scholarly journals Environmental impact on the mechanical properties of Porites spp. corals

Coral Reefs ◽  
2021 ◽  
Author(s):  
Molly A. Moynihan ◽  
Shahrouz Amini ◽  
Nathalie F. Goodkin ◽  
Jani T. I. Tanzil ◽  
J. Q. Isaiah Chua ◽  
...  
Keyword(s):  
Climate Change ◽  
Mechanical Properties ◽  
Chemical Composition ◽  
Structural Integrity ◽  
Organic Content ◽  
Skeletal Structure ◽  
Future Climate Change ◽  
Geochemical Composition ◽  
Wide Range ◽  
Reef Environments

AbstractDespite the economic and ecological importance of corals’ skeletal structure, as well as their predicted vulnerability to future climate change, few studies have examined the skeletal mechanical properties at the nanoscale. As climate change is predicted to alter coral growth and physiology, as well as increase mechanical stress events (e.g., bioerosion, storm frequency), it is crucial to understand how skeletal mechanical properties change with environmental conditions. Moreover, while material properties are intimately linked to the chemical composition of the skeleton, no previous study has examined mechanical properties alongside carbonate geochemical composition. UsingPoritescoral cores from a wide range of reef environments (Thailand, Singapore, Taiwan), we correlated coral’s micro-mechanical properties with chemical composition. In contrast to previous mechanical measurements of reef-building corals, we document unprecedented variability in the hardness, stiffness, and micro-cracking stress ofPoritescorals across reef environments, which may significantly decrease the structural integrity of reef substrate. Corals from environments with low salinity and high sedimentation had higher organic content and fractured at lower loads, suggesting that skeletal organic content caused enhanced embrittlement. Within individual coral cores, we observed seasonal variability in skeletal stiffness, and a relationship between high sea surface temperature, increased stiffness, and high-density. Regionally, lower Sr/Ca and higher Mg/Ca coincided with decreased stiffness and hardness, which is likely driven by increased amorphous calcium carbonate and skeletal organic content. If the coral is significantly embrittled, as measured here in samples from Singapore, faster erosion is expected. A decrease in skeletal stiffness will decrease the quality of reef substrate, enhance the rate of bioerosion by predators and borers, and increase colony dislodgement, resulting in widespread loss of structural complexity.

Anthropogenic climate change detected in natural and human systems of the world’s mountains

2021 ◽  
Author(s):  
Christian Huggel ◽  
Simon K. Allen ◽  
Indra D. Bhatt ◽  
Rithodi Chakraborty ◽  
Fabian Drenkhan ◽  
...  
Keyword(s):  
Climate Change ◽  
Water Resources ◽  
Climate Change Impacts ◽  
Indigenous Communities ◽  
Anthropogenic Climate Change ◽  
Future Climate Change ◽  
Mountain Regions ◽  
Wide Range ◽  
Mountain Systems ◽  
Human Systems

<p>Mountains cover about a quarter of the Earth’s land surface and are home to or serve a substantial fraction of the global population with essential ecosystem services, in particular water, food, energy, and recreation. While mountain systems are expected to be highly exposed to climate change, we currently lack a comprehensive global picture of the extent to which environmental and human systems in mountain regions have been affected by recent anthropogenic climate change.</p><p>Here we undertake an unprecedented effort to detect observed impacts of climate change in mountains regions across all continents. We follow the approach implemented in the IPCC 5<sup>th</sup> Assessment Report (AR5) and follow-up research where we consider whether a natural or human system has changed beyond its baseline behavior in the absence of climate change, and then attribute the observed change to different drivers, including anthropogenic climate change. We apply an extensive review of peer-reviewed and grey literature and identify more than 300 samples of impacts (aggregate and case studies). We show that a wide range of natural and human systems in mountains have been affected by climate change, including the cryosphere, the water cycle and water resources, terrestrial and aquatic ecosystems, energy production, infrastructure, agriculture, health, migration, tourism, community and cultural values and disasters. Our assessment documents that climate change impacts are observed in mountain regions on all continents. However, the explicit distinction of different drivers contributing to or determining an observed change is often highly challenging; particularly due to widespread data scarcity in mountain regions. In that context, we were also able to document a high amount of impacts in previously under-reported continents such as Africa and South America. In particular, we have been able to include a substantial number of place-based insights from local/indigenous communities representing important alternative worldviews.</p><p>The role of human influence in observed climate changes is evaluated using data from multiple gridded observational climate products and global climate models. We find that anthropogenic climate change has a clear and discernable fingerprint in changing natural and human mountain systems across the globe. In the cryosphere, ecosystems, water resources and tourism the contribution of anthropogenic climate change to observed changes is significant, showing the sensitivity of these systems to current and future climate change. Furthermore, our analysis reveals the need to consider the plurality of knowledge systems through which climate change impacts are being understood in mountain regions. Such attempts at inclusivity, which addresses issues of representation and justice, should be deemed necessary in exploring climate change impacts.</p>

scholarly journals The role of glacier dynamics and threshold definition in the characterisation of future streamflow droughts in glacierised catchments

2017 ◽  
Author(s):  
Marit Van Tiel ◽  
Adriaan J. Teuling ◽  
Niko Wanders ◽  
Marc J. P. Vis ◽  
Kerstin Stahl ◽  
...  
Keyword(s):  
Climate Change ◽  
Time Scales ◽  
Future Climate Change ◽  
Climate Change Scenarios ◽  
Glacier Area ◽  
Short Term ◽  
Drought Characteristics ◽  
Wide Range ◽  
Glacier Dynamics ◽  
The Future

Abstract. Glaciers are essential hydrological reservoirs, storing and releasing water at various time scales. Short-term variability in glacier melt is one of the causes of streamflow droughts, defined as below normal water availabilities. Streamflow droughts in glacierised catchments have a wide range of interlinked causing factors related to precipitation and temperature on short and long time scales. Climate change affects glacier storage capacity, with resulting consequences for discharge regimes and drought. Future projections of streamflow drought in glacierised basins can, however, strongly depend on the modelling strategies and analysis approaches applied. Here, we examine the effect of different approaches, concerning the glacier modelling and the drought threshold, on the characterisation of streamflow droughts in glacierised catchments. Streamflow is simulated with the HBV-light model for two case study catchments, the Nigardsbreen catchment in Norway and the Wolverine catchment in Alaska, and two future climate change scenarios (RCP4.5 and RCP8.5). Two types of glacier modelling are applied, a constant and dynamical glacier area conceptualisation. Streamflow droughts are identified with the variable threshold level method and their characteristics are compared between two periods, a historical (1975–2004) and future (2071–2100) period. Two existing threshold approaches to define future droughts are employed, (1) the threshold from the historical period and (2) a transient threshold approach, whereby the threshold adapts every year in the future to the changing regimes. Results show that drought characteristics differ among the combinations of glacier area modelling and thresholds. The historical threshold combined with a dynamical glacier area projects extreme increases in drought severity in the future, caused by the regime shift due to a reduction in glacier area. The historical threshold combined with a constant glacier area results in a drastic decrease of the number of droughts. The drought characteristics between future and historic periods are more similar when the transient threshold is used, for both glacier dynamics conceptualisations. With the transient threshold causing factors of future droughts, can be analysed. This study revealed the different effects of methodological choices on future streamflow drought projections and it highlights how the options can be used to analyse different aspects of future droughts: the transient threshold for analysing future drought processes, the historical threshold to assess changes between periods, the constant glacier area to analyse the effect of short term climate variability on droughts and the dynamical glacier area to model realistic future discharges under climate change.

scholarly journals High thermal plasticity and vulnerability in extreme environments at the warm distributional edge: the case of a tidepool shrimp

2020 ◽  
Author(s):  
Eyal Amsalem ◽  
Gil Rilov
Keyword(s):  
Climate Change ◽  
Prolonged Exposure ◽  
Thermal Environment ◽  
Extreme Environments ◽  
Open Water ◽  
Thermal Fluctuations ◽  
Future Climate Change ◽  
Regional Warming ◽  
Thermal Plasticity ◽  
Wide Range

1.AbstractClimate change threatens the resilience of species, especially at their warm distributional edge in extreme environments. However, not much is known about the thermal vulnerability of marine intertidal species at this edge. We investigated the thermal vulnerability of the tidepool shrimp, Palaemon elegans in the fast-warming southeastern Mediterranean, its warm distributional edge. Tidepool organisms experience strong and fast thermal fluctuations. This might make them more resilient to change, but also bring them closer to their thermal limits during extreme conditions. To test the shrimp’s resilience, we tested three hypotheses: (1) P. elegance in the southeast Mediterranean has higher critical thermal maximum (CTMax) than in cooler regions, (2) the shrimp possess seasonal acclimatization, but (3) long exposure to extreme summer temperatures might erode its thermal performance making it vulnerable to future climate change. We characterized the shrimp’s thermal environment and population dynamics, determined CTMax and tested diverse physiological performance attributes (respiration, digestion, activity, growth) under a wide range of temperatures during winter and summer. P. elegans has a wide optimum performance range between 20-30°C during summer and its CTMax is 38.1°C, higher than its Atlantic counterparts. However, its warming tolerance is only 0.3°C, indicating low capacity for dealing with further warming in pools compared to northeast Atlantic populations that have wider tolerance. Prolonged exposure to current mean summer values in open water (∼ 32°C) would also significantly reduce its performance and increase mortality. This suggests that its population viability may be reduced under continuous regional warming and intensification of extreme events.

scholarly journals Climate Change Impacts on Groundwater Recharge in Cold and Humid Climates: Controlling Processes and Thresholds

Climate ◽  
2022 ◽  
Vol 10 (1) ◽  
pp. 6
Author(s):  
Emmanuel Dubois ◽  
Marie Larocque ◽  
Sylvain Gagné ◽  
Marco Braun
Keyword(s):  
Climate Change ◽  
Groundwater Recharge ◽  
Water Resource Management ◽  
Global Climate Models ◽  
Future Climate Change ◽  
Temperature Changes ◽  
Wide Range ◽  
Long Term Changes ◽  
Precipitation And Temperature

Long-term changes in precipitation and temperature indirectly impact aquifers through groundwater recharge (GWR). Although estimates of future GWR are needed for water resource management, they are uncertain in cold and humid climates due to the wide range in possible future climatic conditions. This work aims to (1) simulate the impacts of climate change on regional GWR for a cold and humid climate and (2) identify precipitation and temperature changes leading to significant long-term changes in GWR. Spatially distributed GWR is simulated in a case study for the southern Province of Quebec (Canada, 36,000 km2) using a water budget model. Climate scenarios from global climate models indicate warming temperatures and wetter conditions (RCP4.5 and RCP8.5; 1951–2100). The results show that annual precipitation increases of >+150 mm/yr or winter precipitation increases of >+25 mm will lead to significantly higher GWR. GWR is expected to decrease if the precipitation changes are lower than these thresholds. Significant GWR changes are produced only when the temperature change exceeds +2 °C. Temperature changes of >+4.5 °C limit the GWR increase to +30 mm/yr. This work provides useful insights into the regional assessment of future GWR in cold and humid climates, thus helping in planning decisions as climate change unfolds. The results are expected to be comparable to those in other regions with similar climates in post-glacial geological environments and future climate change conditions.

Application of a portable indentation rig with Rockwell indenter to determine mechanical properties and residual stresses on an aluminum plate

2020 ◽  
Vol 55 (7-8) ◽  
pp. 246-257
Author(s):  
Saba Salmani Ghanbari ◽  
Amir-Hossein Mahmoudi
Keyword(s):  
Mechanical Properties ◽  
Residual Stresses ◽  
Structural Integrity ◽  
Indentation Load ◽  
Instrumented Indentation ◽  
Unknown Parameters ◽  
Plastic Properties ◽  
Wide Range ◽  
Portable Apparatus ◽  
Non Destructive

Measuring residual stresses is still a dilemma in many engineering applications. It is even more crucial when the industrial requirements demand for a non-destructive technique in order to avoid compromising the structural integrity of the engineering components. Furthermore, estimating the mechanical properties of the materials, especially when the components are aged, is of importance. Instrumented indentation has gained much interest in recent years. There are many studies in the literature which are focused on measuring residual stresses or mechanical properties using instrumented indentation. Since in many cases there is no possibility of transferring large samples or those under service, for possible measurements, having a portable rig can be very useful. Furthermore, indentation procedure is a low-cost non-destructive method with high accuracy which is able to measure the plastic properties of material as well as its residual stresses on which the designing and construction of the portable apparatus were based. The instrumented indentation testing details were followed according to the ASTM E2546-15 standard practice. In this research, a wide range of simulations were performed on a group of aluminum alloys in order to estimate the equi-biaxial residual stresses by analyzing the indentation load–displacement curves which were obtained from the experimental outcomes. Then neural networks were employed to estimate the unknown parameters. The performance accuracy of the designed portable apparatus and the acceptable precision of the introduced method were then verified with experimental tests performed on Al 2024-T351.

Is rainfed crop production in central Europe at risk? Using a regional climate model to produce high resolution agroclimatic information for decision makers

2010 ◽  
Vol 148 (6) ◽  
pp. 639-656 ◽  
Author(s):  
M. TRNKA ◽  
J. EITZINGER ◽  
M. DUBROVSKÝ ◽  
D. SEMERÁDOVÁ ◽  
P. ŠTĚPÁNEK ◽  
...  
Keyword(s):  
Climate Change ◽  
At Risk ◽  
Water Balance ◽  
Central Europe ◽  
Crop Production ◽  
Global Radiation ◽  
Future Climate Change ◽  
Rainfed Agriculture ◽  
Crop Models ◽  
Wide Range

SUMMARYThe reality of climate change has rarely been questioned in Europe in the last few years as a consensus has emerged amongst a wide range of national to local environmental and resource policy makers and stakeholders that climate change has been sufficiently demonstrated in a number of sectors. A number of site-based studies evaluating change of attainable yields of various crops have been conducted in Central Europe, but studies that evaluate agroclimatic potential across more countries in the region are rare. Therefore, the main aim of the present study was to develop and test a technique for a comprehensive evaluation of agroclimatic conditions under expected climate conditions over all of Central Europe with a high spatial resolution in order to answer the question posed in the title of the paper ‘Is rainfed crop production in central Europe at risk?’ The domain covers the entire area of Central Europe between latitudes 45° and 51·5°N and longitudes 8° and 27°E, including at least part of the territories of Austria, the Czech Republic, Germany, Hungary, Poland, Romania, Slovakia, Switzerland and Ukraine. The study is based on a range of agroclimatic indices that are designed to capture complex relations existing between climate and crops (their development and/or production) as well as the agrosystems as a whole. They provide information about various aspects of crop production, but they are not meant to compete with other and sometimes more suitable tools (e.g. process-based crop models, soil workability models, etc.). Instead, the selected indices can be seen as complementary to crop modelling tools that describe aspects not fully addressed or covered by crop models for an overall assessment of crop production conditions. The set of indices includes: sum of effective global radiation, number of effective growing days, Huglin index, water balance during the period from April to June (AMJ) and during the summer (JJA), proportion of days suitable for harvesting of field crops in June and July, and proportion of days suitable for sowing in early spring as well as during the autumn. The study concluded that while the uncertainties about future climate change impacts remain, the increase in the mean production potential of the domain as a whole (expressed in terms of effective global radiation and number of effective growing days) is likely a result of climate change, while inter-annual yield variability and risk may also increase. However, this is not true for the Pannonian (the lowlands between the Alps, the Carpathian Mountains and the Dinaric Alps) and Mediterranean parts of the domain, where increases in the water deficit will further limit rainfed agriculture but will probably lead to an increase in irrigation agriculture if local water resources are dwindling. Increases in the severity of the 20-year drought deficit and more substantial water deficits during the critical part of the growing season are very likely over the central and western part of the domain. Similarly, the inter-annual variability of water balance is likely to increase over the domain. There is also a chance of conditions for sowing during spring deteriorating due to unfavourable weather, which might increase the preference given to winter crops. This is already likely due to their ability to withstand spring drought stress events. Harvesting conditions in June (when harvest of some crops might take place in the future) are not improving beyond the present level, making the planning of the effective harvest time more challenging. Based on the evidence provided by the present study, it could be concluded that rainfed agriculture might indeed face more climate-related risks, but the overall conditions will probably allow for acceptable yield levels in most seasons. However, the evidence also suggests that the risk of extremely unfavourable years, resulting in poor economic returns, is likely to increase.

Methods and uncertainties in bioclimatic envelope modelling under climate change

2006 ◽  
Vol 30 (6) ◽  
pp. 751-777 ◽  
Author(s):  
Risto K. Heikkinen ◽  
Miska Luoto ◽  
Miguel B. Araújo ◽  
Raimo Virkkala ◽  
Wilfried Thuiller ◽  
...  
Keyword(s):  
Climate Change ◽  
Climate Models ◽  
Climatic Factors ◽  
Future Climate Change ◽  
Future Research ◽  
Climate Change Scenarios ◽  
Distribution Models ◽  
Wide Range ◽  
Bioclimatic Modelling ◽  
Bioclimatic Envelope

Potential impacts of projected climate change on biodiversity are often assessed using single-species bioclimatic ‘envelope’models. Such models are a special case of species distribution models in which the current geographical distribution of species is related to climatic variables so to enable projections of distributions under future climate change scenarios. This work reviews a number of critical methodological issues that may lead to uncertainty in predictions from bioclimatic modelling. Particular attention is paid to recent developments of bioclimatic modelling that address some of these issues as well as to the topics where more progress needs to be made. Developing and applying bioclimatic models in a informative way requires good understanding of a wide range of methodologies, including the choice of modelling technique, model validation, collinearity, autocorrelation, biased sampling of explanatory variables, scaling and impacts of non-climatic factors. A key challenge for future research is integrating factors such as land cover, direct CO2 effects, biotic interactions and dispersal mechanisms into species-climate models. We conclude that, although bioclimatic envelope models have a number of important advantages, they need to be applied only when users of models have a thorough understanding of their limitations and uncertainties.

scholarly journals The PROFOUND database for evaluating vegetation models and simulating climate impacts on forests

2019 ◽  
Author(s):  
Christopher P. O. Reyer ◽  
Ramiro Silveyra Gonzalez ◽  
Klara Dolos ◽  
Florian Hartig ◽  
Ylva Hauf ◽  
...  
Keyword(s):  
Climate Change ◽  
Nitrogen Deposition ◽  
Forest Stand ◽  
Climate Impacts ◽  
Ecosystem Dynamics ◽  
Future Climate Change ◽  
Climate Change Scenarios ◽  
Flat File ◽  
Wide Range ◽  
Vegetation Models

Abstract. Process-based vegetation models are widely used to predict local and global ecosystem dynamics and climate change impacts. Due to their complexity, they require careful parameterization and evaluation to ensure that projections are accurate and reliable. The PROFOUND Database (PROFOUND DB) provides a wide range of empirical data to calibrate and evaluate vegetation models that simulate climate impacts at the forest stand scale. A particular advantage of this database is its wide coverage of multiple data sources at different hierarchical and temporal scales, together with environmental driving data as well as the latest climate scenarios. Specifically, the PROFOUND DB provides general site descriptions, soil, climate, CO2, nitrogen deposition, tree and forest stand-level, as well as remote sensing data for nine contrasting forest stands distributed across Europe. Moreover, for a subset of five sites, time series of carbon fluxes, atmospheric heat conduction, and soil water are also available. The climate and nitrogen deposition data contain several datasets for the historic period and a wide range of future climate change scenarios following the Representative Concentration Pathways (RCP2.6, RCP4.5, RCP6.0, RCP8.5). We also provide pre-industrial climate simulations that allow for model runs aimed at disentangling the contribution of climate change to observed forest productivity changes. The PROFOUND DB is available freely as a SQLite relational database or ASCII flat file version (at https://doi.org/10.5880/PIK.2019.008). The data policies of the individual, contributing datasets are provided in the metadata of each data file. The PROFOUND DB can also be accessed via the ProfoundData R-package (https://github.com/COST-FP1304-PROFOUND/ProfoundData), which provides basic functions to explore, plot, and extract the data for model set-up, calibration and evaluation.

scholarly journals 3D Printing of Thermoplastic Elastomers: Role of the Chemical Composition and Printing Parameters in the Production of Parts with Controlled Energy Absorption and Damping Capacity

Polymers ◽  
2021 ◽  
Vol 13 (20) ◽  
pp. 3551
Author(s):  
Marina León-Calero ◽  
Sara Catherine Reyburn Valés ◽  
Ángel Marcos-Fernández ◽  
Juan Rodríguez-Hernandez
Keyword(s):  
Mechanical Properties ◽  
Chemical Composition ◽  
3D Printing ◽  
Energy Absorption ◽  
Thermoplastic Elastomers ◽  
Damping Capacity ◽  
Compression Tests ◽  
Wide Range ◽  
Printing Parameters

Additive manufacturing (AM) is a disruptive technology that enables one to manufacture complex structures reducing both time and manufacturing cost. Among the materials commonly used for AM, thermoplastic elastomers (TPE) are of high interest due to their energy absorption capacity, energy efficiency, cushion factor or damping capacity. Previous investigations have exclusively focused on the optimization of the printing parameters of commercial TPE filaments and the structures to analyse the mechanical properties of the 3D printed parts. In the present paper, the chemical, thermal and mechanical properties for a wide range of commercial thermoplastic polyurethanes (TPU) filaments were investigated. For this purpose, TGA, DSC, 1H-NMR and filament tensile strength experiments were carried out in order to determine the materials characteristics. In addition, compression tests have been carried out to tailor the mechanical properties depending on the 3D printing parameters such as: infill density (10, 20, 50, 80 and 100%) and infill pattern (gyroid, honeycomb and grid). The compression tests were also employed to calculate the specific energy absorption (SEA) and specific damping capacity (SDC) of the materials in order to establish the role of the chemical composition and the geometrical characteristics (infill density and type of infill pattern) on the final properties of the printed part. As a result, optimal SEA and SDC performances were obtained for a honeycomb pattern at a 50% of infill density.

scholarly journals Ecosystem-Based Adaptation for the Impact of Climate Change and Variation in the Water Management Sector of Sri Lanka

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Bhabishya Khaniya ◽  
Miyuru B. Gunathilake ◽  
Upaka Rathnayake
Keyword(s):  
Climate Change ◽  
Water Management ◽  
Water Resources ◽  
Sri Lanka ◽  
Future Climate Change ◽  
Adaptation To Climate Change ◽  
Impact Of Climate Change ◽  
Quality Of Water ◽  
Wide Range ◽  
The Impact

The climate of Sri Lanka has been fluctuating at an alarming rate during the recent past. These changes are reported to have pronounced impacts on the livelihoods of the people in the country. Water is central to the sustainable functioning of ecosystems and wellbeing of mankind. It is evident that pronounced variations in the climate will negatively impact the availability and the quality of water resources. The ecosystem-based adaptation (EbA) approach has proved to be an effective strategy to address the impact of climate change on water resources in many parts of the world. The key aim of this paper is to elaborate the wide range of benefits received through implementation of EbAs in field level, watershed scale, and urban and coastal environments in the context of Sri Lanka. In addition, this paper discusses the benefits of utilizing EbA solutions over grey infrastructure-based solutions to address the issues related to water management. The wide range of benefits received through implementation of EbAs can be broadly classified into three categories: water supply regulation, water quality regulation, and moderation of extreme events. This paper recommends the utilization of EbAs over grey infrastructure-based solutions in adaptation to climate change in the water management sector for the developing region due its cost effectiveness, ecofriendliness, and multiple benefits received on long-term scales. The findings of this study will unequivocally contribute to filling existing knowledge and research gaps in the context of EbAs to future climate change in Sri Lanka. The suggestions and opinions of this study can be taken into account by decision makers and water resources planning agencies for future planning of actions related to climate change adaptation in Sri Lanka.

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