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Quaternary glaciations have created impressive landform assemblages that can be used to understand palaeo-glacier extent, character and behaviour, and hence past global and local glacier forcings. However, in the southern hemisphere and especially in New Zealand, the Quaternary glacial landform record is relatively poorly investigated with regard to glaciological properties. In this study, a 1 m digital elevation model (DEM) was generated from airborne LiDAR data and supplemented with aerial imagery and field observations to analyse the exceptionally well-preserved glacial geomorphology surrounding Lake Tekapo, New Zealand. We describe a rich suite of Last Glacial Maximum (LGM) and recessional ice-marginal, subglacial, supraglacial, glaciofluvial and glaciolacustrine landform assemblages. These represent two landsystems comprising i) fluted till surfaces with low-relief push moraine ridges; and ii) crevasse-squeeze ridges, 'zig-zag' eskers and attenuated lineations. The former landsystem records the behaviour of an active temperate glacier and the latter landsystem, which is superimposed upon and inset within the former, strongly suggests intermittent surge phases. The two landsystem signatures indicate a sequential change in ice-marginal dynamics during recession that was likely to have been partially non-climatically driven. Overall, we present the first evidence of surge-type glacier behaviour in New Zealand. • LiDAR topographic data used to identify glacial landforms in New Zealand • Landform assemblages indicative of landsystem superimposition • Overall active temperate glacier recession punctuated by intermittent surge phases • First evidence of surge-type glacier behaviour in New Zealand • Changes in ice-marginal dynamics partially non-climatically driven [ABSTRACT FROM AUTHOR]

Paleohydrological investigations were carried out in the Luoyang Basin along the Luohe River in the middle reaches of the Yellow River basin. Three units of overbank flood deposits (OFD) were identified in a Holocene aeolian loess-soil profile on the south cliffy river bank at Taixuecun site (TXC). Analytical results including magnetic susceptibility, grain size distribution and geochemical elements indicate that these well-sorted overbank flood deposits were deposited from the suspended sediment load in floodwaters. We identified two episodes of prehistoric extraordinary overbank flooding that were dated to 6000–5500 and 4000–3800 yr BP using AMS 14C and OSL dating techniques with references to the already-known ages of the archaeological remains. Among of the two episodes, the overbank episode at 4000–3800 yr BP likely had a profound impact on the cultural development from the late Longshan Culture (4500–4000 yr BP) to the Erlitou Culture (3700–3500 yr BP) in the alluvial plain of the Luo River within the Luoyang Basin, providing geological evidence for the legends of ancient floods and their social impacts at ca. 4000 yr BP. In addition, an episode of historic overbank flood event was dated to 1800–1700 yr BP, i.e., from the Han to Wei dynasties, during which the ancient capital (Luoyang City) was subjected to frequent flooding. These aforementioned hydro-climatic events are considered to be regional expressions of known climatic events. The study adds our knowledge of the Holocene extraordinary overbank floods and their relationship with monsoonal climate change and human land-use practices, and the social impact of prehistoric environmental changes on human cultural development. [ABSTRACT FROM AUTHOR]

We present a sediment record from Lugu Lake, a large and deep alpine lake in southwestern China, spanning the last c.2500 cal yr BP. This multi-proxy study focussed on subfossil chironomids but also included analyses of chemical elements using inductively coupled plasma-atomic emission spectrometry (ICP-AES), magnetic susceptibility, total organic carbon (TOC), total nitrogen (TN) and grain size. The chironomid assemblage is dominated by Procladius, Tanytarsus gracilentus-type and Polypedilum nubeculosum-type throughout the core. The record reveals that these chironomid taxa responded to two periods of catchment erosion between c.1700-1100 cal yr BP and c.1920 A.D. to the present. We provide evidence which suggests that the recent erosion episode is caused by human activities; however, the earlier event (c.1700-1100 cal yr BP) is likely related to increased regional precipitation, possibly linked to the strengthening of the Indian summer monsoon in the late Holocene. It is notable that the chironomids, through their varied ecologies, are able to detect the human-induced changes as well as natural climate changes, for instance, enhanced precipitation. Coupling palaeoecological studies using chironomids with more traditional catchment erosion indicators is thus a powerful tool for reconstructing past environmental and climate change. [ABSTRACT FROM AUTHOR]

Rockshelters contain some of the most important archives of human activity in Australia but most research has focused on artifacts and cultural context. This study explores geomorphological and geoarchaeological approaches for understanding a sandstone rockshelter in interior northern Australia: Gledswood Shelter 1. At this site, magnetic susceptibility and micromorphology techniques were integrated with bulk sedimentology, soil chemistry and geochronology to better understand the record of human impact and site formation processes. The micromorphology studies indicate that primary depositional fabrics, such as graded bedding or laminations, are absent, and sediment structural development is low throughout the entire sequence, with most samples exhibiting a high degree of post-depositional mixing. The sediment magnetic susceptibility analysis reveals magnetic changes coinciding with human occupation, a result of anthropogenic burning. Specifically we highlight that combustion features are prevalent in this sandstone shelter and provide critical insights into the human usage of the shelter. [ABSTRACT FROM AUTHOR]

Identifying Holocene Indian Summer Monsoon (ISM) variability and its possible mechanism is critical for predicting future environmental changes. In this study, we present a well-dated, ca. 9.4 kyr geochemical and grain size record derived from Lake Ximenglongtan, southwestern China. The record depicts the Holocene ISM evolution and multi-decadal to centennial abrupt precipitation change events superimposed on the long-term climate changes. The results indicate that precipitation was high during the first half of the Holocene from ca. 9.4 to 4.5 cal kyr B.P. but decreased over the later Holocene. On the multi-decadal to centennial time scale, our results show that a pronounced and prolonged drought event occurred between 7.6 and 7.0 cal kyr B.P. In addition, several other low precipitation events occurred at about 8.9, 6.3, 5.2, 4.2, 3.7, 2.5 and 1.7 cal kyr B.P., which correspond well with reported intervals of abrupt ISM weakening events. Our findings suggest that changes in solar activity may have primarily controlled the fluctuations of ISM intensity on the multi-decadal to centennial time-scale. Cooling of the North Atlantic climate and the interactions between tropical-ocean and atmosphere may have amplified the solar signal. [ABSTRACT FROM AUTHOR]

Glacier advances in the southern mid-latitudes during the last glacial cycle ( ca . 110–10 ka) were controlled by changes in temperature and precipitation linked to several important ocean-climate systems. As such, the timing of glacial advance and retreat can yield important insights into the mechanisms of Southern Hemisphere climate change. This is particularly important given that several recent studies have demonstrated significant glacial advances prior to the global Last Glacial Maximum (gLGM) in Patagonia and New Zealand, the cause of which are uncertain. The recent increase in chronological studies in these regions offers the opportunity to compare regional trends in glacial activity. Here, we compile the first consistent 10 Be exposure-dating chronologies for Patagonia and New Zealand to highlight the broad pattern of mid-latitude glacial activity over the last glacial cycle. Our results show that advances or still stands culminated at 26–27 ka, 18–19 ka and 13–14 ka in both Patagonia and New Zealand and were broadly synchronous, but with an offset between regions of up to 900 years that cannot be explained by age calculation or physically plausible erosion differences. Furthermore, there is evidence in both regions for glacial advances culminating from at least 45 ka, during the latter half of Marine Isotope Stage (MIS) 3. Glacial activity prior to the gLGM differed from the large Northern Hemisphere ice sheets, likely due to favourable Southern Hemisphere conditions during late MIS 3: summer insolation reached a minimum, seasonality was reduced, winter duration was increasing, and sea ice had expanded significantly, inducing stratification of the ocean and triggering northward migration of oceanic fronts and the Southern Westerly Winds. Glacial advances in Patagonia and New Zealand during the gLGM were probably primed by underlying orbital parameters. However, the precise timing is likely to have been intrinsically linked to migration of the coupled ocean-atmosphere system, which may account for the small offset between Patagonia and New Zealand due to differences in oceanic frontal migration. During deglaciation, advances or still stands occurred in both regions during the southern Antarctic Cold Reversal ( ca . 14.5–12.9 ka) rather than the northern Younger Dryas ( ca . 12.9–11.7 ka). Our findings suggest that major rearrangements of the Southern Hemisphere climate system occurred at various times during the last glacial cycle, with associated impacts on the position and intensity of the Southern Westerly Winds and oceanic fronts, as well as wind-driven upwelling and degassing of the deep Southern Ocean. Thus, reconstructing the timing of glacial advance/retreat using our compilation is a powerful way to understand the mechanisms of past interhemispheric climate change. [ABSTRACT FROM AUTHOR]

Streamflow patterns support complex ecosystem functions and services. However, the direct impacts of flow regulation and climate change on patterns of streamflow are less studied. This study aims to analyse the sensitivity of streamflow patterns to the effects of flow regulation and climate change in the Goulburn-Broken catchment in Victoria, Australia. Daily streamflow was classified into low, medium, high, and overbank flow metrics using a statistical quantile-based approach. Trends and percent changes in streamflow metrics during the 1977–2018 period were analysed, and effects of change in rainfall, regulation, and flow diversion on streamflow patterns were predicted using a generalized additive model and path analysis. Low flows and medium flows increased by 26%, and high flows and overbank flows decreased by 31% during the period between 1977 and 2018. While current river regulation and flow diversion practices would dominate future change in magnitude, duration, and frequency of the streamflow, the timing of flow metrics would be dominated by variation in rainfall. These could bring a new ecological and environmental risk to the riverine ecosystem. It is recommended to increase the duration of high flows (90–120 days) and overbank flows (10–30 days) and the frequency of overbank flows to at least once every 1–2 years during wet periods to mitigate ecological and environmental risks of climate change and flow regulation in the Goulburn-Broken catchment. [Display omitted] • Identify key streamflow metrics to inform river ecosystem management. • A quantile-based approach for holistic assessment of streamflow patterns. • Streamflow patterns more sensitive to rainfall variation than regulation and diversion. • Quantiles of streamflow metrics directly linked with ecological water demands. • Increased high and overbank flows are needed to manage Goulburn River ecosystems. [ABSTRACT FROM AUTHOR]

Abstract: Extensive exposures through the glacial landforms around southern Lake Pukaki, New Zealand, comprise seven lithofacies (LFs 1–7). LFs 1–3 are grouped together as LFA 1 (Pukaki Member) and record pulsed subaqueous grounding line fan progradation, cohesionless debris flows, underflow activity and rhythmite deposition by suspension settling, iceberg rafting of dropstones, and pulsed traction current activity. Localized disturbance of these deposits by glacitectonic deformation and multi-generational hydrofracture fills records minor readvances by the glacier snout and the emplacement of a glacitectonite (LF 4) derived from cannibalization of glacilacustrine sediments. LFs 4–6 are grouped together as LFA 2 (Twizel Member) and record direct glacigenic deposition of glacitectonite (LF 4), subglacial traction till (LF 5) and supraglacially dumped boulder rubble (LF 6). Stratigraphic relationships between LFA 1 with LFA 2 record the oscillatory behaviour of the former Tasman Glacier snout when it formed a calving margin in a proglacial and locally supraglacial lake dammed by a glacitectonically disturbed outwash head and lateral moraine ridges. This is entirely consistent with the landform–sediment record of its coeval terrestrial margins, where flutings and push moraines are diagnostic of active temperate glacier recession from a glacially overridden outwash head, the latter being recorded by the vertically stacked sub-horizontally bedded and coarse-grained gravels of LF 7 (Waitaki Member). Previous proposals that late Pleistocene lake damming was initiated by an ice-cored moraine arc appear unfounded, because the glacilacustrine deposits only lie above the altitude of the outwash head/lateral moraine arc in locations where they have been glacitectonically compressed. Alternatively, it is proposed that the overdeepened subglacial topography was produced by the construction of an outwash head, leading to a glacilacustrine sediment sink which operates at times when the expanded Tasman Glacier actively retreats from the outwash head apex. The changing landsystem imprint related to the shrinkage of the Tasman Glacier records spatio-temporal landsystem change, involving evolution from a coupled landsystem to a moraine-dammed to an uncoupled landsystem. [Copyright &y& Elsevier]

Streamflow patterns are closely linked with the quality of stream water, but they are often dealt separately. Due to this, the effects of change in streamflow patterns resulting from river regulation and flow diversion on stream water quality remain under-investigated. This study models change in water quality indicators including pollutants (total suspended solids and turbidity), nutrients (total nitrogen and phosphorus), dissolved oxygen, nitrogen (kjeldahl), pH, and salinity caused by the change in streamflow patterns under different scenarios of river regulation, flow diversion, and rainfall. The generalized additive model was used and the Goulburn-Broken catchment, Australia was chosen as the case study. It was found that concentrations of pollutants and nutrients increased by 38% while dissolved oxygen and nitrogen (kjeldahl) decreased by 35% during the period 1990–2018. These changes were associated with an average increase of 20% in low and medium flows, an average decline of 22% in high and overbank flows and a 15% decline in rainfall. Under the scenario of climate change, river regulation and flow diversion, the overbank flow patterns would mimic the effects of low and medium flows on the water quality indicators that would raise the concentration of pollutants, nutrients, and salinity by 19%. Restoration of high flows would decrease these concentrations by 28% relative to current concentrations, however, it would also reduce dissolved oxygen, nitrogen (kjeldahl), and pH. Effects of streamflow patterns on water quality have implications for environmental flow management, thus, this study recommends critical adjustments in low, medium, and high flows for improving water quality. • An approach to link change in stream water quality with change in streamflow pattern. • Overbank flow patterns mimic the effects of low and medium flows on water quality. • Revise current water quality management strategies with minimum computational efforts. • The approach is best suited for rivers with strong streamflow variation. [ABSTRACT FROM AUTHOR]

Lake basins record critical interactions between the hydrosphere, cryosphere and atmosphere. Their sediments and shoreline landforms archive timing, duration, and intensity of past climatic variability and environmental impacts over a variety of timescales. Thousands of lake systems spread across the internally drained Tibetan Plateau today, of which many are only the salty remains of much more expansive paleolakes in the past. This study presents new shoreline ages integrated with quantitative digital topographic analysis and regional geomorphic evidence to reconstruct the sizes and extents of late Quaternary rift lake systems for the south-central Tibetan Plateau. This study presents optically stimulated luminescence (OSL) and the first K-feldspar post-infrared infrared (pIRIR) stimulated luminescence ages for Zabuye Caka and Dawa Tso and tests if these lakes were once part of a singular Pleistocene mega-lake established across four N–S rift systems. Our new results show that two large but separate paleolake systems developed in the latest Pleistocene-earliest Holocene and no lake larger than ∼6460 km2 has existed since at least 41 ka in the Lunggar region. Early Holocene paleolakes expanded up to 7× modern (+220–335 km3) with two to four-fold asymmetric lake expansion in the west compared to the east. Findings corroborate earlier investigations, implying that dramatic runoff increase and/or evapotranspiration reduction prompted rapid earliest Holocene lake expansion. Precipitation variability, in combination with permafrost degradation, temperature and wind strength, governed paleolake moisture balance. Open-system lake behavior and evolving drainage configurations across complex topography explain delayed onsets of lake regression and punctuated lake decline. This suggests abrupt Holocene climate shifts are not necessarily required for punctuated lake decline. Lastly, unique geomorphological and paleoclimatic similarities between Tibetan and East African rift lakes highlight the potential for some Tibetan paleolakes to function as natural climate amplifiers over both short and geologic timescales. • South-central Tibetan paleolakes no larger than ∼6460 km2. • Early Holocene paleolake expansion 2–7x modern (+220–335 km3), with four-fold asymmetric expansion in west. • Open-system behavior and paleolake fragmentation led delayed and punctuated lake response to climate variability. • Some Tibetan rift lakes invoke comparison to East African Rift amplifier lakes. [ABSTRACT FROM AUTHOR]

Widespread travertine deposits occur in the southwestern Great Artesian Basin (GAB) in central Australia. Priestley et al. (2018) reported uranium-series ages of travertine deposits and concluded that elevated travertine deposition rates are synchronous with wet periods and that times of travertine deposition represent times of high regional rainfall. We propose an alternative explanation that CO 2 degassing from the mantle associated with active faulting played a major role in travertine precipitation in the southwestern GAB. • We challenge the notion that travertine deposition is climatically controlled in the southwestern Great Artesian Basin. • Travertine deposition also occurred during dry climate periods. • We argue that a connection between travertine deposition and tectonically-controlled CO2 degassing is more likely. [ABSTRACT FROM AUTHOR]

Montane vegetation belts are sensitive to climate change; however, it is uncertain to what degree their evolution is influenced by changes in mean annual temperature or seasonal climate. In this study, we use pollen assemblages from a high elevation lake (3780 m.a.s.l.) in the Gongga Mountains on the southeast margin of the Qinghai-Tibetan Plateau, China, to study changes in altitudinal vegetation zones during the last 12,000 years. The relationships between vegetation belts and winter and summer climate parameters are analyzed. Results indicate that winter temperature mainly controlled the development of evergreen broadleaved forest (Cyclobalanopsis and Taxodiaceae), deciduous broadleaved forest (Betula), and sub-alpine shrubland (Rosaceae, Cyperaceae and Gramineae dominated). In contrast, the development of temperate coniferous forest (Pinus and Tsuga) and alpine herbfield (Artemisia and Chenopodiaceae) was mainly controlled by summer temperature and precipitation. Results show that winter temperature gradually increased from the Greenlandian to Meghalayan, indicating that the main driving factor was winter solar insolation in the Northern Hemisphere. Meanwhile, changes in summer temperature and precipitation are consistent with the results from Indian monsoon-dominated areas of China, suggesting that the summer climate in this region is mainly driven by the migration of the Intertropical Convergence Zone. Our findings suggest that the influence of seasonal climate changes should be considered on the evolution of montane vegetation belts. • The vegetation dynamics in SW China are reconstructed during the Holocene. • Contrasting effects of seasonal climate on altitudinal vegetation belts evolution. • Winter temperature followed gradual decline with winter insolation in the NH. • Summer climate is mainly driven by migration of the ITCZ under insolation forcing. [ABSTRACT FROM AUTHOR]

Understanding long-term, large cyclone activity is critical for coastal management and disaster prevention and mitigation, particularly with projected rising sea level and increasing cyclone frequency and the intensity. Here we present sedimentary evidence (cyclone overwash deposits, beachrock boulders, and cyclone-induced clastic deposits) of historic large cyclone events from coastal dune deposits on eastern Hainan Island, China. Based on luminescence dating and sedimentological analysis, eight historic tropical cyclone events (at 1095 ± 90 BCE, 900–1000 BCE, 975 ± 50 CE, 1720 ± 20 CE, 1740 ± 35 CE, 1790 ± 25 CE, 1850 ± 15 CE, and 1895 ± 10 CE) have been identified in this region. The elevation of the termination point of cyclone overwash deposit layers that represent the paleo-cyclone minimum wave run-up stage, in combination with knowledge of present-day cyclone events, was applied to assess the intensity of these extreme events. The intensity of these cyclone events was likely greater than that of cyclones in the local instrumental records. Furthermore, these large cyclone events correspond to historic records of devastating cyclones. Through comparison with regional and global climate records, we infer that the variability of large cyclones in the South China Sea was probably modulated by the El Niño-Southern Oscillation, western Pacific warm pool, and local sea surface temperatures over the past 3400 yr. These results provide an improved understanding of long-term, extreme cyclone events and their response to climate change, thereby contributing to regional planning and coastal defense strategies. [ABSTRACT FROM AUTHOR]

Little is known about the Pleistocene climatic context of northern Australia at the time of early human settlement. Here we generate a palaeoprecipitation proxy using stable carbon isotope analysis of modern and archaeological pandanus nutshell from Madjedbebe, Australia's oldest known archaeological site. We document fluctuations in precipitation over the last 65,000 years and identify periods of lower precipitation during the penultimate and last glacial stages, Marine Isotope Stages 4 and 2. However, the lowest effective annual precipitation is recorded at the present time. Periods of lower precipitation, including the earliest phase of occupation, correspond with peaks in exotic stone raw materials and artefact discard at the site. This pattern is interpreted as suggesting increased group mobility and intensified use of the region during drier periods.

The time of arrival of people in Australia is an unresolved question. It is relevant to debates about when modern humans first dispersed out of Africa and when their descendants incorporated genetic material from Neanderthals, Denisovans and possibly other hominins. Humans have also been implicated in the extinction of Australia's megafauna. Here we report the results of new excavations conducted at Madjedbebe, a rock shelter in northern Australia. Artefacts in primary depositional context are concentrated in three dense bands, with the stratigraphic integrity of the deposit demonstrated by artefact refits and by optical dating and other analyses of the sediments. Human occupation began around 65,000 years ago, with a distinctive stone tool assemblage including grinding stones, ground ochres, reflective additives and ground-edge hatchet heads. This evidence sets a new minimum age for the arrival of humans in Australia, the dispersal of modern humans out of Africa, and the subsequent interactions of modern humans with Neanderthals and Denisovans.