Extreme Climatic Fluctuations Research Articles

Evaluating dynamic modulus of cold in-place recycling mixture with foamed bitumen using field core samples

This study evaluates the dynamic modulus of Cold In-Place Recycling with Foamed Bitumen (FB-CIR) pavements, focusing on the influence of various recycled materials—reclaimed asphalt pavement (RAP), reclaimed inorganic binder stabilized aggregate (RAI), and their combination (RAP+RAI). Core samples from three representative FB-CIR projects in China were tested using the MTS-130 system across temperatures of −10°C, 5°C, 20°C, 35°C, and 50°C, and frequencies ranging from 25 Hz to 0.1 Hz. Statistical analysis and the Sigmoidal model were employed to analyze the viscoelastic behavior and establish the master curve for the FB-CIR dynamic modulus. The dynamic modulus of the three FB-CIR mixtures showed pronounced frequency-dependence, decreasing with reduced frequencies, and exhibited temperature sensitivity, with lower values at elevated temperatures. FB-RAI consistently demonstrated higher modulus values due to the hydration of previously unhydrated cement particles, while FB-RAP and FB-RAP+RAI displayed lower values, as RAP behaves similarly to unbound granular material. The construction of the master curve, based on the time-temperature superposition principle, enhanced our understanding of FB-CIR mixtures' mechanical behavior and enabled accurate extrapolation of dynamic modulus values across diverse conditions. Furthermore, FB-RAI's narrow phase angle variation indicates its superior mechanical stability and reduced sensitivity to external changes, making it ideal for areas with extreme climate fluctuations or heavy traffic. The study also identified three distinct phase angle variation patterns in FB-CIR mixtures, underscoring the importance of nuanced pavement design strategies that consider temperature, frequency, and material composition to optimize the performance and durability of FB-CIR pavements.

Monitoring plant responses in field-grown peanuts exposed to exogenously applied chitosan under full and limited irrigation levels

In recent decades, numerous studies have examined the effects of climate change on the responses of plants. These studies have primarily examined the effects of solitary stress on plants, neglecting the simultaneous effects of mixed stress, which are anticipated to transpire frequently as a result of the extreme climatic fluctuations. Therefore, this study investigated the impact of applied chitosan on boosting the resistance responses of peanuts to alkali and mixed drought-alkali stresses. Peanuts were grown in mid-alkaline soil and irrigated with full irrigation water requirements (100%IR), represented alkali condition (100% IR × alkali soil) and stress conditions (70% IR × alkali soil—represented mixed drought-alkali conditions). Additionally, the plants were either untreated or treated with foliar chitosan. The study evaluated various plant physio-chemical characteristics, including element contents (leaves and roots), seed yield, and irrigation water use efficiency (IWUE). Plants that experienced solitary alkali stress were found to be more vulnerable. However, chitosan applications were effective for reducing (soil pH and sodium absorption), alongside promoting examined physio-chemical measurements, yield traits, and IWUE. Importantly, when chitosan was applied under alkali conditions, the accumulations of (phosphorus, calcium, iron, manganese, zinc, and copper) in leaves and roots were maximized. Under mixed drought-alkali stresses, the results revealed a reduction in yield, reaching about 5.1 and 5.8% lower than under (100% IR × alkali), in the first and second seasons, respectively. Interestingly, treated plants under mixed drought-alkali stresses with chitosan recorded highest values of relative water content, proline, yield, IWUE, and nutrient uptake of (nitrogen, potassium, and magnesium) as well as the lowest sodium content in leaves and roots. Enhances the accumulation of (N, K, and Mg) instead of (phosphorus, calcium, iron, manganese, zinc, and copper) was the primary plant response to chitosan applications, which averted severe damage caused by mixed drought-alkali conditions, over time. These findings provide a framework of the nutrient homeostasis changes induced by chitosan under mixed stresses. Based on the findings, it is recommended under mixed drought-alkali conditions to treat plants with chitosan. This approach offers a promising perspective for achieving optimal yield with reduced water usage.

Resilience of an Urban Coastal Ecosystem in the Caribbean: A Remote Sensing Approach in Western Puerto Rico

Utilization of remote sensing-derived meteorological data is a valuable alternative for tropical insular territories such as Puerto Rico (PR). The study of ecosystem resilience in insular territories is an underdeveloped area of investigation. Little research has focused on studying how an ecosystem in PR responds to and recovers from unique meteorological events (e.g., hurricanes). This work aims to investigate how an ecosystem in Western Puerto Rico responds to extreme climate events and fluctuations, with a specific focus on evaluating its innate resilience. The Antillean islands in the Caribbean and Atlantic are vulnerable to intense weather phenomena, such as hurricanes. Due to the distinct tropical conditions inherent to this region, and the ongoing urban development of coastal areas, their ecosystems are constantly affected. Key indicators, including gross primary production (GPP), normalized difference vegetation index (NDVI), actual evapotranspiration (ET), and land surface temperature (LST), are examined to comprehend the interplay between these factors within the context of the Culebrinas River Watershed (CRW) ecosystem over the past decade during the peak of hurricane season. Data processing and analyses were performed on datasets provided by Moderate Resolution Imaging Spectroradiometer (MODIS) and Landsat 8–9 OLI TRIS, supplemented by information sourced from Puerto Rico Water and Energy Balance (PRWEB)—a dataset derived from Geostationary Operational Environmental Satellite (GOES) data. The findings revealed a complex interrelationship among atmospheric events and anthropogenic activities within the CRW, a region prone to recurrent atmospheric disruptions. NDVI and ET values from 2015 to 2019 showed the ecosystem’s capacity to recover after a prolonged drought period (2015) and Hurricanes Irma and Maria (2017). In 2015, the NDVI average was 0.79; after Hurricanes Irma and Maria in 2017, the NDVI dropped to 0.6, while in 2019, it had already increased to 0.8. Similarly, average ET values went from 3.2339 kg/m2/day in 2017 to 2.6513 kg/m2/day in 2018. Meanwhile, by 2019, the average ET was estimated to be 3.8105 kg/m2/day. Data geoprocessing of LST, NDVI, GPP, and ET, coupled with correlation analyses, revealed positive correlations among ET, NDVI, and GPP. Our results showed that areas with little anthropogenic impact displayed a more rapid and resilient restoration of the ecosystem. The spatial distribution of vegetation and impervious surfaces further highlights that areas closer to mountains have shown higher resilience while urban coastal areas have faced greater challenges in recovering from atmospheric events, thus showing the importance of preserving native vegetation, particularly mangroves, for long-term ecosystem stability. This study contributes to a deeper understanding of the dynamic interactions within urban coastal ecosystems in insular territories, emphasizing their resilience in the context of both natural atmospheric events and human activity. The insights gained from this research offer valuable guidance for managing and safeguarding ecosystems in similar regions characterized by their susceptibility to extreme weather phenomena.

TINY HOUSE IN THE DESERT: A study in indoor comfort using moveable insulation and thermal storage

A tiny house for seasonal rangers was designed for the extreme climate and diurnal temperature fluctuations of Joshua Tree National Park. The challenging climate conditions resulted in an extensive investigation of the building envelope to act as a passive thermal storage system to naturally cool and heat the house. The north wall was designed as a “cold battery,” which uses a dynamic internal and external insulation system with a high-mass concrete wall to achieve coolth absorption at night as part of a thermal management system and to achieve indoor thermal comfort under extreme desert climates. A combination of opening an exterior insulation system at night to absorb coolth, closing the exterior insulation system when the temperature rises, and opening the interior insulation system to release coolth was attempted. The goal was to achieve a comfortable indoor temperature without the use of HVAC systems. Several software programs were tested for their capabilities to simulate time lag in concrete and thermal storage including Opaque and IES VE. The design of the north wall was carried out for different conditions such as different modulating profiles, locations and thicknesses of insulation, and the data were collected and analyzed again. IES VE was able to successfully simulate the effects of moving interior and exterior insulation twice a day on different sides of a concrete wall. In consideration of the special occupancy type, the expansion of the comfort zone for seasonal rangers is achieved by the specification of a comfortable temperature range from 65°F to 85°F. In a standard year, consisting of 8,760 hours, simulations were conducted on the entire residence, primarily during the months when seasonal rangers were present, to investigate thermal comfort conditions. These assessments encompassed various aspects, including ventilation (2,941 comfort hours), the north wall (4,653 comfort hours), the base model (2,883 comfort hours), and enhancements to the south wall (5,543 comfort hours) and the east and west glazed facade (6,137 comfort hours). The culmination of these findings significantly contributed to an enhanced overall comfort experience within the tiny house design, specifically tailored to accommodate the needs of seasonal rangers at Joshua Tree National Park. Natural ventilation proved to be a good strategy.

Uncovering the primary drivers of regional variability in the impact of climate change on wheat yields in China

Responses of wheat yield in different regions to separate and joint changes in mean temperature (Tmean), precipitation (Prec), and solar radiation (Rad) are the foundation for sustainable development under climate change; however, these remain uncertain. Here, we quantified the response of wheat yield variation to changes in Tmean, Prec, and Rad by building multiple regression models, de-trending analysis, and MK trend tests. Multi-site meteorological data was obtained from different wheat growing areas and corresponding wheat yield data from provinces. Our findings showed that the effects of different climatic elements on wheat yield are spatially heterogeneous by region, and the combined effects of climatic elements are higher than those of single elements. Climate change caused an increase of 1% and 4.52% in winter and winter-spring wheat areas, respectively, and a loss of 3.72% in spring wheat areas. In addition, the effect of single meteorological factors on wheat yield varied depending on their rate of change. Rad and Prec are the main drivers of wheat yield variability; in winter, spring and winter-spring wheat areas, Rad significantly impacted wheat yield by 0.89%, −1.18%, and 2.46%, respectively, and Prec caused changes of −0.18%, −1.54%, and 1.33%, respectively. Considering normal and extreme climate fluctuations, we found that the contribution of climate change to wheat yield changes in different wheat-growing regions reached 26.1%, 18.6%, and 16.7%, respectively. Our results indicate that the overall climatic conditions in the spring wheat region are moving in an unfavourable direction, while Prec variability has become the main limiting factor for wheat production in the current winter and winter-spring wheat regions. These comprehensive and detailed findings provide a reference for the development of more accurate adaptation strategies and management measures in different regions. Going forward, the results of this study can be better applied to the development of region-specific climate-smart agricultural practices and extended to other crops and regions to better understand the broader impacts of climate change on global food security.

Dynamic and systemic regulatory mechanisms in rainbow trout (Oncorhynchus mykiss) in response to acute hypoxia and reoxygenation stress

Hypoxia frequently occurs in natural aquatic systems and aquaculture environments due to extreme climate fluctuations, high-density farming, environmental pollution and global warming, resulting in serious ecological damage and enormous economic losses. Rainbow trout (Oncorhynchus mykiss), a key economic fish species worldwide, is extremely sensitive to hypoxia. However, the regulatory mechanisms in response to environmental hypoxia and reoxygenation stress remain unknown. Herein, rainbow trout liver transcriptomes and biochemical parameters were investigated in response to hypoxia for different durations (3, 12 and 24 h), reoxygenation (hypoxia for 24 h followed by reoxygenation for 3 h) and normoxia to highlight dynamic changes in molecular regulation and oxidative stress. In RNA-seq analysis, 5906 differentially expressed genes, two significantly expressed gene sets (profiles 10 and 12) and two hypoxia specific modules (MEgreen and MEturquoise) were screened by differential expression analysis, short time-series expression miner (STEM) and weighted gene co-expression network analysis (WGCNA), respectively. The intersection of the above analyses further identified several key hub genes related to hypoxia, including hif-1α, epo, igfbp1, ddit4, pck1, g6pc, cyp1a1 and dusp1. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses revealed different metabolic strategies at different stress stages; signal transmission and protein synthesis process were strongly influenced by hypoxia. The immune system was inhibited, and a switch from programmed to pathological cell death was observed from hypoxia for 12 h to 24 h. After reoxygenation for 3 h, mitochondrial oxidative phosphorylation was strongly activated to provide more cellular ATP. Enzymatic and non-enzymatic antioxidant systems clearly coordinate to alleviate oxidative stress injury caused by hypoxia. This study reveals dynamic and systemic regulatory mechanisms in rainbow trout liver, and lays a foundation for further study on the molecular mechanisms governing responses to environmental hypoxia and reoxygenation stress.

Comprehensive proteomic analysis to elucidate the anti-heat stress effects of nano-selenium in rainbow trout (Oncorhynchus mykiss)

Because of the continuous intensification of global warming, extreme climate fluctuations, and high-density farming, cold-water rainbow trout (Oncorhynchus mykiss) are exposed to conditions of heat stress, which has severely impacted their survival and yield. Nano-selenium (nano-Se) shows higher biological activity and lower toxicity and has emerged as an ideal and ecological Se formulation. Herein rainbow trout were fed either a basal diet (control group) or basal diet plus 5 mg/kg nano-Se (treatment group). Samples were collected before (18 °C for 9 days; CG18, Se18) and after (24 °C for 8 h; CG24, Se24) heat stress. The DIA/SWATH approach was then applied to compare changes at the proteome level. We found 223 and 269 differentially abundant proteins in the CG18-CG24 and Se18-Se24 groups, respectively, which mainly included apoptosis-, heat stress-, and lipid-related proteins. In comparison with the CG18-CG24 group, the Se18-Se24 group showed higher abundance of molecular chaperone, such as Hsp70, Hsp90a.1, Hspa8, Hsp30, DNAJA4, Dnajb1, Bag2 and Ahsa1; on nano-Se supplementation, the heat stress-induced decline in the abundance of the selenoprotein MsrB2 was partially restored. Furthermore, nano-Se supplementation downregulated the abundance of lipid-related (CYP51, EBP, DHCR7, DHCR24, and APOB) and pro-apoptotic (caspase-8 and Bad) proteins. Protein–protein interaction analyses suggested that nano-Se inhibits apoptosis by upregulating the expression of Hsp70, Hsp90a.1, Hspa8, and Dnajb1; further, Hsp70/Hspa8 and MsrB2 appear to play a synergistic role in antioxidant defense under heat stress. Overall, our findings provide novel insights into nano-Se-mediated tolerance of heat stress, demonstrating that nano-Se exerts its anti-heat stress effects in rainbow trout by promoting protein repair, enhancing recovery of antioxidant enzyme activity, and alleviating lipid metabolism and apoptosis.

Hunter-gatherer technological organization and responses to Holocene climate change in coastal, lakeshore, and grassland ecologies of eastern Africa

The Holocene of eastern Africa saw extreme climatic fluctuations between hyper-humid and arid conditions, which manifested differently across the region's lake basins, coastal ecotones, and terrestrial biomes. Changes to resource availability, distribution, and predictability presented different constraints and opportunities to diverse hunter-gatherer communities. Major ongoing questions concern how humans reconfigured economic, social, and technological strategies in different regional settings. The role of more stable coastal environments in these processes remains especially under-studied. Here, we examine and compare relationships between environmental change and the organization of stone tool technology at the site of Panga ya Saidi Cave, eastern Kenya, in strata dating from c. 15-0.2 ka. Located near the Indian Ocean coast, this dataset provides the first insights into Holocene human-environmental relationships in a coastal forest zone of eastern Africa. Integrating the new Panga ya Saidi environmental and archaeological records with other high-resolution records from nearby terrestrial and lacustrine zones, we take a comparative approach to address how climatic fluctuations shaped trajectories of hunter-gatherer adaptations through the Holocene. We argue that lithic technologies deployed within lake basins and coastal zones reflect more stable land-use strategies with less residential mobility compared to those associated with terrestrial foraging. All regions exhibit technological reconfigurations with the arrival of pastoralism, except for the coastal forest which appear largely consistent across the study period. Results inform ongoing debates into the resilience of recent eastern African hunter-gatherers and food-producers and provide an analogical framework for examining human-environmental dynamics deeper in time.

Enriching the stability of solar/wind DC microgrids using battery and superconducting magnetic energy storage based fuzzy logic control

Utilizing robustly-controlled energy storage technologies performs a substantial role in improving the stability of standalone microgrids in terms of voltages and powers. The majority of investigations focused less on integrating energy storage systems (especially superconducting magnetic energy storage 'SMES') within DC-bus microgrids. Besides, implementing fuzzy logic control (FLC) for both batteries and SMES within the DC-bus microgrids to enrich their stability and power quality under extreme climatic and loading variations has been seldomly addressed. Consequently, this paper introduces a comparative analysis of the performance of a hybrid renewable PV/wind DC-bus microgrid that separately implements fuzzy-controlled battery and SMES systems to enhance the microgrid stability and power quality. The proposed FLC approaches supervise energy interchange inside the system, mitigate the DC-bus voltage fluctuations, and smooth out the load power during the different instabilities. The system is examined under distinct normal and extreme climatic fluctuations such as wind gusts and rapid shadow and under sudden balanced and unbalanced loading events. The proposed FLC approaches are established based on quantifying the DC-bus voltage variation and measuring the actual battery and SMES currents which can be employed directly for the control action; hence, reducing both calculations/calibrations and complexity of the control system. Besides, they offer very quick charging/discharging actions for both battery and SMES systems to mitigate unexpected and rapid variations efficiently. For the load side, the study proposes a variable modulation index control based-sinusoidal pulse width modulation for controlling the prime inverter to preserve the load voltage and frequency constant during both balanced and unbalanced loading and extreme climatic disturbances. The obtained findings confirmed the efficacy of the proposed approaches in enriching the microgrid stability. Besides, they unveiled the magnificent performance of SMES over batteries regarding the response time, peak over- and undershoot, load voltage profile, and load power smoothness.

Holocene environmental evolution history based on sporopollenin and micropaleontological reconstruction of KY-01 in the Yellow River Delta

Abstract The Yellow River Delta adjacent to the Bohai Sea is located in the monsoon region of northern China, which is sensitive to global climate change. The core data of KY-01 borehole in the Yellow River Delta and the published records were used to reconstruct the climate environment. Based on the analysis of carbonate content, magnetic susceptibility, Ostracoda, foraminifera, sporopollenin and AMS 14C dating on the KY-01 borehole sediment core, the evolution of both the climate and sedimentary environment has been discussed. The results show that: 7656–4145 cal.aBP, seawater moved toward the land surface and the climate was generally warm and humid, when there were small-scale extreme climate fluctuations; 4145–2544 cal.aBP, transgression and recession occurred, the climate changed from warm-wet to dry-cold and there were small-scale extreme climatic events; and 2544 cal.aBP–1855 AD, the sea level was relatively low, transgression and retreat alternately occurred, the climate was drier and colder than the previous stage and the warming and cooling alternated. During the middle Holocene, cold-dry events occurred between 5737–5422 and 4451–4081 cal.aBP, which is consistent with both Chinese and worldwide climate records.

Understanding the diversification pattern of three subspecies of swamp deer (Rucervus duvaucelii) during the Pleistocene–Holocene based on mitochondrial and Y chromosome markers

The Quaternary period played a vital role in the creation of new ecological and vegetation zones, which shaped the diversification and distribution of species. The present study aimed to document, for the first time, phylogeography of three reported subspecies/populations of swamp deer, Rucervus duvaucelii duvaucelii (northern), R. d. ranjitsinhi (eastern) and R. d. branderi (central), using a fragment of the mitochondrial cyt b gene and the Y chromosome DBY-7. Inferred phylogenetic relationships revealed the presence of three genetically distinct lineages using both historic and contemporary samples. Sequence divergence between the northern and eastern populations was less (1.5%) than between the northern and central populations (1.8%). Molecular dating based on the cyt b gene suggests that swamp deer split into two (northern-eastern and central) major clades from the common ancestor before 1.3 Million years ago. Demography based on Bayesian skyline plot suggested a slight decline in one population (R. d. duvaucelii) but a stable population size in the other two populations (R. d. ranjitsinhi and R. d. branderi). The observed shallow split of the northern population into the Jhilmil Tal Wildlife Conservation Reserve and Dudhwa National Park subpopulations may have been due to extreme climatic fluctuations during the Quaternary period (Holocene) and the subsequent increased human footprint. We also review and discuss the significance of past climatic and vegetation changes due to human settlement and of paleoenvironmental and biogeographic events that may have facilitated the diversification and distribution of habitat-specific swamp deer into small patches across the Indian subcontinent and of the congeneric species, R. schomburgki, from the southeastern area in Thailand with related conservation implications.

Precipitation extremes influence patterns and partitioning of evapotranspiration and transpiration in a deciduous boreal larch forest

High latitude boreal forests are experiencing dramatic changes in climate and hydrology. It is not clear how boreal forests will adapt to hydrological change or how stable they will be to extreme climate fluctuations and shifts in ecosystem water availability (EWA; residuals between precipitation and evapotranspiration). Although there have been numerous studies in North American and European boreal forests, the Siberian boreal region is underrepresented. Moreover, Siberia is dominated by deciduous conifers (larch) that may have different response to shifting hydrology than boreal evergreens do. We observed evapotranspiration (ET) by eddy covariance technique and transpiration (T) by sap-flow probes on a subsample of trees within the flux-tower footprint through two growing seasons in a larch forest in northernmost China. Ecosystems at the margins of their zone could be amongst the first to experience significant shifts in structure and function. At this site there have already been signs of permafrost degradation and more frequent temperature and precipitation anomalies. The canopy-dominant larch accounted for half the total T fluxes. The remaining 50% was distributed evenly among intermediate and suppressed trees. T is the dominant subcomponent in ET, where overall T/ET varies of 66%–84% depending on precipitation patterns. In dormant and early growing seasons, T still constitutes a majority of ET even though the canopy foliage is not fully developed because cold soil creates a negative soil to air vapor pressure gradient that impedes evaporation. However, in the peak growing season, excess precipitation reduces T while providing sufficient wetness for surface evaporation. ET from standard data product based on MODIS satellite reflectance underestimates tower ET by 17%–29%. Solar-induced chlorophyll fluorescence measured by satellite is well correlated with tower ET (r2 = 0.69–0.73) and could provide a better basis for regional ET extrapolations. A global comparison of data for 2000–2018 period reveals that boreal forests not only have the smallest annual MODIS ET but also the least EWA compared to temperate and tropical forests. Also, even though boreal deciduous and evergreens have comparable annual ET, their T/ET and EWA are distinct. This work highlights how short-term precipitation extremes may shift ecosystem function and structure by changing EWA through exported runoff. Sites along boreal ecotones are critical to observe for signs of shifts in their structure, function, and response to climate anomalies.

The Role of Climate and Topography in Shaping the Diversity of Plant Communities in Cabo Verde Islands

The flora and vegetation of the archipelago of Cabo Verde is dominated by Macaronesian, Mediterranean, and particularly by African tropical elements, resulting from its southernmost location, when compared to the other islands of the Macaronesia (i.e., Azores, Madeira, Selvagens, and Canary Islands). Very likely, such a geographical position entailed higher susceptibility to extreme climatic fluctuations, namely those associated with the West African Monsoon oscillations. These fluctuations led to a continuous aridification, which is a clear trend shown by most recent studies based on continental shelf cores. Promoting important environmental shifts, such climatic fluctuations are accepted as determinant to explain the current spatial distribution patterns of taxa, as well as the composition of the plant communities. In this paper, we present a comprehensive characterization of the main plant communities in Cabo Verde, and we discuss the role of the climatic and topoclimatic diversity in shaping the vegetation composition and distribution of this archipelago. Our study reveals a strong variation in the diversity of plant communities across elevation gradients and distinct patterns of richness among plant communities. Moreover, we present an overview of the biogeographical relationships of the Cabo Verde flora and vegetation with the other Macaronesian Islands and northwestern Africa. We discuss how the distribution of plant communities and genetic patterns found among most of the endemic lineages can be related to Africa’s ongoing aridification, exploring the impacts of a process that marks northern Africa from the Late Miocene until the present.

Ice Age theory: a correspondence between Milutin Milanković and Vojislav Mišković

Abstract Ice Ages (IA) and their glacial periods can be regarded as significant natural hazards (NH). Unfortunately, the knowledge of hominid evolution that occurred during IAs, in such extreme climatic fluctuations, is preserved almost exclusively in mythology. The omission of more scientific discourse regarding the history of NH during IAs should be rectified for posterity. As our civilization will likely have to cope with the beginnings of a new glacial phase, a more complete understanding of the mechanisms of IA climate dynamics is crucial. This paper presents an unpublished correspondence between M. Milanković, a polymath and the founder of the Astronomical theory of Ice Ages (ATIA), and the astronomer V. Mišković, one of Milanković’s major contributors to the development of his theory. Additional insight related to the ATIA by M. Milanković is given, particularly regarding the succession of glacial and interglacial periods on Earth. In this completely preserved correspondence, taking place from 1924 until 1952, also reside letters concerning the research of M. Milanković and V. Mišković as it relates to the research of Alfred Wegener and Wladimir Köppen. These letters are on the topic of M. Milanković’s 1920’s work. At the Astronomical Observatory in Belgrade, M. Milanković found useful data in the observatory’s publications and orchestrated the numerical calculations he needed for his ATIA with V. Mišković aid.

Long-term dynamics of pastoral ecology in northern Kenya: An old model for new resilience

As the pace of global climate change accelerates, residents of the arid and semi-arid lands of northern Kenya face significant obstacles to maintain viable communities. Colonial and post-colonial political governance and economic models have broken down traditional mechanisms for coping with ecological stress. An archaeological example from the Chalbi Desert is presented as evidence of longue-durée persistence of human occupations through extreme climatic fluctuations. Occupations spanning from ca. 5000 to 600 years BP indicate the presence of robust regional exchange networks and either continuous or repeated occupation of this hot, dry, mosaic woodland. These systems are contrasted against the extrinsically imposed models that began in the late 1800s with the arrival of colonialism in which political economies are more focused on ethnic-territorial and global interests rather than regional cooperation. A long-term ecological model on how traditional systems evolved to cope with vulnerability associated with extreme climate conditions is needed to build resilient communities.

Long-term trends in seasonal plankton dynamics in Lake Mead (Nevada-Arizona, USA) and implications for climate change

Over the past few decades, Lake Mead (Nevada-Arizona, USA) has experienced multiple ecosystem stressors including drought, increased water demand, and establishment of invasive species (quagga mussels, gizzard shad). Despite these potential stressors, zooplankton and phytoplankton community dynamics in the pelagic regions of Lake Mead have generally followed consistent seasonal patterns. Long-term monitoring results (2007–2015) show that zooplankton and phytoplankton communities remain relatively stable in Lake Mead on an inter-annual basis, but are susceptible to shifts caused by extreme climate fluctuations and alterations in mixing regimes. A warm winter characterized by low snowpack in 2014/2015 preceded a large bloom of toxic cyanobacteria (Microcystis aeruginosa Kutzing) in Las Vegas Bay the following summer. Large bloom events are rare in Lake Mead; however, under future climate scenarios, these types of events may become more frequent. Because of the consistency of plankton community dynamics over an extended period of time, Lake Mead offers an ideal system for the study of future climate change impacts. This study aims to characterize the response of plankton communities in Lake Mead to both linear and dynamic environmental changes.

Spring weather conditions influence breeding phenology and reproductive success in sympatric bat populations.

Climate is known to influence breeding phenology and reproductive success in temperate-zone bats, but long-term population level studies and interspecific comparisons are rare. Investigating the extent to which intrinsic (i.e. age), and extrinsic (i.e. spring weather conditions), factors influence such key demographic parameters as the proportion of females becoming pregnant, or completing lactation, each breeding season, is vital to understanding of bat population ecology and life-history traits. Using data from 12 breeding seasons (2006-2017), encompassing the reproductive histories of 623 Myotis daubentonii and 436Myotis nattereri adult females, we compare rates of recruitment to the breeding population and show that these species differ in their relative sensitivity to environmental conditions and climatic variation, affecting annual reproductive success at the population level. We demonstrate that (1) spring weather conditions influence breeding phenology, with warm, dry and calm conditions leading to earlier parturition dates and advanced juvenile development, whilst cold, wet and windy weather delays birth timing and juvenile growth; (2) reproductive rates in first-year females are influenced by spring weather conditions in that breeding season and in the preceding breeding season when each cohort was born. Pregnancy and lactation rates were both higher when favourable spring foraging conditions were more prevalent; (3)reproductive success increases with age in both species, but at different rates; (4) reproductive rates were consistently higher, and showed less interannual variation, in second-year and older M.daubentonii (mean 91.55%±0.05 SD) than M.nattereri (mean 72.74%±0.15 SD); (5) estimates of reproductive success at the population level were highly correlated with the size of the juvenile cohort recorded each breeding season. Improving understanding of the influence of environmental conditions, especially extreme climatic fluctuations, and the identification of critical periods (i.e. spring for reproductive female bats in temperate zones), which have disproportionate and lasting impacts on breeding phenology and reproductive success at a population level, is critical for improving predictions of the likely impact of climate change on bat populations.

Cave deposits as a sedimentary trap for the Marine Isotope Stage 3 environmental record: The case study of Pod Hradem, Czech Republic

Pod Hradem Cave, located in the Moravian Karst, Czech Republic, offers an excellent opportunity for environmental reconstructions of Marine Isotope Stage 3 (MIS 3) in Central Europe due to its detailed sedimentary record dated 50,000 to 28,000 cal BP. Identifying the natural environments of the Middle to Upper Palaeolithic (MUP) transition is necessary to understand the settlement strategies and related behaviour of both Neanderthals and Anatomically Modern Humans, both of whom may have occupied the region at the same time. A multidisciplinary excavation was carried out between 2011 and 2016. Detailed analyses of the sediments, vertebrate microfauna, pollen and charcoal revealed minor but observable fluctuations in climate, with little change in the surrounding vegetation. The Pod Hradem palaeoenvironmental dataset is complex, but generally reflects a predominantly glacial climate with a range of vegetation types and habitats during the Late Pleistocene, followed by the warmer and more humid Holocene. The MUP transition as recorded in Pod Hradem Cave was a glacial environment interrupted by two relatively warmer periods. Central Europe experienced extreme climate fluctuations during MIS3, as recorded from different sedimentary archives, but it seems that the Pod Hradem Cave environment may have acted as a buffer zone, ameliorating those extremes, and providing a suitable refuge for both bears seeking winter hibernation dens and occasionally visiting humans.

Modeling Grassland Ecosystem Responses to Coupled Climate and Socioeconomic Influences in Multi-Spatial-And-Temporal Scales

Assessment of ecosystem responses to coupled human and environmental impacts is increasingly acknowledged as an important research of environmental informatics. However, current ecological and environmental models are not effective for capturing the coupled influences due to prevalent approaches of separating human interferences from environmental changes, common uses of time-averaged or cumulative data, and the lack of efficient methods integrating environmental observations with socio- economic statistics that are tabulated over different spatial units. In this paper, we presented an integrated modeling framework to tackle these limitations. We developed data-assimilation techniques to integrate ecological and climate data with socioeconomic statistics into a coherent dataset on the basis of conforming spatial units. These data were used in panel regressions to estimate responses of grassland productivity to coupled climate factors (seven) and socioeconomic indicators (ten) across 37 counties for nine 16-day growing periods each year from 2000 to 2010. We also advanced the analysis of climate impacts by allowing for quadratic rather than linear impacts and by incorporating lagged time effects for the dependent variable. The case study was conducted in Inner Mongolia Autonomous Region of China. Our findings provided strong evidence that the grassland productivity responded significantly to variations in both climate factors and socioeconomic variables; displayed significant seasonal, annual, and regional variation; and revealed cumulative influences from prior climate conditions and extreme climate fluctuations. The assimilation of climatic, ecological and socioeconomic data into a big-data set and the application of multi-spatial-and-temporal panel regression model were much more comprehensive than prior studies.

Statistical analysis of iron geochemical data suggests limited late Proterozoic oxygenation.

Sedimentary rocks deposited across the Proterozoic-Phanerozoic transition record extreme climate fluctuations, a potential rise in atmospheric oxygen or re-organization of the seafloor redox landscape, and the initial diversification of animals. It is widely assumed that the inferred redox change facilitated the observed trends in biodiversity. Establishing this palaeoenvironmental context, however, requires that changes in marine redox structure be tracked by means of geochemical proxies and translated into estimates of atmospheric oxygen. Iron-based proxies are among the most effective tools for tracking the redox chemistry of ancient oceans. These proxies are inherently local, but have global implications when analysed collectively and statistically. Here we analyse about 4,700 iron-speciation measurements from shales 2,300 to 360 million years old. Our statistical analyses suggest that subsurface water masses in mid-Proterozoic oceans were predominantly anoxic and ferruginous (depleted in dissolved oxygen and iron-bearing), but with a tendency towards euxinia (sulfide-bearing) that is not observed in the Neoproterozoic era. Analyses further indicate that early animals did not experience appreciable benthic sulfide stress. Finally, unlike proxies based on redox-sensitive trace-metal abundances, iron geochemical data do not show a statistically significant change in oxygen content through the Ediacaran and Cambrian periods, sharply constraining the magnitude of the end-Proterozoic oxygen increase. Indeed, this re-analysis of trace-metal data is consistent with oxygenation continuing well into the Palaeozoic era. Therefore, if changing redox conditions facilitated animal diversification, it did so through a limited rise in oxygen past critical functional and ecological thresholds, as is seen in modern oxygen minimum zone benthic animal communities.