Regional Environmental Change Research Articles

Palaeoenvironmental proxies indicate long-term development of agro-pastoralist landscapes in Inner Asian mountains

A growing body of archaeological research on agro-pastoralist populations of the Inner Asian mountains indicates that these groups adapted various systems of mobile herding and cultivation to ecotopes across the region from as early as 5000 BP. It has been argued that these adaptations allowed the development of flexible social-ecological systems well suited to the long-term management of these mountain landscapes. At present, less attention has been paid to examining the long-term ecological legacy of these adaptations within the sedimentary or palaeoenvironmental record. Here we present sediment, palynomorph and charcoal data that we interpret as indicating agro-pastoralist environmental perturbations, taken from three cores at middle and high altitudes in the Kashmir Valley at the southern end of the Inner Asian mountains. Our data indicate spatially and temporally discontinuous patterns of agro-pastoralist land use beginning close to 4000 BP. Periods of intensification of upland herding are often coincident with phases of regional social or environmental change, in particular we find the strongest signals for agro-pastoralism in the environmental record contemporary with regionally arid conditions. These patterns support previous arguments that specialised agro-pastoralist ecologies across the region are well placed to respond to past and future climate deteriorations. Our data indicating long-term co-evolution of humans and landscape in the study area also have implications for the ongoing management of environments generally perceived as “pristine” or “wilderness”.

Potentially toxic elements in cascade dams-influenced river originated from Tibetan Plateau

Rivers originated from Tibetan Plateau are of great significance due to their environmental sensibility and fragility. However, the pollution of suspended particulate matter (SPM) in these rivers is rarely reported, in particular, the potentially toxic elements (PTEs) contamination. To clarify the status, sources, behavior, and risks of PTEs in SPM, a full investigation was conducted in dams-influenced Lancangjiang River basin. The findings revealed that the PTEs content (mg kg−1) ranked Mn (766) > V (151.7) > Zn (131.0) > Cr (94.6) > Ni (44.2) > Pb (36.7) > Cu (29.4) > Co (14.6) > Sb (2.6) > Mo (1.6) > Tl (0.78) > Cd (0.48). The multi-index assessment suggested that Sb and Cd were moderately severe to severe enriched PTEs with the enrichment factor values of 10.0 and 8.8 and the geo-accumulation index values of 2.2 and 2.0, respectively, while the rest of PTEs were minor/no enrichment. In contrast, Cr and Ni were major toxic elements in SPM which contributed 25 ± 10%, 24 ± 8% to the total toxic risk index. The high partition coefficients (e.g., 6.1 for Cr) were observed in most PTEs and resulted in the 96.3% of Cr, 85.2% of Zn, 83.6% of Pb, 77.8% of Ni, and 63.2% of Cu transportation in the SPM form. Natural inputs (e.g., soil erosion) are the main source (53.6%∼61.9%) of V, Cr, Mn, Co, Ni, and Tl, while fuel burning contributed 40.9% of Zn, 32.5% of Pb, and 37.3% of Cd. Moreover, 51.2% of Sb was attributed to industrial waste source, while porphyry copper/molybdenum deposits related milltailings were the co-source of Mo (54.4%) and Cu (34.8%). Overall, the PTEs geochemistry of SPM showed the potential in tracing regional environmental change.

Method for monitoring regional environmental temperature change data based on 5G internet of things technology

Method for monitoring regional environmental temperature change data based on 5G internet of things technology

Inuvialuit knowledge of Pacific salmon range expansion in the western Canadian Arctic

Rapid climate change is altering Arctic ecosystems and significantly affecting the livelihoods and cultural traditions of Arctic Indigenous peoples. In the Inuvialuit Settlement Region (ISR), growing evidence suggests that climate change is altering marine environments. In this project we recorded and synthesized Inuvialuit knowledge of Pacific salmon. We used methods that are emergent in fisheries science to combine interview information with voluntary harvest data and better understand changes to salmon in the Arctic. We conducted 53 interviews with Inuvialuit fishers about the history of Pacific salmon harvest, how it has changed in recent decades, and concurrent changes to local environments and fish species. Our interviews show that historical, incidental salmon harvest in the ISR ranged from infrequent to common among western communities, but was rare or unprecedented among eastern communities. Participants in all six communities reported a recent increase in salmon harvest and attributed this shift to regional environmental change. Fishers were concerned that salmon would negatively affect their cultural traditions and preferred fish species. Given uncertainty about the effects of salmon on local fisheries, research on salmon in the Arctic, the likelihood of their establishment, and their potential to provide subsidies to Arctic freshwater ecosystems is vital.

Holocene Environmental Changes Inferred From an Aeolian-Palaeosol-Lacustrine Profile in the Mu Us Desert, Northern China

An excavated profile of aeolian-palaeosol-lacustrine sediments (the Wapianliang profile), located at the southeastern part of the Mu Us Desert, Northern China, was studied to reconstruct regional Holocene environmental changes. A chronology was established based on three AMS 14C and two OSL dates, and variations in the lithology and grain size, magnetic susceptibility, soil micromorphology, and chemical elements were used to explore the regional depositional environments during the Holocene. The results showed that since around 14 ka BP, this region had experienced seven alternations of wetting and drying. A shallow lake, which was identified by celadon lacustrine sediments with sporadic freshwater gastropod fossils, occurred in this area from around 13.0 ka BP to 9.9 ka BP. There existed two obvious intervals of soil formation, inferred from the environmental proxies of the palaeosol/sandy palaeosol layers, with relatively fine average grain-size, high magnetic susceptibility value, remarkable pedogenesis features, and strong chemical weathering, in particular, a well-developed palaeosol layer dating from the middle Holocene (8.6 ka BP to 4.2 ka BP). A weakly-developed palaeosol layer (from around 1.2 ka BP) at the upper part of the profile is possibly an indication of the Medieval Warm Period. This implies a forest steppe environment at both of these sedimentary stages. After 0.9 ka BP, a desert environment returned, analogous to before around 13.0 ± 1.4 ka BP, between 9.9 ± 1.1 ka BP to 8.6 ka BP, and between 4.2 ka BP to 1.6 ka BP, indicating the aggravation of aeolian activity and the expansion of mobile sand dunes. The variations in sedimentary environments were mainly triggered by changes in the East Asian Summer Monsoon (EASM).

Wind Features Extracted from Weather Simulations for Wind-Wave Prediction Using High-Resolution Neural Networks

Nearshore wave forecasting is susceptible to changes in regional wind fields and environments. However, surface wind field changes are difficult to determine due to the lack of in situ observational data. Therefore, accurate wind and coastal wave forecasts during typhoon periods are necessary. The purpose of this study is to develop artificial intelligence (AI)-based techniques for forecasting wind–wave processes near coastal areas during typhoons. The proposed integrated models employ combined a numerical weather prediction (NWP) model and AI techniques, namely numerical (NUM)-AI-based wind–wave prediction models. This hybrid model comprising VGGNNet and High-Resolution Network (HRNet) was integrated with recurrent-based gated recurrent unit (GRU). Termed mVHR_GRU, this model was constructed using a convolutional layer for extracting features from spatial images with high-to-low resolution and a recurrent GRU model for time series prediction. To investigate the potential of mVHR_GRU for wind–wave prediction, VGGNet, HRNet, and Two-Step Wind-Wave Prediction (TSWP) were selected as benchmark models. The coastal waters in northeast Taiwan were the study area. The length of the forecast horizon was from 1 to 6 h. The mVHR_GRU model outperformed the HR_GRU, VGGNet, and TSWP models according to the error indicators. The coefficient of mVHR_GRU efficiency improved by 13% to 18% and by 13% to 15% at the Longdong and Guishandao buoys, respectively. In addition, in a comparison of the NUM–AI-based model and a numerical model simulating waves nearshore (SWAN), the SWAN model generated greater errors than the NUM–AI-based model. The results of the NUM–AI-based wind–wave prediction model were in favorable accordance with the observed results, indicating the feasibility of the established model in processing spatial data.

Statistical climate model downscaling for impact projections in the Midwest United States

AbstractFor future climate projections to be useful they must be actionable at the local level. In this study, we develop daily temperature and precipitation climate scenarios suitable for use in projections of drought, energy use, water use, and crop production. We investigate the magnitude of future changes to air temperature and precipitation in the Midwest United States in response to three future climate change scenarios. Results are used to assess changes to incidence of precipitation extremes and human comfort (using heat index) associated with the anticipated climate changes in the region. We use self‐organizing maps and random forest based techniques to generate daily realizations of temperature and precipitation for 279 weather stations in a region centred on Illinois. We determine that the random forest model performs best for maximum and minimum temperatures, while the self‐organizing map performs best for precipitation. Using nine models from the Coupled Model Inter‐Comparison Project Phase 5, downscaled daily temperature and precipitation values are generated for low, moderate, and high greenhouse gas emissions scenarios for historical and future periods. Based on recent trends, we focus our results on the high emissions scenario, and show an average increase of 4.3°C in maximum daily air temperature across the region for the 2071–2100 period. Precipitation decreases by up to 15% in the southern half of the study region, with a similar percentage increase in the northern half of the region. The regional environmental changes result in an increase of 5.8° in average summer heat index, and increase of 48% in the number of days likely to produce extreme heat, and a decrease in the average value of the standardized precipitation and evapotranspiration index of 1.9 (indicating increased drought) across the region by 2100.

Ground-based vertical profile observations of atmospheric composition on the Tibetan Plateau (2017–2019)

Abstract. The Tibetan Plateau (TP) plays an essential role in modulating regional and global climate, and its influence on climate is also affected by human-related processes, including changes in atmospheric composition. However, observations of atmospheric composition, especially vertical profile observations, remain sparse and rare on the TP, due to extremely high altitude, topographical heterogeneity and the grinding environment. Accordingly, the forcing and feedback of atmospheric composition from rapidly changing surrounding regions to regional environmental and climate change in the TP remains poorly understood. This paper introduces a high-time-resolution (∼15 min) vertical profile observational dataset of atmospheric composition (aerosols, NO2, HCHO and HONO) on the TP for more than 1 year (2017–2019) using a passive remote sensing technique. The diurnal pattern, vertical distribution and seasonal variations of these pollutants are documented here in detail. The sharing of this dataset would benefit the scientific community in exploring source–receptor relationships and the forcing and feedback of atmospheric composition on the TP to the regional and global climate. It also provides potential to improve satellite retrievals and to facilitate the development and improvement of models in cold regions. The dataset is freely available at Zenodo (https://doi.org/10.5281/zenodo.5336460; Xing, 2021).

Vegetation history of SE Sicily from feudal land management to post-war agricultural industrialization

A new marine pollen record from SE Sicily is presented. The pollen study was done at a sub-decadal resolution to assess the role and extent of human impact in driving regional environmental and land cover changes over the last four hundred years. The combination of palaeoecological evidence and historical documents provides a detailed report of the main ecological dynamics in relation to socio-economic events, past land use, and land management regulations in Sicily. Our palaeovegetational reconstruction reveals a remarkably stable landscape, preserved by traditional land use practices that have persisted through the long-lasting feudal history of Sicily. After centuries of human-induced environmental stability, an abrupt change in vegetation structure occurred around 1950 AD, reflecting the modern land use policies and agricultural reforms following the Second World War. This vegetational breakpoint in SE Sicily corresponds to a suggested date for the onset of the Anthropocene.

Host–symbiont transcriptomic changes during natural bleaching and recovery in the leaf coral Pavona decussata

Coral bleaching has become a major threat to coral reefs worldwide, but for most coral species little is known about their resilience to environmental changes. We aimed to understand the gene expressional regulation underlying natural bleaching and recovery in Pavona decussata, a dominant species of scleractinian coral in the northern South China Sea. Analyzing samples collected in 2017 from the field revealed distinct zooxanthellae density, chlorophyll a concentration and transcriptomic signatures corresponding to changes in health conditions of the coral holobiont. In the host, normal-looking tissues of partially bleached colonies were frontloaded with stress responsive genes, as indicated by upregulation of immune defense, response to endoplasmic reticulum, and oxidative stress genes. Bleaching was characterized by upregulation of apoptosis-related genes which could cause a reduction in algal symbionts, and downregulation of genes involved in stress responses and metabolic processes. The transcription factors stat5b and irf1 played key roles in bleaching by regulating immune and apoptosis pathways. Recovery from bleaching was characterized by enrichment of pathways involved in mitosis, DNA replication, and recombination for tissue repairing, as well as restoration of energy and metabolism. In the symbionts, bleaching corresponded to imbalance in photosystems I and II activities which enhanced oxidative stress and limited energy production and nutrient assimilation. Overall, our study revealed distinct gene expressional profiles and regulation in the different phases of the bleaching and recovery process, and provided new insight into the molecular mechanisms underlying the holobiont's resilience that may determine the species’ fate in response to global and regional environmental changes.

Speleothem Records of the Hydroclimate Variability throughout the Last Glacial Cycle from Manita peć Cave (Velebit Mountain, Croatia)

We present stable carbon (δ13C) and oxygen (δ18O) isotope records from two partially coeval speleothems from Manita peć Cave, Croatia. The cave is located close to the Adriatic coast (3.7 km) at an elevation of 570 m a.s.l. The site experienced competing Mediterranean and continental climate influences throughout the last glacial cycle and was situated close to the ice limit during the glacial phases. U-Th dating constrains the growth history from Marine Isotope Stage (MIS) 5 to MIS 3 and the transition from MIS 2 to MIS 1. 14C dating was used to estimate the age of the youngest part of one stalagmite found to be rich in detrital thorium and thus undatable by U-Th. On a millennial scale, δ18O variations partly mimic the Dansgaard–Oeschger interstadials recorded in Greenland ice cores (Greenland Interstadials, GI) from GI 22 to GI 13. We interpret our δ18O record as a proxy for variations in precipitation amount and/or moisture sources, and the δ13C record is interpreted as a proxy for changes in soil bioproductivity. The latter indicates a generally reduced vegetation cover towards MIS 3–MIS 4, with shifts of ~8‰ and approaching values close to those of the host rock. However, even during the coldest phases, when a periglacial setting and enhanced aridity sustained long-residence-time groundwater, carbonic-acid dissolution remains the driving force of the karstification processes. Speleothem morphology follows changes in environmental conditions and complements regional results of submerged speleothems findings. Specifically, narrow sections of light porous spelaean calcite precipitated during the glacial/stadial sea-level lowstands, while the warmer and wetter conditions were marked with compact calcite and hiatuses in submerged speleothems due to sea-level highstands. Presumably, the transformation of this littoral site to a continental one with somewhat higher amounts of orographic precipitation was a site-specific effect that masked regional environmental changes.

Late Holocene climate anomaly concurrent with fire activity and ecosystem shifts in the eastern Australian Highlands

The alpine area of the Australian mainland is highly sensitive to climate and environmental change, and potentially vulnerable to ecosystem tipping points. Over the next two decades the Australian alpine region is predicted to experience temperature increases of at least 1 °C, coupled with a substantial decrease in snow cover. Extending the short instrumental record in these regions is imperative to put future change into context, and potentially provide analogues of warming. We reconstructed past temperatures, using a lipid biomarker palaeothermometer technique and mercury flux changes for the past 3500 years from the sediments of Club Lake, a high-altitude alpine tarn in the Snowy Mountains, southeastern Australia. Using a multi-proxy framework, including pollen and charcoal analyses, high-resolution geochemistry, and ancient microbial community composition, supported by high-resolution 210Pb and AMS 14C dating, we investigated local and regional ecological and environmental changes occurring in response to changes in temperature. We find the region experienced a general warming trend over the last 3500 years, with a pronounced climate anomaly occurring between 1000 and 1600 cal yrs. BP. Shifts in vegetation took place during this warm period, characterised by a decline in alpine species and an increase in open woodland taxa which co-occurred with an increase in regional fire activity. Given the narrow altitudinal band of Australian alpine vegetation, any future warming has the potential to result in the extinction of alpine species, including several endemic to the area, as treelines are driven to higher elevations. These findings suggest ongoing conservation efforts will be needed to protect the vulnerable alpine environments from the combined threats of climate changes, fire and invasive species.

Degradation and Aging of Terrestrial Organic Carbon within Estuaries: Biogeochemical and Environmental Implications.

Estuaries are action zones for organic carbon (OC) degradation and aging. These processes influence the nature of terrestrial OC (OCterr) export and the magnitude of OCterr burial in marginal seas, with important environmental implications such as CO2 release and hypoxia. In this study, we determined the contents and carbon isotopic compositions (13C and 14C) of bulk OC and fatty acids (FAs) as well as the sedimentological characteristics of suspended particulate matter (SPM) samples collected from two sites over four seasons and of surface sediment samples from three sites in the Pearl River estuary (PRE) to evaluate processes controlling OCterr degradation and aging along an estuarine gradient. We found that the abundance-weighted average C24-32FA 14C ages increased by an average of ∼1170 years for SPM and by an average of ∼3440 years in PR/PRE sediments, along the ∼60 km PRE transect. These increases in the FA age coincided with an 86% decrease in the corresponding mineral surface area-normalized FA loading along the sediment transport pathway, implying that selective degradation of labile and younger OC resulted in apparent OC aging. These measurements reveal an important shift in the nature of OC, with implications for biogeochemical cycling within estuaries and for regional environmental changes.

Emerging Trends and New Improvements in Stadiums and URBAN DEVELOPMENT Using Cite Space Visualization

Purpose: The stadiums play an important role in the development of a city. It is not only the place to hold sport events, but also an important regulating factor for the development of a city. Under the theme of sustain-able development, how to develop stadiums to play the biggest role in urban development is the topic. This paper aims to make stadium become the driving force of regional environmental change, and provide necessary condi-tions for urban regeneration and renewal, so as to drive the realization of sustainable development of the city through urban renewal and upgrading. Method: In this paper, CiteSpace 5.7.R5 was used as the research tool, the core database of Web of Science was selected as the literature source, the stadiums or venues and urban development and Olympic legacy were taken as the search terms, and the literature type was set as literature. A total of 1912 literature from 2010 to 2021 were selected for visualized analysis to draw the knowledge map of stadiums and urban development, and the number of published papers, institutions and research hotspots of related research on stadiums and urban development were studied. Results: Firstly, according to the published number of related research on the stadiums and urban develop-ment from 2010 to 2021, this period presented three different stages. The number of literature published on topics related to stadiums and urban development from 2010 to 2015 was relatively stable. From 2016 to 2018, the research on stadiums and urban development showed a sharp decrease, and the research enthusiasm began to decline. Between 2018 and 2021, the number of studies gradually increased and reached the highest number. Then, universities at home and abroad were the main research institutions on stadiums and urban development, and kept a continuous focus on this topic. Finally, the research focus in this field focused on the construction and development of stadiums, mega sport events and stadiums and the relationship between stadiums and urban development from architecture and city and link of stadiums, city and mega sport event. Conclusion: From 2010 to 2021, domestic and foreign scholars maintained a certain amount of enthusiasm in the research on stadiums and urban development, with a large number of research results. With the holding of the Olympic Games, the number of literature also increases, which provides reference resources for the follow-up research on the stadium and urban development. Second, universities at home and aboard have conducted more research on stadiums and urban development than other types of institutions. Finally, the research hotspots on stadium and urban development focuses on the analysis of the construction and development of stadium from different perspectives, mega sport events, and the relationship between stadiums and urban development from architecture and city and link of stadiums, city and mega sport event.

Disaggregating climatic and anthropogenic influences on vegetation changes in Beijing-Tianjin-Hebei region of China

The Beijing-Tianjin-Hebei (BTH) region of China is a typical area where both population and economy have been increasing rapidly in recent decades. The rapid economic development and population increase also bring severe environmental stresses. To better understand the factors that contribute to the regional ecological environment change, this study aims to disaggregate the effects of climate and human activity on vegetation dynamics based on a vegetation index derived from remote sensing for the BTH region through time. First, we implemented a linear regression analysis on the Enhanced Vegetation Index (EVI) in the BTH region from 2001 to 2015. We found vegetation greening mainly occurred in the mountainous area in the north and the west of the BTH region, where the forests and grasslands dominate, and the vegetation browning was mainly distributed in the southeast, where the built-up lands and croplands were located. Then, we used the Random Forest (RF) regression model to rank the importance of the climatic and anthropogenic factors. The results showed that temperature was the most influential factor among our climate variables while land cover dominated the anthropogenic variables. Finally, this study applied the RF model to disaggregate the climatic effects from that of the anthropogenic effects on vegetation dynamics by keeping human-activity- or climate-related variables constant. It showed that the method was capable of quantifying climatic and anthropogenic effects on vegetation changes. This study also found that the N deposition significantly negatively correlated with the vegetation growth trend in BTH. The approach this study proposed advanced our understanding of the driving factors of vegetation dynamics, and the approach is applicable elsewhere.

Low diversity of a key phytoplankton group along the West Antarctic Peninsula

The West Antarctic Peninsula (henceforth “Peninsula”) is experiencing rapid warming and melting that is impacting the regional marine food web. The primary phytoplankton groups along the Peninsula are diatoms and cryptophytes. Relative to diatoms, there has been little focus on regional cryptophytes, and thus our understanding of their diversity and ecology is limited, especially at the species level. This gap is important, as diatoms and cryptophytes play distinct roles in the regional marine food web and biogeochemistry. Here, we use a phylogenetic placement approach with 18S rRNA gene amplicon sequence variants to assess surface ocean cryptophyte diversity and its drivers at a high taxonomic resolution along the Peninsula. Data were collected over 5 years (2012–2016) during the regional research cruises of the Palmer Long‐Term Ecological Research program. Our results indicate that there are two major cryptophyte taxa along the Peninsula, consisting of distinct Geminigera spp., which in aggregate always comprise nearly 100% of the cryptophyte community (indicating low taxa evenness). The primary taxon dominates the cryptophyte community across all samples/years, which span a broad range of oceanographic conditions. A shift in cryptophyte community composition between a lower (higher) primary (secondary) taxon percentage is associated with distinct oceanographic conditions, including lower (higher) temperature, salinity, nutrients, and cryptophyte relative abundance (phytoplankton biomass and diatom relative abundance). These results emphasize the need for a full characterization of the ecology of these two taxa, as it is predicted that cryptophytes will increase along the Peninsula given projections of continued regional environmental change.

Research on the Temporal and Spatial Changes Characteristics of the Drought of Natural Vegetation in the Yangtze River Source Area Based on CWSI

Under the combined effect of global climate change and local regional environmental change, drought has developed into a natural disaster with high incidence on the earth. As the Yangtze River is the mother river of Chinese civilization, the drought phenomenon in the source area in recent decades has seriously affected and restricted the development of local agriculture and economic society. With the long-term practice of remote sensing technology, researchers have improved drought monitoring methods, including crop water stress index. Crop water stress index (CWSI) is widely used in agricultural drought research based on the principle of heat balance. In this paper, the spatial and temporal characteristics of drought in the Yangtze River source area and its influencing factors were analyzed by using crop drought index method. The CWSI value of the source area of the Yangtze River featured a slightly downward trend from 2001 to 2018. With a strong spatial heterogeneity in distribution, it gradually decreases from west to east. The severest drought occurs in summer and autumn, and the regions that are mostly influenced by temperature are mainly in southwest part and the ones mostly influenced by precipitation are mainly in east part. By analyzing the temporal and spatial distribution characteristics of drought and the correlation of meteorological factors, this paper provides an effective basis for drought prevention and control in the Yangtze River source area, and then promotes the accelerated development of agriculture and economic society in the Yangtze River source area of our country.

Latest Holocene paleoenvironmental and paleoclimate reconstruction from an alpine bog in the Western Mediterranean region: The Borreguil de los Lavaderos de la Reina record (Sierra Nevada)

Several organic and inorganic geochemical analyses have been carried out in the sedimentary record of the Borreguil de los Lavaderos de la Reina (BdlR-03), an alpine peat bog located on the north face of the Sierra Nevada (southern Iberian Peninsula). This study permitted a high-resolution reconstruction of paleoenvironmental evolution for the last ~2700 cal yr BP in the highest mountain range of southern Iberian Peninsula. An overall trend towards a climatic aridification and a reduction of aquatic environments is observed in this record. Insolation and long-term positive North Atlantic Oscillation trends were the most important factors controlling this aridification, forcing regional and local environmental changes. Four phases are differentiated within the paleoenvironmental evolution of BdlR-03: (1) a pre-bog environment from 2700 to 2600 cal yr BP with important siliciclastic sedimentation and low organic content; (2) a bog environment with important presence of terrestrial vascular plant, water availability and maximum humid conditions between ~2600 and ~1870 cal yr BP, coinciding with the Iberian-Roman Humid Period; (3) a subsequent drier bog environment, between ~1870 and ~300 cal yr BP during the Dark Ages, the Medieval Climate Anomaly and the first stages of the Little Ice Age, characterized by lower productivity that affected the development of terrestrial vascular plants and aquatic environments; and (4) a wetland environment with an increase of aquatic algae, development of ephemeral pools and unstable climate conditions between ~300 cal yr BP and the present, coinciding with the final stages of the Little Ice Age and the Modern Global Warming. This recent environmental pattern, which is opposite to the general aridification trend in the western Mediterranean, is likely explained by the gradual melting of the perennial ice and/or snow packs at higher elevations in the last centuries. Aeolian inputs would have continuously contributed nutrients to these nutrient-impoverished alpine environments. High dust inputs are especially noticed during the last ~200 years, which can be explained by human-induced enhanced aridification and the development of the commercial agriculture in some North African regions. In addition, the environmental signal in the last century seems to be significantly affected by human activities.

The Sr-Nd isotope geochemical tracing of Xiashu Loess and its implications for the material transport mechanism of the Yangtze River

The Xiashu Loess along the middle and lower reaches of the Yangtze River in China is of considerable significance for revealing regional and global climatic and environmental changes since the middle Pleistocene. This study used Sr-Nd isotopic in three different particle fractions (<2 μm, 2–75 μm and >75 μm) to investigate the provenance of Zhoujiashan Xiashu Loess in China, which is essential for understanding the paleoenvironmental conditions. The εNd(0) value ranges from −10.2 to −13.4, and the 87Sr/86Sr ratio value varies from 0.714120 to 0.750325. As particle size increases, the εNd(0) value of the loess does not change significantly, and the 87Sr/86Sr ratio value of the loess decreases significantly. The 87Sr/86Sr ratio and εNd(0) value show a negative correlation. The εNd(0) values of the Xiashu Loess in different fractions are similar to those of the sediments in the Yangtze River and lower than that of loess from the Lingtai section in Northern China, which suggests that both coarse and fine dust come from the nearby river valley. The temporal variation in the Sr-Nd isotopic composition of loess from Zhoujiashan during the past 0.9 Ma reflects the material transport mechanism of the Yangtze River Basin may be the main cause of the aeolian deposition under the influence of the monsoon climate. Therefore, we suggest that the material transport mechanism has been driven by regional climate change in the Yangtze River Basin since 0.9 Ma, and this mechanism is the main reason for aeolian deposition.

Growing at the limit: Reef growth sensitivity to climate and oceanographic changes in the South Western Atlantic

Whilst the impacts of climatic and oceanographic change on lower latitude reefs are increasingly well documented, our understanding of how reef-building has fluctuated in higher latitude settings remains limited. Here, we explore the timing and longevity of reef-building through the mid- to late Holocene in the most southerly known reef (24°S) in the Western Atlantic. Reef core data show that reef growth was driven by a single coral species, Madracis decactis, and occurred over two phases since ~6000 calibrated (cal.) yr B.P.. These records further indicate that there was a clear growth hiatus from ~5500 to 2500 cal. yr B.P., and that there is no evidence of reef accretion on the Queimada Grande Reef (QGR) over the past 2000 yrs. It thus presently exists as a submerged senescent structure colonized largely by non-reef building organisms. Integration of these growth data with those from sites further north (18°S and 21°S) suggests that Intertropical Convergence Zone (ITCZ), South Westerlies Winds (SWW) and El Niño-Southern Oscillation (ENSO) variability and shifts during the Holocene drove changes in the position of the Brazil-Falklands/Malvinas Confluence (BFMC), and that this has had a strong regional influence on the timing and longevity of reef growth. Our results add new evidence to the idea that reef growth in marginal settings can rapidly turn-on or -off according to regional environmental changes, and thus are of relevance for predicting high latitude reef growth potential under climate change.