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This article presents a review of information related to the influence of potential permafrost degradation on the environmental fate of chemical species which are released and stored, classified as potential influence in future Antarctic environment. Considering all data regarding climate change prediction, this topic may prove important issue for the future state of the Antarctic environment. A detailed survey on soil and permafrost data permitted the assumption that this medium may constitute a sink for organic and inorganic pollution (especially for persistent organic pollution, POPs, and heavy metals). The analysis of the environmental fate and potential consequences of the presence of pollutants for the existence of the Antarctic fauna leads to a conclusion that they may cause numerous negative effects (e.g. Endocrine disruptions, DNA damage, cancerogenicity). In the case of temperature increase and enhanced remobilisation processes, this effect may be even stronger, and may disturb natural balance in the environment. Therefore, regular research on the environmental fate of pollution is required, especially in terms of processes of remobilisation from the permafrost reserves., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Over the last decades, regional climate changes, erosion, and heightened agricultural runoffs have increased nutrient and particle input in rivers, unbalancing the biogeochemical cycle of this suspended material along estuaries. In this context, particle fluxes in the euphotic zone, a very productive layer and important to maintain the food chain and estuarine preservation, require better understanding. This study aims to evaluate particle sedimentation fluxes in the photic zone of the Cananéia-Iguape Estuarine-Lagoon Complex (CIELC), considering sectors under different salinities and trophic statuses. A cylindrical sediment trap was installed at the base of the photic layer to measure particle fluxes and photopigments. Meanwhile, water samples were taken to measure temperature, salinity, pH, dissolved oxygen, and nutrients. Valo Grande (a freshwater domain) showed high nutrient concentrations, in which high fluxes of phaeopigments and chlorophyll-b highlighted the contribution of vegetable detritus to particle sinking. In the Batatais mangrove creek, the high fluxes of organic particles (675.32 mg m-2 d-1) and chlorophyll-a (98.40 mg m-2 d-1) evinced a high contribution of microplankton to carbon sinking. During the winter of 2018, flocculation processes were evinced in the flood tide of the Cananéia Bay as an important driver of sedimentation rates, with considerable fluxes of inorganic particles (1161.20 mg m-2 d-1) and chlorophyll-a (83.27 mg m-2 d-1). In the summer of 2019, we observed a lower flux in total particles (451.24 mg m-2 d-1) in a period of haline stratification. In the Ararapira Channel, the lowest organic particle fluxes (<100 mg m-2 d-1) were associated with ultra-oligotrophic conditions, indicating a low influence of microplankton on sinking particles. These findings suggest that freshwater input, tidal variation, and trophic status are relevant controls of sinking particles in different CIELC sectors. [ABSTRACT FROM AUTHOR]

The Elephant Marsh lies on the floodplain of the lower Shire River, in southern Malawi. It is both a cultivated, seasonal floodplain and an area of permanent shallow lakes. The marsh is highly biodiverse, has a productive fishery and supports the livelihoods of a large human population. Chronicles and hand-drawn sketches by 19th-century explorers and subsequent travellers describing the marsh landscape were used to develop an account of the marsh's historic hydromorphology. These anecdotal accounts are supported by Shire River outflows from Lake Malawi, inferred from observed water levels in the lake from c. 1900. Records show that the marsh has experienced regular periods of drying out, followed by periods of greater inundation than it currently experiences. Long-term hydrological trends have been accompanied by anthropogenic influences such as catchment degradation and embankment construction, which have altered sedimentation patterns in the marsh. The marsh exhibits traits of resilience to natural long-term climate change through its ability to return to a similar state during wet periods, even following prolonged dry periods. Over relatively short time frames, however, the ecology of the marsh, as described when it was declared a RAMSAR site in 2017, likely has low resistance to hydrological regimes that are sensitive to climate change. An appreciation of long-term climate and recent human-induced changes afforded a unique opportunity for contextualising its hydromorphological trends within the Anthropocene. [ABSTRACT FROM AUTHOR]

Understanding the driving factors for precipitation extremes matters for adaptation and mitigation measures against the changing hydrometeorological hazards in Yangtze River basin, a habitable area that provides water resources for domestic, farming, and industrial needs. However, the region is naturally subject to major floods linked to monsoonal heavy precipitation during May–September. This study aims to quantify anthropogenic influences on the changing risk of 2-week-long precipitation extremes such as the July 2019 extreme cases, as well as events of shorter durations, over the middle and lower reaches of Yangtze River basin (MLYRB). Precipitation extremes with different durations ranging from 1-day to 14-days maximum precipitation accumulations are investigated. Gridded daily precipitations based on nearly 2,400 meteorological stations across China are used to define maximum accumulated precipitation extremes over the MLYRB in July during 1961–2019. Attribution analysis is conducted by using the Met Office HadGEM3-GA6 modeling system, which comprises two sets of 525-member ensembles for 2019. One is forced with observed sea-surface temperatures (SSTs), sea-ice and all forcings, and the other is forced with preindustrialized SSTs and natural forcings only. The risk ratio between the exceedance probabilities estimated from all-forcing and natural-forcing simulations is calculated to quantify the anthropogenic contribution to the changing risks of the July 2019–like precipitation extremes. The results reveal that anthropogenic warming has reduced the likelihood of 2019-like 14-days heavy precipitation over the mid–lower reaches of the Yangtze River by 20%, but increased that of 2-days extremes by 30%.

Soil organic carbon (SOC) is going through rapid reorganization due to anthropogenic influences. Understanding how biogeochemical transformation and erosion‐induced SOC redistribution influence SOC profiles and stocks is critical to our food security and adaptation to climate change. The important roles of erosion and deposition on SOC dynamics have drawn increasing attention in the past decades, but quantifying such dynamics is still challenging. Here we develop a process‐based quasi 3‐D model that couples surface runoff, soil moisture dynamics, biogeochemical transformation, and landscape evolution. We apply this model to a subcatchment in Iowa to understand how natural forcing and farming practices affect the SOC dynamics in the critical zone. The net soil thickness and SOC stock change rates are −0.336 (mm/yr) and −1.9 (g C/m2/year), respectively. Our model shows that in a fast transport landscape, SOC transport is the dominant control on SOC dynamics compared to biogeochemical transformation. The SOC profiles have "noses" below the surface at depositional sites, which are consistent with cores sampled at the same site. Generally, erosional sites are local net atmospheric carbon sinks and vice versa for depositional sites, but exceptions exist as seen in the simulation results. Furthermore, the mechanical soil mixing arising from tillage enhances SOC stock at erosional sites and reduces it at depositional ones. This study not only helps us understand the evolution of SOC stock and profiles in a watershed but can also serve as an instrument to develop practical means for protecting carbon loss due to human activities. Plain Language Summary: Understanding how soil organic carbon (SOC) content changes in space and time are critical for our food security and adaptation to climate change. It changes through the belowground transformation—decomposition of litter and release of CO2, and surficial transport—lateral physical redistribution. The balance between the two interactions has been strongly shifted by human activities. Quantifying such interactions has remained challenging. Here we developed a 3‐D model, which simulates the movement and burial of SOC and compare the impacts of natural and human activities in the critical zone. We apply this model to a watershed in Iowa. Our results show that the net soil thickness and SOC stock change rates are both decreasing. The fast burial of legacy carbon by modern carbon results in a "nose" profile at depositional sites, which is consistent with soil cores sampled in the watershed. The lateral transport rate can be significantly larger than the transformation rate, but this balance is modified by the mechanical mixing from tillage. Generally, erosional sites are net sinks for atmospheric carbon and depositional sites are net sources. The model can serve as an important tool for protecting soil carbon change caused by both human and natural events. Key Points: A process‐based 3‐D model is developed to simulate the coevolution of soil organic carbon (SOC) and landscape in a watershedVertical SOC profiles evolve heterogeneously across the watershed due to SOC redistribution and biogeochemical transformationGenerally, erosion and deposition sites are local net atmospheric C sinks and sources, respectively, but exceptions exist [ABSTRACT FROM AUTHOR]

Climate change detection and attribution have been the subject of intense research and debate over at least four decades. However, direct attribution of climate change to anthropogenic activities using observed climate and forcing variables through statistical methods has remained elusive, partly caused by difficulties to correctly identify the time-series properties of these variables and by the limited availability of methods to relate nonstationary variables. This paper provides strong evidence concerning the direct attribution of observed climate change to anthropogenic greenhouse gases emissions by first investigating the univariate time-series properties of observed global and hemispheric temperatures and forcing variables and then by proposing statistically adequate multivariate models. The results show that there is a clear anthropogenic fingerprint on both global and hemispheric temperatures. The signal of the well-mixed Greenhouse Gases (GHG) forcing in all temperature series is very clear and accounts for most of their secular movements since the beginning of observations. Both temperature and forcing variables are characterized by piecewise linear trends with abrupt changes in their slopes estimated to occur at different dates. Nevertheless, their long-term movements are so closely related that the observed temperature and forcing trends cancel out. The warming experimented during the last century was mainly due to the increase in GHG which was partially offset by the effect of tropospheric aerosols. Other forcing sources, such as solar, are shown to only contribute to (shorter-term) variations around the GHG forcing trend. [ABSTRACT FROM AUTHOR]

Four cores (GY1, LTY, SZY, GT-2) taken from lowland to mountain sites in southeastern subtropical China were studied. Charcoal and pollen analyses were conducted to examine the regional Holocene fire history and discuss its possible relationship with both climatic changes and anthropogenic activities. Our results show extremely low charcoal influxes between 9.5 and 3.5 cal ka BP, revealing low fire frequency. Meanwhile, high proportions of arboreal pollen demonstrated expansion of subtropical evergreen broadleaf forest. This phase is consistent with heavy precipitation during the early-mid Holocene. After 3.5 cal ka BP., the abrupt increases in fire frequency revealed by core GY1 and LTY were closely related to gradual drying towards the late Holocene, possibly due to the Asian Summer Monsoon weakening and activation of the El Niño Southern Oscillation. Our pollen records also reveal this drying trend after the mid-Holocene, demonstrating a regional retreat of subtropical evergreen forests and local development of Glyptostrobus -dominated wetland community around the LTY and GY1 sites. However, the intensified fires after 3.5 cal ka BP probably resulted mainly from increasing human activities during the Shang-Zhou Bronze age. Pollen results show severe damage of forest by fires, indicated by notable decrease of arboreal pollen and increase of Dicranopteris and herbs. After 2.0 ka, obvious growth of Poaceae, Dicranopteris and Pinus recorded in the GY1 and LTY cores demonstrate agriculture development in low-altitude plains and hills, coinciding with the first human population boom and big progress in agricultural technology during the Warring States to Western Han Dynasty period. Signs of profound human impacts and extensive agriculture in South China appeared after 1.0 cal ka BP, which is revealed by frequent local fires and intensified anthropogenic impact around the mountains sites (SZY and GT-2). Generally, our results reveal a gradual expansion of anthropogenic activities into elevated areas. [ABSTRACT FROM AUTHOR]

A short (50-cm-long) sediment core from Ebinur Lake in arid central Asia has been analyzed for various environmental proxies, including organic matter content, δ13C in organic matter, magnetic susceptibility, heavy metal contents, and stable isotopic compositions of bulk carbonate (δ18O and δ13C). The results reveal that the evolutionary stages inferred from environmental indicators have an asynchronous nature. If the asynchrony of periodic changes in multi-environmental proxies is ignored, important information may be lost, especially regarding anthropogenic influences. On the basis of magnetic susceptibility and heavy metal contents, human activities appear to have resulted in increases in surface erosion and measurable heavy-metal accumulation from the mid-1960s, whereas the organic matter contents, which display an obvious shift in the late 1930s, correlate with regional climate. However, the changes in the stable isotopes of bulk carbonate are mainly controlled by the isotopic composition of the host water which is generally consistent with the lake level. From the late 1870s to the 1960s, the lake was in a natural evolutionary state. From the 1960s to the mid-2000s, the runoff feeding Ebinur Lake dropped rapidly, in association with a sharp increase in agricultural development. Finally, beginning in the early twenty-first century, the climate became wetter than during the earlier two stages, and as agricultural water demand decreased, surface runoff once again increased. It is noted that, although the different proxies respond differently to climate changes and human activities, any analysis of environmental evolution should consider them each individually, in order to fully understand the complex interactions between climate and human influence.

The Pan-Eurasian Experiment (PEEX) is a new multidisciplinary, global change research initiative focusing on understanding biosphere-ocean-cryosphere-climate interactions and feedbacks in Arctic and boreal regions in the Northern Eurasian geographical domain. PEEX operates in an integrative way and it aims at solving the major scientific and society relevant questions in many scales using tools from natural and social sciences and economics. The research agenda identifies the most urgent large scale research questions and topics of the land-atmosphere-aquatic-anthropogenic systems and interactions and feedbacks between the systems for the next decades. Furthermore PEEX actively develops and designs a coordinated and coherent ground station network from Europe via Siberia to China and the coastal line of the Arctic Ocean together with a PEEX-modeling platform. PEEX launches a program for educating the next generation of multidisciplinary researcher and technical experts. This expedites the utilization of the new scientific knowledge for producing a more reliable climate change scenarios in regional and global scales, and enables mitigation and adaptation planning of the Northern societies. PEEX gathers together leading European, Russian and Chinese research groups. With a bottom-up approach, over 40 institutes and universities have contributed the PEEX Science Plan from 18 countries. In 2014 the PEEX community prepared Science Plan and initiated conceptual design of the PEEX land-atmosphere observation network and modeling platform. Here we present the PEEX approach as a whole with the specific attention to research agenda and preliminary design of the PEEX research infrastructure.

The chronostratigraphy of an eastern Mediterranean Holocene fluvial sequence reflects global trends (climate and sea-level), local modulations (hydrological regime and storm surges) and anthropogenic impact. Two continuous cores retrieved from the Tanninim Stream estuary, on the Carmel coast of Israel, are dated by optically stimulated luminescence (OSL) to span the Holocene. The sedimentology and faunal assemblages are analyzed for reconstructing environmental conditions. Despite time gaps recognized in the fluvial successions, three main depositional periods provide distinctive archives capturing natural and anthropogenic centennial to millennial changes. Alternations between enhanced and reduced fluvial activity associated with humid and dry climate conditions, characterized the early to mid-Holocene fluvial record between about 7.8 and 5.7 ka, and may match eastern Mediterranean climate records. The first humid phase, from 8 to 6 ka, features organic-rich fine sediments and proliferating brackish ostracods, foraminifera and molluscs. The appearance of this biofacies indicates the initiation of seepage from the Yarkon-Tanninim aquifer through the brackish oligohaline Enot Timsah springs. The advancing coastline, due to sea-level rise starting about 5.8 ka, resulted in an increasing supply of quartz sands and marine-transported foraminifera. Relatively fast accumulation of organic-rich fine-grained sediments with enhanced preservation of brackish fauna during the late Holocene is probably associated with maintenance of the Tanninim dams during the early Arab period (7th–8th centuries CE). The last century has been characterized by accelerated sedimentation rates that may be associated with reduced vegetation cover due to modern human activity, and by deposition by a high-energy surge event. This study demonstrates that the lower part of a semi-arid southeastern Mediterranean estuary responds to periods of climatic and sea-level change on a regional scale, and to human impact and abrupt past hydrological events on a local scale. [ABSTRACT FROM AUTHOR]

This study investigated the anthropogenic influence on the temporal variability of annual precipitation for the period 1950–2005 as simulated by the CMIP5 models. The temporal variability of both annual precipitation amount (PRCPTOT) and intensity (SDII) was first measured using a metric of statistical dispersion called the Gini coefficient. Comparing simulations driven by both anthropogenic and natural forcing (ALL) with simulations of natural forcing only (NAT), we quantified the anthropogenic contributions to the changes in temporal variability at global, continental and sub-continental scales as a relative difference of the respective Gini coefficients of ALL and NAT. Over the period of 1950–2005, our results indicate that anthropogenic forcing have resulted in decreased uniformity (i.e. increase in unevenness or disparity) in annual precipitation amount and intensity at global as well as continental scales. In addition, out of the 21 sub-continental regions considered, 14 (PRCPTOT) and 17 (SDII) regions showed significant anthropogenic influences. The human impacts are generally larger for SDII compared to PRCTOT, indicating that the temporal variability of precipitation intensity is generally more susceptible to anthropogenic influence than precipitation amount. The results highlight that anthropogenic activities have changed not only the trends but also the temporal variability of annual precipitation, which underscores the need to develop effective adaptation management practices to address the increased disparity.

Salinization threatens the viability of water resources and is common in many important inland freshwater lakes worldwide, especially in arid and semi-arid areas. Bosten Lake is a typical inland freshwater lake that has evolved into a subsaline lake and is located in the arid region of Northwest China. The water resources of Bosten Lake are important for supplying regional drinking water and agricultural irrigation and for economic development. In this study, changes in salinity with time and space were analyzed in Bosten Lake. Overall, the salinity increased from 0.39 g/L in 1958 to 1.87 g/L in 1987, reaching its highest value in 1987. After 1987, the salinity decreased to 1.17 g/L in 2003 and increased to 1.45 g/L in 2010. Increased salinity adversely affects aquatic lake systems, regional eco-environments and water resource use, and has become a serious environmental problem in Bosten Lake. Thus, the causes of increasing salinity are discussed in this paper. Overall, the influences of climate variations and human activities resulted in the salinization of the lake. Understanding the salinization processes in Bosten Lake can be useful for implementing actions that improve water quality and water resource use in the lake. [ABSTRACT FROM AUTHOR]

Homeostasis as an ability to maintain structural-functional parameters of the system at the required level is a basic characteristic for providing the stability of any biological system (from biosphere and separate ecosystems to communities, populations, and individuals). The study of homeostatic mechanisms that provide the stability of biological systems is the main task for solving many theoretical and practical questions. The search for criteria of homeostasis estimation and study of homeostatic mechanism ratio at different levels are principally important in this direction. Estimation of the role of homeostatic mechanisms of the organism and population for providing the stability of biological systems of different levels when using the approach based on estimation of the population state from ontogenetic positions (population developmental biology) seems promising. [ABSTRACT FROM AUTHOR]

Abstract: A natural water hydrochemical investigation was carried out on three watersheds in northern Xinjiang, China to evaluate the climatic, geological and anthropogenic influence on aqueous major element chemistry in an arid environment. Wide spatial variations are observed in the dissolved solids (TDS) and water chemistry. The hydrochemistry is typically carbonate and alkaline in nature, with Ca2+, HCO3 − and SO4 2− dominating the major ion composition. Four major water types, Ca–HCO3, Ca–NDA (non-dominant anion), Ca–SO4 and NDC (non-dominant cation)–NDA or Na–NDA type, are identified in terms of the Piper model. The water chemistry agrees well with the “rock dominance” mechanism, with a TDS value of 80–600mg/L and a Na+/(Na+ +Ca2+) ratio of 0.1–0.6. Correlation analysis suggests that most of the ions derive from multiple sources. Stoichiometric analyses indicate that carbonate weathering is the primary source of dissolved ions, followed by silicate weathering and evaporite dissolution. The effects of local pollution have somewhat greater contribution on the oases and central areas of the Zhungarer watershed. Most parts of the rivers show an increasing trend in the dissolved load toward the lower reaches, which is primarily attributed to an evaporation process control along the water course. Variations in water chemistry show clear correlation with the regional lithological distribution, topography and atmospheric precipitation. Using rainwater as a baseline, contributions from atmospheric precipitation and rock weathering to the tributary chemistry are roughly evaluated to be in the range of 2–39% (average 13%) and 59–98% (average 86%), respectively, implying a high effective control of regional geology on stream chemistry compared with that of atmospheric input. [Copyright &y& Elsevier]

Abstract: Wildfires are expected to increase as a result of climate change. In order to effectively manage and monitor climate-induced changes in Canadian forests, a national-scale understanding of factors influencing wildfire susceptibility is necessary. The goal of this study is to better understand factors influencing large area wildfire susceptibility in Canada. Using year 2000 Canadian land cover data, we identify locations that burned before and after 2000. Pre- and post-fire landscape patterns were assessed and regression tree analyses were used to identify factors influencing national-scale fire susceptibility. Land cover composition, forest pattern, elevation, and anthropogenic influences were quantified for both pre- and post-fire environments. We examined recovery of forest pattern following wildfire events and derived a large-area fire susceptibility model using decision tree classification. Our results indicate that 11.88% of forested ecozones were impacted by large fires. The majority of large wildfires occur in coniferous forests characterized by high forest cover (greater than 45%), few forest patches, large mean forest patch area, and fragmentation-limited forest. Forests occurring at low to intermediate distances from populated places (50–150km) and roads (12–72km) experienced unexpectedly high amounts of fire, as did lower elevation forests. After fire, percentage forest cover, number of forest patches, forest patch size, and proportion forest patches regenerated to pre-fire forest pattern conditions within approximately 20years. Anthropogenic influences on wildfire susceptibility indicate that human activity still dictates national fire regimes. Additionally, knowledge of space–time patterns of fire-landscape interaction and landscape pattern regeneration provides useful baselines for future comparisons with responses to climate change. [Copyright &y& Elsevier]

Anthropogenic influences on the natural world are widespread and well studied from various ecological vantage points. Their behavioural implications, however, are comparatively less well understood. We review four categories of influence on natural animal mating systems: habitat fragmentation, climate change, pollution and selective harvesting. We adopt a predictive approach, first reviewing the ecological determinants of mating system variation and then investigating how these determinants may be affected. Habitat fragmentation and climate change are directly altering the two fundamental predictors of mating system variation: the spatial and temporal distributions of resources. Pollution has implications for mating systems, via, for example, feminizing effects of endocrine disrupters and impeded efficacy of sexual communication. The influences of selective harvesting arise from the removal of phenotypic (and in some cases, genetic) variation in sexually selected traits. The ecological (e.g. by serving as an underlying mechanism contributing to Allee effects) and evolutionary (e.g. by driving microevolutionary trajectories that run counter to sexual selection) consequences of mating system disruption may be severe. The current lack of data, however, makes rigorous assessment of these consequences premature. Nevertheless, there is an analytical framework that can be used to make quantitative predictions, and we argue that applying it more broadly will help improve our understanding of the causes and consequences of anthropogenic influences on natural animal mating systems. [ABSTRACT FROM AUTHOR]

Abstract: A sediment core from Lake Butrint in southwestern Albania contains an annually-layered sequence covering the last ∼300years. It provides thus an exceptionally well-dated time series to study past climate-driven environmental changes, as well as anthropogenic perturbations along the coast of the Ionian Sea. The varves are composed of organic-rich carbonate couplets and detritus-dominated clay layers. The first are deposited during spring-to-fall, and reflect the chemistry of the lake, which, in turn, is sensitive to 1) the relative importance of marine versus freshwater inputs, 2) relative evaporation rates, and 3) the productivity cycle within the lake. The detrital laminae are deposited during winter, reflecting precipitation and runoff conditions during the wet season. A 2–3‰ stable carbon isotope ratio shift in both bulk organics and authigenic carbonates was attributed to increasing eutrophication towards the end of the 20th century, and validated by historical and instrumental data. An increase in the δ 18O of authigenic carbonates by more than 8‰ indicates the progressive salinization of the lake, which can primarily be attributed to man-made perturbations that reduced the freshwater input to the lake and/or enhanced the exchange with seawater from the nearby Ionian Sea. A recent increase in the relative evaporation versus precipitation rates may have additionally contributed to the observed 18O enrichment in the Lake Butrint carbonates. The interdecadal cyclicity in the thickness of the detrital laminae seems to be at least partially controlled by NAO and/or ENSO-like phenomena that modulate precipitation patterns in the eastern Mediterranean. Thus, this study demonstrates the potential of combining microstratigraphic and stable isotopic tools to disentangle anthropogenic and natural environmental changes in Lake Butrint, validated by historical records. [Copyright &y& Elsevier]

Data from eleven meteorological stations in the Tianshan mountains and the north slope of west Kunlun mountains, and eighteen meteorological stations in the Kaidu-Kongque river, Akesu river, Kashiger river and Yankant river oases were examined to assess the differences in changes in potential evaporation from 1960 to 2006 in the mountainous and oasis regions of the Tarim basin and the relationships of these changes to meteorological factors. The decreasing trends in potential evaporation were primarily due to the decrease in the aerodynamic terms in both the mountainous and oasis regions, but the trends in the oasis regions were more pronounced. Based on the complementary relationship between potential and actual evaporation, the decreasing trends in potential evaporation appeared to be related to the increasing trends in precipitation in the mountainous regions and the increasing trends in water consumption in the oasis regions, thus reflecting the different impacts of natural changes and anthropogenic influences. [ABSTRACT FROM AUTHOR]

Accelerated human activity has greatly reduced sediment discharge into the global oceans in recent decades; however, the potential influence on climate change signals carried by sediments during source-to-sink transport processes remains poorly understood. To this end, multiple sedimentological analyses, including X-ray fluorescence scanning, grain-size composition, clay mineralogy, and 210Pb dating, of three short sediment cores retrieved from the Taiwan Strait, East Asia were performed. The results show that the terrigenous sediments of these cores spanning the last 150 years are mainly derived from the Yangtze River, with relatively small contributions from the Taiwan, Zhejiang, and Fujian rivers. The grain-size compositions are predominantly silt and clay (>90%), with minor sand, and the clay mineral assemblages consist of primarily illite, smectite, and chlorite, with moderate kaolinite. Both the clay mineral assemblage and grain-size compositions inferred from both end-member (EM) modeling and standard deviation analysis provide indirect indicators to reveal the East Asian monsoon variations, realized mainly through the current transport processes. The decreased smectite/(illite + chlorite) ratios since the 1850s represent a relatively long-term weakened East Asian winter monsoon (EAWM), while the overall decreased mean grain-size of the fine sensitive component and EM3/(EM1 + EM2) ratio during the 1850s–1950s also implies a gradually weakened EAWM associated with the synchronously weakened Zhe-Min Coastal Current. These sedimentary records of the East Asian monsoon variations can be compared with numerous published paleoclimate records. However, the largely increased mean grain-size of the fine sensitive component and EM3/(EM1 + EM2) ratios since the 1950s indicates a false strengthened EAWM signal, which conflicts with instrumental data and the clay mineralogy record. This observation, coupled with the coarsened terrigenous grain-size and reduced terrigenous fluxes (decreased Ti/Ca ratios), is mainly attributed to intense anthropogenic influences associated mainly with dam proliferation. Therefore, disturbed climate change information preserved in the terrigenous sediments can be linked to increased anthropogenic activities, perhaps representing an additional feature during the Anthropocene epoch. • Both clay mineral and grain-size provide indicators for revealing the East Asian monsoon variations in the TS before the 1950s. • Decreasing terrigenous fluxes and coarsening grain-size are observed in the TS since the 1950s associated with dam proliferation. • Climate change signals preserved in terrigenous sediment have been disturbed since the 1950s because of intense human activities. • Sedimentary proxies for climate changes since the 1950s mixed with anthropogenic signals should be questioned and suspected. [ABSTRACT FROM AUTHOR]

The recent encroachment of woody species threatening many western North American meadows has been attributed to diverse factors. We used a suite of methods in Chittenden Meadow, southwestern British Columbia, Canada, to identify the human, ecological, and physical factors responsible for its historical dynamics and current encroachment by woody vegetation. We evaluated three hypotheses about the origin and processes maintaining the meadow: the meadow is (1) of recent human origin; (2) of ancient human origin, maintained by aboriginal burning; and (3) of ancient non-human origin, not maintained by aboriginal burning. Our data supported the idea that the meadow had ancient non-human origins and its recent history and current status have resulted from complex interactions among landform, climate, and fire. Soil properties (both horizonation and charcoal content) indicate that the meadow is of ancient, non-human origin. Tree ages in the meadow and surrounding forest indicate that encroachment is recent, not related to a variety of recent human activities, and is probably a result of increasing spring temperature and decreasing spring snow depth. Although ethnographic surveys and historical documents revealed indigenous use of the general area over millennia, including the use of fire as a management tool, we found little direct evidence of indigenous use of the meadow. However, there was no proxy record of fire frequency in the meadow that we could have used to determine the role of fire in maintaining the meadow in the past, or the role of humans in igniting those fires. Thus, the historical role of humans in the maintenance of the meadow by prescribed fire remains indeterminate. Based on these conclusions, we combined hypotheses (2) and (3) into an a posteriori hypothesis that reflects changing interactions among people, fire, and climate over time. Without management intervention, we expect that tree encroachment will continue. Several general lessons emerge from our study of Chittenden Meadow. A single modern ecosystem condition may result from diverse antecedents, but ecosystems may not carry a memory of all the processes driving their historical dynamics. The historical role of indigenous reource management activities may be one such process: despite millennia of human occupation and resource use in the region, local First Nations left only a light footprint on Chittenden Meadow. Finally, there is value and challenge in integrating data and perspectives from different disciplines.

• Mountain lakes are affected by global change, but lack ecological indicators. • Community responses were evaluated using diatom archives from lake sediments. • Different indicator taxa revealed diverse responses related to altitude and depth. • Most pronounced and non-linear responses occurred in high-altitude shallow lakes. • Resilience was greatest in deep montane lakes compared to four other lake types. Alpine mountain lake biota are adapted to harsh conditions making them particularly vulnerable to global change. However, as each mountain lake has a different limnology, there are supposed to be differential responses and degrees of resilience to climate change. In this study, 23 lakes in the Bavarian-Tyrolian Alps differing in altitude, size and geology were examined for their diatom community response to climate warming. Subfossil data were related to 210Pb and 137Cs-dated sediment cores. Correspondence and regression analyses revealed five different assemblage developments depending on lake depth, altitude and origin. Planktic species, especially Cyclotella , dominated deeper and lower-altitude mountain lakes earlier and stronger. This depends on the stability and temperature of the epilimnion which in turn determines the tipping point. Instead, shallow lakes exhibit higher species reorganizations of diatom assemblages. Mountain lakes of lower altitudes or affected by water level fluctuations (WLF) establish complex substrata and Achnanthidium accompanied by epiphytic species or Denticula tenuis in WLF-lakes replace dominating Staurosira. Conversely, alpine shallow lakes lack directional shifts and Staurosira dominate, but approach the tipping point of macrophyte establishment. In a deep doline lake, Diploneis species replace Nitzschia denticula with negligible planktic proportions. In mountain lakes with direct anthropogenic influence, enhanced nutrient supply disguises diatom response to global warming. These findings revealed deep mountain lakes with low nutrient levels to be more resilient to climate change than shallow lakes with a higher trophic status as the onset of the response to rising temperatures is earlier and thus smoother. In conclusion, subfossil diatom analyses can provide a powerful tool for climate change assessment and other anthropogenic impacts on mountain lakes. [ABSTRACT FROM AUTHOR]