periods. In order to test this relationship we used a high resolution oxygen isotope record (mean 20 yr resolution) in combination with carbonates and mineral phases, titanium flux, grain size and ostracod abundances derived from a 6.84 m long sediment core in the endorheic Kuhai Lake basin, north-eastern TP. The results confirm 1) continuous positive co-variance between enriched δ18O carb and total carbonates during the last 14 ka, indicative of dominant seasonal influence on multi-decadal to centennial scale isotopic signatures in lake water and respective carbonate precipitation, 2) negative co-variance between allochthonous sediment flux and δ18O carb (and carbonates) attributed to relative increase of flux rates during non-summer seasons, 3) correspondence of lake level variations with carbonate mineral phases and the occurrence/disappearance of ostracod assemblages, and 4) inverse relationships between isotopic signatures in ASM-dominated and MLW-controlled lake records across the TP. Enriched δ18O carb in Kuhai Lake sediments was primarily a result of high evaporation during the summer seasons, while ASM-related rainfall amount did not play an important role, likely counterbalanced by isotopic signatures from different water sources. Conversely, depleted δ18O carb was mainly attributed to water supply during non-summer seasons of colder temperatures and generally light isotopic signatures from MLW-derived sources. This finding may lead to a paradigm shift in such way that depleted δ18O in carbonates is primarily not the result from ASM-related rainfall as previously assumed. The reconstructed hydro-climatic history of Kuhai Lake indicates the dominance of westerly-derived climate during the Younger Dryas interval (12.8–11.5 ka) under very shallow pond-like conditions. Despite climate amelioration during the early Holocene (11.5–7.5 ka) hydrological conditions remained unstable with frequent alternations between dominance of summer and winter seasons. During the middle Holocene (7.5–5.5 ka) the lake experienced highest lake levels dominated by summer monsoon-related water supply, assigned to the Holocene hydro-climatic optimum. Frequent high-amplitude fluctuations afterwards (5.1–2.9 ka) refer to cooling/drying events under enhanced MLW influence accompanied by a strong lake level decline. The late Holocene (2.9 ka- Present) period experienced moderate isotopic variations and fluctuating lake levels in response to variable influence of summer- or winter-related hydro-climatic conditions. This seesaw-like pattern with amplitudes of >10‰ in δ18O carb resembles fluctuations in cave records and variations between air and seawater (Dole effect). High correspondence with cooling events derived from North Atlantic drift ice and meltwater discharge indicate close ties to northern hemispheric climate transmitted by the MLW across the TP. Highlights • Positive co-variance between δ18O carb and total carbonates reflect summer season impact. • Negative co-variance between allochthonous flux and δ18O carb points to non-summer impact. • Seasonal influence is identified by multi-decadal to centennial isotopic signatures. • Inverse relationships exist between isotopic signatures in ASM-dominated and MLW-controlled lake records across the TP. [ABSTRACT FROM AUTHOR]

To explore the relationship between the global cooling, westerlies, and central Asian aridity, we report ∼1.1 Ma local sedimentary environment changes according to physical-chemical parameters from an 800-m core (KT11) from the Kashgar region in the western Tarim Basin, China. Grain size end-member (EM) modelling is employed to quantify the processes of sediment transport and deposition. Four end members with modal values of 272 μm, 144 μm, 45.6 μm and 12.7 μm were extracted and explained 97.9% of the variance in the grain size data, corresponding aeolian dynamics, river energies, delta development and pedogenesis/long-term suspension components transported by wind or water, respectively. Four dominant sedimentation types, including lacustrine facies, delta facies, fluvial facies, and aeolian dunes, were identified through lithology and grain size frequency curves. The 1.1 Ma sedimentary successions experienced delta deposits interbedded with fluvial and aeolian deposits and lacustrines (1.1–0.6 Ma), alternating fluvial and aeolian facies with the occurrence of deltas and lacustrines (0.6–0.15 Ma), and aeolian facies interbedded with deltas and fluvial facies (0.15 Ma-present). Stepwise drying sedimentary conditions and enhanced desertification indicated by increasing rubidium/strontium ratios and proportion of aeolian sands, and decreasing total organic carbon since the past 1.1 Ma, implied intensified westerlies, likely resulted from ice volume expansion and ongoing global cooling according to geological record comparison and simulations during the Last Glacial Maximum compared to preindustrial conditions, which may have controlled the expansion of the permanent deserts in inland Asia. These persistent drying trends and intensified westerly circulation in arid regions during glacial periods after the mid-Pleistocene Transition indicated by larger amplitudes of aeolian sand proportion than prior to 0.6 Ma are similar to those in the interior monsoonal Asia, where the larger-amplitude of median grain size indicated enhanced Asian winter monsoon intensity and drier glacials. • Dominant sedimentation types are identified. • Westerly aridity is reconstructed since mid-Pleistocene. • Concurrently enhanced westerlies and winter monsoon is proposed. • Records and simulations show westerly aridity driven by global cooling. [ABSTRACT FROM AUTHOR]

By virtue of its position adjacent to the Drake Passage, Tierra del Fuego in South America allows examining the vegetation and environmental history of the southernmost continental landmass outside Antarctica, and the evolution of the Southern Westerly Winds-Southern Ocean (SWW–SO) coupled system since the Last Glacial Maximum (LGM). For that purpose, we studied sediment cores from Lago Charquito, a small closed-basin lake in central-west Tierra del Fuego with a continuous lacustrine record since ∼17.3 ka. Ice-free conditions at the site imply a ∼70 km retreat of the Bahía Inútil glacier lobe from its LGM position during a ∼800-year interval, a trend that continued until its disappearance ∼100 km upstream from L. Charquito, ∼800 years later. Our palynological data show an open landscape dominated by cold-tolerant shrubs and herbs between ∼17.3–12.9 ka, with increases in precipitation of SWW origin at ∼16.3 ka, ∼14.7 ka, between ∼8.7–7.6 ka, and after ∼6.8 ka. Warming at ∼12.9 ka initiated an abrupt afforestation trend that stalled during the early Holocene (∼12–8.7 ka) owing to a precipitation decline and wildfires, and later resumed in response to invigorated SWW. We hypothesize that sparse Nothofagus tree populations inhabited the periphery of the Patagonian Ice Sheet (PIS) during the LGM and migrated toward the Andes contemporaneous with glacier recession as temperature rose during the Last Glacial Termination (T1). We posit that besides establishing topographic and climatic barriers for land biota, the PIS enabled the connectivity of cold-tolerant hygrophilous plant populations along a humid fringe adjacent to its land-based perimeter, despite the presumably dry conditions downwind from the eastern PIS margin. Our results suggest that southward shifts or expansion of the SWW toward or beyond Tierra del Fuego enhanced upwelling and ventilation of deep waters in the SO, northward shifts or weakening had the opposite effect. We observe that the time evolution of atmospheric CO 2 concentrations, high-latitude air and sea-surface temperatures, and sea level during T1 fall short in explaining the timing and abruptness of the Bahía Inútil glacier lobe collapse, and quite possibly multiple other glacier lobes from the PIS. • The Lago Charquito record from Tierra del Fuego spans the last ∼17,300 years. • Cold conditions persisted until ∼12.8 ka inhibiting arboreal expansion. • We infer negative hydrologic balance between ∼18–16.4 ka and ∼12–8.7 ka. • Positive hydrologic balance peaked between ∼14.9–12.8 ka and since ∼5.7 ka. • We infer hemispheric-scale changes in the Southern Westerly Winds since ∼17.3 ka. [ABSTRACT FROM AUTHOR]

Considerable ambiguity remains over the triggers for the abrupt climate deterioration that terminated the Last Interglacial Marine Isotope Stage 5e (MIS5e) period. A prevailing explanation is a sudden reduction in Atlantic Meridional Overturning Circulation (AMOC) in response to the reduced boreal summer insolation. Nonetheless, this opinion is challenged by the early weakening of the Asian summer monsoon (ASM) documented in the Chinese speleothem oxygen isotope (δ18O) ratio records. Here we propose a new mechanism involving a northerly shift of the Southern Hemisphere mid-latitude westerlies (SHW), based on saturation magnetization (M s) and stable carbon (δ13C) and oxygen isotopes from a speleothem in northern Tasmania. The M s record shows high-frequent peaks at 122.8–119.7 ka B.P., while δ18O and δ13C ratios first increase significantly (122.8–122.2 ka B.P.) and then decrease (122.2–119.7 ka B.P.). These M s peaks suggest a northward shift of SHW at 122.8–119.7 ka B.P., which precedes the earliest ASM weakening for MIS5e demise and coincides with the reduced Agulhas leakage. This indicates that when SHW reaches a northerly position, the reduced Agulhas leakage leads to an anomalous warming in the southern Indian Ocean, further weakening the cross-equatorial flow. Such a process would aggravate the ASM weakening caused by the decline in boreal summer insolation and initiate an early MIS5e demise. • Reconstruction of Southern Hemisphere mid-latitude westerlies (SHW) during MIS 5e using a stalagmite in northern Tasmania. • The SHW shifted northwards at 122.8 ka B.P., predating the initial decline of Asian summer monsoon. • A northerly position of the SHW aggravated the early MIS 5e demise via the cross-equatorial flow. [ABSTRACT FROM AUTHOR]

Knowing the behavior of the Asian summer monsoon (ASM) and its global correlation help understand roles of the ASM in global climate change. Here we synthesize a stalagmite δ18O record, based on a new record and an available nearby record, both covering the nearly entire Holocene. The synthesized δ18O record correlates with meridional migration of the Intertropical Convergence Zone (ITCZ), and with change in inter-subtropical insolation contrast throughout the Holocene. However, its correlation with the Atlantic meridional overturning circulation (AMOC) broken down during the period of the strongest ASM, when the AMOC weakened. This scenario points to a persistent influence of the ITCZ and subtropical insolation contrast on the change in ASM throughout the Holocene. Our record also correlates with a change in atmospheric CO 2 concentration on the multi-millennial scale. These correlations of our cave record with variations in the ITCZ, subtropical insolation contrast, and CO 2 level indicate that changes in low-latitude climates, including the ASM, were involved in the evolution of the Holocene CO 2 concentration. These changes in the low-latitude climates were likely connected with variation in the Holocene southern westerly wind, which modulated upwelling of carbon-enriched deep ocean water around Antarctica. On the multi-centennial scale, seven weak ASM events are identified, with the magnitudes of the Younger Dryas and the events at 9.8 ka and 8.2 ka event broadly three and two times larger than the other ones. These events have a quasi-period of approximately 1.463 ka. This period in the monsoon regime probably arose from solar activity, but involving the feedback of ENSO. In summary, our study provides insights into the connection of the Holocene ASM with tropical climate, and into the involvement of the ASM in the change of the Holocene CO 2 concentration. • A new Holocene stalagmite record is provided from southwestern China. • The Asian summer monsoon was probably involved in the evolution of the Holocene atmospheric CO 2 concentration. • Weak monsoon events corresponded to states of more El Niño events. [ABSTRACT FROM AUTHOR]

Understanding the evolution and interaction of the mid-latitude westerlies and East Asian monsoon (EAM) is crucial for comprehending Asian climate dynamics. While abundant evidence from loess, lake and speleothem records in arid Central Asia (ACA) and East Asia has revealed the interplay between the mid-latitude westerlies and the EAM on orbital and millennial scales, most of these records only cover the period since the last glacial maximum. Thus, the trade-off relationship between the mid-latitude westerlies and the EAM on glacial-interglacial to millennial timescale since the last interglacial period remains unclear. In this study, we present 150 ka-long grain-size and organic carbon records from two loess sections in the western Chinese Loess Plateau (CLP) and Yili Basin to assess the wind intensity and moisture variability between East Asia and ACA at glacial-interglacial to millennial timescales. Our results indicate that the East Asian winter monsoon (EAWM) and westerly wind exhibit synchronous glacial-interglacial and precession-scale fluctuations. However, the moisture exhibits consistent variations between East Asia and ACA on glacial-interglacial timescale, whereas inconsistent pattern at precessional timescale. The moisture variations in ACA lagged those in the East Asia by 2 kyr during marine isotope stages (MIS)5. Millennial-scale wind and moisture variability in East Asia and ACA are broadly correlated with cooling events in the North Atlantic. Based on the modeling results of the TraCE-21 ka, we suggest that the wind and moisture variations in East Asia and ACA are controlled by the combined effects of ice sheets, insolation, and meltwater flux from orbital to millennial timescales. Therefore, our study provides new insights into the complex interplay between the EAM and mid-latitude westerlies, which can contribute to a better understanding of Asian climate dynamics. • Orbital and millennial-scale monsoon and westerlies variability were reconstructed • East Asian winter monsoon and westerly wind were synchronous on the orbital timescale • Moisture variations in central Asia lagged those in East Asia by 2 kyr during MIS 5 • Millennial scale wind and moisture events in East and central Asia were correlated [ABSTRACT FROM AUTHOR]

We present high resolution pollen and macroscopic charcoal records from Basin Lake, a relatively small mid-latitude (42°S) lake located in central-western Tasmania, Australia, to examine vegetation, fire and climate change since and during the Last Glacial Maximum (LGM). We find dominance of cold-resistant alpine vegetation with buttongrass moorland and scant trees between ∼21.0-17.7 cal kyr BP, with local biomass burning and low lake levels between ∼21.0-20.0 cal kyr BP and a reduction in local biomass burning and a rise in lake levels between ∼20.0-17.7 cal kyr BP. These data suggest glacial-cold conditions during the last millennia of the LGM, with relatively humid conditions between ∼21.0-20.0 cal kyr BP and a further increase in humidity between ∼20.0-17.7 cal kyr BP. These shifts suggest an intensification of the South Westerly Winds (SWW) over the site between ∼20.0-17.7 cal kyr BP. An increase in cold-temperate rainforest taxa followed between ∼17.7-16.0 cal kyr BP along with lake-level lowering, suggesting a warm pulse and southward shift of the SWW at the beginning of the Last Glacial Termination (T1). Subsequent cold-temperate conditions and increased precipitation ensued between ∼16.0-14.9 cal kyr BP promoted by increased SWW influence. A rise in cold-resistant and hygrophilous rainforest taxa and lower biomass burning activity occurred between ∼14.9-12.8 cal kyr BP under colder conditions, enhanced precipitation and major SWW influence. A multi-millennial warm/dry interval began at ∼12.8 cal kyr BP with a decline in rainforest taxa, high fire activity and low lake levels and a further opening of the vegetation in response to elevated biomass burning between ∼11.1-8.9 cal kyr BP. We suggest a decline in the SWW influence that started at ∼12.8 cal kyr BP and accentuated between ∼11.1-8.9 cal kyr BP at the beginning of the Holocene. We detect increases in precipitation between ∼8.9-5.8, ∼3.4-1.9 cal kyr BP and the last ∼900 years, with declines in the intervening intervals. Our data indicate a pronounced and sustained fire-driven shift to a more open and shrub dominant landscape after ∼5.0 cal kyr BP, in synchronous with other pollen data from Tasmania's west, reflecting an increased efficacy of Aboriginal burning under more variable and overall reduced precipitation. Our climate inferences from Basin Lake are coherent with variations of the SWW identified in other terrestrial mid-latitudes records, suggesting synchronic changes in the SWW during and since the LGM. • We studied lake sediments from central-western Tasmania. • Local ice-free conditions established in the Basin Lake area at least since ∼21.0 cal kyr BP. • Cold-resistant alpine and buttongrass vegetation dominated between ∼21.0 and 17.7 cal kyr BP. • An increase in rainforest taxa began at ∼17.7 cal kyr BP. • Enhance fire and more open landscape reflect efficacy of Aboriginal burning during the last 5 kyr. [ABSTRACT FROM AUTHOR]

Paleoshorelines around Lago (Lake) Cardiel in southern Argentina (S48.9°, W71.3°; ∼275 m) record substantial changes in lake area over the past 25 ka. Our results combined with previous research show that during the last glacial maximum (or LGM, 23–21 ka), the lake stood at near modern levels, but had nearly dried up by ∼13 ka. Between 11.3 and 10.1 ka the lake reached its highest point (+54–58 m) and greatest extent in at least the last 40 ka. Lake levels dropped thereafter and experienced two lower-lake periods: 8.5–7.5 ka and 5–3.3 ka; and two higher-lake periods: 7.4–6 and ∼5.2 ka. In the last 3.5 ka, the lake has remained generally near or slightly above its present level. The depth and surface area of Lago Cardiel are controlled mainly by precipitation onto the lake and surrounding catchment, air and water temperature, and wind-speed related to local strength of the Southern Hemispheric Westerlies (SHW). Our lake-level reconstruction combined with evidence from other studies suggest that on average the core of the SHW was located well to the north (<45°S) of the Cardiel basin during the deep lake phase associated with the LGM, and was well to the south (>55°S?) during the hydrologic maximum of Cardiel in the early Holocene. The lower phases of the lake at 20.0–11.5, 8.5–7.5, and 5.0–3.3 ka generally correspond to cold conditions in other records, when we infer that the SHW were strongly focused around the latitudes of Cardiel at 49°S. [ABSTRACT FROM AUTHOR]

Identifying the relationships between moisture changes in arid central Asia and those in East Asia may help us understand the interplay between the westerlies and the Asian summer monsoon. We combined proxy moisture records with the results from a transient simulation forced by changes in orbital parameters to analyse their relationships during the Holocene (9.5–0 ka BP). The proxy records and simulation results generally agree with a relatively dry early Holocene, the wettest period in the middle Holocene, and a dry late Holocene in East Asia. These periods were not solely controlled by precession-driven East Asian summer monsoon variability, but were significantly influenced by precipitation during the other seasons and by evaporation. However, different proxy records show contrasting results for moisture changes in arid central Asia during the Holocene. To study this, we analysed the climatic signals of the competing proxy records by comparing these proxy records with simulation results. We found that speleothem δ 18 O was significantly influenced by water vapour sources and evaporation rather than by the amount of precipitation. Thus, the model data reveals a persistent wetting trend throughout the Holocene that was out-of-phase with the trend in East Asia. The wetting trend in arid central Asia was caused by precipitation that increased faster than evaporation during the Holocene. The enhanced water vapour input from South Asia and the Middle East was the main cause of the increase in precipitation in arid central Asia, which in turn gave rise to the intensification of evaporation. [ABSTRACT FROM AUTHOR]

Arid central Asia (ACA) is one of the largest arid (desert) areas in the world, and its climate is dominated by the westerlies. In this study, we examined sand dune evolution from the Bayanbulak Basin in the Tian Shan (Xinjiang, NW China), aiming to infer the Holocene moisture history of the ACA. Combined with stratigraphic observation and environmental proxies analysis (grain size, magnetic susceptibility and total organic content), large numbers of luminescence ages from multiple sites (eight sections, 79 samples) were applied to reconstruct the evolution of the sand dune accumulation in the study basin. The overall results imply very dry conditions characterized by sand dune accumulation at ∼12–6.5 ka, a wet interval between ∼6.5 and 0.8 ka when soil formation occurred, and decreased moisture during the last 0.8 ka. This moisture variation pattern is generally consistent with that inferred from many lacustrine records in the core zone of ACA, suggesting a widespread dry period in the early-to-middle Holocene and relatively wet middle-to-late Holocene. Thus, the moisture history derived from the current sand dune system contrasts with that in Asian monsoon areas, which are characterized by a strong monsoon (high precipitation) in the early and mid-Holocene and a weak monsoon (low precipitation and dry climate) during the late Holocene. Our results strongly suggest that the winter solar insolation and the external boundary conditions such as atmospheric CO 2 concentration, ice sheets, and meltwater fluxes, have been major influential factors triggering the Holocene moisture evolution in the core zone of ACA. [ABSTRACT FROM AUTHOR]

We synthesized 13 high-resolution charcoal records located within the current zone of strongest correlation between the southern westerly winds (SWW) and rainfall on Earth in an attempt to assess how shifts in the SWW drive climatic change in this region. High regional charcoal influx values are found during the early Holocene (12–8 ka), progressively decreasing and reaching a minimum during the mid-Holocene (∼5 ka). Wavelet coherence analysis between regional charcoal influxes from southern South America (SSA) and western Tasmania (WTAS) shows a tight periodicity coherence from 12 to ∼6 ka, supporting synchronous SWW-driven climatic change in these areas. The same analysis between the regional Tasmania charcoal influx and an ENSO proxy suggests a coherent pattern of frequency variability between these records since ∼6 ka, highlighting the importance of ENSO in altering fire regimes in this region. Our data also provides insights into the non-stationarity of the climate system in space and time and highlights the potential limitations of modern climatic relationships for informing our understanding of the global climate system. [ABSTRACT FROM AUTHOR]

Precipitation atop the Tibetan Plateau (TP) is delivered by the Indian summer monsoon, the Asian summer monsoon, and weather systems associated with the subtropical westerly jet. Variations in the relative importance of the monsoon systems and the westerly jet are hypothesized to have occurred at decadal, millennial and glacial-interglacial scales. However, paleoclimate observations based on explicit climate proxies are still scarce, limiting our understanding of the mechanisms of Holocene climate variability on the Tibetan Plateau (TP). Here we present three independently dated compound specific hydrogen isotope records of sedimentary leaf waxes from lakes on the TP, Bangong Co, Lake Qinghai and Linggo Co. The leaf wax δD records reflect isotopes in precipitation, and we combine these observations with existing isotopic and hydrological data to investigate variations in the influence of the summer monsoon and the westerly jet on the moisture budget of the TP since the Late Pleistocene. δD values of precipitation at all three lakes were relatively positive during the Late Pleistocene indicating a weakened summer monsoon. During the early and mid-Holocene, δD values of precipitation at the three lakes were relatively negative, suggesting the importance of summer monsoon. During the middle to late Holocene, δD values at Bangong Co and Lake Qinghai gradually increased with superimposed episodes of short term of δD variability. However, at Linggo Co in the northern TP, periods of more positive δD values of precipitation correspond to wetter intervals inferred from lake level high stands, and likely reflect variations in moisture associated with the westerly jet. Thus, the δD records at Linggo Co imply the lesser importance of summer monsoon moisture in the hydrologic budget of the northern TP. Collectively, the hydrogen isotope records at these three lakes document millennial and centennial scale variations in the strength of the summer monsoon systems and concurrent changes in the westerly jet. Furthermore, millennial-scale fluctuations in the δD records at the three lakes during the middle to late Holocene suggest episodes of reduced summer monsoonal moisture delivery to these regions, and correspond with intervals of cool sea surface temperatures in the North Atlantic. [ABSTRACT FROM AUTHOR]

We report a fossil diatom record from small closed-basin Lago Lepué (43°S) to examine past changes in freshwater ecosystems and hydrologic balance in northwestern Patagonia since ∼18 ka. The record starts with abundant staurosiroids and the heavily silicified Aulacoseira granulata suggesting deep turbulent mixing during a low lake level stand between ∼18- 16.4 ka. A. distans increased shortly after ∼16.4 ka and achieved maximum abundance between ∼15.4-13.6 ka, while A. granulata disappeared at ∼15.8 ka and A. alpigena rose at ∼14.9 ka to its maximum between ∼13-12 ka. We infer turbulent, cold, and circumneutral to slightly acid lake conditions contemporaneous with a steady lake level rise that started at ∼16.4 ka and culminated between ∼13-12 ka. These trends reversed between ∼11-7.8 ka with the dominance of Discostella stelligera and staurosiroids, suggesting warmer lake conditions and shallower mixing. Subsequent changes include increases of A. distans with D. stelligera between ∼7.8-5.8 ka, dominance of the former between ∼5.8-3.3 ka, a rapid increase in A. perglabra at ∼3.3 ka, and ensuing diversification of benthic acidophilous species. We infer a rapid lake-level decline between ∼11-7.8 ka, with subsequent rising pulses at ∼7.8 ka and ∼5.8 ka, a multimillennial-scale lake acidification trend, and overall high lake levels with centennial-scale reversals between ∼6-0 ka. Coherent variations in terrestrial and aquatic ecosystem changes recorded in the same core suggest negative hydrologic balance between ∼18-16.4 ka and ∼11–7.8 ka, positive balance between ∼14.9-12 ka and ∼6–0 ka, with transitional conditions in the interim, overprinted by millennial-scale changes and enhanced variability since ∼6 ka. Covariation with paleoclimate records at regional, pan-Patagonian, and hemispheric scale suggests millennial to centennial-scale variability superimposed upon a multi-millennial pacing of Southern Westerly Wind evolution since ∼18 ka. • The diatom record from NW Patagonian Lago Lepué spans the last ∼18,000 years. • We infer negative hydrologic balance between ∼18 and 16.4 and ∼11–7.8 ka. • The highest positive hydrologic balance occurred between ∼14.9 and 12 and ∼6–0 ka. • Centennial-scale variations and an acidification trend developed after ∼6 ka. • We infer hemispheric-scale changes in the Southern Westerly Winds since ∼18 ka. [ABSTRACT FROM AUTHOR]

The spatial and temporal interaction of the Westerlies and the Asian Summer Monsoon (ASM) are often suggested to drive the Holocene moisture evolution of semi-arid Mongolia and Central Asia, but so far, it has remained a controversial topic of debate. In this context, we established a high-resolution 7.4 cal ka paleohydrological record from Shireet Naiman Nuur in the central Mongolian Khangai Mountains using compound-specific biomarker δ2H analyses. Our results suggest that drier conditions from 7.4 to 3.6 cal ka BP and wetter conditions since 3.6 cal ka BP until present are indeed related to changes in atmospheric circulation pattern. A strong anti-phasing between our record and records in monsoonal Asia shows that ASM intensification during the Mid Holocene shifted the ASM limit and adjacent subsidence dry-zones northwards, leading to increased dryness at Shireet Naiman Nuur. Overall wetter conditions during the Late Holocene are related to negative North Atlantic Oscillation phases advecting moisture into central Mongolia and Shireet Naiman Nuur by southerly-displaced Westerlies. • High-resolution 7.4 ka compound-specific δ2H record from central Mongolia. • Reconstructed trend from Mid Holocene dryness to Late Holocene wetness. • Strong anti-phasing of Mongolian moisture evolution to monsoonal Asia. • Moisture evolution driven by the spatial interaction of the ASM and Westerlies. [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 patterns and mechanisms of Holocene temperature variability in China remain highly controversial, possibly due to the lack of sufficient high-resolution records and few systematic compilations and reviews of published records. Here, we used branched glycerol dialkyl glycerol tetraethers (brGDGTs) to generate a Holocene mean annual air temperature (MAAT) record from Lake Yangzonghai (YZH) in southwest (SW) China. Our record, largely ruling out the effect of seasonal bias, displays a long-term cooling of ∼1.5 °C since 10 cal ka BP, indicating that the discrepancy of Holocene temperature records (such as long-term cooling vs warming trends) in China cannot be attributed to the seasonal bias in temperature proxies. We compiled 67 published Holocene temperature records from China. These temperature records exhibit a mathematically consistent pattern with a relatively warmer mid-Holocene and colder late Holocene in the Asian summer monsoon (ASM) domain, whilst records show a relatively colder mid-Holocene and warmer late Holocene in the westerlies domain. This spatial heterogeneity of Holocene temperature variability is attributed to the modulation of monsoon systems, including the warming effect of ASM and the cooling effect of the East Asian winter monsoon (EAWM). In the ASM domain, the dominant pattern with the relatively warmer mid-Holocene and colder late Holocene is primarily controlled by the persistent weakening of the warming effect of the ASM and the concurrent strengthening of the cooling effect of the EAWM during the mid-to-late Holocene. In the westerlies domain, the warming effect of the ASM disappears, the cooling effect of the EAWM is confined to the north of the Tibetan Plateau due to the blocking effect of the Tibetan Plateau. This dominant pattern with the relatively colder mid-Holocene and warmer late Holocene is driven by the increases in atmospheric greenhouse gases (GHG) radiative forcing and Northern Hemisphere Annual Insolation (NHAI) forcing during the mid-to-late Holocene. • Long-term cooling of ∼1.5 °C since 10 cal ka BP recorded by brGDGT-based MAAT reconstruction. • Systematic compilation and review of 67 published Holocene temperature records from China. • Spatial heterogeneity of Holocene temperature variability between ASM and westerlies domains. • Monsoon systems control the trend of Holocene temperature variability in China. [ABSTRACT FROM AUTHOR]

The Southern Hemisphere Westerlies (SHW) and their linkages with key ocean and atmospheric processes have the potential to drive abrupt climate change. The westerlies migrate seasonally and are thought to have shifted during past climate events, such as the last glacial termination. However, the timing, magnitude, direction, and mechanisms behind such shifts remain a topic of ongoing study. Here, we contribute to the understanding of past temporal and spatial changes in the SHW by mapping their fluctuations in the South Atlantic region from the last glacial maximum (LGM) to present. We use lake sediment proxies, including plant wax isotopes extracted from two tarns on Mt. Usborne, East Falkland (51.7 °S) to infer changes in paleoclimate and in the mean annual position of the SHW over the last ∼23,000 years. Together, the proxies indicate that the position of the SHW during the LGM lay north of the Falkland Islands. We interpret our plant wax isotopic record as showing a southward migration of the mean annual position of the wind belt beginning just before ∼21 ka, accompanied by warming at Mt. Usborne at ∼16.5 ka. The late-glacial climate was variable at the field site, and the mean annual position of the SHW may have fluctuated around the latitude of the Falkland Islands. The early Holocene was characterized by relatively warm, dry conditions with high evaporation rates, and the SHW may have lain south of the islands. A brief southern excursion at 7–6 ka was followed by gradual northward migration of the SHW for the remainder of the Holocene to the pre-industrial position. This northward migration was paired with increasingly wet, cool conditions in the Falkland Islands, and the islands appear to be experiencing some of the wettest conditions of the last 23,000 years during the late Holocene. • Lake sediment proxies from East Falkland track the SHW over the last 23,000 years. • SHW moved south at ∼21 ka before reversing the trend at the start of the Holocene. • The SHW fluctuated near the Falkland Islands during the late glacial period. • The early Holocene was warm with high evaporation, and a southern SHW position. • The SHW migrated north in the second half of the Holocene. [ABSTRACT FROM AUTHOR]

The role of NAO modes and solar activity, together with their potential relationship, in driving hydroclimatic variability in arid central Asia over the past two millennia remain controversial—partly due to the limitations of the resolution or time span of existing paleoclimatic records. Vegetation ecosystems at high altitudes are very sensitive to hydroclimate variations. Here, we present a vegetation history for the past two millennia based on a pollen record with an average time resolution of four years from Lake Dalongchi in the Tianshan Mountains. Our results show a millennial-scale drying trend during the past 2000 years, with the vegetation changing from forest-steppe and forest to steppe as the intensity of mid-latitude westerlies gradually decreased. We suggest that the dynamic link between the NAO and moisture variability in arid central Asia depends on the NAO phase in the context of changes in westerlies intensity. The moisture variability in arid central Asia shows a positive relationship with NAO phases when the precipitation delivered by the mid-latitude westerlies exceeded a threshold level in the period of 0–1100 CE. However, over the last millennium, the role of the NAO mode was weakened by solar forcing when the regional moisture gradually decreased below this threshold. The decline of the ancient Silk Road was possibly related to this humid-to-try climate shift at∼1100 CE. • High-resolution vegetation dynamics in arid Central Asia over the past 2000 years. • NAO drove moisture changes during periods of high westerlies-supplied precipitation. • Solar forcing weakened the role of NAO following the decreases in westerlies intensity. [ABSTRACT FROM AUTHOR]

Paleoclimate records across the Intermountain West region of North America show significant regional variation in timing and magnitude of wet conditions that accompanied the last glacial-interglacial transition. To understand the climate controls on paleohydrologic change, well-dated records are needed across the region. The Plains of San Agustin (New Mexico, USA) is a closed-basin watershed of the American Southwest influenced by both winter westerly and summer North American Monsoon precipitation. The flat valley floors of the Plains contain lake and groundwater discharge deposits that record multiple periods of past wet climate. We present a record of hydroclimate for the past 26,000 years based on radiocarbon, U–Th series, and OSL dating of these deposits and stratigraphic correlation across the three sub-basins of the lake system. We find that two major lake oscillations occurred, coincident with the global Last Glacial Maximum (∼23–18 ka) and with Heinrich Stadial 1 (∼17–14 ka). The LGM lake cycle created a deep lake in the lowermost sub-basin, fed by marsh/lake overflow in the upper sub-basins. The Heinrich Stadial 1 wet interval attained the highest recorded lake level between ∼17.0 and 15.3 ka, merging the lower two sub-basins into one lake. Both lake cycles agree well in timing and magnitude with other lake-based records from the southwestern U.S., supporting previous interpretations that a south-shifted cool season storm track brought a dipole-like pattern of enhanced moisture to the southwest at the expense of drier conditions in the northwest during the LGM and deglaciation. A transition from lake to groundwater discharge conditions followed during the Bølling-Allerød (14.7–12.9 ka) across the study area. Wet meadows prevailed in the lower sub-basin during the Younger Dryas (12.9–11.7 ka), with marsh and open lake conditions in the upper and middle sub-basins, respectively. During the early Holocene, discrete wet intervals are recorded by ages for wet meadow deposits in all sub-basins with centennial-millennial frequency at 9.9, 8.8, 8.2 ka. These events agree well with other Intermountain West records showing wetter-than-present conditions prior to 8 ka. Two additional wet periods, centered at 6.8 and 5.4 ka, occurred during the driest known interval of the middle Holocene, and likely were partly supported in the Plains of San Agustin by summer moisture associated with the peak strength of the North American Monsoon. Our record highlights that both winter and summer moisture support water resources in New Mexico watersheds. • We present a new lake level-based paleohydrologic history for the San Agustin Plains, New Mexico over the past 26,000 years. • Periods of deep lake conditions and high groundwater discharge coincided with the Last Glacial Maximum and Heinrich Stadial 1. • Lake drying occurred following the Bølling warming, but groundwater discharge persisted until the late Holocene. • Late Pleistocene deep lake conditions were driven by cold temperatures and enhanced winter season precipitation. • Holocene groundwater discharge was supported by cold/wet winters, but also by the mid-Holocene peak North American Monsoon. [ABSTRACT FROM AUTHOR]

This paper presents a new pollen record from Lake Mondsee in the north-eastern European Alps and discusses changes in vegetation composition between 9000 and 7000 a BP in response to the 8.2 ka BP cooling event, which is clearly reflected in a stable oxygen isotope record from the same lake. Pollen and microcharcoal analyses performed at bi-decadal resolution provide detailed insights into the vegetation history and fire regime in the study area. The late Greenlandian and early Northgrippian between ca. 9000 and 8000 a BP were mainly characterised by the gradual expansion of spruce, accompanied by the retreat of hazel. Results of the pollen-based biome reconstruction show that the Greenlandian – Northgrippian boundary at ca. 8280 a BP was marked by a shift in the affinity scores of regional forest biomes, reflecting a decreasing role of temperate broadleaved trees and shrubs and a strengthening of boreal conifers in the study area. During the early Northgrippian between ca. 8000 and 7000 a BP, fir and beech spread around Lake Mondsee, which is in line with other pollen records from the northern Alpine Foreland, indicating cooler and moister conditions. This long-term trend is likely a response to decreasing summer insolation (i.e. decreasing summer temperatures) and the weakening of the Siberian High, which promoted westerly-driven moisture transport from the Atlantic region. Visual inspection of the Lake Mondsee pollen data does not reveal a clear signal of the 8.2 ka BP event. However, biomization results show a distinct minimum in the temperate deciduous biome scores and summed scores of plant functional types representing warm-loving tree and shrub taxa at ca. 8165–8135 a BP. • Bi-decadal resolution pollen record from Lake Mondsee in the NE European Alps. • Changes in vegetation 9000–7000 a BP in response to the 8.2 ka BP cooling event. • Decreasing temperate trees/shrubs at the Greenlandian – Northgrippian boundary. • Distinct minimum in the temperate deciduous biome scores at ca. 8165–8135 a BP. • Kretzschmaria deusta record shows response to the 8.2 ka BP climate oscillation. [ABSTRACT FROM AUTHOR]

Numerical glacier models applied to moraine chronologies provide an opportunity to quantify past climate change. Here we apply a two-dimensional coupled mass balance – ice flow model to well-dated moraine sequences deposited by former alpine glaciers at two central Patagonian sites: Cerro Riñón (43.97°S, 71.64°W) and Río Tranquilo (47.50°S, 72.38°W), to reconstruct the local temperatures during both the Antarctic Cold Reversal (14.7–13 ka) and the Younger Dryas (12.9–11 ka). Modelled temperature anomalies during the Antarctic Cold Reversal are −2.6 ± 0.4 °C at 44°S, and −2.9 ± 0.6 °C at 47°S. At both locations this cold event is followed by temperature increases of +0.6–0.7 °C or precipitation reductions of c. 20% to drive glacier retreat to moraines deposited during Younger Dryas time. The consistent climatic anomalies between these two latitudes suggest this region of Patagonia was responding to a common climatic event. Further, the late-glacial temperature anomalies found here compare well to those determined by similar glacier modelling techniques in New Zealand, at 43–44° S. These results support a trans-Pacific response throughout the southern mid to high latitudes (43–47° S) during the ACR that is best explained by a northward expansion of the south westerly winds. • Glacier modelling reconstructs Patagonian temperatures during late-glacial. • Cooling of −2.7 to −2.9 ° C below modern during the Antarctic Cold Reversal. • Warming of +0.6 ° C from the Antarctic Cold Reversal into the Younger Dryas period. • Climate trends parallel New Zealand glaciers implicating southern westerly winds. [ABSTRACT FROM AUTHOR]

The abrupt shift of the East Asian winter monsoon (EAWM) is closely linked to the Atlantic meridional overturning circulation (AMOC) triggered by freshwater hosing at millennium timescale. However, the mechanisms of the EAWM response to North Atlantic freshwater forcing are still not fully understood. This study focuses on the role of the Tibetan Plateau in millennium-scale EAWM variability, both in terms of the Siberian high and monsoonal northerlies, by performing two groups of sensitivity experiments at 8.2 ka BP forced by the same North Atlantic freshwater hosing, with different scenarios of the topography of the Tibetan Plateau. Simulation results reveal that the Tibetan Plateau played a crucial role in the EAWM response to North Atlantic freshwater forcing. Despite anomalous surface cooling over the Siberian and Mongolian regions caused by the slowdown of the AMOC, North Atlantic freshwater hosing could not effectively enhance the Siberian high with the lower Tibetan Plateau. Furthermore, with the lower Tibetan Plateau, the hosing-induced enhancement of monsoonal northerlies over East Asian coastal regions dramatically dwindled. The role of the Tibetan Plateau was mainly via amplifying the westward shift of the Asian subtropical westerly jet, which was triggered by AMOC-induced increase of meridional thermal gradient at 500 hPa over West Asia. The westerly jet's westward shift generated anomalous updrafts over the Northwest Pacific and Tibetan Plateau. The former updrafts created an anomalous cyclone over the Northwest Pacific, enhancing the monsoonal northerlies. The latter updrafts induced compensating downdrafts over Mongolia, and hence enhanced the Siberian high. Our results emphasize that the enhanced EAWM during the North Atlantic cold events was most likely linked to the upper-level westerly jet rather than the previous proposed local surface cooling. • The Tibetan Plateau played a critical role in millennium-scale EAWM variability. • Freshwater hosing enhanced the EAWM via the westward shift of the westerly jet. • The Tibetan Plateau amplified the westward movement of the westerly jet. [ABSTRACT FROM AUTHOR]

The Southern Hemisphere westerly winds (SWW), a belt of strong zonal winds in the mid-latitudes, play a key role in Southern Hemisphere climate variability. Recent intensification and southwards migration of the SWW is projected to continue due to anthropogenic climate change and despite a recovering Antarctic ozone hole, impacting regional hydroclimate, ocean circulation and carbon cycling. Despite the importance of the SWW, our understanding of their behaviour on centennial to millennial timescales is limited by the inherently short observational record and limited palaeo-archive agreement on the wind belt's Holocene dynamics. Here we utilise dust flux, Itrax core scanning, rare earth element composition and HYSPLIT particle modelling to present a 8700-year (10,500–1700 cal yr BP) reconstruction of local SWW intensity from a Falkland Islands (Islas Malvinas) peat sediment core which, along with other reconstructions, we interpret in a regional South Atlantic and hemispheric context. We find increased dust deposition and variability from ca. 5700 cal yr BP, signalling an intensification and possible southwards shift of the SWW, though Patagonia likely remains the primary distal dust source throughout our record. Additionally, we identify asymmetric behaviour in the SWW belt from 3000 to 1700 cal yr BP over southern South America and the southwest Atlantic. In alignment with these findings, we propose a possible eastwards projection of the Amundsen Sea Low (ASL) into the South Atlantic during this period. Two volcanic eruptions, likely from Mt Burney (ca. 9700 cal yr BP) and Mt Hudson (ca. 4100 cal yr BP), are captured as cryptotephra deposits in the record. Our precisely dated, high-resolution multiproxy record of South Atlantic wind-blown transport provides an important new dataset that accurately constrains SWW Holocene variability over the Falkland Islands. • 8700-year reconstruction of SWW intensity from a Falkland Islands peat sediment core. • Utilise dust flux, Itrax core scanning, REE composition and HYSPLIT modelling. • We find increased dust deposition and variability from ca. 5700 cal yr BP. • We interpret this as an intensification and possible southwards shift of the SWW. [ABSTRACT FROM AUTHOR]