scholarly journals Reconstruction of Thermal Conditions in the Subboreal Inferred from Isotopic Studies of Groundwater and Calcareous Tufa from the Spring Mire Cupola in Wardzyń (Central Poland)

Water ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1945 ◽  
Author(s):  
Tomasz Gruszczyński ◽  
Jerzy Małecki ◽  
Anastasiia Romanova ◽  
Maciej Ziułkiewicz
Keyword(s):  
Stable Isotopes ◽  
Environmental Changes ◽  
Dissolved Inorganic Carbon ◽  
A Priori ◽  
Thermal Conditions ◽  
Climate Conditions ◽  
Calcareous Tufa ◽  
Isotopic Studies ◽  
Living Organisms ◽  
Cool Climate

Studies with application of stable isotopes of oxygen and carbon have been performed on calcareous tufa, groundwater and dissolved inorganic carbon (DIC) from the spring mire cupola in Wardzyń. This study was focused on the verification of the a priori hypothesis that the analysed calcareous tufa is a chemical deposit and on the attempt to supplement an earlier scenario of environmental changes in the Subboreal with oscillations of water temperature. The constructed model of chemical and isotope balance, and δ13C determinations in DIC, allowed for calculating ratios of stable isotopes of carbon in particular speciations and in gaseous CO2. The obtained results coupled with δ13C values in calcite indicate that this mineral precipitated from the solution chemically (without the contribution of living organisms). Additionally, it was possible to reconstruct the temperature range at which the calcareous tufa was formed. The reconstructed scenario of changes in the thermal conditions was refined based on δ18O determinations in groundwater and calcite. Accordingly, the oldest calcareous tufa, with an age of about 5500 cal years BP, was formed in cool climate conditions (with average annual temperatures by about 3 °C lower than presently). The formation of younger series of the calcareous tufa took place between 4400–2900 cal years BP and represents a much warmer period with two distinct cooler episodes at 3900 and 3000 cal years BP, respectively. The course of the obtained temperature curves correlates well with the GISP2 curve and curves obtained for other sites in Northern, and Central Europe.

scholarly journals Future Thermal Assessment for the Phenological Development of Potato [Solanum tuberosum (L.)] in Cuba

2020 ◽  
Vol 4 (1) ◽  
pp. 6
Author(s):  
Alexis Augusto Hernández-Mansilla ◽  
Francisco Estrada-Porrúa ◽  
Oscar Calderón-Bustamante ◽  
Graciela Lucía Binimelis de Raga
Keyword(s):  
Solanum Tuberosum ◽  
Climate Model ◽  
Solanum Tuberosum L ◽  
Regional Climate ◽  
Thermal Conditions ◽  
Climate Change Scenarios ◽  
Thermal Index ◽  
Climate Conditions ◽  
Time Space ◽  
Biological Development

Current changes in climate conditions due to global warming affect the phenological behavior of economically important cultivable plant species, with consequences for the food security of many countries, particularly in small vulnerable islands. Thus, the objective of this study was to evaluate the thermal viability of Solanum tuberosum (L.) through the behavior of the Thermal Index of Biological Development (ITDB) of two cultivation areas in Cuba under different climate change scenarios. For the analysis, we elaborated bioclimatic scenarios by calculating the ITDB through a grounded and parameterized stochastic function based on the thermal values established for the phenological development of the species. We used the mean temperature values from the period 1980 to 2010 (historical reference period) of the Meteorological Stations: 78320 “Güira de Melena” and 78346 “Venezuela”, located at the western and central of Cuba respectively. We also used modeled data from RCP 2.6 scenarios; 4.5 and 8.5 from the PRECIS-CARIBE Regional Climate Model, which used global outputs from the ECHAM5 MCG for the period 2010 to 2100. As result, the scenarios showed that the annual average ITDB ranges from 0.7 to 0.8, which indicates that until 2010 there were temporary spaces with favorable thermal conditions for the species, but not for the period from 2010 to 2100 in RCP 4.5 and 8.5. In these scenarios, there was a progressive decrease in the indicator that warned of a marked loss of Viability of S. tuberosum, reduction of the time-space to cultivate this species (particularly the month of April is the most inappropriate for the ripening of the tuber). These results showed that Cuba requires the establishment of an adaptation program with adjustments in the sowing and production calendar, the use of short-cycle varieties of less than 120 days, the management of genotypes adaptable to high temperatures, and the application of “Agriculture Climate Smart”, to reduce risks in food safety.

Species distribution modeling reveals the ecological niche of extinct megafauna from South America

2021 ◽  
pp. 1-8
Author(s):  
Thaísa Araújo ◽  
Helena Machado ◽  
Dimila Mothé ◽  
Leonardo dos Santos Avilla
Keyword(s):  
South America ◽  
Species Distribution ◽  
Environmental Changes ◽  
Species Distribution Modeling ◽  
Human Action ◽  
Northeastern Brazil ◽  
Climate Conditions ◽  
Middle Holocene ◽  
Distribution Modeling ◽  
The Impact

Abstract Climatic and environmental changes, as well as human action, have been cited as potential causes for the extinction of megafauna in South America at the end of the Pleistocene. Among megamammals lineages with Holarctic origin, only horses and proboscideans went extinct in South America during this period. This study aims to understand how the spatial extent of habitats suitable for Equus neogeus and Notiomastodon platensis changed between the last glacial maximum (LGM) and the middle Holocene in order to determine the impact that climatic and environmental changes had on these taxa. We used species distribution modeling to estimate their potential extent on the continent and found that both species occupied arid and semiarid open lands during the LGM, mainly in the Pampean region of Argentina, southern and northeastern Brazil, and parts of the Andes. However, when climate conditions changed from dry and cold during the LGM to humid and warm during the middle Holocene, the areas suitable for these taxa were reduced dramatically. These results support the hypothesis that climatic changes were a driving cause of extinction of these megamammals in South America, although we cannot rule out the impact of human actions or other potential causes for their extinction.

Instrumental Means for Managing the Rational Behavior of Self-Organizing Autonomous Intelligent Agents

2021 ◽  
Vol 22 (4) ◽  
pp. 171-180
Author(s):  
V. B. Melekhin ◽  
M. V. Khachumov
Keyword(s):  
Intelligent Agents ◽  
Environmental Changes ◽  
A Priori ◽  
Operating Conditions ◽  
Basic Principles ◽  
Purposeful Behavior ◽  
Problem Solvers ◽  
Boundary Estimates ◽  
Self Learning ◽  
Self Organizing

We formulate the basic principles of constructing a sign-signal control for the expedient behavior of autonomous intelligent agents in a priori undescribed conditions of a problematic environment. We clarify the concept of a self-organizing autonomous intelligent agent as a system capable of automatic goal-setting when a certain type of conditional and unconditional signal — signs appears in a problem environment. The procedures for planning the expedient behavior of autonomous intelligent agents have been developed, that imitate trial actions under uncertainty in the process of studying the regularities of transforming situations in a problem environment, which allows avoiding environmental changes in the process of self-learning that are not related to the achievement of a given goal. Boundary estimates of the proposed procedures complexity for planning expedient behavior are determined, confirming the possibility of their effective implementation on the on-board computer of the automatic control system for the expedient activity of autonomous intelligent agents. We carry out an imitation on a personal computer of the proposed procedures for planning purposeful behavior, confirming the effectiveness of their use to build intelligent problem solvers for autonomous intelligent agents in order to endow them with the ability to adapt to a priori undescribed operating conditions. The main types of connections between various conditional and unconditional signal — signs of a problem environment are structured, which allows autonomous intelligent agents to adapt to complex a priori undescribed and unstable conditions of functioning.

scholarly journals A high-altitude peatland record of environmental changes in the NW Argentine Andes (24 ° S) over the last 2100 years

2016 ◽  
Vol 12 (5) ◽  
pp. 1165-1180 ◽  
Author(s):  
Karsten Schittek ◽  
Sebastian T. Kock ◽  
Andreas Lücke ◽  
Jonathan Hense ◽  
Christian Ohlendorf ◽  
...  
Keyword(s):  
High Altitude ◽  
Environmental Changes ◽  
Regional Scale ◽  
Central Andes ◽  
High Accumulation ◽  
Climate Conditions ◽  
Climate Anomalies ◽  
Dry Conditions ◽  
Induced Changes ◽  
The 19Th Century

Abstract. High-altitude cushion peatlands are versatile archives for high-resolution palaeoenvironmental studies, due to their high accumulation rates, range of proxies, and sensitivity to climatic and/or human-induced changes. Especially within the Central Andes, the knowledge about climate conditions during the Holocene is limited. In this study, we present the environmental and climatic history for the last 2100 years of Cerro Tuzgle peatland (CTP), located in the dry Puna of NW Argentina, based on a multi-proxy approach. X-ray fluorescence (XRF), stable isotope and element content analyses (δ13C, δ15N, TN and TOC) were conducted to analyse the inorganic geochemistry throughout the sequence, revealing changes in the peatlands' past redox conditions. Pollen assemblages give an insight into substantial environmental changes on a regional scale. The palaeoclimate varied significantly during the last 2100 years. The results reflect prominent late Holocene climate anomalies and provide evidence that in situ moisture changes were coupled to the migration of the Intertropical Convergence Zone (ITCZ). A period of sustained dry conditions prevailed from around 150 BC to around AD 150. A more humid phase dominated between AD 200 and AD 550. Afterwards, the climate was characterised by changes between drier and wetter conditions, with droughts at around AD 650–800 and AD  1000–1100. Volcanic forcing at the beginning of the 19th century (1815 Tambora eruption) seems to have had an impact on climatic settings in the Central Andes. In the past, the peatland recovered from climatic perturbations. Today, CTP is heavily degraded by human interventions, and the peat deposit is becoming increasingly susceptible to erosion and incision.

scholarly journals Lake water dissolved inorganic carbon dynamics revealed from monthly measurements of radiocarbon in the Fuji Five Lakes, Japan

Elem Sci Anth ◽  
2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Kosuke Ota ◽  
Yusuke Yokoyama ◽  
Yosuke Miyairi ◽  
Shinya Yamamoto ◽  
Toshihiro Miyajima
Keyword(s):  
Lake Water ◽  
Inorganic Carbon ◽  
Environmental Changes ◽  
Dissolved Inorganic Carbon ◽  
Anthropogenic Activities ◽  
Aquatic Organisms ◽  
Human Society ◽  
History Of ◽  
Lake Waters ◽  
Reservoir Age

Lakes are sensitive recorders of anthropogenic activities, as human society often develops in their vicinity. Lake sediments thus have been widely used to reconstruct the history of environmental changes in the past, anthropogenic, or otherwise, and radiocarbon dating provides chronological control of the samples. However, specific values of radiocarbon in different carbon reservoirs due to the different pathways of radiocarbon from the upper atmosphere to the lake, called the radiocarbon reservoir age, is always difficult to evaluate because of dynamic processes in and around lakes. There are few systematic studies on radiocarbon reservoir ages for lakes owing to the complex radiocarbon transfer processes for lakes. Here, we investigate lake waters of the Fuji Five Lakes with monthly monitoring of the radiocarbon reservoir effects. Radiocarbon from dissolved inorganic carbon (DIC) for groundwater and river water is also measured, with resulting concentrations (Δ14C) at their lowest at Lake Kawaguchi in August 2018 (–122.4 ± 3.2‰), and at their highest at Lake Motosu in January 2019 (–22.4 ± 2.5‰), despite a distance of 25 km. However, winter values in both lakes show similar trends of rising Δ14C (about 20‰). Our lake water DIC Δ14C results are compared to previously published records obtained from sediments in Lake Motosu and Lake Kawaguchi. These suggest that total organic carbon and compound-specific radiocarbon found in sediments are heavily influenced by summer blooms of aquatic organisms that fix DIC in water. Thus, future studies to conduct similar analyses at the various lakes would be able to provide further insights into the carbon cycle around inland water, namely understanding the nature of radiocarbon reservoir ages.

scholarly journals Ground-ice stable isotopes and cryostratigraphy reflect late Quaternary palaeoclimate in the Northeast Siberian Arctic (Oyogos Yar coast, Dmitry Laptev Strait)

2017 ◽  
Author(s):  
Thomas Opel ◽  
Sebastian Wetterich ◽  
Hanno Meyer ◽  
Alexander Yu. Dereviagin ◽  
Margret C. Fuchs ◽  
...  
Keyword(s):  
Stable Isotopes ◽  
Stable Isotope ◽  
Late Quaternary ◽  
Cold Winter ◽  
Winter Climate ◽  
Climate Conditions ◽  
Winter Conditions ◽  
Winter Temperatures ◽  
Siberian Arctic ◽  
Ice Wedge

Abstract. To reconstruct palaeoclimate and palaeonvironmental conditions in the Northeast Siberian Arctic, we studied late Quaternary permafrost deposits at the Oyogos Yar coast (Dmitry Laptev Strait). New infrared stimulated luminescence ages for distinctive floodplain deposits of the Kuchchugui Suite (112.5 ± 9.6 kyr) and thermokarst lake deposits of the Krest Yuryakh Suite (102.4 ± 9.7 kyr), respectively, provide new substantial geochronological data and shed light on the landscape history of the Dmitry Laptev Strait region during the Marine Isotope Stage (MIS) 5. Ground ice stable-isotope data are presented together with cryolithological information for eight cryostratigraphic units and are complemented by data from nearby Bol'shoy Lyakhovsky Island. Our combined record of ice-wedge stable isotopes as proxy for past winter climate conditions covers the last about 200 thousand years and is supplemented by texture-ice stable isotopes which contain annual climate conditions overprinted by freezing processes. Our ice wedge stable-water isotope data indicate substantial variations in Northeast Siberian Arctic winter climate conditions during the late Quaternary, in particular between Glacial and Interglacial but also over the last millennia to decades. Stable isotope values of Ice Complex ice wedges indicate cold to very cold winter temperatures about 200 kyr ago (MIS7), very cold winter conditions about 100 kyr ago (MIS5), very cold to moderate winter conditions between about 60 and 30 kyr ago, and extremely cold winter temperatures during the Last Glacial Maximum (MIS2). Much warmer winter conditions are reflected by extensive thermokarst development during the MIS5c and by Holocene ice-wedge stable-isotopes. Modern ice-wedge stable isotopes are most enriched and testify the recent winter warming in the Arctic. Hence, ice-wedge based reconstructions of changes in winter climate conditions add substantial information to those derived from paleoecological proxies stored in permafrost and allow for distinguishing between seasonal trends of past climate dynamics. Future progress in ice-wedge dating and an improved temporal resolution of ice-wedge derived climate information may help to fully explore the palaeoclimatic potential of ice wedges.

Neural Autopoiesis: Organizing Self-Boundaries by Stimulus Avoidance in Biological and Artificial Neural Networks

2020 ◽  
Vol 26 (1) ◽  
pp. 130-151 ◽  
Author(s):  
Atsushi Masumori ◽  
Lana Sinapayen ◽  
Norihiro Maruyama ◽  
Takeshi Mita ◽  
Douglas Bakkum ◽  
...  
Keyword(s):  
Neural Networks ◽  
Artificial Neural Networks ◽  
Environmental Changes ◽  
Spike Timing ◽  
Spiking Neural Networks ◽  
Cultured Neurons ◽  
Autonomous Regulation ◽  
Artificial Neural ◽  
Living Organisms ◽  
External Stimuli

Living organisms must actively maintain themselves in order to continue existing. Autopoiesis is a key concept in the study of living organisms, where the boundaries of the organism are not static but dynamically regulated by the system itself. To study the autonomous regulation of a self-boundary, we focus on neural homeodynamic responses to environmental changes using both biological and artificial neural networks. Previous studies showed that embodied cultured neural networks and spiking neural networks with spike-timing dependent plasticity (STDP) learn an action as they avoid stimulation from outside. In this article, as a result of our experiments using embodied cultured neurons, we find that there is also a second property allowing the network to avoid stimulation: If the agent cannot learn an action to avoid the external stimuli, it tends to decrease the stimulus-evoked spikes, as if to ignore the uncontrollable input. We also show such a behavior is reproduced by spiking neural networks with asymmetric STDP. We consider that these properties are to be regarded as autonomous regulation of self and nonself for the network, in which a controllable neuron is regarded as self, and an uncontrollable neuron is regarded as nonself. Finally, we introduce neural autopoiesis by proposing the principle of stimulus avoidance.

RADIOCARBON RESERVOIR AGES IN THE HOLOCENE DEAD SEA

Radiocarbon ◽  
2020 ◽  
Vol 62 (5) ◽  
pp. 1453-1473
Author(s):  
Nurit Weber ◽  
Boaz Lazar ◽  
Ofra Stern ◽  
George Burr ◽  
Ittai Gavrieli ◽  
...  
Keyword(s):  
Dissolved Inorganic Carbon ◽  
Dead Sea ◽  
Climate Conditions ◽  
The Holocene ◽  
Radiocarbon Age ◽  
The Past ◽  
Organic Debris ◽  
The Dead ◽  
The Difference ◽  
Continuous Deposition

ABSTRACTThe sources and fate of radiocarbon (14C) in the Dead Sea hypersaline solution are evaluated with 14C measurements in organic debris and primary aragonite collected from exposures of the Holocene Ze’elim Formation. The reservoir age (RA) is defined as the difference between the radiocarbon age of the aragonite at time of its precipitation (representing lakeʼs dissolved inorganic carbon [DIC]) and the age of contemporaneous organic debris (representing atmospheric radiocarbon). Evaluation of the data for the past 6000 yr from Dead Sea sediments reveal that the lakeʼs RA decreased from 2890 yr at 6 cal kyr BP to 2300 yr at present. The RA lies at ~2400 yr during the past 3000 yr, when the lake was characterized by continuous deposition of primary aragonite, which implies a continuous supply of freshwater-bicarbonate into the lake. This process reflects the overall stability of the hydrological-climate conditions in the lakeʼs watershed during the late Holocene where bicarbonate originated from dissolution of the surface cover in the watershed that was transported to the Dead Sea by the freshwater runoff. An excellent correlation (R2=0.98) exists between aragonite ages and contemporaneous organic debris, allowing the estimation of ages of various primary deposits where organic debris are not available.

scholarly journals Ocean carbon inventory under warmer climate conditions – the case of the Last Interglacial

2018 ◽  
Vol 14 (12) ◽  
pp. 1961-1976 ◽  
Author(s):  
Augustin Kessler ◽  
Eirik Vinje Galaasen ◽  
Ulysses Silas Ninnemann ◽  
Jerry Tjiputra
Keyword(s):  
Dissolved Inorganic Carbon ◽  
Carbon Sources ◽  
Climatic Conditions ◽  
Interglacial Period ◽  
Quasi Equilibrium ◽  
Biological Pump ◽  
Last Interglacial ◽  
Climate Conditions ◽  
Ocean Carbon ◽  
Carbon Inventory

Abstract. During the Last Interglacial period (LIG), the transition from 125 to 115 ka provides a case study for assessing the response of the carbon system to different levels of high-latitude warmth. Elucidating the mechanisms responsible for interglacial changes in the ocean carbon inventory provides constraints on natural carbon sources and sinks and their climate sensitivity, which are essential for assessing potential future changes. However, the mechanisms leading to modifications of the ocean's carbon budget during this period remain poorly documented and not well understood. Using a state-of-the-art Earth system model, we analyze the changes in oceanic carbon dynamics by comparing two quasi-equilibrium states: the early, warm Eemian (125 ka) versus the cooler, late Eemian (115 ka). We find considerably reduced ocean dissolved inorganic carbon (DIC; −314.1 PgC) storage in the warm climate state at 125 ka as compared to 115 ka, mainly attributed to changes in the biological pump and ocean DIC disequilibrium components. The biological pump is mainly driven by changes in interior ocean ventilation timescales, but the processes controlling the changes in ocean DIC disequilibrium remain difficult to assess and seem more regionally affected. While the Atlantic bottom-water disequilibrium is affected by the organization of sea-ice-induced southern-sourced water (SSW) and northern-sourced water (NSW), the upper-layer changes remain unexplained. Due to its large size, the Pacific accounts for the largest DIC loss, approximately 57 % of the global decrease. This is largely associated with better ventilation of the interior Pacific water mass. However, the largest simulated DIC differences per unit volume are found in the SSWs of the Atlantic. Our study shows that the deep-water geometry and ventilation in the South Atlantic are altered between the two climate states where warmer climatic conditions cause SSWs to retreat southward and NSWs to extent further south. This process is mainly responsible for the simulated DIC reduction by restricting the extent of DIC-rich SSW, thereby reducing the storage of biological remineralized carbon at depth.

scholarly journals Climate Preferences for Tourism: Perceptions Regarding Ideal and Unfavourable Conditions for Hiking in Spain

Atmosphere ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 646 ◽  
Author(s):  
Emilio Martínez-Ibarra ◽  
María Gómez-Martín ◽  
Xosé Armesto-López ◽  
Rubén Pardo-Martínez
Keyword(s):  
Leisure Time ◽  
Positive Impact ◽  
Leisure Activity ◽  
Thermal Conditions ◽  
Future Research ◽  
Climate Conditions ◽  
Tourist Destinations ◽  
Tourism Climatology ◽  
The Aesthetic

Physical activity is an increasingly frequent part of our leisure time. Within this context, hiking is a popular form of tourism which has a positive impact on the quality of life. In spite of the importance of climate conditions for this recreational activity, relatively little research has been done on hiking from the perspective of climate and tourism. With this in mind in this paper we make the first detailed extensive assessment of climate preferences for the practice of hiking tourism in Spain. To this end a review of the theoretical/methodological body of literature on tourism climatology was conducted together with a survey aimed at evaluating the stated climate preferences of hiking tourists. The results are offered within the framework of international research on climate preferences for a range of tourism activities. The comparative analysis of these results with regard to those obtained in previous research highlights various similarities but also certain factors specific to hiking in Spain. Overall, the climate preferences of hiking tourists are similar to those of other segments of the tourism market in terms of the aesthetic and physical aspects of the climate, although they also have certain specific preferences as regards thermal aspects, especially regarding the optimal daily thermal conditions for hiking. The results obtained are useful for assessing the suitability of the climate for the practice of hiking tourism in Spain and for promoting proper management and planning of this leisure activity in tourist destinations, including the development of climate calendars detailing the most suitable times of the year for hiking at these destinations. These issues will be addressed in future research studies.

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