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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Investigating climate feedbacks across forcing magnitudes and time scales using the radiative kernel technique

Jonko, Alexandra 06 September 2012 (has links)
Radiative feedbacks associated with changes in water vapor, temperature, surface albedo and clouds remain a major source of uncertainty in our understanding of climate's response to anthropogenic forcing. In this dissertation climate model data is used to investigate variations in feedbacks that result from changing CO��� forcing and the time scales on which feedbacks operate, focusing on the applicability of one method in particular, the radiative kernel technique, to these problems. This computationally efficient technique uses a uniform, incremental change in feedback variables to infer top-of-atmosphere (TOA) radiative flux changes. The first chapters explore the suitability of the linear radiative kernel technique for large forcing scenarios. We show that kernels based on the present-day climate misestimate TOA flux changes for large perturbations, translating into biased feedback estimates. We address this issue by calculating additional kernels based on a large forcing climate state with eight times present day CO��� concentrations. Differences between these and the present-day kernels result from added absorption of radiation by CO��� and water vapor, and increased longwave emission due to higher temperatures. Combining present-day and 8xCO��� kernels leads to significant improvement in the approximation of TOA flux changes and accuracy of feedback estimates. While climate sensitivity remains constant with increasing CO��� forcing when the inaccurate present-day kernels are used, sensitivity increases significantly when new kernels are used. Comparison of feedbacks in climate models with observations is one way towards understanding the disagreement among models. However, climate change feedbacks operate on time scales that are too long to be evaluated from the observational record. Rather, short-term proxies for greenhouse-gas-driven warming are often used to compute feedbacks from observations. The third chapter of this dissertation examines links between the seasonal cycle and global warming using pattern correlations of spatial distribution of feedback variables and radiative flux changes. We find strong correlations between time scales for changes in surface temperature and climate variables, but not for TOA flux anomalies, reaffirming conclusions drawn in previous work. Finally, we investigate the fitness of the radiative kernel technique for evaluation of short-term feedbacks in a comparison with the more accurate, but more computationally expensive, partial radiative perturbations. / Graduation date: 2013
42

Enhanced CO2 Storage in Confined Geologic Formations

Okwen, Roland Tenjoh 30 September 2009 (has links)
Many geoscientists endorse Carbon Capture and Storage (CCS) as a potential strategy for mitigating emissions of greenhouse gases. Deep saline aquifers have been reported to have larger CO 2 storage capacity than other formation types because of their availability worldwide and less competitive usage. This work proposes an analytical model for screening potential CO 2 storage sites and investigates injection strategies that can be employed to enhance CO 2 storage. The analytical model provides of estimates CO 2 storage efficiency, formation pressure profiles, and CO 2 –brine interface location. The results from the analytical model were compared to those from a sophisticated and reliable numerical model (TOUGH 2 ). The models showed excellent agreement when input conditions applied in both were similar. Results from sensitivity studies indicate that the agreement between the analytical model and TOUGH2 strongly depends on irreducible brine saturation, gravity and on the relationship between relative permeability and brine saturation. A series of numerical experiments have been conducted to study the pros and cons of different injection strategies for CO 2 storage in confined saline aquifers. Vertical, horizontal, and joint vertical and horizontal injection wells were considered. Simulations results show that horizontal wells could be utilized to improve CO 2 storage capacity and efficiency in confined aquifers under pressure-limited conditions with relative permeability ratios greater than or equal to 0:01. In addition, joint wells are more efficient than single vertical wells and less efficient than single horizontal wells for CO 2 storage in anisotropic aquifers.
43

Human dimensions of conservation, land use, and climate change in Huascaran National Park, Peru

Lipton, Jennifer Kristen 04 February 2013 (has links)
This research adopts a multi-scale approach to examine the patterns, processes, and perceptions of landscape change within the core and buffer zone of Huascaran National Park, Peru. Within the park’s boundaries are the extensively glaciated Cordillera Blanca Mountains, where runoff from glaciers feeds into lakes, streams, and wetlands to provide hydrologic resources to populations on the periphery for agriculture, as well as hydropower to populations in distant urban areas. Inhabitants living on the periphery have livelihoods that are dependant upon land and natural resources found within the park’s core and buffer zone, while governance institutions mediate access and resource use. Landscape transformations occurring within and around the park are a result of human agency, biophysical change, and global climate change. A suite of qualitative and quantitative methodologies were used to investigate the coupled social and ecological dynamics of conservation, land use, and implications of climate change in Huascaran National Park. The principal objectives of this research were to assess the spatial and temporal patterns of landscape change using land-use and land-cover data from remotely sensed imagery and to examine the role of institutions on resource governance at multiple scales. A hybrid classification method was used to classify Landsat (TM and ETM+) satellite data for the years of 1987 and 2001. Hypotheses regarding the spatial and temporal dynamics of land-cover change were tested. Results indicate that the percent of land cover from the woodland, cropland, and snow and ice classes were reduced internal to the core of the national park, while the land-cover class of shrubland increased. Interviews with 143 informants revealed perceptions of landscape change and narratives of socio-political land use change. Interview data corroborated the findings of reduced land cover in the snow and ice class. Data also demonstrated that legacies of land tenure and governance are essential for evaluating the adaptive capacity of different institutions and communities confronting conditions of climate change. This research contributes to literature on dynamics and processes of landscape change by bridging analytical frameworks from landscape ecology, cultural and political ecology, and land change science and contributing to human dimensions of global change research. / text
44

Dinâmica de colonização de uma planície hipersalina por espécies de mangue em Guaratiba, RJ / Dynamics of a salt flat colonization by mangroves species in Guaratiba (Rio de Janeiro, Brazil)

Marciel Rocha de Medeiros Estevam 29 August 2013 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Alterações na frequência e amplitude das inundações pelas marés são fatores reguladores da dinâmica das florestas de mangue. Tais alterações podem estar relacionadas à elevação do nível médio relativo do mar (NMRM), que vem sendo atribuída como fator de impacto decorrente das mudanças climáticas globais atuando sobre os ecossistemas costeiros. Durante a década de 90, o Núcleo de Estudos em Manguezais da Universidade do Estado do Rio de Janeiro observou, em Guaratiba (RJ), um processo de colonização de uma planície hipersalina por espécies de mangue, e começou a monitorá-lo. Após seis anos os dados indicaram a consolidação da colonização e juntamente com o desenvolvimento de outros estudos neste sistema, a elevação do NMRM foi atribuída como principal causa deste processo. Os dados gerados por tal monitoramento, de 1998 até o ano de 2011, constituem a base de dados da presente dissertação, que teve como objetivo analisar o desenvolvimento do processo de colonização e verificar suas relações com fatores meteorológicos locais. No ano de 1998 foram demarcadas seis parcelas justapostas, no sentido floresta-planície hipersalina, até onde era percebida a presença das plantas de mangue. Todos os indivíduos foram identificados com etiquetas numeradas e tiveram suas alturas medidas ao longo de todo monitoramento, da mesma forma que novos indivíduos (recrutas). Quando recrutas eram encontrados em áreas mais distantes da floresta, novas parcelas eram incluídas no monitoramento. No ano de 2011, a colonização já havia avançado 75 m de distância da floresta e as treze parcelas monitoradas indicaram diferentes estágios sucessionais: mais próximas à floresta apresentam consolidação do processo de colonização, com redução de densidade e maior desenvolvimento estrutural; intermediárias, com altas densidades, encontra-se em fase menos avançada da colonização; mais externas caracterizam o início da colonização da área por poucos indivíduos. Notou-se, ainda, que o processo de colonização se dá por meio do estabelecimento de coortes, que demonstram variabilidade nos padrões de desenvolvimento estrutural ao longo dos anos (densidade, distribuição e taxa de crescimento), relacionada às condições ambientais distintas (padrões climatológicos). Quanto à disponibilidade hídrica (entre 1985 e 2011), Guaratiba apresentou predomínio de déficit hídrico, com tendência de amenização ao final do período. Períodos de maior disponibilidade de água no sistema coincidiram com marcação de novas parcelas, bem como com picos de recrutamento e elevadas taxas de crescimento das coortes. Assim, foi possível observar que o desenvolvimento das coortes esteve relacionado às condições de disponibilidade de espaço e luz, além de responderem aos processos meteorológicos, relacionados à disponibilidade de água na região. / Changes in the frequency and amplitude of tidal flooding are the main factors regulating the dynamics of mangrove forests. Such changes may be related to the increase of the relative mean sea level (RSL) which has been attributed as an impact consequence of global climate change on coastal ecosystems. At the end of the 90s, the Núcleo de Estudos em Manguezais da Universidade do Estado do Rio de Janeiro (NEMA/UERJ) [Center for Research on Mangroves of the State University of Rio de Janeiro] observed the beginning of a process of colonization the salt flat by mangrove species and began to monitoring it. After six years, this monitoring indicated the consolidation in process and after the development of other studies on the system, the elevation of RSL was attributed as the cause of the process. The results generated by this monitoring until the year 2011 are the data basis of this dissertation which examined the development of the colonization process and its relationship with climatological factors. In 1998, six plots were demarcated juxtaposed towards the forest-salt flat, which was perceived by the presence of mangrove plants. All individuals were identified with numbered labels and had their heights measured over the whole monitoring and in the same way those new individuals (recruits). When recruits were found in more distance areas of the forest, new plots were included in the monitoring. In 2011, the colonization had advanced to 75 m away from the forest and the thirteen monitored plots indicated different successional stages: the closest to the forest present consolidation of the colonization process, with reduced density and higher structural development; the intermediate with high densities, are in earlier stage of colonization; the outer plots characterize the beginning of the colonization of the area by a few individuals. It was also noted that the process of colonization of salt flat occur through the cohorts establishment, demonstrating variability in patterns of development over the years (density, area of occurrence and growth rates). This variability is related to environmental conditions distinct over time (patterns climatological). Guaratiba presented water deficit in most of the time, with a trend of reduction in the end of the period. The periods of increased water availability in the system coincided with the appointment of new plots as well as the peaks of recruitment and higher growth rates of cohorts. Therefore, the development of the cohorts was related both to availability space and light and to climatic conditions in the region, mainly water availability.
45

Dinâmica de colonização de uma planície hipersalina por espécies de mangue em Guaratiba, RJ / Dynamics of a salt flat colonization by mangroves species in Guaratiba (Rio de Janeiro, Brazil)

Marciel Rocha de Medeiros Estevam 29 August 2013 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Alterações na frequência e amplitude das inundações pelas marés são fatores reguladores da dinâmica das florestas de mangue. Tais alterações podem estar relacionadas à elevação do nível médio relativo do mar (NMRM), que vem sendo atribuída como fator de impacto decorrente das mudanças climáticas globais atuando sobre os ecossistemas costeiros. Durante a década de 90, o Núcleo de Estudos em Manguezais da Universidade do Estado do Rio de Janeiro observou, em Guaratiba (RJ), um processo de colonização de uma planície hipersalina por espécies de mangue, e começou a monitorá-lo. Após seis anos os dados indicaram a consolidação da colonização e juntamente com o desenvolvimento de outros estudos neste sistema, a elevação do NMRM foi atribuída como principal causa deste processo. Os dados gerados por tal monitoramento, de 1998 até o ano de 2011, constituem a base de dados da presente dissertação, que teve como objetivo analisar o desenvolvimento do processo de colonização e verificar suas relações com fatores meteorológicos locais. No ano de 1998 foram demarcadas seis parcelas justapostas, no sentido floresta-planície hipersalina, até onde era percebida a presença das plantas de mangue. Todos os indivíduos foram identificados com etiquetas numeradas e tiveram suas alturas medidas ao longo de todo monitoramento, da mesma forma que novos indivíduos (recrutas). Quando recrutas eram encontrados em áreas mais distantes da floresta, novas parcelas eram incluídas no monitoramento. No ano de 2011, a colonização já havia avançado 75 m de distância da floresta e as treze parcelas monitoradas indicaram diferentes estágios sucessionais: mais próximas à floresta apresentam consolidação do processo de colonização, com redução de densidade e maior desenvolvimento estrutural; intermediárias, com altas densidades, encontra-se em fase menos avançada da colonização; mais externas caracterizam o início da colonização da área por poucos indivíduos. Notou-se, ainda, que o processo de colonização se dá por meio do estabelecimento de coortes, que demonstram variabilidade nos padrões de desenvolvimento estrutural ao longo dos anos (densidade, distribuição e taxa de crescimento), relacionada às condições ambientais distintas (padrões climatológicos). Quanto à disponibilidade hídrica (entre 1985 e 2011), Guaratiba apresentou predomínio de déficit hídrico, com tendência de amenização ao final do período. Períodos de maior disponibilidade de água no sistema coincidiram com marcação de novas parcelas, bem como com picos de recrutamento e elevadas taxas de crescimento das coortes. Assim, foi possível observar que o desenvolvimento das coortes esteve relacionado às condições de disponibilidade de espaço e luz, além de responderem aos processos meteorológicos, relacionados à disponibilidade de água na região. / Changes in the frequency and amplitude of tidal flooding are the main factors regulating the dynamics of mangrove forests. Such changes may be related to the increase of the relative mean sea level (RSL) which has been attributed as an impact consequence of global climate change on coastal ecosystems. At the end of the 90s, the Núcleo de Estudos em Manguezais da Universidade do Estado do Rio de Janeiro (NEMA/UERJ) [Center for Research on Mangroves of the State University of Rio de Janeiro] observed the beginning of a process of colonization the salt flat by mangrove species and began to monitoring it. After six years, this monitoring indicated the consolidation in process and after the development of other studies on the system, the elevation of RSL was attributed as the cause of the process. The results generated by this monitoring until the year 2011 are the data basis of this dissertation which examined the development of the colonization process and its relationship with climatological factors. In 1998, six plots were demarcated juxtaposed towards the forest-salt flat, which was perceived by the presence of mangrove plants. All individuals were identified with numbered labels and had their heights measured over the whole monitoring and in the same way those new individuals (recruits). When recruits were found in more distance areas of the forest, new plots were included in the monitoring. In 2011, the colonization had advanced to 75 m away from the forest and the thirteen monitored plots indicated different successional stages: the closest to the forest present consolidation of the colonization process, with reduced density and higher structural development; the intermediate with high densities, are in earlier stage of colonization; the outer plots characterize the beginning of the colonization of the area by a few individuals. It was also noted that the process of colonization of salt flat occur through the cohorts establishment, demonstrating variability in patterns of development over the years (density, area of occurrence and growth rates). This variability is related to environmental conditions distinct over time (patterns climatological). Guaratiba presented water deficit in most of the time, with a trend of reduction in the end of the period. The periods of increased water availability in the system coincided with the appointment of new plots as well as the peaks of recruitment and higher growth rates of cohorts. Therefore, the development of the cohorts was related both to availability space and light and to climatic conditions in the region, mainly water availability.
46

Environmentální zátěž při produkci a zpracování potravinářské pšenice a výrobě chleba / Environmental load during production a processing of food wheat and production of bread

HYŠPLER, Robin January 2011 (has links)
This thesis was made in co-operation with international project M00080- EUS-AT-SUKI Sustainable Kitchen, which is focused to make an inquiry of total emissions of carbon dioxide producted by catering estabilishments and finds possibilities of reducing these emissions. The thesis deals with an emission?s contamination of wheat flour and bread. Informations and data about agriculture, processing and transport of chosen commodities were collected from questionaires and scientific literature. The emission?s contamination of equivalent CO2 per kilogram of particular products and commodities was worked out from data and informations of the Ecoinvent database. The comparision between systems of management and regionality (ie. whether products are imported or local) is included. The main aim of this thesis was to prove whether the consumation of products from organic or conventional farming is environmentally more beneficial, the same comparision were made between regional or imported products
47

Improving Climate Projections Through the Assessment of Model Uncertainty and Bias in the Global Water Cycle

January 2013 (has links)
abstract: The implications of a changing climate have a profound impact on human life, society, and policy making. The need for accurate climate prediction becomes increasingly important as we better understand these implications. Currently, the most widely used climate prediction relies on the synthesis of climate model simulations organized by the Coupled Model Intercomparison Project (CMIP); these simulations are ensemble-averaged to construct projections for the 21st century climate. However, a significant degree of bias and variability in the model simulations for the 20th century climate is well-known at both global and regional scales. Based on that insight, this study provides an alternative approach for constructing climate projections that incorporates knowledge of model bias. This approach is demonstrated to be a viable alternative which can be easily implemented by water resource managers for potentially more accurate projections. Tests of the new approach are provided on a global scale with an emphasis on semiarid regional studies for their particular vulnerability to water resource changes, using both the former CMIP Phase 3 (CMIP3) and current Phase 5 (CMIP5) model archives. This investigation is accompanied by a detailed analysis of the dynamical processes and water budget to understand the behaviors and sources of model biases. Sensitivity studies of selected CMIP5 models are also performed with an atmospheric component model by testing the relationship between climate change forcings and model simulated response. The information derived from each study is used to determine the progressive quality of coupled climate models in simulating the global water cycle by rigorously investigating sources of model bias related to the moisture budget. As such, the conclusions of this project are highly relevant to model development and potentially may be used to further improve climate projections. / Dissertation/Thesis / Ph.D. Mechanical Engineering 2013
48

Anuros do Cerrado em um mundo em mudança: fatores de vulnerabilidade / Cerrado anurans in a changing world: vulnerability factors

PACÍFICO, Eduardo dos Santos 11 February 2011 (has links)
Made available in DSpace on 2014-07-29T16:21:16Z (GMT). No. of bitstreams: 1 dissertacao_eduardo_pacifico.pdf: 1146266 bytes, checksum: 35376f6282f701f0d901fd00680cea93 (MD5) Previous issue date: 2011-02-11 / Endemic species have higher risk of extinction and are the focus of conservation efforts because they are confined to specific areas. Evidently, extinction vulnerability variation among endemic species should be mainly explained by their range distribution. Because they have specific eco-physiological traits, anurans are particularly sensitive to global climate change (GCC). Thus, the goals of this study are to present a new anuran endemic species list of Cerrado, to discuss issues related to endemism and to determine if the current potential distribution is able to predict the species extinction vulnerability in GCC. We analyze anuran species that were considered endemic in previous studies plus recently described species. We used two modeling procedures (Maxent and Mahalanobis distance method), three climate models (CCCma, CSIRO and HadCM3) and two carbon emissions scenarios (A2 and B2). Analyses were performed separately for each set of conditions (method, model and scenario) and then we analyzed the emergent pattern. There are 33 Cerrado endemic anuran species, belonging to ten families, representing 20.4% of Cerrado s anurans and 3.8% of Brazilian anurans. Most species have few occurrence points (mean ± standard deviation: 4.9 ± 4.6). Twelve endemic species have all their occurence points near to the boundaries of Cerrado and twelve have all their occurence points in the center of the biome. Small changes in biome boundaries alter the number of endemic species. Therefore, the endemism concept is strongly linked to the biome definition, the sampling effort, the correct species identification and the existing information released. Using the biome limits defined by the Brazilian government, Cerrado endemic anurans with small range distribution have less overlap between the current and the future distributions than Cerrado endemic anurans with large range distribution, indicating that species with small range have a higher risk of extinction. Nevertheless, Cerrado endemic anurans with small range distribution have more proportional gain of suitable area in the future than Cerrado endemic anurans with large range distribution. Consequently, there will be adequate area for all species. However, only species that could move to suitable places will persist. Hence, species persistence, mainly for species with small range size, depends largely on the connectivity of suitable habitat and dispersal rates that allow the colonization of new areas. / Por estarem restritas a um determinado local, é esperado um maior risco de extinção para as espécies endêmicas, sendo elas o foco de ações conservacionistas. A variação da vulnerabilidade à extinção entre espécies endêmicas deve ser principalmente explicada pelo tamanho de suas distribuições. Por possuírem características eco-fisiológicas específicas, os anuros são especialmente sensíveis às mudanças climáticas globais (MCG). Assim, o objetivo geral é apresentar uma nova lista de espécies de anuros endêmicos do Cerrado, discutir questões relacionadas ao endemismo e determinar se a distribuição potencial atual é capaz de predizer a vulnerabilidade das espécies às MCG. Analisamos as espécies de anuros que foram consideradas endêmicas em estudos prévios e as espécies descritas recentemente. Utilizamos dois procedimentos de modelagem (Maxent e o método de distância de Mahalanobis), três modelos climáticos (CCCma, CSIRO e HADcm3) e dois cenários de emissão de carbono (A2 e B2). As análises foram feitas separadamente para cada conjunto de condições (método, modelo e cenário) e depois analisamos o padrão global. São 33 espécies de anuros endêmicos do Cerrado, de dez famílias, representando 20.4% das espécies que ocorrem no Cerrado e 3.8% das espécies que ocorrem no Brasil. A maioria das espécies possui poucos pontos de ocorrência (média de registros ± desvio padrão: 4.9 ± 4.6). Das espécies endêmicas, 12 têm distribuição exclusivamente marginal no bioma e 12 têm distribuição exclusivamente central. Pequenas mudanças nos limites do bioma alterariam o número de espécies endêmicas. Portanto, o conceito de endemismo está fortemente ligado à definição do bioma, ao esforço amostral, à correta identificação das espécies e à disponibilização e agrupamento das informações existentes. Para os anuros endêmicos do Cerrado, quanto menor o tamanho da distribuição atual da espécie, menor é a sobreposição com sua distribuição futura, indicando que estas espécies estarão expostas a um maior risco de extinção. Entretanto, quanto menor a distribuição atual, maior o ganho proporcional de área adequada no futuro e maior o deslocamento da distribuição em relação presente. Desta forma, existirá área adequada para as espécies, entretanto somente as que se deslocarem persistirão. Portanto, a persistência das espécies, principalmente as de menor tamanho de distribuição atual, dependerá em grande parte da conectividade dos habitats adequados e das taxas de dispersão que permitirão a colonização de novas áreas.
49

Modelagem preditiva de distribuição passada e futura de Ficus adhatodifolia Schott., Ficus insipida Willd. e Ficus citrifolia Mil. (Moraceae) / Predictive modeling of past and future distribution of Ficus adhatodifolia Schott., Ficus insipid Willd. and Ficus citrifolia Mil. (Moraceae)

Paulo Roberto Furini 13 March 2015 (has links)
As glaciações do Quaternário moldaram os padrões filogeográficos das espécies em geral. Em algumas regiões da América do Sul, (e.g. Cerrado e Caatinga) a mudança estrutural foi mais acentuada, havendo o predomino de savanas, ao passo que em outras regiões (e.g. Amazônica e Mata Atlântica) as mudanças foram menores, formando áreas de refúgios florestais. A Modelagem Preditiva de Distribuição de espécies usa associações entre variáveis ambientais e registros de ocorrência da espécie para estimar modelos que representam as condições ambientais favoráveis à espécie. Neste trabalho foram estudadas três espécies de figueiras Neotropicais com características ecológicas distintas, representando duas linhagens filogenéticas independentes, i.e., seções Americana (Ficus citrifolia) e Pharmacosycea (Ficus adhatodifolia e Ficus insipida). Foram gerados modelos para os cenários passados (Interglacial 140.000 e Glacial 21.000 anos atrás), presente e futuro (2050 e 2070, nos cenários otimistas e pessimistas) para as três espécies estudadas usando o programa Maxent 3.3.3k. Os resultados obtidos mostram que para F. adhatodifolia as variáveis mais importantes nos modelos foram temperatura mínima do mês mais frio e precipitação do mês mais seco. Para F. insipida as variáveis mais importantes nos modelos foram temperatura mínima do mês mais frio e precipitação anual. Para F. citrifolia as variáveis mais importantes nos modelos foram temperatura mínima do mês mais frio e precipitação do mês mais chuvoso. Os modelos projetados no cenário interglacial, para as três espécies estudadas, apresentaram áreas de adequabilidade ambiental próximas ao cenário atual. Durante o período glacial F. adhatodifolia mostrou uma mudança considerável em sua área de ocorrência, ocorrendo em regiões consideradas refúgios para algumas espécies. Ficus insipida apresentou uma retração na sua adequabilidade ambiental, porém mantendo-se na região amazônica, enquanto que F. citrifolia teve um aumento na sua área de adequabilidade. Nos cenários futuros (2050 e 2070) F.adhatodifolia apresentou uma diminuição em sua área de ocorrência em ambos os cenários otimista e pessimista, F. insipida apresentou um aumento em sua área de adequabilidade ambiental e F.citrifolia apresentou uma diminuição e fragmentação na região Amazônica nos cenários otimista e pessimista de 2050 e otimista de 2070. As exigências ambientais e os possíveis padrões filogeográficos das três espécies são discutidos no contexto dos modelos preditivos gerados. / The Quaternary glaciations shaped the phylogeographic patterns of species in general. In some regions of South America (e.g.Cerrado and Caatinga) structural change was more pronounced and savannas predominated, whereas in other regions (e.g. Amazon and Atlantic Forest) changes were minor, forming areas of forest refuges. Species distribution Predictive Modeling uses associations between environmental variables and species occurrence records to estimate models that represent the environmental conditions favorable to the species. In the present study we chose three species of Neotropical Ficus with different ecological characteristics, representing two independent phylogenetic lineages, i.e., sections Americana (Ficus citrifolia) and Pharmacosycea (F.adhatodifolia and F.insipida). We generated models for the past (interglacial 140,000 years ago and Glacial 21,000 years ago), present and future scenarios (2050 and 2070 in optimistic and pessimistic scenarios) for the three study species using Maxent 3.3.3k program. Our results showed thatfor F. adhatodifolia the most important variables in the models were minimum temperature in the coldest month and precipitation in the driest month. For F.insipida the most important variables in the models were minimum temperature in the coldest month and annual precipitation. For F. citrifolia the most important variables in the models were minimum temperature in the coldest month and precipitation in the wettest month. The models designed for the interglacial stage showed areas of environmental suitability similar to the current scenario of the three species. During the glacial period F. adhatodifolia showed a considerable change in its range, occurring in regions considered refuges for some species. Ficus insipida had its environmental suitability decreased, but remained in the Amazon region, while F. citrifolia increased its area of suitability. In the future models (2050 and 2070) F.adhatodifolia showed a decrease in its range on both optimistic and pessimistic scenarios, F.insipida showed an increase in its area of environmental suitability and F.citrifolia has been decreasing and fragmentation in the Amazon region in the optimistic and pessimistic scenarios 2050 and optimistic 2070. The environmental requirements and the potential phylogeographic patterns of the study species are discussed in the context of the generated predictive models.
50

Essays on Environmental NGOs and Clean Technologies Adoption

Urban, Ionut Bogdan 30 March 2021 (has links)
Chapter 1. We develop a model of NGO-firm partnerships. An NGO can share environmental expertise with one or two competing firms, and certify their 'clean' production, important for consumers with environmental concerns. The NGO may also obtain funds from a partner firm for an environmental project, important for consumers who derive project participation warm-glow. The NGO benefits from reduced environmental damage and project realization, while firms may gain or avoid loss of profitable custom. This model allows us to understand increasingly common partnerships between firms and NGOs as mutually beneficial in a competitive setting. 'Clean' production and/or the project may be independently viable on the market, supported by consumer preferences. A viable project can then support adoption of a non-viable 'clean' technology, leading to a 'cleaner' market. However, when 'clean' production is viable, we identify a 'dirty' production damage threshold below which the NGO prefers to obtain funds for a non-viable project and partners on production with only one firm, rather than forgo the project and partner on 'clean' production with both firms instead. Moreover, this damage threshold is increasing in consumers' environmental concern, and thus can generate counterintuitive situations: less environmental concern leads to a 'cleaner' market, whereas more concern leads to a 'dirtier' market. Chapter 2. Consumers choosing amongst horizontally-differentiated products (brands) that also embody some degree of an environmental attribute, suffer stigma if they make brown choices. The intensity of that stigmatization is declining in the fraction of other consumers making similarly brown decisions. It is common to suppose that people feeling such stigma would improve environmental outcomes. We show that while the threat of stigma makes it more likely that a consumer will choose the green option from a given menu, it can reduce the incentives for firms to offer green options in the first place. In an asymmetric duopoly setting social stigma can lower or increase the likelihood of clean technology adoption and in plausible circumstances drives the high-cost firm into a 'brown trap' or the low-cost firm into a 'green trap'. While increased competition reduces the 'green trap', it exacerbates the 'brown trap'. Chapter 3. The effect of warm-glow on number of NGOs and welfare is investigated within a charity market with ideologically differentiated public goods. In this setting ideology acts as a warm-glow multiplier on donations and high enough warm-glow can push welfare into negative territory — welfare would be higher if nobody donated. Under first-best we find that an optimal number of NGOs exists even though NGOs have no costs. Under free-entry we obtain the level of warm-glow that would induce the welfare-maximizing number of NGOs to enter. A social planner can determine donor population to behave overall as if they were experiencing the welfare-maximizing level of warm-glow, and thus optimize free-entry welfare, through one of two equivalent and revenue-neutral fiscal policies: by subsidizing/taxing donations either at the source, when the donors make them, or at the destination, when the NGOs receive them.

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