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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

The risk of ending a solar radiation management program abruptly

Agrawal, Shubham 17 August 2010 (has links)
Climate change as a result of anthropogenic activities calls for reduction of greenhouse gas emissions to avoid dangerous consequences on society. However, abatement of emission is a costly process and adversely affects the economic growth. Recent proposals, therefore, suggested a different approach i.e. Geoengineering. Instead of controlling emissions, Geoengineering modifies the climate by changing global energy fluxes either by increasing the amount of outgoing infrared radiation through reduction of greenhouse gases (GHGs) or by decreasing the amount of solar radiation falling upon the earth’s surface by increasing the albedo (reflectivity) of the atmosphere. Most popular geoengineering strategies are Air Capture (AC) and Solar Radiation Management (SRM) and many economic studies have shown large net monetary benefits with their application. But, these studies neglected the risks which can arise due to potential failure to sustain SRM after few decade of its deployment. There is a concern that application of SRM will lead to increase in concentration of carbon-dioxide in atmosphere and its abrupt turning off can lead to rise in temperature and thereby huge monetary losses. In this report, consequences of abruptly turning off of SRM have been analyzed. A modified version of DICE (Dynamic Integrated model of Climate and the Economy) model that incorporates negative SRM forcing and a two phase optimization procedure has been used for the study. Different outcomes such as net change in NPV of climate damage and abatement costs, maximum mean temperature of earth surface, increase in temperature, emissions control rate, carbon taxes, etc due to abrupt ending of SRM have been analyzed. Results show that application of SRM with a risk of abrupt turnoff is still more profitable compared to not using it at all. / text
42

Effects of species and placement of neighbours on the ability to scale plant responses to elevated CO←2

Phillips, Marcus Jonathan Angus January 1997 (has links)
No description available.
43

An investigation of the pattern scaling technique for describing future climates

Mitchell, Timothy D. January 2001 (has links)
No description available.
44

Modelling landfill as a complex biophysical technology

Lowe, Martin January 1998 (has links)
Concerns regarding climate change are becoming a driver behind legislation at both UK and EU levels, and also on the wider, planetary scale. This is the case with emissions from landfills where the release of methane is being targeted for reduction. This thesis uses an integrative approach, incorporating concepts of hierarchy from systems theory, to model landfill as a complex biophysical technology. It assesses the contribution to carbon deposition and global warming of landfill through changes to that technology itself and through changes in the waste stream caused by potential waste policies. The thesis develops an holistic, conceptual model of the landfill system, mapping flows and transformations of carbon within that system. It further develops this conceptual model into a calculating model of landfill as a waste management technology incorporating measurements taken to provide new data and validate published data to calibrate the model. It thus applies modelling techniques to a biophysical technology, producing an integrated model of the landfill that allows the knowledge gained from other research to be used to explore engineering and operational decisions on landfills. The thesis includes results from measurements of the composition of household waste, and of the biochemical methane potential (BMP) of fractions of that waste. It includes measurements of the residual BMP in samples of excavated waste and measurements of gas flows. The main results suggest the following: • Early capping of landfilled waste is important in reducing the global warming impact; • If the rate of degradation of the waste is accelerated in the drive towards sustainability, capping should be carried out even earlier if the global impact is not to be increased; • Although recycling parts of the degradable elements of the waste stream has the effect of reducing the global impact, extensive recycling has implications for landfill engineering.
45

Equilibrium Climate Sensitivity and the Relative Weightings of Various Climate Forcings on Local Temperature Records

Rixey, Caitlin January 2015 (has links)
Thesis advisor: Jeremy Shakun / As recently measured amounts of global atmospheric carbon dioxide concentrations have risen 40% from pre-Industrial levels and will likely reach double by mid-century, climate scientists have expressed concern over the future state of the climate system, and have attempted to gauge the consequences of such a large forcing. The principal parameter for climate scientists is equilibrium climate sensitivity, which is the change in temperature following a doubling of atmospheric CO2 concentrations. Current estimates of climate sensitivity span too expansive of a range to provide a clear understanding of the magnitude of temperature changes one can expect. Therefore, I conduct many individual multivariate analyses as a means of narrowing these ranges of sensitivity and to investigate geographical distributions of sensitivity, at the very least. To do so, I analyze four major climate forcings: greenhouse gas, atmospheric dust, ice volume, and insolation. Using several multiple linear regressions, I calculate the relative weighting of each forcing in driving the temperature signal in 47 local temperature proxy records. The paleoclimate proxy records chosen span glacial cycles over the past 800 kyr. These results provide insight into the geographical distributions of the relative influences of each of the forcings, while working to constrain the range of sensitivity estimates through the weighting of the greenhouse gas forcing. Separating out the individual climate inputs allows me to conclude what percentage of climate change was caused by CO2 in the past, and by implication how much warming might be expected due to GHG forcing in the future. / Thesis (BS) — Boston College, 2015. / Submitted to: Boston College. College of Arts and Sciences. / Discipline: Earth and Environmental Sciences.
46

Effects of increased temperature and copper excess on the physiology, biochemistry and gene expression of Ectocarpus siliculosus (Dillwyn) Lyngbye

Santillán-Sarmiento, Alex Renato January 2018 (has links)
Brown algae are an important group of organisms inhabiting coastal ecosystems worldwide. Because of their sessile nature, they are exposed to natural abiotic stresses such as high and low irradiances, desiccation, thermal fluctuations and mechanical stress, as well as anthropogenic-derived stresses such as chemical pollution. While the impacts of metal pollution affect brown algae on a local scale, there is growing concern on the potential interactions between pollutants and abiotic pressures resulting from global climate change. The main objective of this study was to determine the nature of the interactions (synergistic, additive or antagonistic) of different concentrations of copper in combination with increased temperatures in controlled laboratory experiments using the model brown alga Ectocarpus siliculosus as a proxy for brown seaweeds, which are globally important primary producers and bioengineers of near-shore waters. The responses in E. siliculosus were evaluated at different levels of biological organisation. At the whole organism level Cu or temperature affected growth but no interactions occurred. Antagonistic interactions occurred between stressors in the photosynthetic efficiency response (measured as chlorophyll a fluorescence), being less affected by Cu at higher temperatures. The bioaccumulation of Cu ions showed and antagonistic response to temperature as less Cu ions were accumulated at elevated temperature. The concentrations of H2O2 and lipid peroxides (TBARS), which are indicators of oxidative stress, were synergistically affected by interactions of stressors. In contrast, the concentrations of antioxidants ascorbate and glutathione reflected both additive and antagonistic interactions respectively. This also occurred in the activity of antioxidant 8 enzymes (superoxide dismutase, ascorbate peroxidase, catalase and glutathione reductase) and the expression of related genes. Finally, the results of the biochemical and physiological tests were integrated with the whole transcriptome response to temperature and Cu stress. These results showed that interactions between temperatures and Cu stress could be highly complex, but also lead to the discovery of potential stress markers such as light harvesting complex proteins and several transporters. This research provides new insights into the responses of brown macroalgae to metal and thermal stress. Those responses indicate that synergistic or antagonistic interactions can occur at different levels of organisation, being the regulation of antioxidant metabolism, photosynthetic physiology and related gene expression, the most important mechanisms involved. This information will aid to understand potential effects of climate change on the toxicity of metals for macroalgae in estuaries and coasts affected by pollution.
47

Modeling the effect of activelayer deepening on stocks ofsoil organic carbon in thePechora River Basin

Eriksson, Pia January 2012 (has links)
This study investigates how the estimated thickening of the active layer will affectthe soil organic carbon in permafrost soils. The focus lies on estimating how muchof the upper permafrost soil organic carbon will be affected by the active layerdeepening due to global warming, on what timescale the deepening will take placeand if the estimated changes differ depending on the extent of permafrost in theregion. A model made in a Geographic Information System (GIS) combines datasetsfrom The Northern Circumpolar Soil Carbon Database, field data of soil organiccarbon content (SOCC) in different permafrost soil horizons in the Usa basin anddata of recent and future active layer depth from a spatially distributed permafrostdynamics model in the Pechora River Basin. The model shows that in 1980, 75% ofthe available 0–100 cm Gelisol soil organic carbon mass (SOCM) has affected byseasonal thawing. In 2050 the proportion is increased to 86% and by 2090 almostthe whole study area has an active layer deeper than 1 meter (98%). This indicatesan increase from approximately 0.64% to 0.84% of the total 1–100 cm SOCM in thenorthern permafrost region. The change is more gradual in the isolated and thesporadic permafrost zones and more abrupt in the continuous and discontinuous regions.
48

Melting marvels tourist responses to climate change and glacial melt in the Peruvian Andes /

Wright, Sarah Kelly. January 2009 (has links)
Thesis (M.A.)--Ohio State University, 2009. / Title from first page of PDF file. Includes vita. Includes bibliographical references (p. 105-111).
49

Life cycle global warming emissions for natural gas

Randel, Tony Lynn 29 November 2012 (has links)
Climate change is a topic of social and political commentary and controversy, and is a topic that will continue to be addressed by future scientists and laypersons alike. This report contains information and laboratory exercises for use in a greenhouse gas (GHG) and global warming potential (GWP) learning module, to be employed in secondary or entry level university engineering and environmental science curricula. Exercises include a hands-on experience with the greenhouse effect and calculations of GWP for 20-year and 100-year timeframes. / text
50

Doing our Part to Help Conserve Arizona's Water Resources and Reduce Global Warming by Saving Energy at Home

Artiola, Janick, Crimmins, Michael, Yoklic, Martin 01 1900 (has links)
Revised; Originally Published: 2008 / 6 pp. / Climate change is affecting Arizona's Water Resources adversely and water use is linked to energy consumption. This publication discusses the effects of global warming on the environment and provides tips on how to conserve electricity at home.

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