Global Boundary Research Articles

The East Gotland Basin (Baltic Sea) as a candidate Global boundary Stratotype Section and Point for the Anthropocene series

The short sediment core EMB201/7-4 retrieved from the East Gotland Basin, central Baltic Sea, is explored here as a candidate to host the stratigraphical basis for the Anthropocene series and its equivalent Anthropocene epoch, still to be formalized in the Geological Time Scale. The core has been accurately dated back to 1840 CE using a well-established event stratigraphy approach. A pronounced and significant change occurs at 26.5 cm (dated 1956 ± 4 CE) for a range of geochemical markers including 239+240Pu, 241Am, fly-ash particles, DDT (organochlorine insecticide), total organic carbon, and bulk organic carbon stable isotopes. This stratigraphic level, which corresponds to a change in both lithology and sediment colour related to early anthropogenic-triggered eutrophication of the central Baltic Sea, is proposed as a Global boundary Stratotype Section and Point for the Anthropocene series.

Tropical Indian Ocean basin hydroclimate at the Mid- to Late-Holocene transition and the double drying hypothesis

The spatial pattern of Holocene climate anomalies is crucial to determining the mechanisms of change, distinguishing between unforced and forced climate variability, and understanding potential impacts on past and future human societies. The 4.2 ka event is often regarded as one of the largest and best documented abrupt climate disturbances of the Holocene. Yet outside the data-rich Northern Hemisphere mid-latitudes, the global pattern of climate anomalies is uncertain. In this study we investigate the spatial and temporal variability of the tropical Indian Ocean hydroclimate at the Mid- to Late-Holocene transition. We conducted Monte-Carlo principal component analysis, considering full age uncertainty, on ten high-resolution, precisely dated paleohydroclimate records from around the tropical Indian Ocean basin, all growing continuously or almost continuously between 5 and 3 kyr BP. The results indicate the dominant mode of variability in the region was a drying between 3.97 kyr BP (±0.08 kyr standard error) and 3.76 kyr BP (±0.07 kyr standard error) with dry conditions lasting for an additional 300 years in some records, and a permanent change in others. This drying in PC1, which we interpret as a proxy of summer monsoon variability, fits with a previously recognised tropic wide change in hydroclimate around 4.0 kyr BP. An abrupt event from 4.2 to 3.9 kyr BP is seen locally in individual records but lacks regional coherence.A lack of apparent 4.2 ka event in tropical Indian Ocean hydroclimate has ramifications for climate variability in the Indus valley, and for the Harappan civilization. Through a comparison of existing Indian subcontinent paleoclimate records, upstream climatic variability in the Indian Summer Monsoon and winter Westerly Disturbances source regions, and modern climatology, we present the “Double Drying hypothesis”. A winter rainfall drying between 4.2 and 3.9 kyr BP was followed by a summer rainfall drying between 3.97 kyr BP and at least 3.4 kyr BP. The Double Drying hypothesis provides more detailed climatic context for the Harappan civilization, resolves the cropping paradox, and fits the spatial-temporal pattern of urban abandonment. The consequences for the new Mid- to Late-Holocene Global Boundary Stratotype Section and Point in a stalagmite from Meghalaya are explored.

Working the boundary: science–policy interactions and uneven knowledge politics in IPBES

The rising demand for policy-relevant knowledge has supported the emergence of global boundary organizations at the science–policy interface. By synthesizing environmental knowledge for policy-makers, boundary organizations influence how we know and govern sustainability challenges. Therefore, it is essential to better understand what happens in and through these organizations. This paper examines the very practices that configure science–policy relations in global boundary organizations by studying the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES). Through Science and Technology Studies (STS) and Political Ecology perspectives, we disclose mechanisms of boundary work that demarcate science from non-science and, hereby, determine which expertise becomes authoritative in IPBES. Building on original empirical data, we first examine how science and policy domains were interrelated during the IPBES global assessment process (2016–2019). Second, we investigate how this boundary work shaped the production of biodiversity knowledge. Our findings indicate that integration and demarcation efforts configured science–policy relations through formalized and informal mechanisms. We argue that this boundary work continuously established science as authoritative voice for addressing biodiversity loss in IPBES. Spatial aspects of boundary work highlight power differentials between IPBES member States that manifested in uneven geographies of knowledge. Instead of concealing these inequalities through the norm of political neutrality, we need to recognize boundary organizations as political spaces in which science and policy are co-produced. By adopting a critical and reflexive co-productionist approach, it becomes possible to addresses uneven knowledge–power relations through more inclusive and transparent practices. Boundary organizations, such as IPBES, are then able to provide more diversified environmental explanations and transformative solutions.

Dynamic ocean redox conditions during the end-Triassic mass extinction: Evidence from pyrite framboids

The end-Triassic (∼201 Mya) records one of the five largest mass extinction events of the Phanerozoic. Extinction losses were coincident with large igneous province volcanism in the form of the Central Atlantic Magmatic Province (CAMP) and major carbon isotope excursions (CIEs), suggesting a link between these phenomena. Marine anoxia has been implicated as a causal factor in the crisis, but there remains some uncertainty regarding the role of marine redox changes in marine extinction phases because both intensity and duration of marine anoxia are poorly constrained. We employ high resolution pyrite framboid size-frequency analysis at two Triassic-Jurassic (Tr-J) boundary sections: Kuhjoch in Austria (the Tr-J Global Boundary Stratotype Section and Point; GSSP) and St. Audrie's Bay in England (former GSSP candidate) in order to further evaluate the role of marine anoxia in the end-Triassic mass extinction (ETME). The St. Audrie's Bay section records predominantly anoxic conditions punctuated by weakly oxygenated (dysoxic) conditions through the Tr-J transition, even during shallow-water intervals. Kuhjoch experienced both anoxic and dysoxic conditions during the ETME but became better oxygenated near the Tr-J boundary. Marine anoxia is therefore implicated in the extinction at both locations. A similar redox history is known from the Central European Basin, Western Tethys and Panthalassa, where marine anoxia developed in the lead up to the ETME prior to reoxygenation around the Tr-J boundary. • High-resolution pyrite framboids size distribution from two European Triassic-Jurassic boundary sections. • Global dynamic ocean redox evolution through the Triassic-Jurassic boundary is reconstructed. • Oxygen restriction occurred in extremely shallow waters and was likely one of the key causes of the crisis.

Extracting physical urban areas of 81 major Chinese cities from high-resolution land uses

Past two decades have witnessed a rapid urbanization process in China, with the urbanization ratio suddenly increasing from 30.9 % to 63.9 %. Physical urban areas (PUA) are fundamental indicators to monitoring and evaluating urbanization, which differ from administrative urban areas and are much complicated to identify, as PUA contain heterogeneous land uses which are shaped by variant physical structures and diverse socioeconomic activities. Previous studies extracted PUA by densely populated, night-lighted, built-up, or artificial impervious surfaces, which consider either physical or socioeconomic aspect of PUA, but cannot measure both. Accordingly, this study firstly integrates physical and socioeconomic features derived from high-resolution (HR) satellite images and points of interests (POI) to extract HR land uses; then, a knowledge-based morphological aggregation method is proposed to aggregate different land uses and generate PUA based on spatial land-use structures. As the result, 450 PUA in 81 major Chinese cities are extracted and a China PUA dataset (namely CPUA) is generated. The CPUA is evaluated by reference to a widely-used global urban boundary dataset. The evaluation shows an accuracy of 92.5 %, demonstrating the effectiveness of the proposed method and the reliability of generated dataset. The evaluation also indicates that the generated CPUA outperforms the reference dataset in identifying urban parks and eliminating rural homesteads. Furthermore, the CPUA can be employed as fundamental data to monitor urbanization process and its spatial patterns, and thus plays an important role in evaluating sustainable city development. The CPUA is freely available on http://geoscape.pku.edu.cn/otherdata_en.html.

From planetary to regional boundaries for agricultural nitrogen pollution.

Excessive agricultural nitrogen use causes environmental problems globally1, to an extent that it has been suggested that a safe planetary boundary has been exceeded2. Earlier estimates for the planetary nitrogen boundary3,4, however, did not account for the spatial variability in both ecosystems' sensitivity to nitrogen pollution and agricultural nitrogen losses. Here we use a spatially explicit model to establish regional boundaries for agricultural nitrogen surplus from thresholds for eutrophication of terrestrial and aquatic ecosystems and nitrate in groundwater. We estimate regional boundaries for agricultural nitrogen pollution and find both overuse and room for intensification of agricultural nitrogen. The aggregated global surplus boundary with respect to all thresholds is 43 megatonnes of nitrogen per year, which is 64 per cent lower than the current (2010) nitrogen surplus (119 megatonnes of nitrogen per year). Allowing the nitrogen surplus to increase to close yield gaps in regions where environmental thresholds are not exceeded lifts the planetary nitrogen boundary to 57 megatonnes of nitrogen per year. Feeding the world without trespassing regional and planetary nitrogen boundaries requires large increases in nitrogen use efficiencies accompanied by mitigation of non-agricultural nitrogen sources such as sewage water. This asks for coordinated action that recognizes the heterogeneity of agricultural systems, non-agricultural nitrogen losses and environmental vulnerabilities.

Temporal homogenization formula for viscoelastic–viscoplastic model subjected to local cyclic loading

AbstractIn this study, a temporal homogenization formula was developed to predict the response fields (i.e., stress, strain, and displacement) of a viscoelastic–viscoplastic model under local cyclic loading. It is the first attempt to apply the temporal homogenization formula of constitutive equations with higher‐order differential forms on the viscoelastic–viscoplastic model. The temporal homogenization formula is classified into two types: non‐updated temporal homogenization formula and updated temporal homogenization formula. Initial boundary value problem was classified into the global initial boundary value problem and the local initial boundary value problem. To verify this method, two examples were used: (i) when a uniaxial cyclic load is applied to a one‐dimensional bar and (ii) when a multiaxial cyclic load is applied to a three‐dimensional bar. On comparing the accuracy of the non‐updated and the updated temporal homogenization formula, it can be clearly seen that the updated temporal homogenization formula yielded more accurate results.

Hydrogen-induced volume changes, dipole tensor, and elastic hydrogen-hydrogen interaction in a metallic glass

Hydrogen and its isotopes, absorbed in metals, induce local stress on the atomic structure, which generates a global expansion in proportion to the concentration of hydrogen. The dipole force tensor and its interaction with the stress fields give rise to an effective attractive nonlocal potential between hydrogen atoms---the elastic hydrogen-hydrogen interaction---which is a key quantity governing the phase transitions of hydrogen in metals. While the dipole tensor and the elastic interaction have been researched in crystalline materials, they remain experimentally unexplored in metallic glasses and it is unclear how these quantities are affected by the lack of point group symmetries. Here, we investigate both experimentally and theoretically the volume changes, the components of the force dipole tensor, and ultimately the elastic hydrogen-hydrogen interaction in the metallic glass ${\mathrm{V}}_{80}{\mathrm{Zr}}_{20}$. In situ neutron reflectometry was used to determine the deuterium-induced volume changes as a function of deuterium concentration. The one-dimensional volume expansion is found to change by more than 14% without any structural degradation, up to concentrations of one deuterium atom per metal atom. From the expansion, we determine that the out-of-plane component of the elastic dipole tensor is remarkably similar to a composition weighted sum of the ones found in crystalline vanadium and zirconium. Via ab initio calculations of both free and biaxially constrained expanded metallic structures, we determine that the trace of the dipole tensor varies with hydrogen concentration and is essentially invariant of global elastic boundary conditions. As a consequence, the elastic hydrogen-hydrogen interaction energy is found to be concentration-dependent as well, illustrating that the disordered nature of a metallic glass does not impede the mediation of the elastic attraction, but rather allows it to vary with hydrogen content.

Forward calculation of displacement fields with multilayered unsaturated highway system induced by falling weight deflectometer using dynamic response method

A new dynamic forward model of a multilayered highway structure, which considers the unsaturated characteristics of subgrade soil, is established in this paper to assess the dynamic response induced by the falling weight deflectometer (FWD) load. The Laplace-Hankel transform and dynamic stiffness matrix method are employed to solve the governing equations of the unsaturated soil layer. Combined with the global stiffness matrix and boundary conditions, analytical solutions of the entire system can be derived in the transform domain. A numerical integration method is utilized to perform the Laplace-Hankel inverse transform to obtain time-domain solutions. An analysis of the effects of saturation on the stress, displacement, and pore water pressure is presented. It is revealed that the effect of saturation of unsaturated subgrade soil on vertical stress is negligible, whereas vertical displacement and pore water pressure increase significantly with increasing saturation. Additionally, the vertical displacement response on the pavement surface is sensitive to subgrade deterioration and variations in material properties. Moreover, subgrade deterioration can be reflected in the variation in vertical displacement at approximately 1.2 m from the load center for the studied road structure. The proposed model, which is more realistic and reasonable, can provide a theoretical basis for the back-calculation of the elastic modulus of multilayered highway systems.

Thermo-Ecological Cost (TEC) –comparison of energy-ecological efficiency of renewable and non-renewable energy technologies

The article presents problems related to the assessment of local energy efficiency of energy systems. In practice, local energy efficiency is commonly used to evaluate these systems, which is not a correct criterion to compare different energy technologies, especially non-renewable and renewable energy systems. For the correct assessment of efficiency, a system analysis in the global balance boundary should be used. In the paper system analysis algorithm is discussed - Thermo-Ecological Cost (TEC), which is a correct tool to compare energy and ecological efficiency of different energy systems. Problems with the correct application of the energy and environmental efficiency assessment are illustrated with examples of results of local and system (TEC) evaluation of non-renewable and renewable energy systems efficiency.

High resolution C-isotopic data from microbialites in the aftermath of the end-Permian mass extinction in South China

Globally, Late Permian to Early Triassic carbonate rocks record several pronounced positive and negative C-isotope excursions, indicating a dramatic reorganization of the global carbon cycle. These C-isotopic anomalies provide important constraints on environmental changes that occurred during the end-Permian extinction and the subsequent delayed biotic recovery. In this study, we present high-resolution carbonate C-isotopic data (δ13Ccarb) spanning the Permian-Triassic transition at Dajiang, South China. Our results reveal a general decrease in δ13Ccarb of ∼3.3‰ during the microbialite formation which was followed by an increase. C-isotopic chemostratigraphic correlation between the Dajiang section and the Global Boundary Stratotype Section and Point (GSSP) at Meishan suggest a hiatus of several thousands of years between the pre-extinction skeletal limestones and the microbialite deposition in the aftermath of the end-Permian extinction in South China. We suggest that multiple sources of 13C-depleted dissolved carbon are required to explain the negative δ13Ccarb excursions as well as the δ13Ccarb differences among microbialites deposited in various paleogeographic locations. Our study shows that carbon cycles during the formation of microbialite may have been more complex than previously thought, and cessation of microbialite formation may have been controlled by both global and local environmental changes.

The developmental trajectories of children's reorientation to global and local properties of environmental geometry.

The way in which organisms represent the shape of their environments during navigation has been debated in cognitive, comparative, and developmental psychology. While there is evidence that adult humans encode the entire boundary shape of an environment (a global-shape representation), there are also data demonstrating that organisms reorient using only segments of the boundary that signal a goal location (a local-shape representation). Developmental studies offer unique insights into this debate; however, most studies have used designs that cannot dissociate the type of boundary-shape representation that children use to guide reorientation. Thus, we examined the developmental trajectories of children's reorientation according to local and global boundary shape. Participants aged 6-12 years were trained to find a goal hidden in one corner of a virtual arena, after which they were required to reorient in a novel test arena. From 10.5 years, children performed above chance when the test arena permitted reorientation based only on local-shape (Experiment 2), or only global-shape (Experiment 3) information. Moreover, when these responses were placed into conflict, older children reoriented with respect to global-shape information (Experiment 4). These age-related findings were not due to older children being better able to reorient in virtual environments per se: when trained and tested within the same environment (Experiment 1), children performed above chance from 6 years. Together, our results suggest (a) the ability to reorient on the basis of global- and local-shape representations develops in parallel, and (b) shape-based information is weighted to determine which representation informs reorientation. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Future population transgress climatic risk boundaries of extreme temperature and precipitation

Anthropogenic climate change is influencing the frequencies of extreme weather events. Considering the adaptability to extreme climatic risks in the future, we focused on determining whether humans have been exposed to the risks before. We define the rim of two-dimensional histograms of population under 20-year extreme temperature and precipitation as a climatic risk boundary. More than 30% (16.3%) of world population in South Asia, sub-Saharan Africa, and other regions will transgress the climatic risk boundary by the end of this century under RCP8.5 (RCP2.6) scenario. While many areas with large cities will remain within the global climatic risk boundary, they will transgress their regional climatic risk boundaries. This study shows that it is also necessary to consider the limits to adaptation for each appropriate area, considering the cultural, technological, and social transferability of adaptation. This study will help refine public perceptions of extreme climatic risks and lead to more efficient policy making.

An Analysis of the Spatiotemporal Characteristics and Diversity of Grain Production Resource Utilization Efficiency under the Constraint of Carbon Emissions: Evidence from Major Grain-Producing Areas in China.

As the most important driving force for ensuring the effective supply of grain in the country, the production stability of the major grain-producing areas directly concerns the national security of China. In this paper, considering the “water–soil–energy–carbon” correlation, water, soil and energy resource factors, and carbon emission constraints were included in an index system, and the global common frontier boundary three-stage super-efficient EBM–GML model was used to measure the grain production resource utilization efficiency of the major grain-producing areas in China from 2000 to 2019. This paper also analyzed the static and dynamic spatiotemporal characteristics and the restrictions of utilization efficiency. The results showed that, under the measurement of the traditional data envelopment analysis model, the grain production resource utilization efficiency in the major producing areas is relatively high, but there is still room to improve by more than 20%, and grain production still has enormous growth potential. After excluding external environmental and random factors, it was found that the utilization efficiency of grain production resources in the major producing areas decreased, and the efficiency and ranking of provinces changed significantly. External factors inhibit pure technical efficiency and expand the scale efficiency. The utilization efficiency of Northeast China was much higher than that of the Huang-Huai-Hai region and the middle and upper reaches of the Yangtze River region, and its grain production resource allocation management had obvious advantages. The total factor productivity index of food production resources showed an upward trend as a whole, and its change was affected by both technological efficiency and technological progress, of which technological progress had the greater impact. Therefore, reducing the differences in the external environment of different regions while making adjustments in accordance with their own potential is an effective way to further improve the utilization efficiency of food production resources.

Optimal boundary control problems for a hierarchical age-structured two-species model

This paper discusses the optimal control problems for a nonlinear age-structured two-species model, where elder individuals are more competitive than younger ones, and each species is described by a nonlinear integropartial differential equation with a global feedback boundary condition. First, we establish the existence of a unique nonnegative bounded solution by means of frozen coefficients and the fixed-point theorem. More importantly, we discuss the least deviation-cost problem and the most benefit-cost problem. For the least deviation-cost problem, the existence of an optimal strategy is established by means of Ekeland’s variational principle, and the minimum principle is obtained via an adjoint system. Meanwhile, the corresponding results for the most benefit-cost problem are given. In addition, some numerical experiment results are presented to examine the effects of parameters on the optimal policies and indexes.

Asymptotic critical behavior of holographic superconductor phase transition — the spectrum of excited states becomes continuous at T = 0

Within the framework of AdS/CFT duality, excited states of the conformal field living at the global AdS boundary of a four-dimensional spacetime Einstein gravity are investigated analytically in the probe limit where the field equations are linearized. At asymptotically large values, the threshold chemical potential for the appearance of excited condensate states are discrete, equal spacing, with the gap approaches zero logarithmically in the limit T → 0. Remarkably, numerical results show that, this behavior applies even for states as low as for the first or the second excited state of the condensate. This is especially significant on the liquid side of the black hole van der Waals-like phase transition (small or zero topological charge) where there seems to be no gap between the ground state and the first excited state at zero temperature. We postulate that, at the exact limit T = 0 where the gap is zero, the spectrum of threshold chemical potentials becomes continuous, all excited states of the condensate are activated above a finite chemical potential, suggesting a new quantum phase transition as a function of the chemical potential. Previous studies have largely missed this continuous spectrum of excited states in the T → 0 limit. This fact should be taken into account carefully in AdS/CFT duality studies.

Thermochemical nonequilibrium effects on high-enthalpy double-wedge flows

A hypersonic laminar flow over double wedges with a fixed forward angle of 15° and varied aft angles is studied using computational fluid dynamics and global stability analysis (GSA) at a free-stream Mach number of 12.82 and a total enthalpy of 21.77 MJ/kg. The specific total enthalpy is high enough to trigger evident vibrational excitation and air chemistry. To assess the effects of thermal and chemical nonequilibrium, three different thermochemistry models of air are considered, including frozen, thermal nonequilibrium, and thermochemical nonequilibrium gases. Two-dimensional base-flow simulations indicate that the onset of incipient and secondary separation is insensitive to the inclusion of thermochemistry, although the size of the separation region is substantially reduced. GSA is then performed on the base flows and identifies a three-dimensional stationary global instability beyond a critical aft angle, which is also insensitive to thermochemical nonequilibrium. The criterion of the global stability boundary established for the supersonic flow over compression corners in a calorically perfect gas in terms of a scaled deflection angle [Hao et al., “Occurrence of global instability in hypersonic compression corner flow,” J. Fluid Mech. 919, A4 (2021)] is, thus, extended to high-enthalpy conditions.

The Global Boundary Stratotype Section and Point (GSSP) for the base of the Coniacian Stage (Salzgitter-Salder, Germany) and its auxiliary sections (Słupia Nadbrzeżna, central Poland; Střeleč, Czech Republic; and El Rosario, NE Mexico)

Ireneusz Walaszczyk, Stanislav Čech, James S. Crampton, Zofia Dubicka, Christina Ifrim, Ian Jarvis, William J. Kennedy, Jackie A. Lees, Damian Lodowski, Martin Pearce, Danuta Peryt, Bradley B. Sageman, Poul Schiøler, Jordan Todes, David Uličný, Silke Voigt, Frank Wiese, With contributions by Christian Linnert, Tobias Püttmann, Seiichi Toshimitsu. Episodes 2022;45:181-220. https://doi.org/10.18814/epiiugs/2021/021022

Global Well-Posedness and Boundary Layer Effects of Radially Symmetric Solutions for the Singular Keller–Segel Model

Global Well-Posedness and Boundary Layer Effects of Radially Symmetric Solutions for the Singular Keller–Segel Model

Imperial Cartography and National Mapping in Afghanistan

Afghanistan assumed its modern cartographic form in piecemeal fashion between the late 1860s and early 1890s in the context of British imperial boundary-making projects in South Asia and the Middle East. The bordering of Afghanistan was contextualized by the global British empire and multiple boundary conflicts and frontier anxieties involving the British and the French, German, Russian, and other imperial powers as well as local rulers. The fundamental point here is that the map of Afghanistan is a product of imperial and interimperial concerns, and it has not benefited the Afghan people. The map of Afghanistan may or may not have served the imperial purposes for which it was created, but more importantly, by uncritically accepting it and its imperial heritage, we Afghans have become victims of an imperial map of ourselves. Afghans and non-Afghans will benefit from directly confronting the coercive impact of imperial mapping agendas on the largely invisible people “on the map” of Afghanistan. This essay historicizes the production of maps of modern Afghanistan, exposing imperial and crypto-colonial influences upon our national cartography. In so doing, it critically reimagines our spatial politics and reconfigures our intellectual infrastructure. It is an exercise in historical recentering designed to instill Afghan humanity and agency onto the map of Afghanistan.