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This paper presents an exploratory study on the taxonomic diversity of pre-Hispanic archaeofaunas in the South-Central Andes (SCA; western South America) from the Pleistocene-Holocene boundary to the Late-Holocene. The SCA is a complex of diverse environments and has undergone distinct climate events for the last 13,000 years, such as the occurrence of warmer and drier conditions in the Middle-Holocene. The South-Central Andean area was part of the larger Andes interaction area, which was a primary center for animal and plant domestication and the emergence of agro-pastoralist economies. Since subsistence was key to these processes, the SCA provides a relevant case study on the interactions among environment, foodways and sociocultural evolution. Taxonomic diversity was used here as a proxy for diet breadth. A total of 268 archaeofaunal assemblages were sampled from the zooarchaeological literature. Reviewed variables included the cultural chronology and spatial coordinates of the assemblages, as well as the presence and abundance of taxa at the family rank. Taxonomic diversity covered two dimensions: composition (families present in each assemblage) and structure (quantitative relationships among taxa), which was measured through richness (NTAXA), ubiquity and relative abundance (NISP based rank-order). Despite the uneven distribution of samples, the analyses revealed the following trends: (1) a moderate relationship between NTAXA and distance from coastline for most of the Holocene; (2) a potential decrease in assemblage richness for coastal ecoregions during the Late-Holocene; and (3) a generalized increase in the relative abundance of Camelidae. [ABSTRACT FROM AUTHOR]

Detailed and systematic analyses of the magnetic and grain-size properties of the Weihe River sediments were conducted to explore effective proxies that could reflect variations in the runoff. Ultimately, the magnetic parameter χARM/χlf was considered a reliable proxy owing to the close relationship with grain-size fraction larger than 63 μm, with a correlation coefficient of 0.90. By combining accelerator mass spectrometry radiocarbon (AMS 14C) dating, a timescale ranging from 12,900 year BP to the present was established for the section. Accordingly, the reconstructed runoff variations showed that, from 12,900 to 9,600 year BP, the hydrodynamic force of the river was relatively strong, and the runoff was large. From 9,600 to 7,500 year BP, these two parameters varied from weak to strong, and the trend continued to increase from 7,500 to 5,300 year BP. At 5,300 year BP, the sediments shifted from the fluvial to the continental environment, indicating a marked decrease in the runoff. Although the resolution and pattern of this reconstruction were rough, this is a significant analysis among the historical runoff studies based on floodplain sediments, and the results showed trends that to some extent coincide with the variations in the intensity of the East Asian Summer Monsoon. HIGHLIGHTS An integrated study of Weihe River sediments using environmental magnetism and particle size analysis.; Establishing a chronological framework for the Weihe sedimentary profile using AMS14C dating.; The magnetic ratio parameter χARM/χlf is extracted as an effective proxy for indicating river runoff.; The results show that the runoff process of the Weihe River is mainly controlled by the East Asian summer winds.;

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The widespread Early Holocene sea-level rise observed along the global coastal realms reinvigorated the need to decipher sea-level variability on a local and regional scale, yet limited attempts were made on simultaneously addressing sea-level and climate variability. The southwest coast of India is endowed with several geomorphic features providing cues on the paleosea-level and climate variability engrossed with its sedimentary sequence in the lowlands. In view of this, the present study aims to decipher the Holocene sea-level and climate variability based on geochemical and palynological proxies supported by 10 AMS radiocarbon ages on a 32 m long sediment core (L7) raised from Upper Kuttanad Kole wetlands (Kuttoor), Kerala, Southwest India. The study demonstrated high sea-level along with warm and wet climate due to Indian summer monsoon (ISM) intensification during 9.69–7.56 ka corroborating with the Holocene Climate Optimum (HCO). However, a break in the sediment deposition is observed between 7.56 and 3.51 ka, the reason for which is yet to be fully understood. During 3.51–2.55 ka, the gradual weakening of ISM has been invoked with an intermittent monsoon spell during 3.20–3.40 ka. After 2.55 ka the sediment core records occurrence of coarser clastics indicating sediment deposition by the migrating distributary channel of the Pamba-Manimala rivers. The high sea level during HCO attests that the core location plausibly represented the southward extension of the Vembanad lagoon which transformed into part of the terrestrial system due to the gradual sea regression during the mid-late Holocene period followed by deposition of alluvial sediments from the hinterland rivers. [ABSTRACT FROM AUTHOR]

Transient simulations of the global fully coupled climate model COSMOS under realistic varying orbital and greenhouse gas forcings are systematically compared to diatom oxygen isotope (δ18Odiatom) records from Russian lakes with focus on Eurasian Holocene climate trends. The measured δ18Odiatom decrease and other temperature proxies are interpreted as large‐scale cooling throughout the Holocene while the model simulations are biased too warm, likely through missing radiative forcings. This large‐scale warm bias also dictates the modeled δ18Oprecipitation. Hence, at locations where the signs of model and proxy temperature/precipitation trends agree, measured δ18Odiatom and modeled δ18Oprecipitation trends show notable accordance. An increased temporal variability of modeled δ18Oprecipitation is linked to persistent atmospheric circulation patterns. Applying the transient forcings in an accelerated way (every 10th year only) yields a similar, yet weaker or delayed model response, especially in the ocean. [ABSTRACT FROM AUTHOR]

We reconstructed the Holocene climate in the study area using data from a BZ section in the Baiyangdian paleo-lake. Samples were analyzed for multiple proxies for climate conditions, including grain size, magnetic susceptibility (MS), and carbonate content, which were combined with accelerator mass spectrometry (AMS) 14C data. The results show that from 10.0 to 6.3 kyr BP, the study area experienced an interval of increasing precipitation and rising water level at Lake Baiyangdian. For a very short period, ~ 8.4 kyr BP, the extent of the lake reached the sampling point. The climate during this stage was relatively humid. The water level dropped abruptly at 6.5 kyr BP as a result of a weak monsoon event. From 6.3 to 2.9 kyr BP the climate became humid once again. The continuous lacustrine sediment of the strata indicated that the water level of Lake Baiyangdian expanded rapidly during this period and reached the sampling point. After 2.9 kyr BP, the climate in the region changed again from humid to dry. The abrupt increase in MS after ~1 kyr BP (993 AD) is consistent with records of human activities in local chronicles, which indicates that the environment in the study area was influenced by human activities. Through a comparison of the BZ section and the East Asian summer monsoon (EASM) records, we found that precipitation in the study area was controlled by the EASM. A series of cold Holocene events were clearly recorded by the sediment in the BZ section, and these events are synchronous with the North Atlantic ice-rafting events (IRD). The connection between the characteristics of the BZ section and the EASM and IRD indicate that climate evolution in the study area was strongly affected by EASM and IRD. [ABSTRACT FROM AUTHOR]

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Information on past dryland environments is commonly derived from geomorphological landforms and sediments ('geoproxies'). The Okavango Delta in the middle Kalahari, Botswana, has been subject to a long history of arid–humid transitions but its potentially rich archive of fluvial geoproxies is largely untapped. Previous palaeoenvironmental studies in the Delta region have focused mainly on aeolian dunes, lacustrine beach ridges, and rare pollen sequences in surrounding locations, and the Delta's channel dynamics have remained poorly constrained, both chronologically and in quantitative palaeohydrological terms. Focusing on the Delta's Xugana region, we present the first optically stimulated luminescence ages for palaeochannel fills and scroll bars, revealing significantly enhanced fluvial activity in the ~7–4 ka interval. Along 120–150 m‐wide, sand‐bed, sinuous palaeochannels, lateral migration and bend cutoffs were driven by palaeodischarges up to ~350–450 m3 s−1, at least nine times those of the present‐day channels. These palaeochannels represent the last major phase of meander activity in the middle and lower Delta. The palaeodischarges imply significantly higher rainfall over the catchment in the mid Holocene, possibly resulting from a southwards shift of the African tropical rainbelt. Over the last few thousand years, diminished fluvial activity in the Xugana region has continued; <20 m‐wide channels with discharges typically <40 m3 s−1 have been more laterally stable, albeit subject to local avulsions. These findings provide the 'missing link' between evidence for past intervals of enhanced rainfall in the Delta's tributary catchments in the northwest and west and the filling of large lacustrine basins to the southeast and east. The findings contribute to improved understanding of changing Kalahari hydroclimates and support growing evidence indicating that the mid to late Holocene was a time of significant fluvial transformation across many of the world's drylands. [ABSTRACT FROM AUTHOR]

The Gonghe Basin (GHB) on the northeastern Qinghai-Tibet Plateau (NE-QTP) is sensitive to climatic change due to the interplay of the Asian summer monsoon and the westerlies. Extensive aeolian sediments in the basin represent important archives of regional environmental evolution. However, the paleosol development timing is still not clear because of limited number of optically stimulated luminescence (OSL) sampling and dating, which restricts our understanding of past aeolian activities during the Holocene in GHB. In this study, a loess-paleosol section, Najiao (NJ), from the southeastern margin of GHB was investigated. Eighteen OSL samples were obtained from the 400-cm section in order to construct a high-resolution chronological framework. Paleoenvironmental proxies including grain size distribution (GS), magnetic susceptibility (MS), total organic carbon (TOC), and geochemical elements were measured to reconstruct the Holocene aeolian activity. Results show a successive accumulation from Early to Middle Holocene at NJ section, but a c. 3 ka sedimentary hiatus is found between c. 5 and 1.5 ka. Paleosol ages are constrained by high-resolution OSL ages which are from c. 7–5 ka. Consistent with previous studies, strong aeolian activities occurred in GHB during the Early Holocene (c. 13–9 ka), indicating dry climate conditions. Initiation of pedogenesis was at c. 9 ka, and the intensified soil development and lowest aeolian activity were between c. 7 and 5 ka. The increased sand content after c. 1.5 ka indicates enhanced human activities in the interior of GHB in the Late Holocene.

Existing global mean surface temperature reconstructions for the Holocene lack high-frequency variability that is essential for contextualising recent trends and extremes in the Earth’s climate system. Here, we isolate and recombine archive-specific climate signals to generate a frequency-optimised record of interannual to multi-millennial temperature changes for the past 12 000 years. Average temperatures before ∼8000 years BP and after ∼4000 years BP were 0.26 (±2.84) °C and 0.07 (±2.11) °C cooler than the long-term mean (0–12 000 years BP), while the Holocene Climate Optimum ∼7000–4000 years BP was 0.40 (±1.86) °C warmer. Biased towards Northern Hemisphere summer temperatures, our multi-proxy record captures the spectral properties of transient Earth system model simulations for the same spatial and season domain. The new frequency-optimised trajectory emphasises the importance and complex interplay of natural climate forcing factors throughout the Holocene, with an approximation of the full range of past temperature changes providing novel insights for policymakers addressing the risks of recent anthropogenic warming.

The Holocene sedimentary history of the Turbio River valley in semi-arid north-central Chile and its relationship to climate variability is presented in this study. Fluvial landforms and sedimentary deposits serve as essential records for studying the long-term dynamics of fluvial systems in response to external factors such as tectonic and climatic influences. The study area, located in the Andean Mountain range, is highly sensitive to hydrodynamic changes and sediment transport processes, making it suitable for studying fluvial dynamics and their relationship to climate fluctuations over millennia. In particular, the transitional semi-arid conditions of this region provide an opportunity to link Holocene fluvial sediments to climatic shifts. This study presents the analysis of well-preserved sedimentary deposits that outcrop along the valley walls, including grain-size distribution, stratigraphy, geochemical composition and radiocarbon dating to establish the chronological context. Facies association analysis, along with geochemical data, allowed the interpretation of depositional sub-environments and their evolution through time. We interpret the Holocene sedimentary evolution for the Turbio River valley as six time periods that reflect shifts in sediment source, energy regime, flow types, and sedimentary processes linked to fluctuations between wet and dry climatic conditions. The sedimentary sequence is interpreted as reflecting an initial high-energy period with continuous surface runoff followed by two periods of formation of extensive lakes, likely separated by periods of runoff intensification. The later part of the sequence reflects a more stable fluvial landscape that led to the excavation of the sedimentary fill. This sedimentary record provides valuable insights into past climate variations and their impact on the hydrodynamic conditions of the fluvial system in the region. Comparisons with other regional records support a broader understanding of climate change in the semi-arid Andes of Chile. • Rio Turbio sedimentary record is studied to reconstruct Holocene river dynamics. • Fluctuations in fluvial processes are related to alternating wet and dry periods. • A new model explains how the river evolved in response to Holocene climate variations. • Fluvial record provide valuable insights into past climates. [ABSTRACT FROM AUTHOR]

In this study, Holocene humification records were derived from four ombrotrophic peatlands to investigate the millennial-scale and decadal-centennial-scale variability of peat decomposition and to explore the paleoclimatic and paleohydrological implications. After eliminating the species-specific and site-specific noise and removing the time-dependency effect for each of four peat sequences, the averaged residuals of four peat humification sequences exhibit two-order variations. The millennial-scale variation of averaged residuals of four peat humification is characterized by a bow-shaped curve and is basically moisture-dependent. In detail, the humification in the middle Holocene (~8200–~4000 cal. yr BP) was higher than in the early Holocene (before ~8200 cal. yr BP) and also than in the late Holocene (after ~4000 cal. yr BP). The decadal/centennial-scale variations are superimposed on the bow-shaped curve and have been primarily paced by the sea surface temperature in the North Atlantic whose signals were propagated to Central Asia via the prevailing westerlies, which implies that lower temperature and lower temperature-suppressed evaporation (i.e. elevated moisture level) were most likely responsible for limiting the decomposition activity in the uppermost peat layer. These results indicate the potential for humification records from ombrotrophic peatlands in Central Asia to elucidate paleoclimate variability. [ABSTRACT FROM AUTHOR]

Thermokarst lakes form following the thaw of ice‐rich permafrost and drain after a few decades to millennia. Drained thermokarst lake basins (DTLBs) become epicenters for peat accumulation and re‐aggradation of ice‐rich permafrost. This re‐aggradation of permafrost may be interrupted by subsequent thermokarst lake formation with sufficient disturbance. Thermokarst lakes and DTLBs are abundant near Old Crow, Yukon, Canada, but little is known about their evolution through the Holocene. In this study, we investigate the hydrology and drainage histories of seven DTLBs from the Old Crow Flats on the basis of cryostratigraphy, radiocarbon dating, and pore‐ice δ18O and δ2H records. Cryostratigraphic evidence implies only one of the seven studied DTLBs underwent multiple thermokarst cycles. Radiocarbon age–depth models demonstrate a slowdown in the rate of post‐drainage peat accumulation with time. Pore‐ice isotope analyses reveal a spectrum of possible post‐drainage isotopic histories resulting from spatial variability in permafrost, vegetation, and hydrology. Unlike lacustrine silt, post‐drainage peat contains relatively constant pore‐ice isotope trends. In light of our findings, we propose that syngenetic peat permafrost in DTLBs preserve a warm‐season sampling of local meteoric waters. These pore‐ice δ18O and δ2H records may aid millennial‐scale paleoclimate investigations, as we demonstrate through our reconstruction of Holocene climate change in northern Yukon. [ABSTRACT FROM AUTHOR]

Variations in the magnetic and geochemical properties of the sediments of Lake Bolshoe Yarovoe (Altai Territory) were studied. The data were derived from five core columns (up to 4.5 m long) covering a time interval of more than 8000 years. In addition, coercive spectra were obtained for 792 samples taken every 2 cm. Coercive spectra were then used to identify soft magnetic (10-15 mT) and hard magnetic (35-50 mT) components. The soft magnetic component is detrital, and the hard magnetic component is biogenic, which is confirmed by microscopic studies. Moreover, the samples contain micrometeorite particles. Variations in geochemical properties allow reconstruction of the environmental history of the lake. Sediments in the lower part of the section vary both in the content of ferrimagnetic components and in geochemical properties, which indicates a sharp environmental change between ~6100 and ~7600 years ago. Quasiperiodic alternation of warm (dry) and cool (humid) periods is observed higher in the section, between ~4100 and ~6100 years ago. The variations in the magnetic components are consistent with the environmental changes and can be used for the historical reconstruction. [ABSTRACT FROM AUTHOR]

The eastern North American Arctic has a complex 5000-year prehistory, during which many human population movements occurred over great distances. Archaeologists have interpreted these movements as resulting from many factors, however the effects of climate change are often hypothesized as primary drivers that can "push" human groups to leave some regions, or "pull" them to move to others. Here, we examine climate change at the regional scale over the Common Era using Arctic paleoclimate data derived from a wide suite of biological proxies and geochemical tracers. We consider available statistical composites of high resolution (sub-decadal) paleo-temperature reconstructions for the Arctic region, as well as local-scale reconstructions at century or sub-century scale resolution in three focal regions of archaeological significance relevant to population movements: Victoria Island, Foxe Basin/Baffin Island, and the High Arctic (Ellesmere Island/Northwestern Greenland). We emphasize the two most widespread, though variable, climate change events characteristic of this period: the Medieval Climatic Anomaly and Little Ice Age in the second millennium AD; we also evaluate the evidence for the Roman Warm Period and Dark Ages Cold Period in the first millennium AD, as context for later events. We integrate information on the timing and magnitude of these events across the Canadian Arctic Archipelago, and assess the degree to which they coincide with current understanding of major population movements, with particular emphasis on three migration episodes. First, the expansion of Late Dorset Paleo-Inuit to the Central and High Arctic beginning in the late first millennium AD is plausibly linked to warming temperatures of the MCA. Second, the migration of Thule Inuit from Alaska to the Eastern Arctic beginning ca AD 1250 is not linked to warmer temperatures as previously hypothesized, and is therefore more likely related to social factors in Alaska. Third, the abandonment of northern regions and new settlement of southern regions by Inuit in the mid-second millennium AD is likely linked to a combination of cooling climate and increasing availability of European trade goods. Together, these three case studies indicate that linkages between climate change and migration are complex, variable, and mediated through social and economic factors. [ABSTRACT FROM AUTHOR]

We present a comprehensive record of Holocene (11,590–628 cal. yr BP) climate and hydrographic changes around the Wular Lake located in Kashmir Valley, India. Based on the multi-proxy investigations, we have identified three phases of wet climate conditions that prevailed from the commencement of the Holocene Epoch – 9000 cal. yr BP, 8100–6650 cal. yr BP and 6350–5000 cal. yr BP, whereas periods of dry climate were observed during 9000–8100 cal. yr BP, 6650–6350 cal. yr BP and ~5000 to 4000 cal. yr BP. The results also suggested that the lake widened and deepened significantly around 6350–5000 cal. yr BP. The results indicated desiccation and the exposure of the lake margin around 5000–4500 cal. yr BP. The sedimentation rate since 4500–628 cal. yr BP was quite low for detailed paleoclimate interpretations. Oscillations in lake extension and deepening appear to be due to changing intensity of westerly moisture in the region, and we correlate several of the low lake-level phases to the Bond events caused by North Atlantic ice rafting events. [ABSTRACT FROM AUTHOR]

This study quantitatively reconstructs Holocene climate based on a palynological analysis of a 745-cm lake core at Gun Nuur in the northern Mongolian Plateau. The core is precisely dated with 49 dates and the dataset comprises 372 pollen samples providing high temporal resolution. We obtained quantitative reconstructions of annual temperature (Tann) and precipitation (Pann) based on comparison with a modern pollen dataset comprising 604 data sites for which climate correlation coefficients are high (R2 = 0.76 for Tann and R2 = 0.70 for Pann) and the uncertainties are relatively small (RMSEP = 1.99 °C for Tann and RMSEP = 46.22 mm for Pann). Results show that the climate in the northern Mongolian Plateau experienced a warm-dry climate in the early Holocene (∼10,300 to ∼7900 cal. yr BP), a stable cool-wet climate in the middle and early-late Holocene (∼7900 to ∼2300 cal. yr BP), and an increasingly cool-wet climate in more recent times (last ∼2300 years). The high temperature in the northern Mongolian Plateau before ∼7900 cal. yr BP is attributable to the thermal sensitivity of the interior Asian continent to high summer insolation. The nearly constant and rather stable temperature during the past ∼7900 years is most likely the result of the thermal insensitivity of the well-developed and densely-covered Taiga forests in south Siberia to declining summer insolation. Increasing precipitation in the northern Mongolian Plateau in the period before ∼7900 cal. yr BP is similar to coeval records from the Altai Mountains, the Yinshan Mountains and the Lake Baikal basin, and most likely resulted from rising sea surface temperature both in the North Atlantic Ocean and in the Western Tropical Pacific Ocean. The stable and nearly constant precipitation during the past ∼7900 years most likely resulted from the combined effect of decreasing water vapor supply from the cooling Western Tropical Pacific Ocean and the increasing water vapor supply from the warming North Atlantic Ocean. • Holocene temperature variations were attributed to the temperature sensitivity to the summer insolation. • Holocene precipitation variations were mainly controlled by North Atlantic SST and Western Tropical Pacific SST. [ABSTRACT FROM AUTHOR]

The Neolithic and Eneolithic sites in the Low Volga River region have been poorly investigated in comparison with other territories due to a small number of excavated sites. On the Algay site and the Oroshaemoe I settlement there is evidence of the earliest appearance of Neolithic pottery and the first sign of domestication in the Eneolithic period within the Volgo-Ural territory. Archaeological, lithological, grain-size analyses, mineralogical-geochemical methods and radiocarbon dating of cultural deposits have been applied to reconstruct the palaeoenvironment in the Holocene in this area. The results show that the landscape-climatic conditions in the steppe area of the Lower Volga basin strongly affected the development and adaptation of ancient societies.

Temperate forests in the Northern Hemisphere are strongly affected by increasing annual temperatures and natural disturbances such as droughts, fires, and pest outbreaks. In many regions, alternatives are explored by the forestry industry for previously commercialized tree species which are rapidly declining in areas outside their optimal climatic niches. However, as the current ranges of tree species have been mainly constrained by human activity, their true climatic and ecological niches are likely different from our observations. For example, little is known about environmental niches and population dynamics of tree species with limited dispersal ability, such as silver fir (Abies alba). Long-term (paleo) records of past landscape composition, past climate, and past disturbances can help to reveal the natural environmental niches of tree species. This study focuses on the Bohemian Forest (Šumava) in Czechia, where the human alteration of forests in higher elevations (>1000 m asl) has only been demonstrated from Medieval times onward. We present an interdisciplinary approach of geochemistry, pollen, charcoal, botanical and insect macro remains from a high-elevation peat record for the last seven millennia. Our multi-proxy study aimed to identify episodes of increased fire and other disturbances such as insect outbreaks, which could have influenced forest dynamics and vegetation succession in this montane region. However, the charcoal and macro-fossil records do not indicate any large local fires, insect outbreaks, browsing, or other disturbances (e.g., anthropogenic) for a major part of the record, suggesting that changes in the vegetation after 6500 cal yr BP were mainly caused by climatic fluctuations. Silver fir (Abies alba) expanded from 4300 cal yr BP, and likely became the dominant tree species at this locality for the next 2000 years, with extremely high pollen values up to 60%. During the establishment of silver fir around the peat bog around 5600 cal yr BP and its expansion around 4300 cal yr BP, the geochemical record and low counts of the testate amoeba Archerella flavum indicate drier conditions on the peat bog. Comparison with climatic simulations on a 1 × 1-km scale from the CHELSA database suggests that the local expansion of silver fir possibly coincided with a decrease in precipitation during both the wettest and warmest quarter of the year, related to a decreasing trend in seasonality of annual precipitation; this might confirm the species' higher tolerance to drought. Although silver fir is currently extremely rare in the Bohemian Forest, it has the potential for local expansion if logging, fire, and game browsing are kept to a minimum. • Multi-proxy record from Blatenská slat', Bohemian Forest. • Prominent dominance of Abies alba over Picea abies between ca. 4000–1200 cal yr BP. • Indicators for disturbances (fire, insect outbreaks, browsing) were not found. • Climate simulations match the local geochemical record, suggesting declining precipitation. • Silver fir populations in central Europe could expand in the absence of disturbances. [ABSTRACT FROM AUTHOR]

The geomorphological disposition of (para/peri) glacial landforms, elemental geochemistry, and optical chronology of the relict lake sediment in the Southern Zanskar ranges, northwest Himalaya are used to understand the relationship between glacial dynamics and the lake sedimentation during the mid-Holocene climate variability. Following the Last Glacial Maxima (LGM), pulsating deposition of outwash gravels until the early Holocene overwhelmed the Zanskar valley. The obstruction of Tsarap Chu (chu = river) by alluvial fans during the mid-Holocene led to the development of Padum Lake. In the present study, cirque glacier moraines representing three minor glacial advances were mapped along with sedimentological details and dated using Optically Stimulated Luminescence (OSL) dating technique. The oldest cirque glacier advance - Padum Cirque moraine-3 (PDCm-3) is dated to 11.4 ± 0.9 ka. The succeeding advance (PDCm-2) is dated to 5.3 ± 0.6 and 4.8 ± 0.8 ka whereas, the younger cirque glacier advance (PDCm-1) remains undated. The mid to late Holocene climate variability inferred using major and trace element geochemistry of the relict Padum lake sediments supported by optical chronology indicates six centennial to millennial-scale climatic phases. The prominent warmer phases are represented by decreased mineralogical fine grain flux (low K/Ti, Fe/Si, and Al/Si) with a corresponding increased coarse grain flux (higher Ti/Al and Sr/Al ratios). These phases are dated between 5.9 and 5.5 ka (phase-I), 3.8 and 3.4 ka (phase-IV), and 2.8 and 2.5 ka (phase-VI). The increased mineralogical finer fraction (higher K/Ti, Fe/Si, and Al/Si) between 5.5 and 5.1 ka (phase-II) and 3.4 and 2.8 ka (phase-V) indicate reduced meltwater flux during cooler phases. The intervening phase-III (5.1–3.8 ka) is characterized by increased mineralogical coarse grain flux (decreasing K/Ti, Fe/Si, Al/Si) suggesting gradual warming. The oscillatory climate at millennial scale was further used to understand glacier dynamics. The PDCm-2 advance in the lake record corresponds to the first major cooling (5.5 and 5.1 ka; phase-II) and continued until ∼3.8 ka. Using geochemical data of lake record, a major recession is inferred after 3.8 ka that persisted until around 3.4 ka (phase-IV). Similarly, the undated younger cirque glacier advance (PDCm-1) is assigned to the second cooling event (3.4 and 2.8 ka; phase-V). Thereafter, the cirque glaciers receded, most likely under increasing dryness and fluctuating climate (2.8–2.5 ka, phase-VI). After ∼2.6 ka, the development of ice-wedge pseudomorphs indicates the onset of permafrost conditions that degraded after ∼2.5 ka implying an increase in air temperature. The lake sedimentation terminates with the deposition of multiple younger alluvial fan facies. The climate variability shows a close correspondence with regional climate records suggesting that marginal glacier advancements were triggered by enhanced moisture via atmospheric rivers and cooler winter temperatures. The study highlights the potential of relict lake sediment in association with para- and peri-glacial landforms to reconstruct the pattern of minor glacier responses to climate variability during the Holocene. [Display omitted] • Mid-Holocene glacier fluctuations inferred from relict glacial lake and landforms. • Cirque glaciers responded to minor climatic perturbations ∼12, 6, and 4 ka. • Glacier advances triggered by westerlies and atmospheric rivers. • Deglaciation pulsating in nature with major aggradation in the early Holocene. • Permafrost conditions deteriorated after ∼2.5 ka due to increased temperature. [ABSTRACT FROM AUTHOR]

Lacustrine sediments represent an important data source for glacial and palaeoclimatic reconstructions. Having a number of certain advantages, they can be successfully used as a means of specification of glacier situation and age of moraine deposits, as well as a basis for detailed climatic models of the Holocene. The article focuses on the coring of sediments of Lake Kakakel (Western Caucasus) that has its goal to clarify the Holocene climatic history for the region, providing the sampling methods, lithologic description of the sediment core, obtained radiocarbon dating and the element composition of the sediments. The primary outlook over the results of coring of the sediments of the Lake Karakyol helped to reconsider the conventional opinion on the glacial fluctuations in the valley of Teberda and to assume the future possibility for high-definition palaeoclimatic reconstruction for Western Caucasus.

The article covers the origin of paleolimnological method in glaciology, concerns the theoretical background of the approach, and focuses on the principal methods of analysis of the lake sediments and creating the sedimentary age-depth models. Lake sediments can provide a basis for creating uninterrupted reconstructions of the Holocene glacier variations with high resolution. The fundament of paleolimnological method is based on the differences between glacial and non-glacial components of the bottom sediments of proglacial lakes. The glacial signal in the lake sediments was originally distinguished by measuring the organic content of the sediment (normally with loss-on-ignition) and the magnetic properties of the sediment. Subsequent methods of analysis could yield more precision and normally include geochemical composition (with the use of high-resolution scanning x-ray fluorescence analysis), use of biogenic indicators (such as pollen and diatoms contained in the sediment) and more. Obtaining the most accurate age of the sediment is a crucial question in subsequent application of the sediment parameters for reconstruction of glacier variability. The article covers various methods of dating the lake sediment – radiocarbon, Cs- and Pb-isotope dating, varve counting. Techniques of creating age-depth models are taken into account. A state-of-the-art application of sedimentary properties in paleoglaciology yields a reconstruction of a former equilibrium line altitude – ELA. The article focuses on the basis of the ELA reconstruction approach. Successful examples of reconstructions of glacier variations based on the lake sediments can be found throughout the majority of the glaciated regions of the planet. The article states the most prominent of them and gives an update on the current progress in paleolimnological research in the Caucasus Mountains.

Laminated sediments of the continental slope off the Makran coast in the northern Arabian Sea are well-known climate archives and record productivity, as well as supply of material from land. Here, we studied sediment core 275KL off Pakistan in concert with sediment trap, dust and river samples in order to characterize and quantify land-derived material deposited in varves and event layers. We analysed grain sizes, mineral assemblages, bulk components and stable isotopes (δ13C, δ18O) of carbonates. In winter, enhanced river discharge is the main source of lithogenic matter contributing the major amounts to the total annual sedimentation of the northern Arabian Sea. During the late summer season, lithogenic matter accumulation is slightly enhanced, probably carried along with the south-eastward blowing Levar winds from the Balochistan and the Sistan Basins and the summer monsoon discharge maximum of perennial streams. C/N ratios and stable carbon and oxygen isotopes could not be used to distinguish between organic matter produced on land and in the ocean, whereas stable carbon and oxygen isotope ratios of carbonates suggest that sedimentation of event layers is dominated by direct inputs from land. Catastrophic denudation and storm events occur on average once every 50 years and lead to sedimentation rates that exceed the mean annual sedimentations of 983 g m−2 yr−1 by 6 to 10 times. Nevertheless, due to their rare occurrence, they contributed only 7% to the total sedimentation during the last ca. 5000 years. End-member modelling of grain sizes in accordance with lithogenic matter accumulation rates and event layer frequencies showed that arid conditions prevailed between 4000 and 5000 a BP while more humid conditions commenced around 2000 ka BP in accordance with the Pacific ENSO record. [ABSTRACT FROM AUTHOR]

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The Sierra Mojada District comprises multiple types of near-surface mineral concentrations ranging from polymetallic sulfide zones, “nonsulfide Zn” (NSZ) deposits, and a silver-rich Pb carbonate deposit hosted by lower Cretaceous carbonate strata. Hypogene concentrations of Fe-Zn-Pb-Cu-Ag sulfides and sulfosalts are locally preserved and are associated with hydrothermal dolomite and silica. Alteration mineralogy and sulfur isotope data suggest primary Zn-Pb-Ag mineralization from circa 200 °C hydrothermal fluids. The NSZ deposits dominantly consist of smithsonite and hemimorphite associated with local Mn-Fe oxides. The Red Zinc Zone consists of strata-bound zones dominantly of hemimorphite that fills pores in residual and resedimented Fe oxides. The White Zinc Zone shows local dissolution features, including internal sediments interbanded with and cemented by smithsonite. Similar Pb isotopic compositions of smithsonite, hemimorphite, and cerussite to Sierra Mojada galena document that the NSZ deposits originated from polymetallic carbonate-replacement sulfide deposits, with flow of metal-bearing groundwater being controlled by local topography and structural features in this extensional terrane. Oxygen isotope values for Sierra Mojada smithsonite are relatively constant (δ18OVSMOW = 20.9 to 23.3‰) but are unusually low compared to other supergene smithsonites. Using δ18OVSMOW (− 8‰) of modern groundwater at nearby Cuatrociénegas, smithsonite formational temperatures are calculated to have been between 26 to 35 °C. Smithsonite precipitation was favored by near-neutral conditions typical of carbonate terranes, whereas hemimorphite precipitated by reaction with wallrock silica and locally, or episodically, more acidic conditions resulting from sulfide oxidation. Transition to, and stabilization of, the modern desert climate over the past 9000 years from the Late Pleistocene wetter, cooler climate of northern Mexico resulted in episodic drawdown of the water table and termination of local supergene metal mobilization. [ABSTRACT FROM AUTHOR]

Low altitude coastal lakes along the Antarctic margin often contain both marine and lacustrine sediments as a result of relative sea level changes due to deglaciation. The sediments also record changes in regional climate. A sediment core from a coastal lake in Larsemann Hills, East Antarctica, viz. Stepped Lake (Heart Lake), records distinct changes in C, N, C/Natomic ratio, δ 13COM, δ 15NOM and diatom abundance during the mid-Holocene (8.3 to 4.6 kyr BP). Lower values (Corg ~1%; C/N 8, 13COM ~ -18‰) during the early Holocene (8.3-4 kyr BP) are consistent with marine conditions, while higher values [Corg 6%; C/N 12; 13COM ~ -12‰) suggest a shift to lacustrine conditions (5.5-4.6 kyr BP). The diatom community shows similar shift with the major part of Holocene (8.3-5.5 kyr BP) dominated by sea-ice and open-ocean diatoms while the core-top sections (5.5-4.6 kyr BP) transitions to lacustrine diatoms (Stauroforma inermis). These observations confirm that the basin was marine, and later became isolated as a result of postglacial isostatic uplift after 4.7 kyr BP. [ABSTRACT FROM AUTHOR]

The eastern coast of Fuerteventura (Canary Islands, Spain) hosts the most complete and representative emergent Holocene marine deposits in the middle latitudes (27°N to 30°N) of the eastern Atlantic Ocean. The deposits consist of berms of gravel and foreshore sands which form beach rocks comprising >62 bed sets, with each bed set containing dozens of individual laminations suggesting a cyclical cause as, for example, the orbital movement of the Earth. Calibrated radiocarbon ages place a group of older Holocene highstands of Fuerteventura at around the Mid-Late Holocene boundary (around 4.2 kyr B.P.), and another group of more recent highstands in the Dark Age Period (around 1.4 kyr B.P.) of the Northern Hemisphere. They have been recorded at 4 m and 3.5 m apmsl respectively. The present-day tidal amplitude is around 3 m. Assuming a similar value for the Holocene, the corresponding relative sea level rises were around 2.5 m and 2 m apmsl respectively. Moreover, terrestrial deposits intercalated between the marine deposits indicate a lowering of the sea level at ca. 3 kyr B.P. When the sea levels reached their highstands during these two periods, the sea surface temperatures (SST) at the southern tip of the cold Canary Current were, respectively, 0.5 and 1.5 °C colder than the present-day SST (21.23 °C). The fossil fauna content confirms that these highstands occurred in cold conditions. In contrast, the present SST reaches the range of temperatures of the Holocene Optimum in the area. Fuerteventura has been vertically stable since the last interglacial period, and the sedimentology of the deposits precludes an origin from tsunamis or storms. This island is in a far-field region in terms of glacial isostatic adjustment (GIA) processes. Here, we suggest that the deposits may be related to GIA and ice mass losses effects in the Southern Hemisphere. [ABSTRACT FROM AUTHOR]

The abundance of the southern Pacific mollusk loco (Concholepas concholepas), among other conspicuous marine supplies, are often cited as critical resources behind the long-term cultural and demographic fluctuations of prehistoric hunter-gatherers in the coastal Atacama Desert. These societies inhabited one of the world's most productive marine environments flanked by one the world's driest deserts. Both of these environments have witnessed significant ecological variation since people first colonized them at the end of the Pleistocene (c. 13,000 cal yr BP). Here, we examine the relationship between the relative abundance of shellfish (a staple resource) along a 9,500-year sequence of archeological shell midden accumulations at Caleta (a small inlet or cove) Vitor, with past demographic trends (established via summed probability distributions of radiocarbon ages) and technological innovations together with paleoceanographic data on past primary productivity. We find that shellfish extraction varied considerably from one cultural period to the next in terms of the number of species and their abundance, with diversity increasing during periods of regionally decreased productivity. Such shifts in consumption patterns are considered community based management decisions, and for the most part they were synchronous with large and unusual regional demographic fluctuations experienced by prehistoric coastal societies in northern Chile. When taken together with their technological innovations, our data illustrates how these human groups tailored their socio-cultural patterns to what were often abrupt and prolonged environmental changes throughout the Holocene.

Perennial ice deposits in caves represent unique, but underexplored, terrestrial sequences that potentially contain outstanding palaeoclimatic records. Here, we present a pioneer palaeoenvironmental study of an ice deposit preserved in a small sag-type cave (A294) in the Central Pyrenees (northern Iberian Peninsula). The 9.25-m-thick sequence, which is dated from 6100 ± 107 to 1888 ± 64 cal BP, represents the oldest known firn ice record worldwide. The stratigraphy (detrital layers, unconformities, and cross stratification), plant macrofossils, and isotopic signature (similarity between the ice linear distribution, δ 2 H = 7.83 δ 18 O + 8.4 , and the Global Meteoric Water Line) of the ice point to the diagenesis of snow introduced to the cave by winter snowstorms. Four phases of rapid ice accumulation (6100–5515, 4945–4250, 3810–3155, and 2450–1890 cal BP) are related to wetter and colder winters. Comparison of the isotopic composition ( δ 18 O and deuterium excess) of the ice with other paleoclimate records show that both source effects and the North Atlantic Oscillation (NAO) mechanism exert a dominant influence on the ice cave record. The NAO signal may be a combination of source effects and rainfall amount. Three intervals with low ice accumulation occurred between the phases of rapid accumulation and were related to drier, and possibly warmer, winters. These centennial-scale episodes appear to be in-phase with regional arid events, as established from high altitude lacustrine records and can be correlated to global Rapid Climate Change events. The current warming trend has dramatically decreased the volume of the ice deposit in cave A294. [ABSTRACT FROM AUTHOR]

Understanding changes in Holocene erosion is essential for predicting soil erosion in the future. However, the quantitative response of natural erosion to Holocene climate change is limited for the Loess Plateau of China. In this study, two soil profiles were investigated on the Luochuan and Yanchang sites in the central Loess Plateau of China; and four climate indicators, i.e. magnetic susceptibility, calcium carbonate content, total organic carbon content, and clay content (< 0.005 mm), were analyzed to describe climate change. The equations fitted using modern pedogenic susceptibility, precipitation, and temperature were used to quantitatively reconstruct paleoprecipitation and paleotemperature in the Holocene. The current relationship between soil erosion intensity and precipitation was determined and used to estimate historical erosion. Results indicated that climate was coldest and driest between 12,000 and 8500 cal. yr BP, and became warmer and wetter during 8500 to 5500 cal. yr BP. The warmest and wettest climate was from 5500 to 3000 cal. yr BP and was getting colder and dryer over the last 3000 years. Holocene erosion intensity changed with fluctuation of mean annual precipitation, and these changes were different on both sites. The peak erosion values were 20,966 t·km − 2 ·yr − 1 in 7500 cal. yr BP and 21,148 t·km − 2 ·yr − 1 in 3300 cal. yr BP on the Luochuan and Yanchang sites, respectively. Furthermore, more severe soil erosion with a faster increase was estimated on the Yanchang site than Luochuan site with a range between 6547 and 11,177 t·km − 2 ·yr − 1 during the last 1800 years. This study proposed a new method to quantify historical soil erosion triggered by climate change, which not only can derive detailed soil erosion intensity change with variation of climate, but also provide a way to compare soil losses between different areas. [ABSTRACT FROM AUTHOR]

Lipid biomarkers extracted from a sediment-peat sequence from the Sanjiang Plain were analyzed to assess the change in regional vegetation and climate during the last 8 ky. The combination of n- alkane and n- alkanoic acid distributions and published pollen and plant macrofossil records for the lake sediments underlying the peat reveal that the region experienced a warmer and wetter period before ca. 6 ka that corresponds to the monsoon maximum and Holocene climate optimum in northeast China. The climate then entered a cold and wet period from 6 to 4 ka. A shift to warmer and drier conditions starting 4 ka is recorded as a transformation from a shallow lake to a peat deposit. From 1.5 to 0.4 ka, the region entered a cold and wet period that was followed by warm and dry conditions for the most recent 0.4 ky. Our lipid-based paleoclimate reconstruction was compared with Holocene reconstructions based on lipid records from the nearby Hani peat sequence, peat cellulose δ 13 C results from the Jinchuan peat sequence, and pollen records from other lakes in northeast China. Most of the regional paleoclimate changes reconstructed from the lipid proxies in the Sanjiang Plain peat sequence have a strong link with sea surface temperature changes in the Sea of Japan that were influenced by summer solar insolation at 65°N and the East Asia summer monsoon. In contrast, the change to the warmer and drier conditions of the last four centuries seems to be mainly a consequence of human activity. [ABSTRACT FROM AUTHOR]

Two high-altitude lake-sediment sequences (Lake Lia, 1910 m a.s.l. and Lake Bucura, 2040 m a.s.l.) from the Retezat Mountains (South Carpathians, Romania) were analysed using multi-proxy methods to study responses of treeline, timberline and alpine/subalpine vegetation to climate change and human impact during the past 16,000 years. Woody species (Pinus mugo, Pinus cembra, Picea abies and Juniperus communis) reached Lake Lia between 12,000 and 11,800 cal. yr BP, whereas P. mugo colonised the shores of Lake Bucura at 9600 cal. yr BP. Lake Lia was in the timberline ecotone between 8000 and 3200 cal. yr BP, in semi-open P. cembra and Picea abies woodland, probably mixed with P. mugo on the steeper slopes. Lake Bucura was surrounded by the upper part of the krummholz zone during the mid-Holocene. The increase in P. cembra after c. 6000 cal. yr BP around Lake Lia suggests that the composition of the timberline forest changed. The disappearance of P. cembra and Picea abies around Lake Lia at ∼3000 cal. yr BP reflects descent of the timberline. A large mean July temperature decline between 3300 and 2800 cal. yr BP may have driven or at least contributed to the descent of the Picea abies-P. cembra forests. An increase in human indicator pollen types in Lake Bucura around 4200 cal. yr BP may reflect human impact in the naturally open alpine zone in the Late Bronze Age. In contrast, human impact likely appeared considerably later, around 2650 cal. yr BP (Early Iron Age) around Lake Lia in the upper subalpine zone. Human impact likely intensified after 2200 cal. yr BP at both sites that resulted in the lowering of the krummholz zone. We conclude that climate change and human impact both played an important role in the lowering of the treeline and timberline in the late-Holocene. [ABSTRACT FROM AUTHOR]

D/H ratios of leaf lipids from lacustrine aquatic macrophytes have been shown to record precipitation δD values, which can reflect precipitation-weighted mean annual temperature (MAT) in the northeastern United States. Here we report a high-resolution hydrogen isotopic record from Little Pond, Massachusetts, USA, which we compare with other paleoclimate data from the region, including a similar δD record from Blood Pond, Massachusetts. Together the two datasets provide a >16 ka record of δD variability in the region, affording new insights into Holocene climate history. First, the long-term trends in δD correlate significantly with regional temperatures inferred from alkenone records from nearby areas of the North Atlantic and lake-level inferred changes in precipitation and evaporation. The long-term δD trends reflect a period of maximum regional warmth at ca. 8–6 ka after the collapse of the Laurentide Ice Sheet. Second, unlike the positive relationship between temperature and δD observed over the long-term and during early events like the Younger Dryas, we find that a series of warm and dry events at 4.9–4.6, 4.2–3.9, 2.9–2.1, and 1.3–1.2 cal kya BP coincide with negative δD excursions from the long trends. These events were likely driven by summer drought dynamics. [ABSTRACT FROM AUTHOR]

The southern Kerala coast in SW India has experienced dramatic changes in climate and sea level during Holocene. These changes are apparently well preserved in the sedimentary archives of the estuarine basins that are entrenched on the uplifted Neogene deposits. Here we report the sedimentary processes, palaeoclimate and sea level records decoded from two borehole cores – Puthenthuruthu and Munrothuruthu borehole cores – retrieved respectively from the marine and fluvial ends of the second largest estuarine basin in SW India, the Ashtamudi estuary, using sedimentology, palynology and stable isotopes as the major proxies. The heavy rainfall event at the latter half of Early Holocene (6117 ± 101 BP) is reflected well in the isotopic signatures of the Puthenthuruthu borehole core. The higher level of lighter isotopes of oxygen and carbon at 10–15 m below ground level is a clear indication of freshwater influx from the hinterland due to intensified monsoon activity. This, in turn, was responsible for the development of Bay Head Delta in the fluvial end of the estuary during Early–Middle Holocene period. Palynological contents below the level indicate a facies change as freshwater and terrestrial elements dominate over marine contents. Further, the occurrence of desmids shows the marine facies is being gradually replaced by freshwater to continental facies. This was followed by the deposition of littoral sands as Flood Tide Islands within the estuarine basin. The palynological investigations of sediments with radiocarbon age of 4350 ± 90 BP in the Munrothuruthu borehole core show a dry phase with high saline depositional environment in the beginning which is followed by influx of freshwater as indicated by the higher content of lighter isotopes of carbon and oxygen in the calcareous nodules (algal pisolites) embedded in the sediments. The occurrence of pteridophytic spores and a few pollen of Cullenia in the palynological preparations in the upper half of the silt and clay dominated intervening layers reiterate this view. [ABSTRACT FROM AUTHOR]

Understanding the response of ecosystems to past climate is critical for evaluating the impacts of future climate changes. A large-scale abrupt shift of vegetation in response to the Holocene gradual climate changes has been well documented for the Sahara-Sahel ecosystem. Whether such a non-linear response is of universal significance remains to be further addressed. Here, we examine the vegetation-climate relationships in central Asia based on a compilation of 38 high-quality pollen records. The results show that the Holocene vegetation experienced two major abrupt shifts, one in the early Holocene (Shift I, establishing shift) and another in the late Holocene (Shift II, collapsing shift), while the mid-Holocene vegetation remained rather stable. The timings of these shifts in different regions are asynchronous, which are not readily linkable with any known abrupt climate shifts, but are highly correlated with the local rainfalls. These new findings suggest that the observed vegetation shifts are attributable to the threshold effects of the orbital-induced gradual climate changes. During the early Holocene, the orbital-induced precipitation increase would have first reached the threshold for vegetation 'establishment' for moister areas, but significantly later for drier areas. In contrast, the orbital-induced precipitation decrease during the late Holocene would have first reached the threshold, and led to the vegetation 'collapse' for drier areas, but delayed for moister areas. The well-known 4.2 kyr BP drought event and human intervention would have also helped the vegetation collapses at some sites. These interpretations are strongly supported by our surface pollen-climate analyses and ecosystem simulations. These results also imply that future climate changes may cause abrupt changes in the dry ecosystem once the threshold is reached. [ABSTRACT FROM AUTHOR]