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The paper deals with an overview of early anthropogenic impact on the landscapes of the southeastern Baltic region and is based on the results of palaeolimnological and archaeological studies carried out on the Vishtynets Upland, Kaliningrad oblast, Russian Federation. The detailed study of available palynological (including microcharcoal), geochemical and archaeological data has revealed possible signs of anthropogenic impact on the landscape from the Early Mesolithic to the Middle Ages, while the results of lithological, geochronological and diatom analyses provided a basis for a better understanding of natural processes. Palynological data have shown that the first signs of human impact on landscapes date back to the Early Mesolithic (approximately from 10,000 cal yr. BP), indicating the existence of local deforested areas. The presence of pollen from plantindicators of open habitats and pastures, as well as Pteridium and Corylus , combined with elevated Ba and Sr values as indicators of burning, suggests the deliberate burning of forests for the enhancement of hunting and mobility, as well as for the propagation of edible plants. The correlation of microcharcoal and pollen data has revealed several peaks of human activity in the Neolithic and showed that cultivation of Cerealia on the Vishtynets Upland began during this period (5120 - 4000 cal yr. BP). The first signs of metallurgy in the region emerged in the period 4500–3000 cal yr. BP (the late Neolithic – the Bronze Age) and are indicated by the simultaneous growth of V, Pb, Ni, Zn, As, Fe 2 O 3 and microcharcoal curves. [ABSTRACT FROM AUTHOR]

Although there is a long history of palaeoecological investigation in the Massif Central, detailed reconstruction of the flora, vegetation, and environment in the Late Pleniglacial, the Würmian (Weichselian) Late-Glacial, and early Holocene in the Monts du Forez (Massif Central, France) is still largely lacking. We inferred the palaeoecology of the area from pollen, spores, and plant macrofossils preserved in the sediments of the palaeolake Gourds des Aillères (1335 m a.s.l.). The lake formed in a glacial depression left by retreating glaciers at the start of the Bølling period, ca. 14700 cal yr BP. Sediment chronology is based on radiocarbon dating and correlation with other, radiocarbon-dated palynological records from the Monts du Forez. Changes in the regional and local vegetation during the Late-Glacial and early Holocene could be correlated to the major climatic events identified in the Greenland oxygen isotope records. We made a highly detailed reconstruction of the changes in the floral diversity and vegetation in and around the lake. After the steppe-tundra of the Late Pleniglacial, local vegetation cover increased and developed into shrub tundra with a few trees forming the tree line in the Bølling and Allerød, with a short reversion during the Older Dryas. During the Younger Dryas trees were eliminated around the site and vegetation was reduced in diversity and density. In the early Holocene, birch (Betula) woodland with some pine (Pinus) developed and was then replaced by mixed oak woodlands with Corylus. The forest limit rose above the lake. Changes in the lake ecosystem, lake-levels, and nutrient availability were also reconstructed. Hydroseral overgrowth of the lake to a Sphagnum peatbog took >6000 years. [ABSTRACT FROM AUTHOR]

Lentic waterbodies provide terrestrial sedimentary archives of palaeoenvironmental change in deglaciated areas of the Antarctic. Knowledge of the long-term evolution of Antarctic palaeoenvironments affords important context to the current marked impacts of climate change in the Polar regions. Here, we present a comprehensively dated, multi-proxy sedimentary record from Monolith Lake, a distal proglacial lake in one of the largest ice-free areas of the Antarctic Peninsula region. Of the two defined sedimentary units in the cores studied, the lower Unit 1 exhibits a homogeneous composition and unvarying proxy data profiles, suggesting rapid clastic deposition under uniform, ice-proximal conditions with a sedimentation rate of ∼1 mm yr−1. 14C and optically stimulated luminescence (OSL) dating bracket the deposition interval to 1.5–2.5 ka BP, with the older age being more probable when compared to independent dating of the local deglaciation. The uppermost 11 cm of the record spans the last ∼2.2 ka BP (maximum age), suggesting a markedly decreased sedimentation rate of ∼0.05 mm yr−1 within Unit 2. Whereas Unit 1 shows only scarce evidence of biological activity, Unit 2 provides an uninterrupted record of diatoms (with 29 species recorded) and faunal subfossils, including the fairy shrimp Branchinecta gaini. Concentrations of organically-derived elements, as well as diatoms and faunal remains, are consistent, implying a gradual increase in lake productivity. These results provide an example of long-term Antarctic 'greening' (i.e. increasing organic productivity in terrestrial habitats) from a palaeolimnological perspective. The boundary between Units 1 and 2, therefore, marks the timing of local deglaciation at the final stages of a period of negative glacier mass balance, i.e. the Mid-Late Holocene Hypsithermal. Subsequent Neoglacial cooling is evidenced by the abated influence of glacial meltwater streams and turbidity decline linked to reduced glacier runoff, although most proxy responses mirror the natural proglacial lake ontogeny. • Antarctic lake sediments record rapid deglaciation ∼2.5 ka ago and subsequent lake ontogeny. • Portable optically stimulated luminescence (pOSL) enhanced absolute OSL and 14C dating. • For the last ∼2.2 ka, biodiversity hotspot persisted despite the Neoglacial cooling. • Fairy shrimp Branchinecta gaini did not become extinct on James Ross Island. • We present an example of long-term Antarctic greening from a palaeolimnological perspective. [ABSTRACT FROM AUTHOR]

Lake Neusiedl, the largest steppe lake in Europe, is particularly sensitive to climate variations due to its extreme shallowness (z max = 1.8 m) and low ratio of catchment to lake area (3.5 : 1). Changes in water budget, salinity and turbidity have key implications for the lake's ecology and management. Here, we present a multi-proxy palaeolimnological reconstruction of the evolution of Lake Neusiedl since the end of its last complete desiccation (1865–1868), based on an undisturbed radiometrically dated core taken from the open water portion of the lake. Geochemical and biological (algal) proxies outline the succession of three major ecological stages since 1873 ± 16 yrs, with the first major changes appearing already in the 1930s as driven by climate related hydrological variability. Subfossil diatoms proved to be reliable for tracking long-term changes in the trophic conditions of Lake Neusiedl while diatom-inferred lake conductivity revealed to be unreliable due to a combination of lake environmental settings and the absence of a site-specific training set. Nonetheless, multivariate statistical analyses and comparisons with limnological data confirm a great potential of subfossil diatoms for revealing past ecological changes and tipping points of shallow lakes, as long as studies rely on a multi-proxy approach. In agreement with limnological surveys, the sediment record corroborates the high vulnerability of Lake Neusiedl, both in present and past times, towards climate-driven changes in water level and salinity, and allows the prediction, by analogy with the past, of future ecological changes in a context of global warming and increasing nutrient inputs from non-point sources. [ABSTRACT FROM AUTHOR]

The South Kenya Rift is comprised of a series of N-S-oriented grabens with sediments that preserve an approximate one-million-year environmental history that reflects the interplay of climate, tectonism and volcanism. This study attempts to disentangle the relative roles of these major controls by comparing the geochemical records preserved in three sedimentary basins. The study focuses on the Koora Basin using bulk geochemical data in a 139-m-long core. This record is then compared with geochemical data and environmental histories from a 196-m-long core at Magadi and outcrops in the Olorgesailie Basin. Four climatic phases (1000–850; 850–470; 470–400; 400–0 ka) are recognised at Koora, which can also be distinguished in the Magadi and Olorgesailie Basins. However, inter-basin contrasts also suggest that additional, non-climatic factors influenced these geochemical histories, particularly during four intervals. These include 1) the Magadi Transition (MT; ∼770–700 ka), 2) the Magadi Tectonic Event (MTE; ∼540 ka), 3) the Koora Instability Period (KIP; ∼325–180 ka), and 4) the Trona Precipitation Period (TPP; ∼105–0 ka). Prior to the MT, Zr/TiO 2 , La/Lu, Mo, As, V and Na/Ca in Magadi and Koora cores were similar but afterwards diverged. Major reductions in transition metals at Magadi during the MTE reflect tectonically-induced cross-rift drainage diversion. This contrasts with the Koora and Olorgesailie basins where these metals were constant from ∼1000 to 300 ka. The KIP represents a significant increase in volcanic inputs to the Koora Basin and increased geochemical variability. Bromine (Br), which reflects peralkaline volcanic activity and/or evaporative concentration, is elevated during the KIP at Koora but is below detection limits in the rest of the Koora core. Br in the Magadi core does not correlate with that in the Koora record, suggesting contrasting accumulation processes. The TPP represents a phase of trona precipitation at Magadi but not at Koora. This difference partly reflects increased magmatic CO 2 rising along faults in the Magadi basin during a period of increasing aridity. Rare-earth element patterns indicate a major change at Magadi with many anomalies after about 325 ka to the present, caused by the development of hypersaline waters, which did not occur at Koora or Olorgesailie. The geochemical data from the three basins help to partially separate climatic controls from those related to volcanism, tectonism and local geomorphology. • Lake level changes in South Kenya Rift basins show only partial correlations with global glacial-interglacial cycles. • Geochemical and mineralogical contrasts between basins reflect four local and regional tectono-volcanic events • Bromine concentrations indicate volcanic sources and evaporative concentration • Rare earth elements anomalies reflect trachytic and basaltic source rocks and the impact of high lake alkalinities • Trona deposition reflects the combined effect of increasing aridity and magmatic CO 2 inputs • Transition metal stratigraphies reflect drainage diversions caused by faulting [ABSTRACT FROM AUTHOR]

• Historical cyanobacteria abundance and composition studies in two contrasting lakes. • Picocyanobacteria dominant prior to European settlement (∼1840 CE). • Bloom forming cyanobacteria appeared first in smaller shallower lake. • Bloom forming cyanobacteria now abundant in both lakes. • Nutrients are the most likely cause of the onset and intensification of the blooms. Cyanobacterial blooms are one of the most significant threats to global water security and freshwater biodiversity. Interactions among multiple stressors, including habitat degradation, species invasions, increased nutrient runoff, and climate change, are key drivers. However, assessing the role of anthropogenic activity on the onset of cyanobacterial blooms and exploring response variation amongst lakes of varying size and depth is usually limited by lack of historical records. In the present study we applied molecular, paleolimnological (trace metal, Itrax-µ-XRF and hyperspectral scanning, chronology), paleobotanical (pollen) and historical data to reconstruct cyanobacterial abundance and community composition and anthropogenic impacts in two dune lakes over a period of up to 1200 years. Metabarcoding and droplet digital PCR results showed very low levels of picocyanobacteria present in the lakes prior to about CE 1854 (1839–1870 CE) in the smaller shallow Lake Alice and CE 1970 (1963–1875 CE) in the larger deeper Lake Wiritoa. Hereafter bloom-forming cyanobacteria were detected and increased notably in abundance post CE 1984 (1982–1985 CE) in Lake Alice and CE 1997 (1990–2007 CE) in Lake Wiritoa. Currently, the magnitude of blooms is more pronounced in Lake Wiritoa, potentially attributable to hypoxia-induced release of phosphorus from sediment, introducing an additional source of nutrients. Generalized linear modelling was used to investigate the contribution of nutrients (proxy = bacterial functions), temperature, redox conditions (Mn:Fe), and erosion (Ti:Inc) in driving the abundance of cyanobacteria (ddPCR). In Lake Alice nutrients and erosion had a statistically significant effect, while in Lake Wiritoa nutrients and redox conditions were significant. [ABSTRACT FROM AUTHOR]

The interpretations of late Quaternary climate variation in the Kalahari are controversial. Only few speleothem humidity records do exist and reconstruction of aridity periods using aeolian sediments is challenged by considerable dating uncertainties. On the other hand studies on the large structural lake basins of the Kalahari have to cope with tectonics and the active catchment being far in the north, in a different climate zone. Thus hydrological signals from such palaeolakes may not or only partly reflect Kalahari palaeoclimate. The sediments of a regional drainage basin, west of the Tsodilo Hills, northern Kalahari, archive hydrological signals not superimposed by remote river catchment and tectonics. A ca. 3 m thick sediment profile near the palaeoshore of the former lake exhibits two lake highstands dated to MIS 3b and LGM. Geomorphological studies, fossil aquatic assemblages, their comparison to modern analogues and geochemical analyses, including sclerochronological stable isotope patterns from gastropod shells, suggest relatively deep, freshwater to oligohaline, open-basin lake periods. The data indicates that the climate was more humid than today, with two intra-annual rainfall maxima during the LGM, but likely under temperature regimes similar to modern times. The lake highstands were probably in phase with an inter-hemispheric Atlantic climate seesaw, which may imply that the main moisture source was rather the southern Atlantic than the Indian Ocean. [ABSTRACT FROM AUTHOR]

Lacustrine systems are complex and highly sensitive in responding to allogenic factors like tectonics, climate and volcanism but also present within lake processes that are difficult to disentangle. The Agua de la Zorra Formation (Middle–Upper Triassic) outcropping in the Paramillos de Uspallata sub-basin, Cuyana rift Basin (SW Gondwana), is composed of deltaic–fluvial–lacustrine–volcaniclastic deposits. The lacustrine system presents carbonate deposits, as almost every other sub-basin within the Cuyana rift. This makes it an exceptional case for analysing limnogeological questions in an extensional tectonic regime linked to volcanism (basalt flow and tuff deposits) and studying lacustrine carbonate in that particular setting. This study focuses on a high-resolution stratigraphic, sedimentologic, petrographic and limnogeological investigation of the Agua de la Zorra depositional system to understand its evolution through space and time; and to reconstruct the development of the carbonate factory within the palaeolake. Stratigraphic correlation of five sedimentary logs across the sub-basin allowed the identification of a deltaic–lacustrine facies association and a progradational–retrogradational stacking pattern interpreting the palaeolake as an overfilled lake basin type. Five facies associations represent a delta front, prodelta, lake margin, lake centre and volcanic episodes. The stratigraphic analysis allowed interpreting that volcanic episodes were diachronous during the evolution of the Agua de la Zorra system; the development of a well-established axial fluvial system upsection and the coeval migration of the highest accommodation point and lake centre northwards. Carbonate deposits are part of the lake margin subenvironment and immediately overlie volcanic basalts and are laterally linked to altered sandstones in contact with basalts. Their microfabric is characterised by fibro-radial spar mosaics and laminated carbonate, interpreted as inorganic authigenic calcite precipitation. This and their restricted extent support that alkaline lava flows in contact with the palaeolake water column triggered carbonate precipitation. Stratigraphic, sedimentologic, limnogeological and petrographic analyses strongly support volcanism and tectonics as the main allogenic factors controlling the Agua de La Zorra lacustrine system evolution. [Display omitted] • The Agua de la Zorra Formation (Middle–Upper Triassic) presents lacustrine carbonates. • The carbonate factory shows fibro-radial spar mosaic and laminated carbonates. • The Triassic alkaline volcanism triggered the precipitation of the carbonates. • Tectonics controlled the northwards migration of accommodation in the lake basin. • The stratigraphic trend shows development of a N–S axial fluvial system. [ABSTRACT FROM AUTHOR]

Herein, the late Quaternary charophyte flora from the Pheneos palaeolake in north Peloponnese (Greece) is examined for the first time. The Pheneos palaeolake was located in the south region of the Pheneos polje, where late Quaternary relict shoreline segments are still preserved. These shorelines correspond to the fluctuation of the water level at different periods reflecting the polje's successive flooding and draining. Sediment sampling was conducted at 4 levels representing ancient shorelines of the lake. Up to five charophyte taxa have been identified and illustrated based on parautochtonous oospores and gyrogonites i.e., Nitella cf. hyalina , Sphaerochara prolifera , Chara vulgaris , Chara sp. and Nitellopsis obtusa. The distribution of the flora within the four studied levels allows the distinction of three different palaeoenvironmental conditions that prevailed at the paleolake´s margins during the late Quaternary. The occurrence of S. prolifera in the lowest elevation level indicates the prevalence of ephemeral annual flooding conditions of the lake´s margin. N. obtusa has been recovered from both the lowest and the upper lowest levels reflecting permanent, oligohaline, oligotrophic, and cold-water conditions. Chara vulgaris and Chara sp. are present in the uppermost two levels reflecting less permanent and oligotrophic conditions. The distribution of the charophyte flora in the Pheneos palaeolake suggests major changes in the palaeoecological conditions of the lake ranging from permanent, cold and oligotrophic to ephemeral and more eutrophic. • Five charophyte taxa described in the late Quaternary Pheneos palaeolake. • New records of the endangered Nitella hyalina and Nitellopsis obtusa. • Surface palaeoshoreline sampling to identify the Pheneos polje evolution. • Τhe palaeolake changed from deep, cold and oligotrophic to warmer and eutrophic. [ABSTRACT FROM AUTHOR]

Differentiating thermokarst basin sediments with respect to the involved processes and environmental conditions is an important tool to understand permafrost landscape dynamics and scenarios and future trajectories in a warming Arctic and Subarctic. Thermokarst basin deposits have complex sedimentary structures due to the variability of Yedoma source sediments, reworking during the Late Glacial to Holocene climate changes, and different stages of thermokarst history. Here we reconstruct the dynamic growth of thermokarst lakes and basins and related changes of depositional conditions preserved in sediment sequences using a combination of biogeochemical data and robust grain-size endmember analysis (rEMMA). This multi-proxy approach is used on 10 sediment cores (each 300–400 cm deep) from two key thermokarst sites to distinguish four time slices that describe the Holocene thermokarst (lake) basin evolution in Central Yakutia (CY). Biogeochemical proxies and rEMMA reveal fine-grained sedimentation with rather high lake levels and/or reducing conditions, and coarse-grained sedimentation with rather shallow lake levels and/or oxidizing (i.e. terrestrial) conditions in relation to distal and proximal depositional and post-sedimentary conditions. Statistical analysis suggests that the biogeochemical parameters are almost independent of thermokarst deposit sedimentology. Thus, the biogeochemical parameters are considered as signals of secondary (post-sedimentary) reworking. The rEMMA results are clearly reflecting grain-size variations and depositional conditions. This indicates small-scale varying depositional environments, frequently changing lake levels, and predominantly lateral expansion at the edges of rapidly growing small thermokarst lakes and basins. These small bodies finally coalesced, forming the large thermokarst basins we see today in CY. Considering previous paleoenvironmental reconstructions in Siberia, we show the initiation of thaw and subsidence during the Late Glacial to Holocene transition between about 11 and 9 cal kyrs BP, intensive and extensive thermokarst activity for the Holocene Thermal Maximum (HTM) at about 7 to 5 cal kyrs BP, severely fluctuating water levels and further lateral basin growth between 3.5 cal kyrs BP and 1.5 cal kyrs BP, and the cessation of thermokarst activity and extensive frost-induced processes (i.e. permafrost aggradation) after about 1.5 cal kyrs BP. However, gradual permafrost warming over recent decades, in addition to human impacts, has led to renewed high rates of subsidence and abrupt, rapid CY thermokarst processes. • Small thermokarst lakes and basins grew rapidly during the Holocene Thermal Maximum. • Short-term phases of forcing climate lead to very active thermokarst processes. • Endmember analysis reveals different depositional environments in growing lakes. • Distal and proximal depositional and post-sedimentary conditions are differentiated. • Sedimentological and biogeochemical characteristics are weakly correlated. [ABSTRACT FROM AUTHOR]

Lacustrine sediments generally record landscape development in the lake's catchment area controlled by palaeoclimatic and human induced changes. To improve our understanding on the anthropogenic and climatic influences on landscape development in Southern Greece for the last 2500 years, we report a 2 m-long, continuous high-resolution sedimentary record from shallow Lake Stymphalia (Peloponnese, Greece). Our proxies record climatically as well as anthropogenically induced landscape changes, influencing the lake area and lake depth. The Classical-Hellenistic era reflects a moderate, stable Mediterranean climate with low sedimentation rates. The parallel existence of the highly populated, major ancient city of Stymphalos, on the contemporary lake edge, doesn't seem to have caused lasting alterations in the record. The construction of the Hadrianic Aqueduct in the Roman era, ca. 130 AD, however causes an influential transformation in the lake development. It has a lasting effect on the lake hydrology as well as the vulnerability of this ecosystem. During Late Roman times, 5th to 6th century cal AD, the abandonment of the aqueduct combined with cooler climate conditions allows lake levels to recover. A phase of very high climatic instability was identified for the subsequent Early Byzantine (EB) period, during the 7th and 8th century cal AD. For this period, the later phase of the Late Antique Little Ice Age (LALIA), our proxies indicate further cooling and highly fluctuating water availability in a rather small lake area. The Middle Byzantine (MB) Period (9th-12th century AD) is characterized by an over fivefold increase in sedimentation rates. Since local population was still well below Classical levels, we explain this singular period through an interaction of modest increase in land use but marked by careless management of deforested areas, warm and wet climatic conditions during the Medieval Warm Period and long-term effects of vulnerability caused by the aqueduct construction. Probably during this phase, the lake level rose through unparalleled sedimentary infill to flood and bury a significant part of the Lower Town of the abandoned ancient city. The Late Byzantine Period (13th and 14th century AD) sees core evidence for erosion of established, non-vegetated soils (high magnetic susceptibility), in a period of almost total depopulation. In the subsequent Ottoman era (late 15th – early 19th centuries AD) local settlement made only slight recovery, the climatic conditions seem less stable during the Little Ice Age (LIA) and the lake seasonally and later periodically starts to dry up, cumulating in a longer dry phase at the end of the 19th century AD, when agricultural activity on the polje floor was possible. The conclusion conforms with recent modelling of environmental change, critical of mono-causation, rather focussing on complex interactions of human and natural factors in the inception of landscape transformation. [ABSTRACT FROM AUTHOR]

Abstract Proxy records of past climate change spanning beyond the radiocarbon range commonly derive their chronologies from orbital tuning strategies, thus bounding our spatio-temporal reconstructions to a priori assumptions that can not be directly tested. Here we present a tephrochronologically constrained framework of past environmental and climatic changes in the central Mediterranean region during the last ca. 190 ka. Our research is based on a high-resolution, multi-proxy study of a sedimentary record (cores F1-F3) retrieved from the Fucino Basin lacustrine succession, central Italy, in 2015. We update the existing tephrostratigraphic framework of the F1-F3 record with the finding of the widespread Campanian Ignimbrite tephra marker layer and produce a robust and independent chronology based on new and published 40Ar/39Ar and 14C dating of 17 tephra layers. Observed palaeoenvironmental changes are tracked in other lacustrine, marine and speleothem records across the Mediterranean and North Atlantic regions via tephrostratigraphic correlations and chronological matching providing a robust assessment of age uncertainties. Results show a complex interplay between local environmental changes and broad-scale climatic processes highlighting a strong orbital forcing on glacial-interglacial changes. Along with these major changes we detect prominent millennial-scale variability. During times of intermediate global ice volumes, Mediterranean mountain ecosystems oscillated around an "interglacial" state suggesting that climatic shifts, although large, did not exceed the local environmental tolerance-resilience threshold. Conversely, during periods of large global ice volume, we observe subdued millennial-scale variability with ecosystems operating in a strictly ruled glacial environment. Highlights • Palaeoenvironmental record of the last 190 ka. • Independent tephrochronology. • Orbital and sub-orbital scale variability. [ABSTRACT FROM AUTHOR]

Abstract Understanding the long-term environmental forcings driving Caspian Sea (CS) water levels is of utmost importance, not only owing to its large size, or to the surrounding developing economies but also to improve global climate models and forecasts. However, Late Quaternary CS level changes and their amplitude are mostly documented from incomplete coastal sediment records. Because of the CS idiosyncrasies, that behaves neither as a sea nor as a lake, the methods used to reconstruct water levels in the global ocean or in freshwater lakes do not always apply. Here, we propose a first step toward the use of dinoflagellate cysts records to reconstruct qualitative changes in water mass, focusing on new and published deep-water sedimentary sequences from the south and middle CS basins. Trends in water level changes are reconstructed on the relative proportions of dinocyst assemblages with different levels of brackishness. A higher highstand than previously seen is reconstructed post-Mangyshlak lowstand. A reverse water flow gradient from S to N, not previously detected, is identified at 8.5–8 to 4 cal ka BP. A major turnover in dinocyst assemblage is found at 4 cal ka BP. While the Volga River is the main source of water nowadays, we propose that the source of water to maintain the 8.5–8 to 4 cal ka BP highstand is the now-disconnected drainage basin of the Amu-Darya. The CS was at that time most likely strongly influenced by low latitude climates, with more precipitation over the Karakum and, perhaps, even indirect monsoonal influence. Highlights • Dinocysts grouped by salinity, providing long-term water level/flow reconstructions. • Dinocysts show a higher highstand after the Mangyshlak lowstand than previously seen. • A South to North water flow gradient at 8.5–4 cal ka BP, reversed from the current one. • Water level influenced by precipitation over Karakum and perhaps indirectly monsoon. • A major turnover in dinocyst assemblages in all three sequences at c. 4 cal. ka BP. [ABSTRACT FROM AUTHOR]

Abstract The Pannonian Basin of Croatia is the largest back-arc extensional basin on the European continent, located between the Alps, Carpathians and Dinarides. Syn-rift subsidence started at ~18 Ma and predated the onset of the Miocene Climate Optimum (MCO; 17–14.7 Ma). In this paper, we investigate the evolution of the fluvial-lacustrine palaeoenvironment just prior to the transgression of the Central Paratethys Sea. Studies are based on a 17-m-thick section of the Požega palaeolake in the Southern Pannonian Basin using palaeobiological (mollusks, ostracods, palynomorphs, fish otoliths), mineralogical and sedimentological data. Our results reveal fluctuating freshwater and brackish conditions and a pulsating water budget, which we relate to phases in which the basin was, alternatively, hydrologically open and closed. We infer that the alternating environmental conditions can be best-explained by dry and wet periods, respectively. Droughts produced stagnant conditions, algae overproduction and increased salinity levels, supporting the survival of sporadically invading brackish water species. The wet periods, on the other hand, led to lake highstand episodes, expansion of lake area, and to the widespread development of profundal facies. The lake basin eventually became overfilled and connected through outflowing rivers with the Central Paratethys sea. However, the absence of brackish-marine assemblages in the Požega palaeolake nevertheless indicates that there was no marine water inflow from the Central Paratethys at that time. Highlights • Integrative, multiproxy-study on the palaeoenvironmental history of Pannonian Basin palaeolakes predating marine flooding • Effect of the global warming (Miocene Climatic Optimum) on studied lacustrine environment was evaluated. • Depositional history is related to regional climate fluctuations and to the astronomical forcing by insolation periodicity. • Faunal migration patterns and exchange with the Paratethys and Mediterranean basins were evaluated. • New palaeo(bio)geographic scheme for the early middle Miocene time window of Central and NE Europe is proposed. [ABSTRACT FROM AUTHOR]

Abstract Multi-proxy records (pollen, particle size, loss on ignition, C:N ratios and radioisotopes, 210Pb and 137Cs) of natural and anthropogenic environmental change are reported for sediment cores from three lakes in the Songnen Plain of northeastern China. These data provide high-resolution records of vegetation history and catchment dynamics for the region over the past 200 years. Records show that vegetation initially responded to a cooler and drier climate during the Little Ice Age with high values of Pinus , Ephedra and Amaranthaceae and low values of Cyperaceae. As anthropogenic activity increased in northeastern China, Pinus gradually declined while broad-leaved deciduous vegetation increased in the region from 1900 CE. Aquatic taxa also increased from 1900 CE as the wetlands responded to changing lake water levels and agricultural activities. Land policy implementation had a profound impact on the vegetation with arboreal pollen in Keqin and Hongyan lakes declining from 1900 CE as marginal land was reclaimed, and agricultural activities increased. Vegetation diversity increased as agricultural activities caused environmental disturbance, with pollen taxa indicating human disturbance including Humulus , Polygonum and Xanthium. Silt and organic content increased and C:N ratios declined after 1940 CE as erosion in the catchment and productivity in the lakes increased. Re-vegetation strategies introduced in the late 1990s caused an increase in arboreal taxa in the pollen record. This multi-proxy palaeoenvironmental study improves understanding of the long-term relationship between natural and anthropogenic environmental change in northeastern China. Highlights • Pine dominated the original vegetation reflecting the cool, dry climate of the Little Ice Age. • Anthropogenic activity has changed the natural vegetation in northeastern China. • Selective logging and anthropogenic activities removed arboreal taxa. • Forest cover declined and plant diversity increased from 1950 CE. • Climate, agricultural activities and declining arboreal taxa changed aquatic ecosystems. [ABSTRACT FROM AUTHOR]

Abstract Multi-proxy analyses of an 8 m sediment core from Lake Hayk, a closed, freshwater lake in the north-central highlands of Ethiopia, provide a record of changing lake level and inferred regional climatic change for the last 15.6 cal ka years. Between ca. 15.6–15.2 cal ka BP, a lowstand was synchronous with Heinrich Event 1 and an intense drought across Eastern Africa. At ca. 15.2 cal ka BP a lake began to develop at the core site in response to wetter conditions, at the onset of the African Humid Period (AHP). However, in contrast to other lakes in eastern Africa, Hayk lake level fell around ca. 14.8 cal ka BP, indicating a climate shift towards aridity. The lake began filling again at ca. 12.3 cal ka BP and reached maximum water depth between ca. 12.0–10.0 cal ka BP. Lake level declined slowly during the Holocene, culminating in the termination of the AHP at Hayk between ca. 5.2–4.6 cal ka BP. In the late Holocene, ca. 2.2–1.3 cal ka BP, Lake Hayk was again deep and fresh with some evidence of short-term lake level variability. The palaeo-record from Lake Hayk indicates that while it experienced, to a broad degree, the same glacial-interglacial dynamics and sub-millennial shifts in climate found in other palaeolimnological records from eastern Africa, there are offsets in timing and rate of response. These differences reflect chronological discrepancies between records, as well as the varying climate sensitivities and site-specific factors of individual lake basins. This record highlights the different responses by lakes in a climatically vulnerable area of Ethiopia. Highlights • Discrepancies in the timing of the Younger Dryas Stadial proper. • No evidence for the catastrophic shift in climate centred at 8.2 ka. • Diatom evidence suggesting relatively rapid AHP termination. • High-resolution evidence of millennial to multi-decadal variability at Lake Hayk. • Regional discrepancies in the timing and expression of climatic events. [ABSTRACT FROM AUTHOR]

Abstract The transition from the mid-to late-Holocene in MesoAmerica saw increasing complexity in spatial patterns of change. Records from the western part of the region are sparse, with lacustrine sequences affected by long term anthropogenic disturbance or lacking chronological resolution. Here, we present a continuous palaeoecological and geochemical record from Laguna de Juanacatlán, a remote lake in the mountains of the western TMVB. Diatom assemblages, XRF scanning data and bulk organic geochemistry from a well-dated, 7.25-m laminated sequence were combined with summary pollen data from a 9-m partially laminated core to provide a continuous record of catchment and lake ecosystem changes over the last c. 6000 years. Relatively humid conditions prevailed prior to c. 5.1 cal ka, which supported dense oak-pine forest cover around a deep, stratified lake. A trend towards drier conditions began c. 5.1 cal ka, intensifying after 4.0 cal ka, consistent with weakening of the North American Monsoon. Between 3.0 and 1.2 cal ka, lower lake levels and variable catchment run-off are consistent with increasing ENSO influence observed in the Late Holocene in the neotropics. From 1.2 to 0.9 cal ka, a marked change to catchment stability and more intense stratification reflected drier conditions and/or reduced rainfall variability and possibly warmer temperatures. After 0.9 cal ka, conditions were wetter, with an increase in catchment disturbance associated with the combined effects of climate and human activity. In recent decades, the lake ecosystem has changed markedly, possibly in response to recent climate change as well as local catchment dynamics. Highlights • A new palaeoecological and geochemical record from Laguna de Juanacatlán, Mexico. • Onset of drier conditions from 5.1 to 4.0 cal ka with increasing variability from 3.0 cal ka. • Complex response to changes in the relative importance of Pacific and Atlantic forcings over the last 1200 years. • Anthropogenic disturbance is less intense and more recent than other Mexican sites. [ABSTRACT FROM AUTHOR]

Abstract The lakes of the eastern Africa Rift often contain great thicknesses of sediment that may provide continuous records of environmental change over decadal to million-year timescales. However interpretation of these changes is greatly compromised without a reliable chronology. Luminescence dating has not been used extensively in lacustrine settings; instead previous studies have often relied upon radiocarbon dating, using extrapolation beyond the upper limit of that technique, and employing opportunistic sampling of tephra and palaeomagnetic signatures where possible. This study from Lake Tana, Ethiopia, demonstrates that recent advances in luminescence methodology can provide long chronologies for lake sediments that are not dependent on the intermittent presence of dateable material, as is the case for radiocarbon and tephra-based methods. Specifically, this study generates luminescence ages that agree with independent chronology based on radiocarbon dating in the upper part of the core, and extends significantly beyond the range of radiocarbon dating to provide one of the longest independently dated lacustrine sediment records in eastern Africa, thus demonstrating the tremendous potential of luminescence for constructing lacustrine sediment chronologies over 100,000 year timescales. Highlights • Recent advances make it timely to apply luminescence methods to date lake sediments. • Luminescence dating can provide long chronologies throughout lake sediment cores. • The application of luminescence dating to sediments from Lake Tana is discussed. • One of the longest independently dated lake records in eastern Africa. • Demonstrates the contribution luminescence dating can make to lacustrine studies. [ABSTRACT FROM AUTHOR]

Abstract Lake Suigetsu (Japan) is a key site for radiocarbon (14C) calibration and palaeo-environmental reconstruction in East Asia. Here we present a description of the sediment (micro)facies, which in combination with a new approach to varve interpolation allows construction of a revised varve based chronology that extends the previous 2012 varve based chronology by ∼10 ka, back to ∼50 ka BP. Challenges in varve counting and interpolation, which were previously discussed in detail only for the Last Glacial-Interglacial Transition, are described here back to ∼50 ka BP. Furthermore, the relative merits of varve counting by μXRF scanning and by thin-section microscopy are discussed. Facies analysis reveals four facies zones, their transitions driven by both local and climatic controls. The lamination quality of the sediment is highly variable and varve interpolation reveals that in the analysed time interval, on average, only 50% of the annual cycles are represented by seasonal layers. In the remaining years seasonal layers are indistinguishable, i.e. either did not form or were not preserved. For varve interpolation an advanced version of the Varve Interpolation Program was used, which enabled the construction of the longest, purely varve dated chronology published, despite long intervals of poor lamination quality. The calculated interpolation uncertainty is +8.9% and −4.6%, which is well within expectations considering the high degree of interpolation and the length of the record. Highlights • New facies and microfacies data from Lake Suigetsu are presented. • Analysis covers the time frame from 50 to 10 ka BP. • Detailed description varve characteristics for the complete analysed interval. • Discussion of μXRF as a tool for varve counting compared to microscope counting. • Detailed discussion of strength and weaknesses of the Suigetsu varve chronology. [ABSTRACT FROM AUTHOR]

Abstract Human activities over the last ∼100 years have fundamentally changed the biogeochemistry of the global nitrogen cycle. For example, increased nitrogen deposition from industrial and agricultural sources has been linked to lake acidification and nutrient fertilization, and thus it has the potential to significantly influence lake ecosystems. Records of anthropogenic nitrogen deposition from alpine lakes are sparse in China, which limits our understanding of its effects on remote alpine lake ecosystems. In this study, we analyzed multiple geochemical proxies at Tianchi Lake (2430 m a.s.l.), which is part of the Liupan Mountains National Nature Reserve in the central Chinese Loess Plateau (CLP). We measured total nitrogen (TN) concentrations, C/N ratios and nitrogen stable isotope ratios (δ15N), as well as a biological proxy (spectrally-inferred chlorophyll a), from a well-dated sediment core spanning the past ∼200 years. Our aim was to examine anthropogenic nitrogen deposition to the lake and to assess its implications for lake primary production. We found that δ15N was stable prior to ∼1980, but it decreased significantly thereafter. This is consistent with documented changes in anthropogenic nitrogen deposition over the past ∼200 years, and it indicates that the δ15N record of Tianchi Lake likely reflects anthropogenic nitrogen deposition, at least in this region. Prior to ∼1980, the trend in primary production of Tianchi Lake agrees with the trend of reconstructed regional temperature, when reactive nitrogen emissions in China were very low. This suggests that temperature was likely the main factor driving lake primary production before ∼1980. Primary production has increased significantly since ∼1980, consistent with the continued rising temperature and with enhanced nitrogen deposition, indicating that both factors are simultaneous drivers. Although the current data for Tianchi Lake are insufficient to unequivocally determine which of the two stressors is more important after the 1980s, temperature likely played the more significant role in driving primary production. This is because the lake is phosphorus-limited today, and in addition there is a strong association between temperature and chlorophyll a over the past ∼200 years. Continuing global warming and increasing nitrogen deposition in the future will likely further affect the fragile alpine ecosystems in the region. [ABSTRACT FROM AUTHOR]

The stable carbon isotope ratio (δ 13 C value) of Daphnia spp. resting egg shells (ephippia) provides information on past changes in Daphnia diet. Measurements are typically performed on samples of ≥20 ephippia, which obscures the range of values associated with individual ephippia. Using a recently developed laser ablation-based technique, we perform multiple δ 13 C analyses on individual ephippia, which show a high degree of reproducibility (standard deviations 0.1–0.5‰). We further measured δ 13 C values of 13 ephippia from surface sediments of three Swiss lakes. In the well-oxygenated lake with low methane concentrations, δ 13 C values are close to values typical for algae (−31.4‰) and the range in values is relatively small (5.8‰). This variability is likely driven by seasonal (or inter-annual) variability in algae δ 13 C values. In two seasonally anoxic lakes with higher methane concentrations, average values were lower (−41.4 and −43.9‰, respectively) and the ranges much larger (10.7 and 20.0‰). We attribute this variability to seasonal variation in incorporation of methane-derived carbon. In one lake we identify two statistically distinct isotopic populations, which may reflect separate production peaks. The potentially large within-sample variability should be considered when interpreting small-amplitude, short-lived isotope excursions based on samples consisting of few ephippia. We show that measurements on single ephippia can be performed using laser ablation, which allows for refined assessments of past Daphnia diet and carbon cycling in lake food webs. Furthermore, our study provides a basis for similar measurements on other chitinous remains (e.g. from chironomids, bryozoans). [ABSTRACT FROM AUTHOR]

Sediment cores from aquatic environments can provide valuable information about historical pollution levels and sources. However, there is little understanding of the uncertainties associated with these findings. The aim of this study is to fill this knowledge gap by proposing a framework for quantifying the uncertainties in historical heavy metal pollution records reconstructed from sediment cores. This uncertainty framework consists of six sources of uncertainty: uncertainties in (1) metals analysis methods, (2) spatial variability of sediment core heavy metal profiles, (3) sub-sampling intervals, (4) the sediment chronology, (5) the assumption that metal levels in bed sediments reflect the magnitude of metal inputs into the aquatic system, and (6) post-depositional transformation of metals. We apply this uncertainty framework to an urban floodplain lake in South-East Australia (Willsmere Billabong). We find that for this site, uncertainties in historical dated heavy metal profiles can be up to 176%, largely due to uncertainties in the sediment chronology, and in the assumption that the settled heavy metal mass is equivalent to the heavy metal mass entering the aquatic system. As such, we recommend that future studies reconstructing historical pollution records using sediment cores from aquatic systems undertake an investigation of the uncertainties in the reconstructed pollution record, using the uncertainty framework provided in this study. We envisage that quantifying and understanding the uncertainties associated with the reconstructed pollution records will facilitate the practical application of sediment core heavy metal profiles in environmental management projects. [ABSTRACT FROM AUTHOR]

Palaeoenvironmental reconstructions of ecosystem responses to external forcing are generally limited by the difficulty of understanding the geosystem as a whole, because of the complex interactions between ecological compartments. Therefore, identifying which geosystem compartments or proxies co-vary is a prerequisite in unravelling the propagation of disturbances (e.g. climatic or anthropogenic) from one compartment to another. A multiproxy study of a continuous 13,500-year sedimentary profile cored in Lake Allos (European Alps, 2200 m a.s.l) was carried out on the basis of high-resolution sedimentological, geochemical, and botanical analyses, as well as determination of aquatic biotic proxies (diatoms, ostracods). These multiproxy datasets are rare at these high altitudes. Major changes occurred in the course of the palaeoenvironmental history of this alpine watershed at 12,000, 8600, 7200 and 3000 cal. BP. During the Holocene, two main transitions were recorded in all the ecological compartments (8600 and 3000 cal. BP), but the period 4500-3000 cal. BP stands out because of major changes that concerned only the lacustrine ecosystem. The frequent switches in lake level might correspond to the 4.2 ka climatic event. Proximity of this alpine lake to climatically-sensitive thresholds (ice-cover, thermal stratification, hydrological balance) may have amplified climatic signals in the lake ecosystem. This study illustrates the difficulties inherent to the use of common intra-Holocene stratigraphical limits, given that ecological compartments are likely to have different responses to forcing factors depending on the characteristics of the watershed and its capacity to accommodate disturbances. [ABSTRACT FROM AUTHOR]

A detailed environmental magnetic investigation has been performed on a sub-alpine sedimentary succession deposited over the past 15,400 years in Daping Swamp in the western Nanling Mountains of South China. Magnetic parameters reveal that fine grains of pseudo-single domain (PSD) magnetite or titanomagnetite are the dominant magnetic minerals in the lake sediments and surface soils collected from the catchment, which suggests that magnetic minerals in lake sediments mainly originated from surface soil erosion of the catchment. Variation of surface runoff caused by rainfall is interpreted as the main process for transportation of weathered soils into the lake. In the Last Deglacial period (LGP, 15,400–11,500 cal a BP), the influx of magnetic minerals of detrital material may have been significantly affected by the severe dry and cold conditions of the Last Glacial Maximum. Stabilised conditions of the catchment associated with increased vegetation coverage (e.g., 8000–4500 and 2500–1000 cal a BP) limited the input of magnetic minerals. Intensive soil erosion caused by increased human activity may have given rise to abnormal increases in multiple magnetic parameters after 1000 cal a BP. Because changes in runoff and vegetation coverage are closely related to Asian summer monsoon (ASM) intensity, the sedimentary magnetism of Daping Swamp provides another source of information to investigate the evolution of the ASM. [ABSTRACT FROM AUTHOR]

Mountain lakes are usually sensitive to the effects of global and regional environmental changes. Since the second half of the 20th century, surface-water acidification has become a significant ecological problem, and many lakes in Europe and North America have anthropogenically acidified. Additionally, following reduction in emissions of sulfur (S) and nitrogen (N) compounds, recovery from acidification has been observed in many lakes. In this study, we used changes in diatom communities to reconstruct the pH histories based on changes recorded in nine Tatra lakes (Western Carpathians, Poland) since approximately 1850 AD. Overall, results indicate that acidic precipitation had little influence on lake-water pH in the Tatra Mountain lakes. Changes in diatom-inferred pH (DI-pH) generally were small and showed little evidence of acidification during the time of the highest air pollution (since the 1960s), and have shown little change since the reduction of acidic deposition since the 1990s. Lakes that showed some evidence of acidification included dystrophic lakes with low acid neutralizing capacity. However, as illustrated by the PCA trajectories of the diatom assemblages, the majority of the lakes currently contain diatom assemblages that are unlike the diatom floras that existed ca. 1850. [ABSTRACT FROM AUTHOR]

Here, a charophyte assemblage from lower Pleistocene deposits at the coal mine locality of Dursunlu (Ilgın Basin, Turkey) is described and illustrated for the first time. The assemblage is composed of 11 species recovered from 50 samples taken from an 18 m-thick sedimentary sequence. The base of the sequence is dominated by lignites and organic-rich claystones/siltstones with root marks attributed to palustrine facies. The charophyte assemblage in this palustrine interval is dominated by Chara vulgaris and C. globularis. The upper part of the section is constituted by light grey-yellowish marls, siltstones and a limestone bed related to shallow lacustrine deposits. Two charophyte species dominate this lacustrine interval, Chara hispida and Nitellopsis obtusa , which occurred in intervals in association with Chara pappii , Chara molassica var. notata , Chara sp.1, Chara sp.2, Sphaerochara prolifera , Sphaerochara intricata and Lychnothamnus barbatus var. antiquus. The palaeoenvironmental characteristics and evolution of the Ilgın palaeolake during the Early Pleistocene (Günz glaciation) are inferred from a facies analysis and the ecological requirements of the charophyte assemblages. The results suggest that during this glacial period, the Ilgın Basin was occupied by a very shallow eutrophic lake with a dense palustrine vegetation belt, which evolved to a shallow (2–15 m deep), stable, oligotrophic, alkaline and oligohaline lake. The increase in water availability in the palaeolake can be related to climatic oscillation during the Günz glaciation. Finally, the lake depocentre migrated towards the NW due to tectonism, and these deposits were later subjected to intense pedogenic alteration. • Eleven charophyte species are described in the Pleistocene of Dursunlu (Turkey). • Chara vulgaris and C. globularis are dominant in organic-rich palustrine facies. • C. hispida and Nitellopsis obtusa are conspicuous in shallow lacustrine deposits. • A very shallow eutrophic lake evolved to a more stable, oligotrophic and alkaline. • Lakes of Central Anatolia acted as a charophyte refugia during pleniglacials. [ABSTRACT FROM AUTHOR]

The Sahara is the world's largest dust source with significant impacts on trans -Atlantic terrestrial and large-scale marine ecosystems. Contested views about a gradual or abrupt onset of Saharan aridity at the end of the African Humid Period dominate the current scientific debate about the Holocene Saharan desiccation. In this study, we present a 19.63 m sediment core sequence from Lake Sidi Ali (Middle Atlas, Morocco) at the North African desert margin. We reconstruct the interaction between Saharan dust supply and Western Mediterranean hydro-climatic variability during the last 12,000 yr based on analyses of lithogenic grain-sizes, XRF geochemistry and stable isotopes of ostracod shells. A robust chronological model based on AMS 14 C dated pollen concentrates supports our multi-proxy study. At orbital-scale there is an overall increase in southern dust supply from the Early Holocene to the Late Holocene, but our Northern Saharan dust record indicates that a gradual Saharan desiccation was interrupted by multiple abrupt dust increases before the ‘southern dust mode‘ was finally established at 4.7 cal ka BP. The Sidi Ali record features millennial peaks in Saharan dust increase at about 11.1, 10.2, 9.4, 8.2, 7.3, 6.6, 6.0, and 5.0 cal ka BP. Early Holocene Saharan dust peaks coincide with Western Mediterranean winter rain minima and North Atlantic cooling events. In contrast, Late Holocene dust peaks correspond mostly with prevailing positive phases of the North Atlantic Oscillation. By comparing with other North African records, we suggest that increases in Northern Saharan dust supply do not solely indicate sub-regional to regional aridity in Mediterranean Northwest Africa but might reflect aridity at a trans -Saharan scale. In particular, our findings support major bimillennial phases of trans -Saharan aridity at 10.2, 8.2, 6.0 and 4.2 cal ka BP. These phases coincide with North Atlantic cooling and a weak African monsoon. [ABSTRACT FROM AUTHOR]

Compilation of spore-pollen, diatom and biochemical analyses of samples from the top 80-cm sediments of Manzherok Lake, located on the western foothills of the Altai Mountains (51°49′15.5″N, 85°48′35.7″E, 400 m a.s.l.), revealed influence of regional climate changes during the past 1350 years on the hydrological budget of the lake and the dynamics of the surrounding vegetation. Based on indicator species of diatom complexes in the lake sediments, the reconstructed lake level and pH can be deciphered as (1) shallow pond with relatively high pH prior to the Medieval Warm Period (MWP), (2) dramatic flooding with freshwater in the MWP, (3) lowering of the lake level during the Little Ice Age (LIA), and (4) contemporary rise of the lake level after the LIA. Increased concentrations of the detrital elements and severe degradation of diatom assemblages in the lake sediments took place during the dramatic flooding stage. The reconstructed lake level based on the diatom assemblages is in good agreement with the palynological data which indicate changes from birch forest-steppe to pine and cedar forests in the beginning of MWP, and then to birch-pine anthropogenically transformed forest-steppe in the LIA. Sharp maxima of non pollen palynomorphs Anabaena and Bryales/Algae at the 43–46 cm depth (∼900 a BP) possibly mark ecological crises in lake's biotope. Cold and dry conditions during the LIA were clearly expressed in pollen diagram of Manzherok Lake by decline of maxima of Siberian pine pollen and increase of Artemisia pollen. This study provides evidence to support a dry episode in the 9th century, wet climatic conditions in the MWP and a dry LIA in the Russian Altai Mountains in contrast to the opposite pattern revealed for arid regions of Central Asia and NW China during the same periods (Chen et al., 2010; Eichler et al., 2011; Chen et al., 2015). Our study indicates that, as a small and shallow lake located in the forest-steppe western foothills of the Altai Mountains, Manzherok Lake is more sensitive to high-resolution (less than centennial scale) climatic and environmental variations, in comparison with the large and deep Teletskoye Lake located in the mountain taiga zone of the northern Altai. [ABSTRACT FROM AUTHOR]

Understanding the dynamics of ecosystem services (ESs) is crucial for sustainable resource management. Palaeolimnological records have a great potential to reveal long-term variations and dynamic interactions in ESs, especially supporting/regulating services, which are not easily quantified by documentary records. To elucidate the variations between eight important ESs in shallow lake ecosystems, we combined documentary records with palaeolimnological proxies (covering the past 100 years) from two typical lakes (Lakes Taibai and Zhangdu) of the Yangtze River basin. Although all supporting services and some provisioning services have increased, the regulating services of the two lakes have markedly declined, in particular since the 1950s. Human activities, including hydrological intervention, nutrient input and land-use change, were identified as the main factors behind the observed variations. Both in Lake Taibai and Zhangdu, primary production and biodiversity (supporting services) have increased (synergies), whereas climate and water purification (regulating services) have significantly decreased (tradeoffs) since the 1950s when attempts were made by the local population to reach a higher land/fish ESs level. By considering long-term records, dynamic tradeoff and synergy relationship between various ESs relative to different types of human “modification” in a temporal perspective, we suggest valuable information can be gained in future lake management initiatives. [ABSTRACT FROM AUTHOR]

The analysis of fossil chironomid and diatom assemblages from a sedimentary record from Les Roustières peat bog (Massif Central, France, 1196 m asl) allows the reconstruction of past environmental and climate changes during the late-glacial and early Holocene. Chironomid assemblages showed that the infilling of the palaeolake had commenced during the Oldest Dryas (GS-2b) as suggested by the rapid decrease in chironomid species associated with the cold and deep zone of lakes and by their replacement by littoral and eutrophic taxa. Quantitative July temperature reconstructions, based on the chironomid data, suggest that mean July air temperature (Tjul) ranged between 6 °C and 11 °C at the termination of the Oldest Dryas period (GS-2b). Climate began to warm at the start of the Bølling period (GI-1e), between 15,000 and 14,800 cal yr BP, with a rise in Tjul of about 4 °C. This climate warming is contemporaneous with lake eutrophication as suggested by diatoms and chironomids. Maximum temperatures of 13–14 °C were reached around 13,600 cal yr BP during the Allerød period (GI-1c–GI-1a). The Younger Dryas period (GS-1) is marked by a return to cold conditions with Tjul of about 10 °C during a first phase, then 13 °C in its terminal part. A probable increase in the duration of the ice-cover may have favoured arctic and alpine diatom species. The early-Holocene climate improvement is marked by a rise in Tjul of about 3 °C. [ABSTRACT FROM AUTHOR]

• C/N ratios and δ13C suggest regional similarities in floodplain lake carbon cycling one century ago. • Timings of shifts in sedimentary proxies indicate larger responses to eutrophication than dam installation in the 20th century. • Eutrophication influences production and burial of autochthonous carbon by stimulating aquatic plant or algal growth. Carbon cycling in shallow floodplain lakes is complex due to variability in delivery of flood-derived allochthonous organic matter (OM). Human activities have potential to significantly modify the carbon balance of lakes by damming which restricts external OM inputs and via eutrophication which can increase the in-lake production of algae and/or aquatic plants. In order to understand how these human activities influence carbon cycling in shallow floodplain lakes over decadal-centennial timescales, we analysed C/N ratios and δ13C from terrestrial plants, catchment soils, aquatic plants and dated sediment cores from six heavily modified lakes in the middle Yangtze floodplain. Submerged macrophytes (−21.4 ± 4.6 ‰) had higher δ13C than C 3 plants from the catchment (−26.6 ± 0.6 ‰) and emergent and floating plants (−26.6 ± 4.0 ‰). Increases in sedimentary chlorophyll a (from primary producers) were associated with a decline in sedimentary δ13C in the severely eutrophic Dongting, Luhu, Wanghu and Poyang Lakes after the 1980s. In contrast, sedimentary δ13C increased in Honghu and Futou Lakes which have abundant submerged macrophytes. The timing and scale of sedimentary δ13C changes indicated stronger responses to eutrophication than damming, with eutrophication responses ranging from a macrophyte proliferation to the dominance of phytoplankton. [ABSTRACT FROM AUTHOR]

Fire is an important disturbance agent worldwide and one of the major causes of geomorphological change. Dependent on its characteristics (size, duration, temperature), fire induces changes in soil stability, modifying infiltration and promoting soil erosion. Here, we employ a suite of physical (mineral magnetic, loss-on-ignition), geochemical (XRF derived elemental data), biological (macro-charcoal, pollen) proxies and dating measurements (AMS 14 C, 210 Pb and 137 Cs) to examine the relationship between fire activity, sedimentary characteristics and geomorphological change over the Holocene. Our results highlight that fire events imprint a magnetic signature characterised by secondary ferrimagnetic assemblage particularly very fine superparamagnetic (SP) magnetite and maghemite. In Lake Buhăiescu Mare, the early Holocene is characterised by moderate fire activity and coarser sediment particle size indicating a relatively unstable catchment affected by burning events which activated erosional processes. Subsequently, the late Holocene (4,000–0 cal yr. BP) is marked by intermittently variable fire activity with sporadic increases between 3,400 and 3,200 cal yr. BP and around 2,000 cal yr. BP when burning was strong enough to lead to the magnetic enrichment of topsoil and detrital inputs to the lake. In our high resolution record, Lake Știol, the interval 2,500–700 cal yr. BP, and also the last 100 years, are characterised by intense burning that coincides with sustained surface soil erosion and magnetic enrichment. The fire–erosion–landscape relationship varies over time being highly dependent on fire behaviour, fire temporal and spatial distribution and landscape features (slope, soil type, vegetation cover). [ABSTRACT FROM AUTHOR]

A regional network of quantitative reconstructions of past climate variability is required to test climate models. In recent studies, temperature calibration models based on the relative abundances of sedimentary glycerol dialkyl glycerol tetraethers (GDGTs) have enabled past temperature reconstructions in both marine and terrestrial environments. Nevertheless, to date these methods have not been widely applied in high latitude environments due to poor performance of the GDGT–temperature calibrations at lower temperatures. To address this we studied 32 lakes from Antarctica, the sub-Antarctic Islands and Southern Chile to: 1) quantify their GDGT composition and investigate the environmental controls on GDGT composition; and 2) develop a GDGT–temperature calibration model for inferring past temperatures from Antarctic and sub-Antarctic lakes. GDGTs were found in all 32 lakes studied and in 31 lakes branched GDGTs (brGDGTs) were the dominant compounds. Statistical analyses of brGDGT composition in relation to temperature, pH, conductivity and water depth showed that the composition of brGDGTs is strongly correlated with mean summer air temperature (MSAT). This enabled the development of the first regional brGDGT–temperature calibration for use in Antarctic and sub-Antarctic lakes using four brGDGT compounds (GDGT-Ib, GDGT-II, GDGT-III and GDGT-IIIb). A key discovery was that GDGT-IIIb is of particular importance in cold lacustrine environments. The addition of this compound significantly improved the model's performance from r 2 = 0.67 , RMSEP-LOO (leave-one-out) = 2.23 °C, RMSEP-H ( h -block) = 2.37 °C when applying the re-calibrated global GDGT–temperature calibration to our Antarctic dataset to r 2 = 0.83 , RMSEP-LOO = 1.68 °C, RMSEP-H = 1.65 °C for our new Antarctic calibration. This shows that Antarctic and sub-Antarctic, and possibly other high latitude, palaeotemperature reconstructions should be based on a regional GDGT–temperature calibration where specific compounds can be identified and included to improve model performance. Finally, downcore temperature reconstructions using the new Antarctic brGDGT–temperature calibration were tested in sub-Antarctic Fan Lake from South Georgia providing a proof of concept for the new calibration model in the Southern Hemisphere. [ABSTRACT FROM AUTHOR]

Especially in combination with other proxies, the oxygen isotope composition of diatom silica (δ 18 O diatom ) from lake sediments is useful for interpreting past climate conditions. This paper presents the first oxygen isotope data of fossil diatoms from Kamchatka, Russia, derived from sediment cores from Two-Yurts Lake (TYL). For reconstructing Late Holocene climate change, palaeolimnological investigations also included diatom, pollen and chironomid analysis. The most recent diatom sample (δ 18 O diatom = + 23.3‰) corresponds well with the present day isotopic composition of the TYL water (mean δ 18 O = − 14.8‰) displaying a reasonable isotope fractionation in the system silica-water. Nonetheless, the TYL δ 18 O diatom record is mainly controlled by changes in the isotopic composition of the lake water. TYL is considered as a dynamic system triggered by differential environmental changes closely linked with lake-internal hydrological factors. The diatom silica isotope record displays large variations in δ 18 O diatom from + 27.3‰ to + 23.3‰ from about ~ 4.5 kyr BP until today. A continuous depletion in δ 18 O diatom of 4.0‰ is observed in the past 4.5 kyr, which is in good accordance with other hemispheric environmental changes (i.e. a summer insolation-driven Mid- to Late Holocene cooling). The overall cooling trend is superimposed by regional hydrological and atmospheric–oceanic changes. These are related to the interplay between Siberian High and Aleutian Low as well as to the ice dynamics in the Sea of Okhotsk. Additionally, combined δ 18 O diatom and chironomid interpretations provide new information on changes related to meltwater input to lakes. Hence, this diatom isotope study provides further insight into hydrology and climate dynamics of this remote, rarely investigated area. [ABSTRACT FROM AUTHOR]

Within the scope of Russian–German palaeoenvironmental research, Two-Yurts Lake (TYL, Dvuh-Yurtochnoe in Russian) was chosen as the main scientific target area to decipher Holocene climate variability on Kamchatka. The 5 × 2 km large and 26 m deep lake is of proglacial origin and situated on the eastern flank of Sredinny Ridge at the northwestern end of the Central Kamchatka Valley, outside the direct influence of active volcanism. Here, we present results of a multi-proxy study on sediment cores, spanning about the last 7000 years. The general tenor of the TYL record is an increase in continentality and winter snow cover in conjunction with a decrease in temperature, humidity, and biological productivity after 5000–4500 cal yrs BP, inferred from pollen and diatom data and the isotopic composition of organic carbon. The TYL proxy data also show that the late Holocene was punctuated by two colder spells, roughly between 4500 and 3500 cal yrs BP and between 1000 and 200 cal yrs BP, as local expressions of the Neoglacial and Little Ice Age, respectively. These environmental changes can be regarded as direct and indirect responses to climate change, as also demonstrated by other records in the regional terrestrial and marine realm. Long-term climate deterioration was driven by decreasing insolation, while the short-term climate excursions are best explained by local climatic processes. The latter affect the configuration of atmospheric pressure systems that control the sources as well as the temperature and moisture of air masses reaching Kamchatka. [ABSTRACT FROM AUTHOR]

The high-altitude lake Tso Moriri (32°55′46″N, 78°19′24″E; 4522 m a.s.l.) is situated at the margin of the Indian Summer Monsoon and westerly influences in the Trans-Himalayan region of Ladakh. Human settlements are rare and domestic and wild animals are concentrated in the alpine meadows. A set of modern surface samples and fossil pollen from a deep-water core was evaluated with focus on indicator types revealing human impact, grazing activities and lake system development during the last ca. 12 cal ka BP. The non-pollen palynomorph (NPP) record, comprising remains of limnic algae and invertebrates as well as fungal spores and charred plant tissue fragments, were examined in order to attest palaeolimnic phases and human impact, respectively. Changes in the early and middle Holocene limnic environment are mainly influenced by regional climatic conditions and glacier-fed meltwater flow in the catchment area. The NPP record indicates low lake productivity with high influx of freshwater between ca. 11.5 and 4.5 cal ka BP which is in agreement with the regional monsoon dynamics and published climate reconstructions. Geomorphologic observations suggest that during this period of enhanced precipitation the lake had a regular outflow and contributed large amounts of water to the Sutlej River, the lower reaches of which were integral part of the Indus Civilisation area. The inferred minimum freshwater input and maximum lake productivity between ca. 4.5–1.8 cal ka BP coincides with the reconstruction of greatest aridity and glaciation in the Korzong Valley, resulting in significantly reduced or even ceased outflow. We suggest that lowered lake levels and river discharge at a larger regional scale may have caused irrigation problems and harvest losses in the Indus Valley and lowlands occupied by sedentary agricultural communities. This scenario, in turn, supports the hypothesis that Mature Harappan urbanism (ca. 4.5–3.9 cal ka BP) emerged in order to facilitate storage, protection, administration, and redistribution of crop yields, and secondly, the eventual decline of the Harappan Culture (ca. 3.5–3 cal ka BP) was promoted by prolonged aridity. There is no clear evidence for human impact around Tso Moriri prior to ca. 3.7 cal ka BP, with a more distinct record since ca. 2.7 cal ka BP. This suggests that the sedimentary record from Tso Moriri primarily archives the regional climate history. [ABSTRACT FROM AUTHOR]

During the Maya early Anthropocene (2000 BCE – 1000 CE) in Mesoamerica, socio-environmental interactions contributed to the rise and decline of the ancient Maya civilisation. At the scale of the exploitation territories of the Maya cities, the temporal variations of hydrological and sedimentary dynamics in response to anthropogenic and climate drivers are still poorly known. This constrains diachronic analyses of socio-ecosystems and, more particularly, of water and soil resources in the hinterlands. This manuscript analyses and presents a regional comparison of the dynamics of one of the most transformed hydrosystems and morpho-sedimentary systems by the societies of the Southern Maya Lowlands (SMLs), during the second half of the Holocene. It focuses on the lake basin of the polje named El Infierno bajo and its watershed, which was the main water storage area for the Maya city of Naachtun – a large regional capital between 150 and 950 CE –, and which contains many remains of hydraulic and agrarian structures. This integrated palaeolimnological, geoarchaeological and hydrological approach, based on the analyses of morpho-sedimentary archives, LiDAR altimetry data and hydrological data, resulted in the construction of hydro-sedimentary baselines (pre- syn- and post-ancient Maya anthropogenic impacts). Currently, the intermittent lake (civale) of this bajo responds to strong seasonal and interannual hydrological variabilities, under climate control. During the past 5500 years, hydro-sedimentary fluctuations were marked by the alternation of seven main hydrological periods (HP), characterised by high and low lake levels (alternately perennial, intermittent and dry lake) and six main erosion and sediment transfer periods (ESTP), marked by strong and low alluvial and colluvial detrital inputs in the lowlands. Anthropogenic and climate forcings have independently or jointly controlled the hydrologic and sedimentary budgets of the lake basin. Lithofacies, depositional processes, accumulation rates and drivers of the anthropogenic detrital inputs – the so-called "Maya clays" –, are analysed and quantified from ∼1500 BCE to ∼1150 CE. It thus reveals one of the longest periods of occupation and exploitation of natural resources of the SMLs, for over 2500 years during the Preclassic, Classic and Post-classic Maya periods. The hydro-sedimentary dynamics in the bajos of the SMLs Elevated Interior Region (EIR), such as El Infierno, enabled the long-term exploitation of water and soil resources for agrarian purposes, thanks to the construction of hydraulic and agrarian palimpsest landscapes shaped by the socio-ecosystems. • Wetlands palaeolimnology, geoarchaeology and hydrology based on sedimentary, LiDAR and hydrological data. • Current strong seasonal and interannual hydrological variabilities of the bajos, under climate control. • 7 hydrological periods and 6 erosion and sediment transfer periods during the past 5500 years. • Anthropogenic and climate forcings controlled the hydrologic and sedimentary budgets of the lake. • A long-term exploitation of water and soil resources in Maya Lowlands EIR (1500 BCE to 1150 CE). [ABSTRACT FROM AUTHOR]

The importance of climate change, specifically drought, across the Maya region in the northern Neotropics, remains a topic of lively debate. Part of this discussion hinges on the coherency of response to climatic variability across different archives and proxies. In this paper we present a 6600-year palaeolimnological record from Yaal Chac, a carbonate lake (known locally as a cenote) in the northern lowlands of the Yucatan Peninsula, < 2 km from the location of the previously published Aguada X'Caamal record. The Yaal Chac sequence has been analysed for loss-on-ignition (LOI), stable isotopes (δ18O, δ13C) and elemental analysis using μXRF, complemented by some mineralogical, charcoal and pigment data. Mid Holocene sediments, predating evidence of human impact, are carbonate dominated and finely laminated. δ18O values are positive (>2‰), but show no covariation with δ13C. A major transition occurs at ca. 4360 cal yr BP, with a change to generally more organic sediments and increased variability in all proxies. Although direct evidence for anthropogenic activity in the Yaal Chac catchment is limited, it seems feasible that human impact was affecting the system. Comparison with other records from the Northern Maya lowlands and the wider region shows little coherence in the mid Holocene, when Yaal Chac seems to have been quite stable, but possibly responsive to increased climatic seasonality, driving the production of seasonal laminae. In the late Holocene, when the climate was generally more variable, there is more coherence between Yaal Chac and other regional records, including the so called Pan Caribbean Dry Period (3500–2500 cal yr BP) and the droughts of the late Pre-Classic period (1800–1600 cal yr BP). The Yaal Chac record shows no evidence of drought at the time of either the Maya 'hiatus' or the Maya 'collapse' of the Terminal Classic, but does record drying from the 14th to 19th centuries CE, in keeping with other proxy and historical records. This new record from Yaal Chac highlights the spatial variability of responses to climate forcings and the importance of recognising individual system sensitivity. • A new 6600 year palaeolimnological record from Yaal Chac in the northern Maya lowlands. • Finely laminated, carbonate dominated sediments until ca. 4360 cal yr BP, then major transition. • Mid Holocene record seems to reflect enhanced seasonality in an otherwise stable climatic regime. • Late Holocene increased climatic variability and more regional coherence. • No evidence for severe drought at the time of the Maya 'hiatus' or the Maya 'collapse'. [ABSTRACT FROM AUTHOR]

Abstract: The Randeck Maar in S. Germany is a well-known fossil lagerstätte with exceptionally preserved fossils, particularly insects and plants, which thrived in and around the maar lake during the Mid-Miocene Climatic Optimum (late Early/early Middle Miocene, mammal zone MN5). We provide the first critical and detailed overview of the fauna and flora with lists of 363 previously published, partially revised, and newly identified taxa. Plant remains are the most diverse group (168 taxa), followed by insects (79). The flora points towards subhumid sclerophyllous forests and mixed mesophytic forests, the former being an indication for the occurrence of seasonal drought. Three main sections can be differentiated for the habitats of the Randeck Maar lake system: (1) Deep- and open-water lake habitats with local and short-termed mass occurrences of insect larvae, amphibians, and/or gastropods, while fish is particularly scarce. The interpretation of the water chemistry is problematic because contradictive palaeoenvironmental indicators for both brackish and freshwater conditions exist. (2) Shallow parts of the lake comprise a narrow reed-belt with insects and gastropods living on the exposed plant stems as well as turtles. (3) Crater slopes and surrounding plateaus were mainly covered by subhumid sclerophyllous to mixed mesophytic forests depending on sun exposition and soil conditions. Horses and other forest-dwellers preferably lived in forested habitats while proboscideans and rhinoceratids occupied more open habitats. Our study also brings up contradictive results that cannot be untangled with the current state of knowledge and thus directions for future studies are discussed. [Copyright &y& Elsevier]

Abstract: The Aral Sea has shrunk drastically over the past 50years, largely due to water abstraction from the Amu Darya and Syr Darya rivers for land irrigation. Over a longer timescale, Holocene palaeolimnological reconstruction of variability in water levels of the Aral Sea since 11,700BP indicates a long history of alternating phases of regression and transgression, which have been attributed variously to climate, tectonic and anthropogenic forcing. The hydrological history of the Aral Sea has been investigated by application of a variety of scientific approaches, including archaeology, palaeolimnological palaeoclimate reconstruction, geophysics, sedimentology, and more recently, space science. Many issues concerning lake level variability over the Holocene and more recent timescales, and the processes that drive the changes, are still a matter for active debate. Our aim in this article is to review the current debates regarding key issues surrounding the causes and magnitude of Aral Sea level variability on a variety of timescales from months to thousands of years. Many researchers have shown that the main driving force of Aral Sea regressions and transgressions is climate change, while other authors have argued that anthropogenic forcing is the main cause of Aral Sea water level variations over the Holocene. Particular emphasis is made on contributions from satellite remote sensing data in order to improve our understanding of the influence of groundwater on the current hydrological water budget of the Aral Sea since 2005. Over this period of time, water balance computation has been performed and has shown that the underground water inflow to the Aral Sea is close to zero with an uncertainty of 3km3/year. [Copyright &y& Elsevier]

Highlights: [•] We reconstructed a lake on basis of sedimentological and ostracode analyses. [•] The highest lake level in the region occurs between the early to middle Holocene. [•] The permafrost-landscape were affected by repeating degradation processes. [ABSTRACT FROM AUTHOR]

Abstract: The Last Interglacial Period (LIP) is often regarded as a good analogue for potential climatic conditions under predicted global warming scenarios. Despite this, there is still debate over the nature, duration and frequency of climatic changes during this period. One particularly contentious issue has been the apparent evidence of climatic instability identified in many marine cores but seemingly lacking from many terrestrial archives, especially within the Arctic, a key region for global climate change research. In this paper, geochemical records from Lake El'gygytgyn, north-eastern Russia, are used to infer past climatic changes during the LIP from within the high Arctic. With a sampling resolution of ~20–~90years, these records offer the potential for detailed, high-resolution palaeoclimate reconstruction. This study shows that the LIP commenced in central Chukotka ~129thousand years ago (ka), with the warmest climatic conditions occurring between ~128 and 127ka before being interrupted by a short-lived cold reversal. Mild climatic conditions then persisted until ~122ka when a marked reduction in the sedimentation rate suggests a decrease in precipitation. A further climatic deterioration at ~118ka marks the return to glacial conditions. This study highlights the value of incorporating several geochemical proxies when inferring past climatic conditions, thus providing the potential to identify signals related to environmental change within the catchment. We also demonstrate the importance of considering how changes in sedimentation rate influence proxy records, in order to develop robust palaeoenvironmental reconstructions. [Copyright &y& Elsevier]

Abstract: Stratigraphic boundaries are ideally defined by distinct lithological, geochemical, and palaeobiological signatures, to which a chronological framework can be applied. We present a range of observations that illustrate how the Holocene–Anthropocene transition meets these criteria in its expression in sediments from remote arctic and alpine lakes, removed from direct, catchment-scale, anthropogenic influences. In glaciated lake basins, the retreat of glaciers commonly leads to lithological successions from proglacial clastic sedimentation to non-glacial organic deposition. Sediments from the majority of lakes record marked depletions in the nitrogen stable isotopic composition of sediment organic matter, reflecting anthropogenic influences on the global nitrogen cycle. In all cases, siliceous microfossil assemblages (diatoms and chrysophytes) change markedly and directionally, with regional nuances. These stratigraphic fingerprints begin to appear in the sediment record after AD 1850, but accelerate in pulses between AD 1950 and 1970 and again after AD 1980. Our review indicates that recent environmental changes associated with humankind''s dominance of key global biogeochemical cycles are sufficiently pervasive to be imprinted on the sediment record of remote lakes. Moreover, these changes are of sufficient magnitude to conclude that the Holocene has effectively ended, and that the concept of Anthropocene more aptly describes current planetary dynamics. The synthesis of these observations pertains directly to ongoing discussions concerning the eventual formalization of a new stratigraphic boundary. [Copyright &y& Elsevier]

Abstract: This research develops a detailed palaeoenvironmental history for sediments at Munya wa Gicheru (southern Kenya Rift) and explores the roles of tectonics and climate in the formation of palaeolakes and their use in regional climate correlation. The lacustrine facies of the Munya wa Gicheru deposits were formed from ~1.9 to 1.65Ma and consist of massive and laminated diatomites and diatomaceous silts. Fresh water diatoms include Stephanodiscus transilvanicus, Stephanodiscus niagarae, Aulacoseira agassizi, Aulacoseira ambigua, Aulacoseira goetzeana, Aulacoseira granulata var. valida, A. granulata var. angustissima and Pseudostaurosira zeilleri. One moderately saline phase is marked by the dominance of Cyclotella meneghiniana and by the presence of rare Thalassiosira rudolfii. Twenty-five diatom-based zones and subzones can be distinguished, representing eight high-lake periods and eight shallow-water phases. Erosion surfaces and desiccation cracks indicate two periods of emergence. Lake waters ranged in pH from 7.2 to 9, with conductivities of ~200–11,000μScm−1, but mostly <1000μScm−1. In contrast, the uppermost sediments are comprised of fluvial silts, sands and gravels formed in fluvial, sheetwash and terrestrial settings and represent termination of lacustrine conditions. REE data suggest that the Limuru Trachytes are the dominant source of siliciclastics materials. Geochemical information indicates that catchment weathering was moderate and that CaO concentrations in the sediments are very low. Carbonate rhizoliths are absent. SEM images show minimal corrosion or alteration of the diatom silica. [Copyright &y& Elsevier]

Abstract: During the period of instrumental records, the North Atlantic Oscillation (NAO) has strongly influenced inter-annual precipitation variations in the western Mediterranean, while some eastern parts of the basin have shown an anti-phase relationship in precipitation and atmospheric pressure. Here we explore how the NAO and other atmospheric circulation modes operated over the longer timescales of the Medieval Climate Anomaly (MCA) and Little Ice Age (LIA). High-resolution palaeolimnological evidence from opposite ends of the Mediterranean basin, supplemented by other palaeoclimate data, is used to track shifts in regional hydro-climatic conditions. Multiple geochemical, sedimentological, isotopic and palaeoecological proxies from Estanya and Montcortés lakes in northeast Spain and Nar lake in central Turkey have been cross-correlated at decadal time intervals since AD 900. These dryland lakes capture sensitively changes in precipitation/evaporation (P/E) balance by adjustments in water level and salinity, and are especially valuable for reconstructing variability over decadal–centennial timescales. Iberian lakes show lower water levels and higher salinities during the 11th to 13th centuries synchronous with the MCA and generally more humid conditions during the ‘LIA’ (15th–19th centuries). This pattern is also clearly evident in tree-ring records from Morocco and from marine cores in the western Mediterranean Sea. In the eastern Mediterranean, palaeoclimatic records from Turkey, Greece and the Levant show generally drier hydro-climatic conditions during the LIA and a wetter phase during the MCA. This implies that a bipolar climate see-saw has operated in the Mediterranean for the last 1100years. However, while western Mediterranean aridity appears consistent with persistent positive NAO state during the MCA, the pattern is less clear in the eastern Mediterranean. Here the strongest evidence for higher winter season precipitation during the MCA comes from central Turkey in the northeastern sector of the Mediterranean basin. This in turn implies that the LIA/MCA hydro-climatic pattern in the Mediterranean was determined by a combination of different climate modes along with major physical geographical controls, and not by NAO forcing alone, or that the character of the NAO and its teleconnections have been non-stationary. [Copyright &y& Elsevier]

Abstract: Macrofossil analysis of a composite 19 m long sediment core from Rano Raraku Lake (Easter Island) was related to litho-sedimentary and geochemical features of the sediment. Strong stratigraphical patterns are shown by indirect gradient analyses of the data. The good correspondence between the stratigraphical patterns derived from macrofossil (Correspondence Analysis) and sedimentary and geochemical data (Principal Component Analysis) shows that macrofossil associations provide sound palaeolimnological information in conjunction with sedimentary data. The main taphonomic factors influencing the macrofossil assemblages are run-off from the catchment, the littoral plant belt, and the depositional environment within the basin. Five main stages during the last 34,000 calibrated years BP (cal yr BP) are characterised from the lithological, geochemical, and macrofossil data. From 34 to 14.6 cal kyr BP (last glacial period) the sediments were largely derived from the catchment, indicating a high energy lake environment with much erosion and run-off bringing abundant plant trichomes, lichens, and mosses into the centre of Raraku Lake. During the early Holocene the infilling of the lake basin and warmer conditions favoured the growth of a littoral plant belt that obstructed terrigenous input. Cladoceran remains and Solanaceae seeds are indicative of reduced run-off and higher values of N and organic C indicate increased aquatic and catchment productivity. From 8.7 to 4.5 cal kyr BP a swamp occupied the entire basin. The increase of Cyperaceae seeds reflects this swamp development and, with oribatid mites and coleopteran remains, indicates a peaty environment and more anoxic conditions in Raraku. At around 4.5 cal kyr BP dry conditions prevented peat growth and there is a sedimentary hiatus. About 800 cal yr BP, peat deposition resumed. Finally, in the last few centuries, a small lake formed within the surrounding swamp. Evidence of human activity is recorded in these uppermost sediments. [Copyright &y& Elsevier]

Abstract: A multi-proxy palaeoecological study of the lateglacial and early Holocene sediments of Jansvatnet, Hammerfest, northernmost Norway (70°39′ N) showed that cold and arid conditions prevailed in both the lateglacial interstadial and the Younger Dryas. Terrestrial proxies are macrofossils and pollen. Aquatic proxies are plant and invertebrate macrofossils, pollen, diatoms, and chironomids. Mean July temperatures were reconstructed using pollen and chironomid calibration functions and ecological knowledge of the fossil flora and fauna. Lake-water pH was reconstructed using a diatom pH-calibration function. Above sterile basal deglacial silts, biotic activity was detected around 14600 years ago in the interstadial (chronologically equivalent to the Bølling-Allerød in the Greenland Ice-Core Chronology). Catchment vegetation resembled polar desert and ultra-cold stenothermic chironomids lived in the lake. However, diatom assemblages were diverse and dynamic. In the Younger Dryas stadial, conditions deteriorated. In the early Younger Dryas chironomid-inferred air temperatures (CI-Tjul) fell about 1 °C. Pollen-inferred temperatures (PI-Tjul) did not fall and the terrestrial vegetation hardly changed because of the extreme aridity. The lake water was turbid from suspended clay which diminished aquatic life. Later in the Younger Dryas (ca 12400 cal yr BP) reconstructed mean July temperatures fell by a further 3 °C and were close to the minimum to support life, at around 3–4 °C. However, decreased turbidity allowed moss growth on the lake bottom that provided habitats for invertebrates and diatoms. In the last 200 years of the Younger Dryas temperatures increased by 2–3 °C and terrestrial and aquatic organisms responded quickly. At the start of the Holocene a rapid increase of more than 3 °C in PI-Tjul to 9.5 °C initiated the replacement of sparse arctic tundra by low-arctic dwarf-shrub heath. Simultaneously, a further 2 °C increase in CI-Tjul to 10–11 °C reflected a regime shift in the lake. Aquatic macrophytes rapidly replaced the moss carpet, diatom assemblages stabilised and diatom plankton developed, and cold stenotherm chironomids were replaced by cool-temperate taxa. Productivity increased as CI-Tjul reached a steady maximum of around 12 °C and PI-Tjul reached 10.5 °C at about 10000 cal yr BP. At this time, tree-birch arrived and woodland developed over the catchment. Birch could have immigrated from the south up the west coast or from the east along the Barents Sea coast. Acidophilous aquatic taxa increased as diatom-inferred pH gradually decreased from 7.3 to 6.6. After ca 9380 cal yr BP, the density and extent of birch woodland decreased and species of exposed rocky areas increased, reflecting increased windiness, precipitation, and possibly a small decrease in July temperatures. Birch now formed the arctic tree-line at Jansvatnet. The lateglacial climatic pattern at Jansvatnet resembles patterns detected elsewhere in northern Norway and Svalbard and in marine records from the Norwegian and Barents Seas but contrasts with patterns in southern Norway. [Copyright &y& Elsevier]

Abstract: The Roman Period is considered a crucial phase in the evolution of Holocene landscapes, due to the coincidence of major climatic, environmental, economic and cultural changes. However, there is still debate as to the regional expression of these changes, and to the mechanisms involved, particularly in the topographically and climatically complex region of the Mediterranean. In order to improve our understanding of the synergies between societal and environmental change during this period in central Spain, we present a comprehensive case study based on the integration of multi-proxy palaeoenvironmental, archaeological and historical data. High-resolution, interdisciplinary research has been performed on a 3.8m thick sediment record from the Somolinos tufa lake (1280masl), located in a continental Mediterranean area. The analyses include pollen, non-pollen palynomorphs (NPPs), macrocharcoal, ostracods, diatoms, other biotic remains and sedimentology. The Somolinos sequence extends from the 9th century calBC (Pre-Roman) to the 8th century AD (Early Medieval). The multi-proxy data reveal substantial climate variability during this period. More humid conditions prevailed from 700 to 250calBC, while the climate became more arid during the Roman Period (50calBC to 70calAD). Later on, increased humidity characterized the period from 100calAD to 400calAD, followed by a progressive arid phase (400 to 715calAD) that culminated in total desiccation of the lake. During this time the Romans introduced a new and complex system of resource management in the area, including large-scale farming, grazing, forestry and mining. A strong shift in land use occurred after 80calBC, resulting in extensive woodland clearing throughout the range, and in an enhancement of soil erosion and lake productivity. The high-resolution analysis indicates that the peak in Roman impact occurred one century later than the climate changed towards drier conditions. In contrast, social–economical decline and aridification were synchronous in Visigothic times (from 5th to 8th centuries AD). The Somolinos record indicates that Roman ‘humid period’ is not a simple phase as some suggest. The observed environmental changes resulted from the interaction of different driving factors. [Copyright &y& Elsevier]

Abstract: The recent disintegration of Antarctic Peninsula ice shelves, and the associated accelerated discharge and retreat of continental glaciers, has highlighted the necessity of quantifying the current rate of Antarctic ice mass loss and the regional contributions to future sea-level rise. Observations of present day ice mass change need to be corrected for ongoing glacial isostatic adjustment, a process which must be constrained by geological data. However, there are relatively little geological data on the geometry, volume and melt history of the Antarctic Peninsula Ice Sheet (APIS) after Termination 1, and during the Holocene so the glacial isostatic correction remains poorly constrained. To address this we provide field constraints on the timing and rate of APIS deglaciation, and changes in relative sea-level (RSL) for the north-eastern Antarctic Peninsula based on geomorphological evidence of former marine limits, and radiocarbon-dated marine-freshwater transitions from a series of isolation basins at different altitudes on Beak Island. Relative sea-level fell from a maximum of c. 15 m above present at c. 8000 cal yr BP, at a rate of 3.91 mm yr−1 declining to c. 2.11 mm yr−1 between c. 6900–2900 cal yr BP, 1.63 mm yr−1 between c. 2900–1800 cal yr BP, and finally to 0.29 mm yr−1 during the last c. 1800 years. The new Beak Island RSL curve improves the spatial coverage of RSL data in the Antarctic. It is in broad agreement with some glacio-isostatic adjustment models applied to this location, and with work undertaken elsewhere on the Antarctic Peninsula. These geological and RSL constraints from Beak Island imply significant thinning of the north-eastern APIS by the early Holocene. Further, they provide key data for the glacial isostatic correction required by satellite-derived gravity measurements of contemporary ice mass loss, which can be used to better assess the future contribution of the APIS to rising sea-levels. [Copyright &y& Elsevier]

Abstract: The large landmass of northern Russia has the potential to influence global climate through amplification of climate change. Reconstructing climate in this region over millennial timescales is crucial for understanding the processes that affect the global climate system. Chironomids, preserved in lake sediments, have the potential to produce high resolution, low error, quantitative summer air temperature reconstructions. Canonical correspondence analysis of modern surface sediments from high-latitude lakes, located in northern European Russia and central Siberia, suggests that mean July air temperature is the most significant variable explaining chironomid distribution and abundance. This strong relationship enabled the development of a chironomid-based mean July air temperature-inference model based on 81 lakes and 89 taxa which has a r jack 2 =0.92 and RMSEP=0.89°C. Comparison of taxon responses to July temperature between this Russian and existing Norwegian data-sets shows that the temperature optima of individual taxa were between 1 and 3°C higher in the Russian data regardless of modelling technique. Reconstructions based on fossil assemblages from a Russian tundra lake core (VORK5) using a Norwegian chironomid-based inference model provide mean July air temperature estimates that are 1.0–2.7°C colder than from the 81-lake Russian model and are also lower than the instrumental record from a nearby meteorological station. The Norwegian model also did not reconstruct decadal-scale fluctuations in temperature seen in the instrumental record. These observations suggest that chironomid-based inference models should only be applied to sediment cores which have similar climate regimes to the geographic area of the training set. In addition a 149 lake, 120 taxa chironomid-based continentality inference model was also developed from the modern Norwegian and Russian training sets. A 2-component WA-PLS model was the minimal adequate model with r jack 2 =0.73 and RMSEP=9.9 using the Gorczynski continentality index. Comparison of reconstructed continentality indices from the tundra lake, VORK5, show close agreement with local instrumental records over the past 70 years and suggest that the model is reliable. Recent warming in the Arctic has been spatially and seasonally heterogeneous; in many areas warming is more pronounced in the spring and autumn leading to a lengthening of the summer, while summer temperatures have remained relatively stable. A continentality inference model has the potential to detect these seasonal changes in climate. [Copyright &y& Elsevier]