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The regional impact of abrupt glacial climate variability remains poorly constrained for arid southwestern Asia, particularly winter dynamics during Marine Isotope Stage 3, due to limited paleoarchives in the Middle East. Here, we present continuous speleothem records of δ18O and δ13C with robust chronologies for southwestern and central Iran, spanning ∼50–30 ka. Stable‐isotope signals in the two stalagmites are generally uncorrelated and do not exhibit a consistent response to Greenland stadials or interstadials; however, both show a positive δ18O excursion that coincides with Heinrich event 4. We explore the potential mechanisms for intermittent coupling of speleothem δ18O across Iran through isotope‐enabled atmospheric modeling outputs, from which we utilize the spatial δ18O gradient as a proxy for wintertime westerly versus southerly jet strength. Our results suggest that during Heinrich event 4 and several Greenland stadials, stronger westerly winds enhanced Mediterranean moisture contributions to both sites and reduced aridity in southern Iran. Plain Language Summary: Stalagmites are useful archives to reconstruct the climate of the past. In order to shed light on the past climate of western Asia and the response of this region to the rapid climate changes, here we present two stalagmites from central and southwestern Iran that span 50,000 to 30,000 yrs ago. Our findings suggest that during extreme cold events, the moisture originates mostly from the west, whereas out of these extraordinarily cold periods moisture comes mostly from the south. Key Points: Continuous high‐resolution speleothem record of climatic change in southwestern and central Iran between 50 and 30 kaDecoupled responses of stable‐isotope gradients in central and southern Iran to glacial climate variability, except during Heinrich event 4Decreased impact of southerly moisture sources and reinforced westerlies during extreme cold events [ABSTRACT FROM AUTHOR]

The pace of current climate change is expected to be problematic for alpine flora and fauna, as their adaptive capacity may be limited by small population size. Yet, despite substantial genetic drift following post-glacial recolonization of alpine habitats, alpine species are notable for their success surviving in highly heterogeneous environments. Population genomic analyses demonstrating how alpine species have adapted to novel environments with limited genetic diversity remain rare, yet are important in understanding the potential for species to respond to contemporary climate change. In this study, we explored the evolutionary history of alpine ground beetles in the Nebria ingens complex, including the demographic and adaptive changes that followed the last glacier retreat. We first tested alternative models of evolutionary divergence in the species complex. Using millions of genome-wide SNP markers from hundreds of beetles, we found evidence that the N. ingens complex has been formed by past admixture of lineages responding to glacial cycles. Recolonization of alpine sites involved a distributional range shift to higher elevation, which was accompanied by a reduction in suitable habitat and the emergence of complex spatial genetic structure. We tested several possible genetic pathways involved in adaptation to heterogeneous local environments using genome scan and genotype–environment association approaches. From the identified genes, we found enriched functions associated with abiotic stress responses, with strong evidence for adaptation to hypoxia-related pathways. The results demonstrate that despite rapid demographic change, alpine beetles in the N. ingens complex underwent rapid physiological evolution. [ABSTRACT FROM AUTHOR]

Glacial lake outburst floods (GLOF) hazards in alpine areas are increasing. The effects of climate change on GLOF hazards are unclear. This study examined 37 glacial lakes and climate data from 15 meteorological stations and explored the correlation between climate variations at different temporal scales. The results indicate that 19 GLOFs hazards occurred in El Niño (warm) years, 8 GLOFs hazards occurred in La Niña (cold) years, 3 GLOFs hazards occurred in cold/warm or warm/cold transition years, and 7 GLOFs hazards occurred in normal years. The higher the fluctuations, the higher the probability of GLOF hazards. Climatic conditions can be divided into three categories: extreme temperature and precipitation, as represented by the Guangxie Co GLOF; extreme precipitation, as represented by the Poge Co GLOF; and extreme temperature, as represented by the Tsho Ga GLOF. [ABSTRACT FROM AUTHOR]

Climate change is an emerging challenge that is triggering natural variabilities and disasters globally. In Gilgit–Baltistan (GB) region of Pakistan, Glacial Lake Outburst Floods (GLOFs) have been occurring frequently due to glacier surges, increasing the vulnerability of mountain communities, particularly small farmers. This research aims to investigate the climate change-induced GLOFs of the Shishper glacier in Hunza valley of GB with the intent of studying the farming activities; local awareness and perceptions toward climate change; impacts of climate change and GLOFs on agriculture; and adaptation mechanisms based on indigenous knowledge. Mixed-methods research approach was employed for a field survey in two villages inhabited by farmers of the Burusho community. Quantitative data were gathered from a sample of 180 respondents by using a structured questionnaire, whereas field observation coupled with photography and spot interviews were undertaken to accumulate qualitative data. Results revealed that many farmers lost their fertile land, and their crops and fruit orchards were severely damaged as a result of the devastating effects of climate change and recent GLOFs in 2019 and 2020, resulting in low crop yield and agricultural income. Local communities typically respond to GLOFs through self-help strategies and indigenous methods to sustain their livelihoods. However, our findings suggest that current adaptation practices are insufficient in light of rising climate risks. Thus, there is an urgent need to assist mountain communities by providing maximum support and interventions to enhance their resilience to future GLOFs and to increase people's adaptive capacity by strengthening their socioeconomic conditions. [ABSTRACT FROM AUTHOR]

There are few studies on the climate and glacial scale in the mountains east of the Qinghai–Tibet Plateau. So, we used glacial features to determine the range of the area's paleoglaciers and the equilibrium line altitude (ELA) of theGlA modern and paleoglaciers in the Tianchi area of the Changbai Mountains. Then, the GlaRe toolbox 2015 () was used to reconstruct the surface of the paleoglaciers. The probable air temperature during the glacial advances of the LGM was calculated by applying the P-T and LR models. The results showed the following: (1) the change in ELA is 950 m in the Tianchi area of the Changbai Mountains; (2) glacial coverage in the Tianchi area of the Changbai Mountains during the LGM period was ~27.05 km2 and the glacial volume was ~9.94 km3; and (3) the mean temperature in the Tianchi area of the Changbai Mountains during the LGM was 6.6–9.0 °C lower than today's, and was the principal factor controlling the growth of glaciers. There is a difference in the climate change in monsoon-influenced mountains during the LGM, and this difference may be related to the precipitation in the mountains. [ABSTRACT FROM AUTHOR]

With global warming, changes in glaciers and glacial lakes on the Tibetan Plateau call for a serious inspection. The Southeastern Tibetan Plateau (SETP) is a typical monsoonal marine glacier area that is extremely vulnerable to climate change. It is affected by both humid and warm Indian Ocean currents. Outlines of glaciers and glacial lakes in SETP have been extracted from Landsat satellite images with an automatic extraction method based on image compositing with Google Earth Engine and Random Forest algorithm. Alongside the outlines, meteorological data have been collected from 1990 to 2021. The results show that since 1990 the glacier area of SETP has retreated by about 2165.33 km2 (~25.28%), the glacial lake area has increased by about 36.41 km2 (~21.45%), and their number has increased by 477 (~27.32%). The reliability and scientific validity of this study is proven by comparison with existing glacier inventories. By analyzing the meteorological data, the inverse correlation between the glacier area and temperature has been found. Despite decreases in cumulative precipitation, the glacial lake level rise and consequent area expansion have been observed. A fitting equation for the response pattern of glacier changes to temperature and precipitation change is presented and will provide a basis for future studies. [ABSTRACT FROM AUTHOR]

Ice core records from Greenland provide evidence for multiple abrupt cold–warm– cold events recurring at millennial time scales during the last glacial interval. Although climate variations resembling Dansgaard–Oeschger (DO) oscillations have been identified in climate archives across the globe, our understanding of the climate and ecosystem impacts of the Greenland warming events in lower latitudes remains incomplete. Here, we investigate the influence of DO-cold-to-warm transitions on the global atmospheric circulation pattern. We comprehensively analyze δ18O changes during DO transitions in a globally distributed dataset of speleothems and set those in context with simulations of a comprehensive high-resolution climate model featuring internal millennial-scale variations of similar magnitude. Across the globe, speleothem δ18O signals and model results indicate consistent large-scale changes in precipitation amount, moisture source, or seasonality of precipitation associated with the DO transitions, in agreement with northward shifts of the Hadley circulation. Furthermore, we identify a decreasing trend in the amplitude of DO transitions with increasing distances from the North Atlantic region. This provides quantitative observational evidence for previous suggestions of the North Atlantic region being the focal point for these archetypes of past abrupt climate changes. [ABSTRACT FROM AUTHOR]

Climate classifications supply climate visualization with inference about general vegetation types. The Köppen classification system of thermal classes and an arid class is widely used, but options are available to strengthen climate change detection. For this study, I incorporated temperature and aridity information into all climate classes to isolate climate change, added a hypertropical class to better detect warming and drying in tropical zones, and developed a consistent ruleset of thermal classes with one temperature variable for streamlined application, yet maintained primary Köppen thermal classes. I compared climate currently to 6000 years ago (ka; Mid-Holocene) and 22 ka (Last Glacial Maximum) worldwide. Growing degree days > 0 °C was the most efficient variable for modeling thermal classes. Climate classes based on growing degree days matched 86% of Köppen thermal classes. Current climate shared 80% and 23% of class assignments with the Mid-Holocene and Last Glacial Maximum, respectively, with dry conditions shifting to the tropical and hypertropical classes under current climate. Contributing to our understanding of global environmental change, this classification demonstrated that the hypertropical class experienced the greatest change in area since 6 ka and the second greatest change in area since 22 ka, and the greatest increase in percentage arid classes during both intervals. The added hypertropical class with aridity information delivered sensitive detection of warming and drying for relevant climate classes under climate change. [ABSTRACT FROM AUTHOR]

Present and historical climate conditions jointly determine contemporary biodiversity patterns and ecosystem functions. However, it remains unclear how contemporary climate and paleoclimate changes together affect the three dimensions of biodiversity (i.e., taxonomic diversity, functional diversity and phylogenetic diversity) and their relationship with ecosystem functions. Here, we assess the impact of current climate, paleoclimate and its anomalies on contemporary biodiversity and ecosystem functions. We estimated the taxonomic, functional and phylogenetic diversity of grassland on the Mongolian Plateau using vegetation survey data and trait information. We then used random forest and structural equation models to assess the relative importance of the present, the Mid-Holocene and the Last Glacial Maximum climate as well as paleoclimate changes as determinants of diversity and aboveground biomass. Our results showed that paleoclimate changes and modern climate jointly determined contemporary biodiversity patterns, while community biomass was mainly affected by modern climate, namely the aridity index. Modern aridity and temperature were two major influences on all three dimensions of biodiversity. Mid-Holocene climate anomalies had a strong effect on species richness and phylogenetic diversity, while functional diversity had mainly been affected by temperature anomalies since the Last Glacial Maximum. These findings suggest that contemporary biodiversity patterns may be affected by processes at divergent temporal scales. Our results show that simultaneously exploring the response of the three dimensions of biodiversity in different periods of climate change and the theoretical framework for its impact on community biomass is helpful to provide a more comprehensive understanding of patterns of biodiversity and its relationship with ecosystem functions. [ABSTRACT FROM AUTHOR]

The marine dissolved organic carbon (DOC) reservoir rivals the atmospheric carbon inventory in size. Recent work has suggested that the size of the DOC reservoir may respond to variations in sea temperature and global overturning circulation strength. Moreover, mobilization of marine DOC has been implicated in paleoclimate events including Cryogenian glaciation and Eocene hyperthermals. Despite these suggestions, the dynamics of the marine DOC reservoir are poorly understood, and previous carbon cycle modeling has generally assumed this reservoir to be static. In this study, we utilize an Earth system model of intermediate complexity to assess the response of the marine DOC reservoir to various glacial boundary conditions. Our results indicate that the marine DOC reservoir is responsive to glacial perturbations and may shrink or expand on the order of 10–100 Pg C. In contrast to recent studies that emphasize the importance of DOC degradation in driving the mobility of DOC reservoir, our study indicates the importance of DOC production. In the experiment under full glacial boundary conditions, for example, a 19% drop in net primary production leads to an 81 Pg C reduction in the DOC pool, without which the atmospheric CO2 concentration would have been lower by approximately 38 ppm by dissolved inorganic carbon changes alone. Thus, DOC reservoir variability is necessary to fully account for the simulated changes in atmospheric CO2 concentration. Our findings based on glacial experiments are corroborated in a different set of simulations using freshwater flux to induce weakening of the Atlantic meridional overturning circulation. Plain Language Summary: There is a significant reservoir of dissolved organic carbon (DOC) in the ocean originating from the production and decay of microbes, nearly equal to the amount of carbon contained as carbon dioxide (CO2) in the atmosphere. Studies have suggested that the total amount of DOC in the ocean may respond to climate effects on ocean temperatures and circulation, and that releases of DOC from the ocean as CO2 to the atmosphere may have contributed to some climate change events in Earth's history. To date, however, little modeling work has been done to understand this suggestion. In this study, we used a computer model of the earth's ocean and atmosphere to simulate the response of marine DOC to climate conditions representing the height of Earth's last glacial period. We found that the total amount of marine DOC simulated in our model could vary in response to the specific climate conditions applied and the modeled impacts on ocean biological production. Importantly, we found that these changes in the DOC reservoir are sufficiently large that without it, changes in atmospheric CO2 levels cannot be fully understood. Our results suggest that understanding marine DOC is crucial in understanding global climate changes throughout Earth's history. Key Points: The marine dissolved organic carbon (DOC) reservoir is mobile in response to glacial climate forcing and rapid changes in the meridional overturning circulationChanges in the size of the DOC reservoir are primarily driven by changes in DOC production rather than DOC degradationMarine DOC cycling is directly related to atmospheric pCO2 over simulated climate change events [ABSTRACT FROM AUTHOR]

Understanding genetic patterns at the regional level and the environmental influence on them is important for the conservation and sustainable use of economically important plant species. In this study, we focused on Thespesia populnea, a coastal species valued for its ecological and economic benefits across its pantropical distribution range. We aimed to understand the phylogeographic pattern, the current spatial distribution of genetic diversity, and range dynamics of the species with changing environmental conditions to better inform conservation and development actions. We genotyped 482 individuals, collected from 33 natural populations, at five chloroplast DNA loci and identified the influence of historical processes on the contemporary population structure of the species in the Indo-West Pacific (IWP) region. Environmental niche modeling (ENM) was used to identify the species' glacial and future climate refugia. High genetic diversity at the species level was observed. Nearly one-third of the populations showed no polymorphism, possibly due to extinction-recolonization events induced by glacial sea-level changes, as evident from the analysis of demographic history. The evolutionary relationship between the haplotypes suggested a strong phylogeographic structure. The clustering algorithms identified two genetic lineages that diverged around the Pleistocene epoch. The difference between the climatic niches of the two lineages was not significant. The ensembled ENM indicated range expansion of the species in the future. Based on the findings, we proposed sustainable use of genetically diverse populations, outlined measures to preserve the evolutionary potential of the lineages, and identified areas that should be prioritized for conservation actions of this important plant species. [ABSTRACT FROM AUTHOR]

Effective moisture (EM) distribution in the Indian summer monsoon (ISM) region is strongly related to regional topography. An understanding of climate change and the interactions between climate variables can help predict future climate variations. Here, we reconstruct a stack EM record for Southwest China over the past 90 kyr using environmental magnetism in lake sediment. The EM in Southwest China at the orbital scale was closely linked to precession‐induced change in North Hemisphere solar insolation, as well as the ISM variability. However, at the glacial‐interglacial scale, it was decoupled with ISM intensity, being wetter during glacial periods (weakened ISM) and drier during interglacial periods (enhanced ISM). Combined with modern meteorological observations, we suggest that the topographical barrier effect and temperature induced dryness are responsible for the decoupling between ISM intensity and EM. The terrestrial topography and temperature strongly influence EM distribution by altering the dynamics of onshore airflow and evapotranspiration. Plain Language Summary: Effective moisture (EM) directly affects hydrological cycle and wider‐scale socio‐economic development. Reconstruction of prehistoric EM levels is essential for deeper understanding of the global climate system, developing climate models and improving prediction of future climate variations. Here, we reconstruct a high‐resolution EM record over the past ∼90,000 years from lake sediments in Tengchong, Yunnan province, Southwest China. We found that the variation of precession (shifts in the rotational axis of the Earth) and solar insolation are the key contributors to the EM variability at the orbital scale. Unusually, a wetter climate during the glacial period and relatively drier interglacial periods were observed in our records, which is opposite to those found in previous studies (arid glacial and humid interglacial) in monsoon regions, indicating a decoupling pattern between monsoon intensity and EM in study region. Based on a comprehensive analysis of the modern meteorological observations, we conclude that the topography and temperature exert a considerable role in modulating EM distribution and response to the decoupling pattern. Key Points: The long‐term effective moisture (EM) record in Southwest China since ∼90 kyr was reconstructedThe EM variability at the orbital scale in terrestrial Indian summer monsoon region is primarily dominated by precessionThe topographic barrier and temperature induced aridification contribute to the decoupling of monsoon intensity and EM [ABSTRACT FROM AUTHOR]

Due To the effects of climate change, tourist locations such as glacial landscapes are increasingly becoming last-chance tourism (LCT) destinations. LCT is paradoxical: although visitors to such locations possess high environmental awareness, their travel generates greenhouse gas emissions that threaten these destinations. However, visiting LCT destinations and observing glacial landscapes threatened by climate change may positively affect pro-environmental behaviour. This article aims to explore how experiencing receding glaciers can influence intentions to adopt pro-environmental behaviour. A quantitative survey of 284 visitors to a major glacier tourism site in France (Montenvers-mer-de-Glace) was caried out to test the influence of landscape, emotions, satisfaction, and LCT-related motivations on intentions to adopt pro-environmental behaviours. The results show that landscapes perceived as symbolic of climate change, LCT motivations, and overall satisfaction positively influenced pro-environmental behaviour intentions. To further encourage such intentions, stakeholders should promote practices based on education and experience. [ABSTRACT FROM AUTHOR]

Disentangling the effects of glaciers and climate on vegetation is complicated by the confounding role that climate plays in both systems. We reconstructed changes in vegetation occurring over the Holocene at Jøkelvatnet, a lake located directly downstream from the Langfjordjøkel glacier in northern Norway. We used a sedimentary ancient DNA (sedaDNA) metabarcoding dataset of 38 samples from a lake sediment core spanning 10,400 years using primers targeting the P6 loop of the trnL (UAA) intron. A total of 193 plant taxa were identified revealing a pattern of continually increasing richness over the time period. Vegetation surveys conducted around Jøkelvatnet show a high concordance with the taxa identified through sedaDNA metabarcoding. We identified four distinct vegetation assemblage zones with transitions at ca. 9.7, 8.4 and 4.3 ka with the first and last mirroring climatic shifts recorded by the Langfjordjøkel glacier. Soil disturbance trait values of the vegetation increased with glacial activity, suggesting that the glacier had a direct impact on plants growing in the catchment. Temperature optimum and moisture trait values correlated with both glacial activity and reconstructed climatic variables showing direct and indirect effects of climate change on the vegetation. In contrast to other catchments without an active glacier, the vegetation at Jøkelvatnet has displayed an increased sensitivity to climate change throughout the Middle and Late Holocene. Beyond the direct impact of climate change on arctic and alpine vegetation, our results suggest the ongoing disappearance of glaciers will have an additional effect on plant communities. [ABSTRACT FROM AUTHOR]

Climate during the last glacial period was marked by abrupt instability on millennial timescales that included large swings of temperature in and around Greenland (Daansgard–Oeschger events) and smaller, more gradual changes in Antarctica (AIM events). Less is known about the existence and nature of similar variability during older glacial periods, especially during the early Pleistocene when glacial cycles were dominantly occurring at 41 kyr intervals compared to the much longer and deeper glaciations of the more recent period. Here, we report a continuous millennially resolved record of stable isotopes of planktic and benthic foraminifera at IODP Site U1385 (the "Shackleton Site") from the southwestern Iberian margin for the last 1.5 million years, which includes the Middle Pleistocene Transition (MPT). Our results demonstrate that millennial climate variability (MCV) was a persistent feature of glacial climate, both before and after the MPT. Prior to 1.2 Ma in the early Pleistocene, the amplitude of MCV was modulated by the 41 kyr obliquity cycle and increased when axial tilt dropped below 23.5 ∘ and benthic δ18O exceeded ∼3.8 ‰ (corrected to Uvigerina), indicating a threshold response to orbital forcing. Afterwards, MCV became focused mainly on the transitions into and out of glacial states (i.e. inceptions and terminations) and during times of intermediate ice volume. After 1.2 Ma, obliquity continued to play a role in modulating the amplitude of MCV, especially during times of glacial inceptions, which are always associated with declining obliquity. A non-linear role for obliquity is also indicated by the appearance of multiples (82, 123 kyr) and combination tones (28 kyr) of the 41 kyr cycle. Near the end of the MPT (∼0.65 Ma), obliquity modulation of MCV amplitude wanes as quasi-periodic 100 kyr and precession power increase, coinciding with the growth of oversized ice sheets on North America and the appearance of Heinrich layers in North Atlantic sediments. Whereas the planktic δ18O of Site U1385 shows a strong resemblance to Greenland temperature and atmospheric methane (i.e. Northern Hemisphere climate), millennial changes in benthic δ18O closely follow the temperature history of Antarctica for the past 800 kyr. The phasing of millennial planktic and benthic δ18O variation is similar to that observed for MIS 3 throughout much of the record, which has been suggested to mimic the signature of the bipolar seesaw – i.e. an interhemispheric asymmetry between the timing of cooling in Antarctica and warming in Greenland. The Iberian margin isotopic record suggests that bipolar asymmetry was a robust feature of interhemispheric glacial climate variations for at least the past 1.5 Ma despite changing glacial boundary conditions. A strong correlation exists between millennial increases in planktic δ18O (cooling) and decreases in benthic δ13C , indicating that millennial variations in North Atlantic surface temperature are mirrored by changes in deep-water circulation and remineralization of carbon in the abyssal ocean. We find strong evidence that climate variability on millennial and orbital scales is coupled across different timescales and interacts in both directions, which may be important for linking internal climate dynamics and external astronomical forcing. [ABSTRACT FROM AUTHOR]

The profile of the Lipowo palaeolake (NE Poland) preserves a record of environmental and climate changes from the Last Glacial Termination (16.5k cal ka BP), stretching from the Oldest Dryas to the youngest Allerød warm oscillation. In this interdisciplinary study of the lacustrine succession at Lipowo, we used biological and geochemical indicators and multiproxy analyses to reconstruct environmental changes in the lake ecosystem, such as mollusc, zooplankton and vegetation development, trophic state, water temperature and water level. Four cold and four warm climate oscillations of different durations were identified on this basis: the Older Dryas climate deterioration and two short‐term coolings within the Allerød Interstadial, separated by warm periods in the Bølling and Allerød. The covering of the lake series by diamicton deposits from the melting of dead‐ice blocks is a particularly interesting and rare phenomenon for a postglacial area. The hydrological system of the catchment was generally closed, with a periodically opening and existing flow‐through lake. Over the period of the lake's existence, vegetation changed in general from steppe tundra to forest with birch and pine. For most of this time, the palaeolake was mainly oligotrophic, with increased productivity and a higher trophic level only notable during the middle Bølling. [ABSTRACT FROM AUTHOR]

Indian Ocean sea surface temperatures impact precipitation across the basin through coupled ocean‐atmosphere responses to changes in climate. To understand the hydroclimate response over the western Indian Ocean and equatorial east Africa to different forcing mechanisms, we present four new proxy reconstructions from core VM19‐193 (2.98°N, 51.47°E) that span the last 250 ky. Sub‐surface water temperatures (Sub‐T; TEX86) show strong precessional (23 ky) variability that is primarily influenced by maximum incoming solar radiation (insolation) during the Northern Hemisphere spring season, likely indicating that local insolation dominates the upper water column at this tropical location over time. Leaf waxes, on the other hand, reflect two different precipitation signals: δ13Cwax (in phase with boreal fall insolation) is likely reflecting vegetation changes in response to local rainfall over east Africa, whereas δDprecip (primarily driven by boreal summer insolation) represents changes in regional circulation associated with the summer monsoon. Glacial‐interglacial changes in ocean temperatures support glacial shelf exposure over the Maritime Continent in the eastern Indian Ocean and the subsequent weakening of the Indian Walker Circulation as a mechanism driving 100 ky climate variability across the tropical Indo‐Pacific. Additionally, the 100 ky spectral power in δDprecip supports a basin‐wide weakening of summer monsoon circulation in response to glacial climates. Overall, the proxy records from VM19‐193 indicate that both precession and glacial‐interglacial cycles exert control over hydroclimate at this tropical location. Key Points: New multi‐proxy reconstructions from the tropical western Indian Ocean show both precession and glacial‐interglacial variabilityA new precipitation isotope record likely reflects large‐scale Indian summer monsoon circulation changes over timeGlacial‐scale changes in upper water column structure across the Indian Ocean support shelf exposure as a primary hydroclimate influence [ABSTRACT FROM AUTHOR]

During abrupt climate changes of the last glacial period paleorecords show large amplitude changes in the dust cycle. We use Earth System model simulations to evaluate processes operating across these events. Idealized Heinrich stadial‐like simulations show a southwards migration of tropical rainfall that dries the Sahel and reduces wet deposition causing a widespread enhancement of tropical dust loading. However, several discrepancies with marine core dust deposition reconstructions are evident. Simulations with a more limited freshwater forcing (0.4 Sv instead of 1.0 Sv) and weaker cooling over the North Atlantic (less than 3°C) show a switch in sign of the stadial dust deposition anomaly in several regions, improving agreement with paleorecords. The simulated dust cycle therefore displays in places a non‐linear response to abrupt change. The global‐mean stadial dust radiative forcing in the more realistic simulations is around −0.2 to −0.6 W m−2 and so could represent an amplifying feedback during these events. Plain Language Summary: Mineral dust in the atmosphere is mostly sourced from arid regions like the Sahara desert. The amount and geographical spread of this dust in the atmosphere is sensitive to environmental conditions such as drought. Paleoclimate records show that rapid cooling events centered on the North Atlantic during the last ice‐age also saw large increases in the rate of dust deposited over the ocean. Earth System models are a computational tool that can be used to understand the links between climate and the dust cycle. Using a series of such simulations we found that abrupt cooling events in the North Atlantic can lead to a massive increase in dust over the equatorial (tropical) regions. However, the model's response is in many places non‐linear, meaning that the change in dust is very sensitive to the magnitude of the climate changes occurring. This non‐linearity is mostly due to interactions between changes in the water cycle and the dust. We show that a less severe cooling produces a more realistic dust response when evaluated against paleo‐dust records. Since dust scatters incoming sunlight, increased atmospheric dust during these events may have amplified and even extended the cold phases. Key Points: Freshwater hosing forcing increases tropical dust loading in Earth System model simulations of the last glacial maximumSimulated response is non‐linear with forcing in some regions, particularly North AfricaWeaker events improve agreement with data and emitted dust produces a self‐amplifying feedback [ABSTRACT FROM AUTHOR]

Heinrich-type ice-sheet surges are one of the prominent signals of glacial climate variability. They are characterised as abrupt, quasi-periodic episodes of ice-sheet instabilities during which large numbers of icebergs are released from the Laurentide ice sheet. The mechanisms controlling the timing and occurrence of Heinrich-type ice-sheet surges remain poorly constrained to this day. Here, we use a coupled ice sheet–solid Earth model to identify and quantify the importance of boundary forcing for the surge cycle length of Heinrich-type ice-sheet surges for two prominent ice streams of the Laurentide ice sheet – the land-terminating Mackenzie ice stream and the marine-terminating Hudson ice stream. Both ice streams show responses of similar magnitude to surface mass balance and geothermal heat flux perturbations, but Mackenzie ice stream is more sensitive to ice surface temperature perturbations, a fact likely caused by the warmer climate in this region. Ocean and sea-level forcing as well as different frequencies of the same forcing have a negligible effect on the surge cycle length. The simulations also highlight the fact that only a certain parameter space exists under which ice-sheet oscillations can be maintained. Transitioning from an oscillatory state to a persistent ice streaming state can result in an ice volume loss of up to 30 % for the respective ice stream drainage basin under otherwise constant climate conditions. We show that Mackenzie ice stream is susceptible to undergoing such a transition in response to all tested positive climate perturbations. This underlines the potential of the Mackenzie region to have contributed to prominent abrupt climate change events of the last deglaciation. [ABSTRACT FROM AUTHOR]

Sea ice decline in the North Atlantic and Nordic Seas has been proposed to contribute to the repeated abrupt atmospheric warmings recorded in Greenland ice cores during the last glacial period, known as Dansgaard-Oeschger (D-O) events. However, the understanding of how sea ice changes were coupled with abrupt climate changes during D-O events has remained incomplete due to a lack of suitable high-resolution sea ice proxy records from northwestern North Atlantic regions. Here, we present a subdecadal-scale bromine enrichment (Brenr) record from the NEEM ice core (Northwest Greenland) and sediment core biomarker records to reconstruct the variability of seasonal sea ice in the Baffin Bay and Labrador Sea over a suite of D-O events between 34 and 42 ka. Our results reveal repeated shifts between stable, multiyear sea ice (MYSI) conditions during cold stadials and unstable, seasonal sea ice conditions during warmer interstadials. The shift from stadial to interstadial sea ice conditions occurred rapidly and synchronously with the atmospheric warming over Greenland, while the amplitude of high-frequency sea ice fluctuations increased through interstadials. Our findings suggest that the rapid replacement of widespread MYSI with seasonal sea ice amplified the abrupt climate warming over the course of D-O events and highlight the role of feedbacks associated with late-interstadial seasonal sea ice expansion in driving the North Atlantic ocean-climate system back to stadial conditions. [ABSTRACT FROM AUTHOR]

Tertiary relicts often show evolutionary stasis in morphology and ecology and have been hypothesized to retain stable population sizes in refugia. However, recent studies have reported that some relicts evolutionarily shifted their physiology, ecology, and morphology and experienced various patterns of demography. To understand the historical survival of relict plants, a multidimensional study investigating the evolution of ecological and morphological traits as well as population demographic history is needed. The genus Tanakaea (Saxifragaceae) comprises two species in China and Japan. These species share most vegetative characteristics and are sometimes treated as a single species. The distribution pattern is relictual, as the populations are confined to small areas in mesic warm temperate forests less influenced by Quaternary glacial climates. Focusing on the relictual plant group, this study tested the hypotheses of evolutionary stasis and population stability in long‐term refugia. Genetic analyses using plastome sequences and genome‐wide single‐nucleotide polymorphisms revealed divergence of the two species approximately 6.8 million years ago and strong genetic differentiation of the regional populations. Demographic analysis revealed that almost all populations retained stable population sizes during glacial–interglacial climate changes, supporting the traditional view. However, morphological assessments revealed a simultaneous shift in breeding systems (from hermaphrodite to dioecy/non‐clonal to clonal reproduction) in Japanese species and intraspecific differentiation of leaf traits. Therefore, the relict species do not show evolutionary stasis in every aspect. Changes in reproductive characteristics may have contributed to their long‐term in situ survival. [ABSTRACT FROM AUTHOR]

The timing and rate of ecosystem response to abrupt climate change is a product of numerous complex interactions between biotic and abiotic drivers. Palaeoecological studies from long sedimentary records, particularly those that span periods of dynamic climate such as the last glacial cycle, can help to contextualise ecosystem responses to climate variability through time. Detailed studies that compare proxy data from multiple sites, with high chronological precision, have the potential to ascribe mutual climate drivers, and, therefore, track spatiotemporal variability in ecosystem responses. Here, we interrogate the vegetation impact of past climate change in the eastern Mediterranean, using three sub-centennially resolved pollen archives from Greece. The widespread Campanian Ignimbrite (CI/Y-5; ca. 39.85 ka BP) tephra marker is used as an isochron to directly correlate pollen records from Ioannina (NW Greece), Tenaghi Philippon (NE Greece), and Megali Limni (NE Aegean). Our results reveal spatiotemporal variability in the timing of vegetation response in the Mediterranean to climate forcing across Heinrich Stadial 4 (40.2–38.3 ka BP), a period of known abrupt climatic change. We identify a decline in tree pollen in all three sites, likely related to the onset of enhanced regional aridity, with vegetation at Tenaghi Philippon responding prior to the CI/Y-5, in contrast to at Megali Limni and Ioannina, where much of the vegetation change occurs following tephra deposition. • The Campanian Ignimbrite (CI/Y-5) tephra marker is used to interrogate the timing of vegetation response to HS4. • The timing of tree pollen minima across HS4 varies between three centennial-scale pollen records. • Temporal offsets may reflect site-specific characteristics and/or the fast and slow components of millennial-scale change. [ABSTRACT FROM AUTHOR]

The Himalayan, Karakoram, and Hindu Kush (HKH-TMHA) are the three main mountain ranges in the high-mountain Asia region, covering the China–Pakistan Economic Corridor (CPEC). In this study, we identified glacial lakes in the HKH-TMHA region based on multitemporal Landsat images taken from 1990 to 2020. We analyzed the spatial distribution and evolution of glacial lakes in the HKH-TMHA region from the perspective of their elevation, size, and terrain aspect; then, we described their temporal changes. The results showed that approximately 84.56% of the glacial lakes (84.1% of the total lake area) were located at elevations between 4000 m and 5500 m, and glacial lakes with areas ranging from 0.01–0.5 km2 accounted for approximately 95.21% of the number and 63.01% of the total area of glacial lakes. The number (38.64%) and area (58.83%) of south-facing glacial lakes were largest in HKH-TMHA and expanded significantly over time. There were 5835 (664.84 ± 89.72 km2) glacial lakes in 1990; from 1990 to 2020, the number of glacial lakes in the HKH-TMHA region increased by 5974 (408.93 km2) in total; and the annual average increase in the area of glacial lakes reached 13.63 km2 (11.15%). In 2020, the total number of glacial lake reached to 9673 (899.66 ± 120.63 km2). In addition, most glacial lakes were located in the Eastern Himalayan, China, and the Indus Basin. Based on the precipitation and temperature analyses performed in our study area, we found inconsistent climate characteristics and changes in the three mountain ranges. In general, the daily precipitation (temperature) increased by 1.0766 mm (1.0311 °C), 0.8544 mm (0.8346 °C), and 0.8245 mm (−0.1042 °C) on the yearly, summer, and winter scales, respectively. Glacial melting and climate change are common contributors to glacial lake expansion. The investigation of glacial lakes in this region can provide basic supporting data for research on glacial lake-related disasters, land cover, and climate change in the high-mountain Asia region. [ABSTRACT FROM AUTHOR]

High‐latitude glacierized coastal catchments of the Gulf of Alaska (GoA) are undergoing rapid hydrologic changes in response to climate change and glacial recession. These catchments deliver important nutrients in the form of both inorganic and organic matter to the nearshore marine environment, yet are relatively understudied with respect to characterization of the sediment and solute generation processes and total yields. Using multiple linear regression informed by Bayesian Information Criterion analysis we empirically demonstrate how watershed characteristics affect suspended sediment and solute generation as represented by concentration‐discharge relationships. We find that watershed mean slope and relief control solute generation and that solute yields are influenced most by glacier coverage. We contribute a new flux and concentration‐discharge based conceptualization for understanding solute cycles across a hydroclimatic gradient of GoA watersheds that can be used to better understand future watershed responses to rapid hydrologic change. Plain Language Summary: The Gulf of Alaska (GoA) region is experiencing rapid changes in climate causing glaciers to recede. Streams and rivers within basins that contain glaciers deliver vital nutrients to the ocean. However, regional studies to quantify the generation and delivery of rock‐derived nutrients from watersheds to the ocean are lacking. This study uses statistical analysis to identify the mechanisms controlling the release of nutrients and to demonstrate the physical watershed characteristics that influence the flux of nutrients at the watershed scale. We find that topographic characteristics (slope and relief) control nutrient‐generating processes and that glacier coverage is an important factor controlling the total amount of nutrients exported by streams. This contribution presents a new conceptualization for understanding nutrient delivery to the GoA that can be used to understand future responses to changing climate regimes. Key Points: Catchment glacial coverage controls annual solute yields consistent with the global trend in basins with similar glacier coverageWatershed geomorphology has strong controls on concentration‐discharge relationshipsSolute yields are most significantly influenced by glacier coverage [ABSTRACT FROM AUTHOR]

The multiple equilibrium behavior of the Atlantic meridional overturning circulation (AMOC) is related to the mode transition of the AMOC, which played an important role in abrupt glacial climate changes. However, the difference between modern and glacial climates is not well understood. Here, we examined the structure of the multiple equilibria of the AMOC under the modern and glacial climates through hysteresis experiments using an earth system model of intermediate complexity. The glacial AMOC exhibited a shallower AMOC mode but not the off mode, and a narrower range of multiple equilibria than the modern AMOC. This glacial hysteresis behavior occurred associated with a shift of deep water formation due to changes in surface air temperature and sea ice, whereas that of the modern AMOC is attributed to the basin‐scale salinity feedback. These features were commonly found in two glacial simulations with different strengths of the AMOC at the Last Glacial Maximum. Plain Language Summary: The Atlantic meridional overturning circulation (AMOC) is the Atlantic part of the density‐driven deep ocean circulation and contributes to the warm climate in the North Atlantic through meridional heat transport. The AMOC is known to have multiple modes and transitions between them are deeply connected to abrupt climate changes during glacial periods. We compared the structures of the AMOC modes during present‐day and glacial climates by imposing a gradually changing freshwater flux on the North Atlantic using an earth system model of intermediate complexity. The glacial AMOC shows a shallow‐AMOC mode that is absent in the modern AMOC. In addition, the range of the bistable regime is narrower in the glacial climate than in the modern climate. These features are explained by different mechanisms that drive mode transitions between the modern and glacial climates. In the present‐day climate, salt transport into the Atlantic by the AMOC itself acts as dominant feedback for mode transitions. In the glacial climate, however, a stable shallow‐AMOC mode appears because of the changes in the deep water formation site caused by atmospheric cooling. Interactions among deep water formation, air temperature, and sea ice are important for the glacial mode shift. Key Points: The glacial Atlantic meridional overturning circulation (AMOC) shows different hysteresis behaviors from the modern AMOC in an earth system model of intermediate complexityThe differences in hysteresis are commonly found in two simulations showing different reproducibility of the glacial AMOCAn atmospheric thermal feedback becomes important rather than basin‐scale salinity feedback for the glacial AMOC mode transitions [ABSTRACT FROM AUTHOR]

Quaternary palynology in the Tibetan Plateau (TP) was initiated in the 1960s to meet the needs of economic development in western China. Pollen analysis was conducted for the first time on a 200-m long core of Quaternary lacustrine sediments taken from the main body of the TP in order to study pollen assemblages as well as vegetation and climate changes of glacial (cold)/interglacial (warm) periods. Pollen analysis of alpine snow and ice began at the first scientific expedition to the TP in the 1970s. After the 1980s, a series of international collaborative programs were carried out under Sino-French, Sino-German, Sino-Australian, and Sino-American cooperation, marking the integration of Chinese Quaternary palynology society with the international community. New methods for Quaternary palynology were gradually promoted and applied, changing the vegetational and climatic interpretation of Quaternary palynology from qualitative to quantitative. Since the 1990s, many palynologists have carried out extensive Quaternary palynological studies on fossil pollen sites of more than 60 lakes/sections and alpine glaciers in the TP to discuss the spatiotemporal vegetation changes and climatic and environmental evolution of the TP since the Pleistocene. Over the past half-century, Quaternary palynology in the TP has contributed to the establishment of the Chinese Quaternary pollen database and the study of vegetation and climate evolution since the Last Glacial Maximum (LGM) in the TP. Currently available pollen records revealed the spatial and temporal distribution of vegetation in the TP since the LGM, exhibiting expansions and shrinkages of forest, meadow, grassland and desert in different periods such as the LGM, the last deglaciation, and Holocene optimum period. The paleomonsoon reflected by paleovegetation since the LGM has undergone the changes of weak-strengthening-strong-weakening but still active-shrinking, which is mainly affected by solar insolation. [ABSTRACT FROM AUTHOR]

In a period of ongoing climate changes, identifying drivers of overall and endemic species diversity is a key element in constructing new ecological patterns and determining the main goals of conservation. Such studies are especially crucial if they concern biodiversity hotspot areas. In this study, we explore patterns and drivers of plant endemism (the proportion of endemic plant species to overall plant species richness; PE) in Tajikistan. We used three groups of climatic measures featuring the contemporary and glacial climates as well as climatic changes since the Last Glacial Maximum in the Pleistocene (LGM). To explore relationships between PE and climatic groups, and the most important climatic variables, we applied the Generalised Additive Model and regression trees method respectively. Glacial climate predicted PE variation the most (74.3%), followed by climate stability (55.4%) and current climate (62.4%). The most important variables represented change in precipitation of driest quarter, glacial mean annual temperature and current annual precipitation. LGM climate and its change to date have the greatest influence on contemporary PE patterns in Tajikistan, revealing the evolutionary dependencies between limited-range plants and past climate. Accordingly, annual temperature and precipitation regimes have been the most crucial drivers of PE since the LGM until today. The study revealed the dependence of the PE on a stabilized water-energy supply. The changing temperature and precipitations regimes during the ongoing climate warming may, therefore, increases the threat to geographically isolated cryophilous plants of Tajikistan, while their escape potential to suitable cold habitats is highly topographically limited. [ABSTRACT FROM AUTHOR]

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Aim: The aim of this study is to model the past, current, and future distribution of J. phoenicea s.s., J. turbinata, and J. canariensis, based on bioclimatic variables using a maximum entropy model (Maxent) in the Mediterranean and Macaronesian regions. Location: Mediterranean and Macaronesian. Taxon: Cupressaceae, Juniperus. Methods: Data on the occurrence of the J. phoenicea complex were obtained from the Global Biodiversity Information Facility (GBIF.org), the literature, herbaria, and the authors' field notes. Bioclimatic variables were obtained from the WorldClim database and Paleoclim. The climate data related to species localities were used for predictions of niches by implementation of Maxent, and the model was evaluated with ENMeval. Results: The potential niches of Juniperus phoenicea during the Last Interglacial period (LIG), Last Glacial Maximum climate (LGM), and Mid‐Holocene (MH) covered 30%, 10%, and almost 100%, respectively, of the current potential niche. Climate warming may reduce potential niches by 30% in RCP2.6 and by 90% in RCP8.5. The potential niches of Juniperus turbinata had a broad circum‐Mediterranean and Canarian distribution during the LIG and the MH; its distribution extended during the LGM when it was found in more areas than at present. The predicted warming in scenarios RCP2.6 and RCP8.5 could reduce the current potential niche by 30% and 50%, respectively. The model did not find suitable niches for J. canariensis during the LIG and the LGM, but during the MH its potential niche was 30% larger than at present. The climate warming scenario RCP2.6 indicates a reduction in the potential niche by 30%, while RCP8.5 so indicates a reduction of almost 60%. Main conclusions: This research can provide information for increasing the protection of the juniper forest and for counteracting the phenomenon of local extinctions caused by anthropic pressure and climate changes. [ABSTRACT FROM AUTHOR]

Data availability and temporal resolution make it challenging to unravel the anatomy (duration and temporal phasing) of the Last Glacial abrupt climate changes. Here, we address these limitations by investigating the anatomy of abrupt changes using sub-decadal-scale records from Greenland ice cores. We highlight the absence of a systematic pattern in the anatomy of abrupt changes as recorded in different ice parameters. This diversity in the sequence of changes seen in ice-core data is also observed in climate parameters derived from numerical simulations which exhibit self-sustained abrupt variability arising from internal atmosphere-ice-ocean interactions. Our analysis of two ice cores shows that the diversity of abrupt warming transitions represents variability inherent to the climate system and not archive-specific noise. Our results hint that during these abrupt events, it may not be possible to infer statistically-robust leads and lags between the different components of the climate system because of their tight coupling. Palaeodata resolution and dating limit the study of the sequence of changes across Earth during past abrupt warmings. Here, the authors show tight decadal-scale coupling between Greenland climate, North Atlantic sea ice and atmospheric circulation during these past events using two highly resolved ice-core records. [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]

We present a continuous and well-resolved record of climatic variability for the past 100 000 years from a marine sediment core taken in Delagoa Bight, off southeastern Africa. In addition to providing a sea surface temperature reconstruction for the past ca. 100 000 years, this record also allows a high-resolution continental climatic reconstruction. Climate sensitive organic proxies, like the distribution and isotopic composition of plant-wax lipids as well as elemental indicators of fluvial input and weathering type provide information on climatic changes in the adjacent catchment areas (Incomati, Matola and Lusutfu rivers). At the transition between glacials and interglacials, shifts in vegetation correlate with changes in sea surface temperature in the Agulhas Current. The local hydrology, however, does not follow these orbitally paced shifts. Instead, precipitation patterns follow millennial-scale variations with different forcing mechanisms in glacial vs. interglacial climatic states. During glacials, southward displacement of the Intertropical Convergence Zone facilitates a transmission of northern hemispheric signals (e.g., Heinrich events) to the southern hemispheric subtropics. Furthermore, the southern hemispheric westerlies become a more direct source of precipitation as they shift northward over the study site, especially during Antarctic cold phases. During interglacials, the observed short-term hydrological variability is also a function of Antarctic climate variability; however, it is driven by the indirect influence of the southern hemispheric westerlies and the associated South African high-pressure cell blocking the South Indian Ocean Convergence Zone related precipitation. As a consequence of the interplay of these effects, small-scale climatic zones exist. We propose a conceptual model describing latitudinal shifts of these zones along the southeastern African coast as tropical and temperate climate systems shift over glacial and interglacial cycles. The proposed model explains some of the apparent contradictions between several paleoclimate records in the region. [ABSTRACT FROM AUTHOR]

Constraining the past sea ice variability in the Nordic Seas is critical for a comprehensive understanding of the abrupt Dansgaard- Oeschger (D-O) climate changes during the last glacial. Here we present unprecedentedly detailed sea ice proxy evidence from two Norwegian Sea sediment cores and an East Greenland ice core to resolve and constrain sea ice variations during four D-O events between 32 and 41 ka. Our independent sea ice records consistently reveal a millennial-scale variability and threshold response between an extensive seasonal sea ice cover in the Nordic Seas during cold stadials and reduced seasonal sea ice conditions during warmer interstadials. They document substantial and rapid sea ice reductions that may have happened within 250 y or less, concomitant with reinvigoration of deep convection in the Nordic Seas and the abrupt warming transitions in Greenland. Our empirical evidence thus underpins the cardinal role of rapid sea ice decline and related feedbacks to trigger abrupt and large-amplitude climate change of the glacial D-O events. [ABSTRACT FROM AUTHOR]

The end of the Pleistocene in North America saw the extinction of 38 genera of mostly large mammals. As their disappearance seemingly coincided with the arrival of people in the Americas, their extinction is often attributed to human overkill, notwithstanding a dearth of archaeological evidence of human predation. Moreover, this period saw the extinction of other species, along with significant changes in many surviving taxa, suggesting a broader cause, notably, the ecological upheaval that occurred as Earth shifted from a glacial to an interglacial climate. But, overkill advocates ask, if extinctions were due to climate changes, why did these large mammals survive previous glacial-interglacial transitions, only to vanish at the one when human hunters were present? This question rests on two assumptions: that previous glacial-interglacial transitions were similar to the end of the Pleistocene, and that the large mammal genera survived unchanged over multiple such cycles. Neither is demonstrably correct. Resolving the cause of large mammal extinctions requires greater knowledge of individual species' histories and their adaptive tolerances, a fuller understanding of how past climatic and ecological changes impacted those animals and their biotic communities, and what changes occurred at the Pleistocene-Holocene boundary that might have led to those genera going extinct at that time. Then we will be able to ascertain whether the sole ecologically significant difference between previous glacial-interglacial transitions and the very last one was a human presence. [ABSTRACT FROM AUTHOR]

Eco-environmental changes during interglacials with an astronomical background similar to that of the Holocene are potentially helpful for understanding the future climatic evolution. Marine oxygen isotope stage (MIS) 19 is similar to the Holocene in astronomical background, both being characterized by a low eccentricity of the Earth's orbit. However, MIS 19 has attracted research attention only recently and therefore less is known about eco-environmental changes during this interval, especially based on terrestrial records. In the Chinese Loess Plateau (CLP), the S7 paleosol can provide valuable terrestrial paleoclimatic and paleoenvironmental record for MIS 19. Here, high-resolution terrestrial snail records from the L8-L7 strata of the Huining, Xifeng and Luochuan sequences in the CLP were analyzed in order to characterize spatio-temporal changes in climate and eco-environment during MIS 20–18. The results show that in all three sections the late part of MIS 20 was dominated by abundant cold-aridiphilous mollusc species, indicating that cold and dry climatic conditions prevailed across the entire CLP, under the strong influence of the winter monsoon. The mollusc fauna of MIS 19 were dominated by warmth-loving and thermohumidiphilous species that enable the definition of two climatic stages. The early part of MIS 19 (∼790–778 ka) was marked by warm and humid conditions, as evidenced by high abundances of warmth-loving and thermo-humidiphilous species. This interval was slightly warmer than today and it lasted for ∼12 kyr. The climate of the later part of MIS 19 (∼778–761 ka) was more moderate, and increased proportions of cold-aridiphilous and warmth-loving species were recorded. The warmth of this period was similar to that of today, but the climatic fluctuations were stronger. During the early part of MIS 18 (∼761–745 ka), the Xifeng and Luochuan sections in the eastern CLP still maintained high abundances of warmth-loving and thermo-humidiphilous species, indicating that the moderate climatic conditions during late MIS 19 continued during early MIS 18, lasting for another ∼15 kyr, and that the influence of the summer monsoon remained strong in the eastern CLP during early MIS 18. However, in the western CLP, cold-aridiphilous species in the Huining section became dominant during early MIS 18, reflecting the prevalence of a cold and dry glacial climate, with the strong influence of the winter monsoon. These findings indicate that a steeper climatic gradient and a pronounced regional environmental difference existed between the eastern and western CLP during the early part of MIS 18. Comparison of our mollusc results with the variation of Earth orbital parameters suggested that climate changes in the CLP during MIS 20-18 were likely controlled mainly by insolation changes forced by the configuration of Earth orbital parameters. The unique orbital configuration during the low eccentricity interglacial-to-glacial transition could have strengthened the East Asian summer monsoon which favored the amelioration of the eco-environment in the CLP, especially in the eastern CLP where the summer monsoon exerted a strong influence. Thus we speculate that, under natural climatic conditions, the climate of the CLP may remain in a warm, humid state for another 30 kyr, although climatic instability and the seasonal differences between winter and summer could strengthen. [ABSTRACT FROM AUTHOR]

Pulse-like carbon dioxide release to the atmosphere on centennial time scales has only been identified for the most recent glacial and deglacial periods and is thought to be absent during warmer climate conditions. Here, we present a high-resolution carbon dioxide record from 330,000 to 450,000 years before present, revealing pronounced carbon dioxide jumps (CDJ) under cold and warm climate conditions. CDJ come in two varieties that we attribute to invigoration or weakening of the Atlantic meridional overturning circulation (AMOC) and associated northward and southward shifts of the intertropical convergence zone, respectively. We find that CDJ are pervasive features of the carbon cycle that can occur during interglacial climate conditions if land ice masses are sufficiently extended to be able to disturb the AMOC by freshwater input. [ABSTRACT FROM AUTHOR]

There is a growing appreciation of the uncertainties in the estimation of snow‐melt and glacier‐melt as a result of climate change in high elevation catchments. Through a detailed examination of three hydrological models in two catchments, and interpretation of results from previous studies, we observed that many variations in estimated streamflow could be explained by the selection of a best parameter set from the possible good model parameters. The importance of understanding changing glacial dynamics is critically important for our study areas in the Upper Indus Basin where Pakistan's policymakers are planning infrastructure to meet the future energy and water needs of hundreds of millions of people downstream. Yet, the effect of climate on glacial runoff and climate on snowmelt runoff is poorly understood. With the HBV model, for example, we estimated glacial melt as between 56% and 89% for the Hunza catchment. When rainfall was a scaled parameter, the models estimated glacial melt as between 20% and 100% of streamflow. These parameter sets produced wildly different projections of future climate for RCP8.5 scenarios in 2046–2075 compared to 1976–2005. Assuming no glacial shrinkage, for one climate projection, we found that the choice among good parameter sets resulted in projected values of future streamflow across a range from +54% to +125%. Parameter selection was the most significant source of uncertainty in the glaciated catchment and amplified climate model uncertainty, whereas climate model choice was more important in the rainfall dominated catchment. Although the study focuses on Pakistan, the overall conclusions are instructive for other similar regions in the world. We suggest that modellers of glaciated catchments should present results from at least the book‐ends: models with low sensitivity to ice‐melt and models with high sensitivity to ice‐melt. This would reduce confusion among decision makers when they are faced with similar contrasting results. [ABSTRACT FROM AUTHOR]

Some lateral moraines contain a rich record of Holocene glacial expansion. Previous workers have used such evidence to document glacial fluctuations in western Canada, Alaska, and the U.S. Pacific Northwest, but similar studies in Patagonia are uncommon. Here we report on the late Holocene behavior of Stoppani Glacier, a 75 km2 glacier sourced in the Cordillera Darwin, southernmost Patagonia. Based on radiocarbon-dated wood and organic material contained in the glacier's northeast lateral moraine, we infer that Stoppani Glacier advanced shortly before 3.8–3.6, at 3.2–2.8, 2.3–2.1, and 0.3–0.2, and possibly sometime before 1.4–1.3 and 0.8–0.7 cal ka BP. These advances culminated at 0.3–0.2 cal ka BP, when the glacier constructed a prominent end moraine, marking its greatest extent of the past 4000 years. Although the timing of several of the advances overlap with the age range of glacial expansion recognized elsewhere in Patagonia, some do not. Asynchronous behavior observed in the glacial record may arise from the type of evidence (e.g., lateral stratigraphy vs. end moraine) used to document glacial fluctuations or variations in climate or glacial response times. A significant difference between the Stoppani record and some other Patagonian records is that the former indicates general expansion of ice over the last 4000 years, whereas the latter indicate a net decrease in extent over that period. [ABSTRACT FROM AUTHOR]

Many stable isotope paleoaltimetry studies have focused on paleoelevation reconstructions of orogenic plateaus such as the Tibetan or Andean Plateaus. We address the opportunities and challenges of applying stable isotope paleoaltimetry to "smaller" orogens. We do this using a high‐resolution isotope tracking general circulation model (ECHAM5‐wiso) and explore the precipitation δ18O (δ18Op) signal of Cenozoic paleoclimate and topographic change in the European Alps. Results predict a maximum δ18Op change of 4–5‰ (relative to present day) during topographic development of the Alps. This signal of topographic change has the same magnitude as changes in δ18Op values resulting from Pliocene and Last Glacial Maximum global climatic change. Despite the similar magnitude of the isotopic signals resulting from topographic and paleoclimate changes, their spatial patterns across central Europe differ. Our results suggest that an integration of paleoclimate modeling, multiproxy approaches, and low‐elevation reference proxy records distal from an orogen improve topographic reconstructions. Plain Language Summary: Here we use a climate model with water isotopes implemented to explore the maximum precipitation isotopic signal of Cenozoic topographic and paleoclimate change in the European Alps. Our results show that the impact of topography change has the same magnitude as changes in the isotopic composition of local precipitation resulting from Pliocene and Last Glacial Maximum global climatic change. Key Points: High‐resolution isotope tracking general circulation model (ECHAM5‐wiso) is used to explore changes in past oxygen isotope ratios in precipitation in the AlpsModel‐simulated isotopic signals of topographic change and difference between glacials and interglacials show the same magnitudeLow‐elevation proxy records improve reconstructions of paleotopography by reducing long‐term climate change bias [ABSTRACT FROM AUTHOR]

In addressing the controversial issues of the Late Pleistocene paleogeography of the Caspian basin, an important role is given to the results of the spore-pollen analysis and based on them reconstructions of climate and vegetation changes in the Northern Caspian region during the development of the Early Khvalynian transgression. In this paper we present the main results of the palynological study of deposits (chocolate clays and the overlying and underlying layers from the Srednyaya Akhtuba section) of maximum stage of the Early Khvalynian transgression; the materials are illustrated by pollen diagram with the data of spore-pollen analysis and the detailed list of palynoflora recovered from the studied Lower Khvalynian sequences, and complemented with photographs of pollen belonging to the principal autochtonous taxa and, for comparison, to some redeposited palynomorphs. Palynological materials indicate subaqual (brackish marine and freshwater) sedimentation of the sediments studied in periglacial landscapes and, for the most part, under very harsh climatic conditions. The performed climate-stratigraphic reconstructions do not contradict the data of absolute dating on the accumulation of the studied deposits during the Late Valdai (Ostashkov) late Glacial period. During this interval in the territory of the study area, plant communities of the glacial climate — tundra-steppe, periglacial forest-steppe, periglacial steppe, periglacial parklands and periglacial forests — were developed. The widespread occurrence in the composition of the periglacial vegetation cover of the studied region of the yernik formations from Betula nana and shrub communities from Betula fruticosa , B. nana , Alnaster fruticosus , Juniperus , etc. testifies to the severe climatic conditions and, possibly, the existence of sporadic permafrost in the cold stages (stadials) of the Ostashkov Late Glacial period. [ABSTRACT FROM AUTHOR]

Aim: To investigate cerrado responses to glacial–interglacial climate change and the potential for connective rain forest corridors between the Atlantic Coastal Forest and Amazonian rain forest. Location: The crater lake of Serra Negra (18 °S, 46 °W) in Minas Gerais, Brazil. Taxon: 117 fossil pollen types, 22 non‐pollen palynomorphs were documented. Methods: We recovered 7.82 m of sediment from the lake, and analysed fossil pollen at 62 depth intervals throughout the core. We derived a chronology based on radiocarbon dating with simple rate extrapolation to the base of the core. Results: The c. 90,000‐year fossil record showed a trend towards cooler climates at the Last Glacial Maximum (LGM), but interstadial warming coupled with reduced evaporative stress allowed the expansion of woodlands under cool, moist conditions. Cool‐adapted trees were most abundant between c. 67,000 and 48,000 years ago. A cool cerrado‐like environment marked full glacial conditions between c. 48,000 and 34,000 years ago. The peak of the LGM between c. 34,000 and 17,000 years ago is inferred to have been dry as no sediment accumulated in the system. Main conclusions: Expanded ranges of cold‐tolerant forest taxa led to establishment of a series of assemblages without modern analogue. A system characteristic of modern cerrado was rare in the history of this site. Multiple forest expansions were observed, each differing in composition. The periods of forest abundance at Serra Negra were not temporally aligned with forest expansion in the Atlantic Coastal Forest, and did not provide a continuous corridor of similar forest that connected the cerrado to the Atlantic Coastal Forest. [ABSTRACT FROM AUTHOR]

Climate change and glacial retreat are changing the runoff behavior of Alpine springs and streams. For example, in the extremely dry and hot summer of 2018, many springs used for drinking water supply lost up to 50 percent of their average discharge; a few springs have even run dry. In order to ensure drinking water supply in the future, springs featuring large and constantly sufficient discharge rates will have to be identified and tapped. A case study was undertaken at the Tuxbachquelle because catchment area and temporal variation of physicochemical and hydrochemical properties were previously unknown. Tracer tests with uranine proved a hydraulic connection between this karst spring and a stream a few kilometers uphill. At low runoff, uranine needed about 4½ hours from the sink to the spring, whereas at high runoff more than four days was required. It became evident that discharge, electrical conductivity, temperature, and turbidity of the Tuxbachquelle respond within a few hours to precipitation events. The water quality and an examination of the water balance resulted in a significantly larger catchment area. It is assumed that widely karstified calcite marble subterraneously drains a considerable part of the Tuxertal (Tux Valley), including some active rock glaciers. [ABSTRACT FROM AUTHOR]

This paper investigates the correlation between climate, environment and human land use in the Westernmost Mediterranean on both sides of the Strait of Gibraltar during the Late Glacial. Using a multi-proxy approach on a sample of 300 sites from the Solutrean and Magdalenian of the Iberian Peninsula and from the Iberomaurusian in Morocco, we find evidence for significant changes in settlement patterns and site density after the Last Glacial Maximum. In Southern Iberia, during Heinrich Stadial 1, hyperarid zones expanded drastically from the south-eastern coast to the West through the Interior. This aridification process heavily affected Magdalenian settlement in the South and caused a strong decline of hunter-gatherer population. Southern Iberia during Heinrich Stadial 1 turned out to be a high-risk environment when compared to Northern Iberia. At the same time, the Late Iberomaurusian of Morocco, although considered to be situated in a high-risk environment as well, experiences an increase of sites and expansion of settlement area. [ABSTRACT FROM AUTHOR]

Dual proxies were used to estimate paleo sea surface temperatures (SST) for the Bay of Plenty, north of New Zealand. U37K′ and Mg/Ca in the planktonic foraminifera Globogerina bulloides reconstruct SST for the growth seasons for the organisms they are based upon. U37K′ SST (summer) were consistently ~ 3.5 °C warmer than Mg/Ca (spring), suggesting that Bay of Plenty SST during the last glacial maximum (LGM) was 17.3 °C in summer and 13.8 °C in spring. Combining these results with published data based on the same proxies from other sites around New Zealand shows cooling of 3–4 °C in both seasons at all sites in the LGM relative to the Holocene. This indicates that overall, glacial surface water cooling was similar in subtropical and subpolar waters in both spring and summer. This contrasts with published foraminiferal assemblage reconstructions suggesting greater subantarctic cooling during the LGM. Deglacial warming across the region was characterized by changes in both seasonal and latitudinal temperature differences. Warming began in subtropical waters at ~21 ka, ~ 1.5 ka earlier than in subantarctic water. In the Bay of Plenty, the seasons maintained a consistent offset, while in Hawke Bay, springs stayed cold while summers warmed until after the Antarctic Cold Reversal. In contrast, subantarctic spring SST warmed rapidly, causing temperature differences to decrease between the Chatham Rise (subantarctic) and subtropical sites, possibly caused by shifting westerly winds. The use of multiple proxies enhances our understanding by adding a seasonal component to the glacial story of climate change in the southwest Pacific Ocean. Key Points: Alkenone and foraminiferal Mg/Ca provide seasonal temperature reconstructions for late winter/early spring versus summer in the New Zealand areaSea surface temperatures were 3–4 °C cooler in both seasons during the last glaciation in both subtropical and subantarctic watersSignificant changes in seasonality and latitudinal gradients in SST were only seen during the deglaciation from 35 to 45°S around New Zealand [ABSTRACT FROM AUTHOR]

Effectively identifying the genetic structure and related factors of a species can facilitate understanding the evolutionary history of the species. Phylogeographic patterns and genetic data are essential in investigating the species historical processes and diversification that response to environmental, climatic and geological influences. In this study, Specific Length Amplified Fragment Sequencing (SLAF-seq) data and ecological niche models (ENMs) are combined to identify the genetic structure and demographic modeling of Quercus spinosa , and evaluate the impacts of historical range shifts, climatic variation, and landscape factors on this species. The population topology and genetic divergence of the Cenozoic were inferred by a site frequency spectrum based composite-likelihood approach which is a novel strategy for maximizing the utility of linked SLAF markers. The overall genetic structure using model-based and model-free clustering methods was consistently identified as two geographically distinct genetic clusters. A deep divergence between two natural lineages (i.e., a western Himalaya-Hengduan Mountains lineage and an eastern Qin-ling Mountains lineage) was observed. The demographic modeling and Niche reconstruction indicated that the two groups were diverged in the late Miocene and then presented as two distinct genetic lineages. With the Quaternary glacial climate fluctuation, two groups had continuous asymmetrical secondary contact and gene exchange in the Sichuan Basin during the last glacial maximum. Besides, a significant relationship between genetic distance and geography in all individuals was identified by the Mantel test. Overall, this study 1) contributes to a better understanding of the role played by Quaternary climatic fluctuation in the present-day distributions of Q. spinosa ; 2) provides a comprehensive view of the genome-wide variation of sclerophyllous forests in ecological adaptive evolution; 3) indicates that dispersal limitation and ecological divergence contribute to the genome-wide differentiation of Q. spinosa , which supports a hypothesis that complex geography and climatic changes strongly influence the evolutionary origin and history of the species. [ABSTRACT FROM AUTHOR]

Beetles of the family Tenebrionidae, particularly those of the subfamily Pimeliinae, are highly diverse and abundant in desert ecosystems. The sensitivity of the many wingless species to geographical and ecological isolation makes them ideal candidates for studying effects of climatological and/or geophysical changes on organismal diversity. Our study focuses on Brinckia , the only genus of the subtribe Hypomelina adapted to coastal sand dune hummocks (nabkhas) and restricted to that environment along the Namib Desert and the transitional Namib south of the Orange River. Today, Brinckia appear to be common along the coast, albeit with different species, wherever the absence of shifting sand dunes enables the beach hummocks to form, mainly around Salsola and Zygophyllum species. Therefore, past diversification can probably be directly attributed to temporary extinctions of this habitat in certain coastal regions. The presumed center of origin and diversification of Brinckia is on the Gariep Karoo coastline between Port Nolloth and Lüderitz. Our molecular phylogenetic analysis suggests that the first split within Brinckia occurred ∼2.3 Ma, i.e., relatively recently, and may be associated with aridification that occurred at that time due to global climate change. However, subsequent speciation is more likely the result of the emergence of extensive dune fields, which may have been responsible for temporary habitat degradation in the supralittoral zone. More recent, recurrent and ongoing diversification since the mid-Pleistocene transition, as observed for tenebrionids along the coast of the Atacama and Peruvian deserts, is not typical of Brinckia and supports the stability of their coastal habitat despite glacial climate oscillations. [Display omitted] • Brinckia is adapted and restricted to beach hummocks along the Namib coastline. • The supposed center of origin and diversification is in the Gariep Karoo. • The first split 2.3 Ma might be related to aridification due to global climate change. • Further splits could be related to local habitat degradation from shifting sand dunes. [ABSTRACT FROM AUTHOR]

The Indian summer monsoon (ISM) is a significant component of global climate and plays a key role in transporting heat and moisture from tropical oceans to the Indian subcontinent. The ISM has a critical role in ecosystem functioning as well as the development of regional agriculture and societies. However, it is difficult to ascertain the extent to which these two drivers interact and impact regional biogeochemistry from contemporary process studies because of the widespread human footprint, and millennial-scale ISM dynamics remain poorly understood over the last 20,000 years. Here we used high-resolution diatoms from alpine lakes at different elevations in the southwest monsoon region to reconstruct summer temperature and environmental variability since the Last Glacial Maximum (LGM). By comparing with other proxy-based temperature reconstructions of the Tibetan Plateau and the monsoon proxy records from South Asia, we found a 3–6 °C warming trend and ISM strengthening since the LGM. Our results indicate that summer temperature began to increase since 17.5 cal. kyr BP, marking the onset of deglacial warming. During the early to middle Holocene, the climate clearly warmed and then decreased afterward. The maximum warm interval occurred during the mid-Holocene, which followed changes in Northern Hemisphere summer insolation. Additionally, examinations of fossil diatom assemblages revealed that changes in compositions were closely linked with global and Indian monsoon climate changes on glacial and interglacial time scales. The abrupt temperature increases from extreme cold to warm transition during the Late-glacial/Holocene boundary (∼3 °C) are strongly associated with regional replacement of major biotic species compositions. The presence of biotic transition and the increased rate of temperature increase during the Late-glacial/Holocene transition confirm the importance of climate change in restructuring biological communities. This suggests that biotic structures necessary to survive such rapid climate regime were susceptible to impacts of the speed and magnitude of temperature change in monsoon region. • Composite mean July temperature inferred by diatoms from multiple lakes and comparison with palaeoclimatic bio-proxies. • Quantitative estimates show a regionally coherent Holocene maximum warmth over the southeastern Tibetan Plateau. • Temperature increases by ca. 1.5–3.4 °C since the Holocene represent a first threshold in ecosystem responses to climate warming [ABSTRACT FROM AUTHOR]