Digital Commons Network^™

Labor Migration Triggered By Covid-19 And Its Impact On Climate Change Adaptation Of Producers In Sunsari District, Nepal, Amrit Shrestha

Masters Theses

Due to the COVID-19 pandemic, many temporary labor workers who were employed in foreign countries lost their jobs and had to return to their homeland. These skilled laborers are involved in daily household tasks and farming decision-making processes. This study investigates the role of labor migrants who returned to their households due to COVID-19 on the climate change adaptation of farmers. The migrant laborers are relatively better educated, willing to adopt modern technology, and receive training. An ordered logistic regression was used to analyze the impact of COVID-19 on household’s access to institutional factors (Extension services, subsidies, and internet) as …

Joint Failure Probability Of Dams Based On Probabilistic Flood Hazard Analysis, Matthew G. Montgomery

Masters Theses

Probabilistic risk methods are becoming increasingly accepted as a means of carrying out risk-informed decision making regarding the design and operation of structures such as dams. Probabilistic risk calculations require the quantification of epistemic and aleatory uncertainties not investigated through deterministic methodologies. In this hydrological study, a stochastic sampling methodology is employed to investigate the joint failure probability of three dams in adjacent, similarly sized watersheds within the same Hydrologic Unit Code (HUC) 6 basin. A Probabilistic Flood Hazard Analysis (PFHA) framework is used to simulate the hydrologic loading of a wide range of extreme precipitation events across the combined …

Science Education To The Rescue? Assessing The Relationship Between Scientific Literacy And Carbon Emissions, Anthony Schmidt

Doctoral Dissertations

Human activities have radically changed the climate, negatively impacting all life on earth. The technical means to address this climate crisis exist, but there are major social and political hurdles that stand in the way. Education has been touted as one possible means for helping to move forward necessary action on climate change. A hybrid model of planned behavior and human capital helps explain how education can affect climate change. The current dissertation sought to assess what relationship may exist between changes in per capita carbon emissions and science education as measured by the Programme for International Student Achievement (PISA). …

The Influence Of Traits On Species Responses To Climate Change: Does Warming Negatively Impact Native Species More Than Invasive Species?, Margaret Anne Mamantov

Doctoral Dissertations

Current climate change is increasing global temperatures so that many organisms are now experiencing temperatures outside of their thermal tolerance, which threatens their survival. Organisms respond to physiologically stressful temperatures to reduce this threat. Organisms respond to warming through three main mechanisms: range shifts, adjustments via phenotypic plasticity, and evolutionary adaptation. Organisms vary in their ability to utilize these three mechanisms, leading to differences in the magnitude and success of their adjustments to temperature change. Here, I examine how organismal traits influence variation in species response to climate change. Chapter one addresses how physiological tolerance may influence the rate of …

Evaluating Current And Future Potential Distribution Of Epiphytic Orchids In The Congo Basin With Ecological Niche Models, Michael L. Ngoh

Masters Theses

The Congo Basin Forest harbors a rich diversity of epiphytic communities, with the Orchidaceae alone making up more than 50% of all epiphytes in the region. Despite the huge diversity of epiphytes, many species, including epiphytic orchids, are at risk to a diverse array of threats. Climate change for instance poses severe threats to epiphytic orchids due to elevated temperatures, prolonged periods of droughts, as well as reduced rainfall across the Congo Basin Forest. In this study, we used ecological niche modeling and GIS techniques to identify spatial patterns of species richness, potential future climate refugia, and novel climatic suitability …

Impacts Of Summer Drought And Climate Change Conditions On Hydropower Resources And Power System Reliability In The Pjm Region, William J. Tingen Ii

Masters Theses

The United States power grid is a large, complex, and interconnected system that involves the coordination of numerous entities (e.g., power plant owners/operators, regulators, stakeholders, etc.). As such, any type of extreme event can potentially threaten the economic, safe, and reliable operation of the grid. One such example is summer drought (i.e., events predominantly characterized by elevated temperatures and reduced precipitation), which have impacts spanning all aspects of the power system, especially generation resources through changes in water availability and temperature. Additionally, although heavily dependent on region, climate change can potentially increase the likelihood and severity of drought conditions, illustrating …

Geographic Patterns Of Genetic Diversity Under Climate Change: Linking Genes And Ecosystems, Shannon L. Bayliss

Doctoral Dissertations

Climate change is having profound effects on species distributions. However, much less is understood about how climate change may alter the distribution of genetic variation within species across landscapes. Maintaining genetic diversity within populations is essential for the survival of species in the face of rapid climatic changes, but importantly, losses of genetic variation will also have significant consequences on entire ecosystems. The objective of this dissertation is to understand how genetic variation in a riparian cottonwood species, Populus angustifolia, affects mass and energy exchange between the land and atmosphere across ~1700 km of latitude of the western United …

Risk Management Potential Of Supplemental Irrigation For Cotton In A Sub-Humid Climate Under Climate Change, Wen Liu

Masters Theses

Adoption of supplemental irrigation to reduce cotton yield losses is a potential risk management strategy for farmers given increasingly frequent drought periods due to climate change. However, cotton farmers in the rolling landscape areas of the lower Mississippi River Basin (MRB) are concerned about whether an investment in supplemental irrigation is economically feasible. This study determined the impacts of the effects of risk exposure on optimal irrigation strategies for cotton production under climate change in West Tennessee. A crop simulation model was calibrated and validated using measured data from cotton irrigation experiments at Jackson, TN over three years (2006–2008). Simulated …

Evolution And Resurrection Ecology Of A Foundational Coastal Marsh Plant, Jennifer L. Summers

Doctoral Dissertations

Stratified storage of dormant seeds in soil can result in natural archives useful for studying evolutionary responses to environmental change. However, few studies leverage soil-stored seed banks as natural archives, in part because of concerns over attrition, bias, and sediment mixing. Here, I examine the persistent seed bank of Schoenoplectus americanus, a foundational brackish marsh sedge, to a) determine whether it can serve as a resource for reconstructing demographic and population genetic/genomic variation, b) whether and how evolution may be occurring across a century. After extracting seeds from radionuclide-dated soil cores taken across the Chesapeake Bay, I “resurrected” age …

Coffee Supply Chain Planning Under Climate Change, Rui Zhou

Masters Theses

Coffee is a valuable crop for many tropical countries and provides an export value estimated at US$30.1 billion in 2019 worldwide. Coffee trees are climate sensitive. Published studies show that climate change is projected to have a negative impact on suitable growing areas for coffee beans, so the coffee bean production is facing a rising risk. At the same time, the consumption of coffee is increasing in recent years, especially in Asian countries. Therefore, the sustainability of the coffee industry has become a concern shared by all participants along the coffee supply chains. Decision making in arabica coffee bean cultivation, …

Within-Reach Temperature Heterogeneity Is Limited In A Southern Appalachian Stream Network: Implications For Climate Change Refugia And Reach-Scale Temperature Mapping, Anna Kaz, Matthew Troia Dr., Xingli Giam Dr.

Chancellor’s Honors Program Projects

No abstract provided.

Assessing Interactions Of Future Climate Change, Wildfires, And Terrestrial Biogeochemical Feedbacks, Cheng-En Yang

Doctoral Dissertations

Rising anthropogenic emissions of radiatively active greenhouse gases and particulate matter (PM) are altering Earth’s climate, increasing human and ecosystem health risks, and inducing feedbacks from terrestrial and marine ecosystems on future atmospheric carbon dioxide (CO2) levels and PM concentrations. Process-based Earth system models (ESMs) and regional climate and chemistry transport models offer the best approach for quantifying these feedbacks and their uncertainties, projecting future atmospheric CO2 levels and resulting temperature increases and wildfire risks, predicting hazardous PM concentrations and human health risks, and understanding the impacts of potential mitigation efforts. In this dissertation, I address these globally significant environmental …

Optimizing Urban Infrastructure Resilience Under Precipitation And Population Growth Uncertainties, Masoud Barah

Doctoral Dissertations

Increased urbanization, infrastructure degradation, and climate change threaten to overwhelm stromwater systems across the nation, rendering them ineffective. Green Infrastructure (GI) practices are low cost, low regret strategies that can contribute to urban runoff management. However, questions remain as to how to best distribute GI practices through urban watersheds given the precipitation uncertainty and the hydrological responses to them.First, we develop a two-stage stochastic robust programming model to determine the optimal placement of GI practices across a set of candidate locations in a watershed to minimize the total expected runoff under medium-term precipitation uncertainties. We develop a systemic approach to …

Opportunities And Constraints Related To The Production And Use Of Knowledge For Climate Change Adaptation Efforts In Urban, Energy, And Water Systems, Kathleen Marie Ernst

Doctoral Dissertations

Urban, energy, and water system decision-makers are increasingly focused on preparing for the impacts of climate change. These impacts combine with social, economic, and environmental changes to create nuanced localized effects across systems. Climate change adaptation efforts have largely been organized by sector, even though coupled systems approaches could identify negative consequences and mutually-beneficial actions that occur across systems. These insights are missed when coupled systems are not considered in adaptation efforts. However, constraints inhibit adaptation processes within coupled systems. For example, United States energy-water nexus adaptation is constrained by insufficient data and information, path dependence, and institutional fragmentation and …

Digging Deeper: Development And Application Of An Untargeted Exometabolomics Approach To Identify Biogeochemical Hotspots Of Dissolved Organic Matter Vulnerability In Arctic Soils, Mallory Paige Ladd

Doctoral Dissertations

Arctic soils contain vast reserves of carbon (C) that, with rising temperatures, may become a significant source of greenhouse gases (GHGs) (i.e. CO₂, CH₄, N₂O) due to increased microbial decomposition of soil organic matter (SOM). However, there are significant spatial variations in GHG production that lead to hotspots of C release across the landscape, creating significant uncertainty in climate models. Reliably predicting the magnitude of C loss via microbial production of GHGs, and the proportion lost as either CO₂ or CH₄, depends on many factors, including soil temperature and moisture, …

Food Security In The United States: A Futures Analysis Via Systems Modeling, Jennifer Lynn Trumbo

Masters Theses

Food insecurity is a pressing issue not only in developing countries, but in communities across the United States (US). Food insecurity is the lack of nutritious, sufficient, accessible, and reliable culturally-appropriate food. At least 42.2 million people across the US face food insecurity. Food insecurity has been associated with institutional barriers, gender, indigeneity, citizenship, human immunodeficiency virus (HIV) status, racialization, and poverty. Further, a lack of sufficient, nutritious food is associated with serious health outcomes. Food insecure populations have higher rates of chronic disease, mental health issues, and obesity. Considering the negative health outcomes associated with food insecurity, and its …

Plasticity And Biotic Interactions Mediate Plant Persistence In A Changing World, Alix Ann Pfennigwerth

Masters Theses

Anthropogenic global change is occurring today at a faster rate and larger scale than ever before. Understanding how plants will respond to such large-scale disturbance is critical for biodiversity conservation, yet the ecological and evolutionary mechanisms underlying these responses remain poorly understood. In this thesis, I investigated the mechanisms underlying plant response to two major drivers of global change, climate change and the widespread mortality of foundation species. First, I examined genetic and plastic plant trait responses to climatic variation using elevation gradients, which serve as space-for-time substitutions for climate change. Through field observations in three populations of the North …

Exploring Enrichment Cultures Of Denitrifying Microorganisms From El Yunque National Forest, Samiha Ahsan, Jenny Onley, Frank Loeffler

Chancellor’s Honors Program Projects

No abstract provided.

Impacts Of Climate Change On The Evolution Of The Electrical Grid, Melissa Ree Allen

Doctoral Dissertations

Maintaining interdependent infrastructures exposed to a changing climate requires understanding 1) the local impact on power assets; 2) how the infrastructure will evolve as the demand for infrastructure changes location and volume and; 3) what vulnerabilities are introduced by these changing infrastructure topologies. This dissertation attempts to develop a methodology that will a) downscale the climate direct effect on the infrastructure; b) allow population to redistribute in response to increasing extreme events that will increase under climate impacts; and c) project new distributions of electricity demand in the mid-21^st century.

The research was structured in three parts. The first …

Wood Decomposition In A Warmer World, Emily Elizabeth Austin

Doctoral Dissertations

Climatic warming is altering species distributions and ecosystem functions across the globe. Wood is an important carbon pool and the fungal communities in wood are relatively simple compared to those in soil. These factors make decomposing wood an ideal system for exploring the influence of decomposer community on the response of decomposition to warming. My research has focused on the effects of warming wood decomposition rates and wood decomposing communities. Using field and lab- based manipulative experiments and field observations I explore the influence of tree species, wood decomposition stage, geography and warming on fungal community structure and activity. In …

Religion’S Influence On Environmental Concern: U.S. Evangelicals’ Construction Of Climate Change Perceptions, Aaron S. Routhe

Doctoral Dissertations

Scholars identify an emerging religious social base to U.S. environmentalism and public concern about anthropogenic global climate change. Surveys also show religious and political conservatives express skepticism about this environmental problem and oppose environmental regulations addressing it. White conservative Protestants reflect this contrast by denying human activity causes it and opposing climate policy for mitigating anthropogenic effects on Earth’s atmosphere, while concern and activism for climate protection simultaneously increases among other environmental evangelical Christians. Decades of quantitative investigations reveal religion’s role in environmental concern remains murky. Little clarity exists about how biblical literalism, “end times” eschatology, and religious environmental stewardship …

Ant Community Dynamics And The Effects Of Global Warming, Katharine Lisa Stuble

Doctoral Dissertations

This dissertation seeks to provide an understanding of how species coexist and, further, how climate change may alter communities by acting on the mechanisms that promote coexistence. Specifically, I examined coexistence among ant species in eastern deciduous forests and the effects that warming may have on foraging activity. Through a series of field observations, I sought evidence for the importance of four of the most commonly cited mechanisms for coexistence among ant species: the dominance – discovery tradeoff, the dominance – thermal tolerance tradeoff, spatial segregation, and niche partitioning. In this system, I did not find evidence for any of …

Public Land In A Changing Climate: Planning For An Uncertain Future, Kathleen Marie Hauser

Masters Theses

This thesis investigates the ways in which institutions and actors consider climate change, and how the inclusion of diverse perspectives and challenges in the planning process shapes climate change governance. In particular, I asked how the participants, place-specific contexts, and decision-making processes affect environmental decision-making in Alaska’s National Parks. I discuss the literature on geographical perspectives on climate change, environmental and climate change governance, how uncertainty and risk affect decision-making in the context of climate change, and the history of land use management in the United States. This project incorporates qualitative methods to research the Climate Change Scenario Planning project …

Microbial Community Structure And Ecosystem Function In A Changing World, Melissa Ann Cregger

Doctoral Dissertations

Understanding the effects climate change will have on the structure and function of global ecosystems is a pressing ecological and social issue. Global change driven changes in atmospheric warming and precipitation régimes have begun to alter the distribution of plants and animals in, as well as the function of, ecosystems. Using two large-scale climate change manipulations, I assessed the effect of changing precipitation and temperature regimes on soil microbial community structure and function. Soil microbial communities regulate decomposition and nutrient cycling rates in ecosystems, thus understanding their response to climatic changes will enable scientists to better predict carbon feedbacks to …

Response Of Inland Lakes To Climate Change Across The Tibetan Plateau Investigated Using Landsat And Icesat Data, Zewen Liu

Masters Theses

The Tibetan Plateau experienced tremendous climate change during the past four decades. Due to the large size, widely distribution of cryosphere, and diverse landforms, different parts of the plateau may experience different climate and cryosphere changing patterns. The changes of inland lakes within the plateau are important indicators of climate change as these lakes are fed by precipitation, permafrost degradation, and glacier melting that are all sensitive to climate change. To examine the spatial and temporal differences of lake variations across the Tibetan Plateau, Landsat images and ICESat/GLAS altimetry data were used to extract the changes in surface areas of …

Tree Growth Dynamics, Fire History, And Fire-Climate Relationships In Pine Rocklands Of The Florida Keys, U.S.A., Grant Logan Harley

Doctoral Dissertations

Pine rocklands are globally endangered, fire-maintained communities currently restricted to small habitat areas in southern Florida, Cuba, and the Bahamas. The purpose of this dissertation research was to identify the long-term ecological disturbance regimes and climatic trends responsible for the persistence of pine rocklands, and examine how human-induced changes during the 20^th century contributed to decline of these communities. This research applied techniques of dendrochronology in extreme southern Florida, in a subtropical region where tree‐ring science has never been applied, to increase the understanding of how anthropogenic and natural disturbance events have decreased the spatial distribution of South Florida …

Anticipated Changes In Precipitation Events Over The 21st Century Using Community Climate System Model, Version 4, Scott Tavish Deneale

Masters Theses

Future global daily precipitation data from Community Climate System Model, version 4 (CCSM4) were analyzed to evaluate changes in a variety of precipitation parameters over the 21st century. Multiple ensemble members of 21st century Representative Community Pathways (RCP) radiative scenarios were included in the model to provide an array of potential future climate change results. Multiple ensembles of historic daily precipitation data from CCSM4 were compared with Global Precipitation Climatology Project (GPCP) V1DD daily precipitation data and Climate Prediction Center (CPC) Merged Analysis of Precipitation (CMAP) monthly precipitation data. Annual average and 95th percentile precipitation values were averaged from 1997-2005 …