<p>Scientists expect temperatures on Earth to get substantially warmer over the course of the 21st century, causing storm systems to intensify and sea-level rise to accelerate--these changes will likely have dramatic impacts on how the coastlines of tomorrow will evolve. Humans are also playing an increasingly important role in shaping Earth's coastal systems. Coastal scientists have only a general understanding of how these three factors--humans, storms, and sea-level rise--will alter the evolution of coastlines over the coming century, however. I conduct numerical modeling experiments to shed light on the relative importance of these factors on the evolution of coastline geomorphology.</p><p>In a series of experiments using a numerical model of large-scale (1 to 100's km) and long-term (years to centuries) coastline evolution that results from gradients in alongshore sediment transport, I explore how the patterns and rates of shoreline erosion and accretion are affected by shifts in 'wave climate' (the mix of influences on alongshore sediment transport of waves approaching from different directions) induced by intensified storm systems and the direct manipulation of the shoreline system by humans through beach nourishment (periodically placing sand on an eroding beach). I use a cuspate-cape coastline, similar to the Outer Banks, North and South Carolina, USA, as an important case study in my experiments. I observe that moderate shifts in the wave climate can alter the patterns of shoreline erosion and accretion, potentially increasing migration rates by several times that which we see today, and nearly an order-of-magnitude larger than sea-level rise-related erosion alone. I also find that under possible wave climate futures, beach nourishment may also induce shoreline change on the same order of magnitude as does sea-level rise.</p><p>The decision humans make whether or not to nourish their beach often depends upon a favorable economic outcome in the endeavor. In further experiments, I couple a cost-benefit economic model of human decision making to the numerical model of coastline evolution and test a hypothetical scenario where two communities (one 'rich' and one 'poor') nourish their beaches in tandem, under different sets of economic and wave climate parameters. I observe that two adjacent communities can benefit substantially from each other's nourishment activity, and these effects persist even if the two communities are separated by several tens of kilometers.</p><p>In a separate effort, I employ techniques from dynamic capital theory coupled to a physically-realistic model of coastline evolution to find the optimum time a community should wait between beach nourishment episodes ('rotation length') to maximize the utility to beach-front property owners. In a series of experiments, I explore the sensitivity of the rotation length to economic parameters, including the discount rate, the fixed and variable costs of beach nourishment, and the benefits from beach nourishment, and physical parameters including the background erosion rate and the exponential rate at which both the cross-shore profile and the plan-view coastline shape re-adjusts following a beach nourishment episode ('decay rate' of nourishment sand). Some results I obtained were expected: if property values, the hedonic value of beach width, the baseline retreat rate, the fixed cost of beach nourishment, and the discount rate increase, then the rotation length of nourishment decreases. Some results I obtained, however, were unexpected: the rotation length of nourishment can either increase or decrease when the decay rate of nourishment sand varies versus the discount rate and when the variable costs of beach nourishment increase.</p> / Dissertation

The effects of water vapor and carbon dioxide on temperature and heat transfer in the troposphere layer, which is less than the altitude of 10 km, in the atmosphere are presented in this work. Accounting for realistic temperature- and pressure- or concentration-dependent radiative properties, this work systematically evaluates heat transfer encountered in atmosphere. For simplicity, the heat transfer is assumed to be one-dimensional and pure conduction and radiation modes. The solar irradiation penetrates through the atmosphere within its short wavelength range near around visible range between 0.4-0.7 £gm, and absorbed and reflected by the earth ground with a gray body property. The ground emits radiation in longwave range. Water vapor is transparent to longwave range 8-12 £gm and absorbed in five long wavelength bands centered at 71, 6.3, 2.7, 1.87, 1.38 £gm, whereas carbon dioxide is absorbed in four long wavelength bands centered at 15, 4.3, 2.7 and 2.0 £gm. The computed results quantitatively show that water vapor and carbon dioxide are the most important factors affecting temperature difference around 2 Celsius degrees.

¡@¡@The impacts of global warming and climate change were the important issue in the last few decades. The sea level rising was one of most discussion topics of physical impact which derived from global warming. In this study, about forty year¡¦s sea level records (from Harbor & Marine Technology Center) were used to analysis the long term water level trends at Keelung Harbor, Taichung Harbor and Kaohsiung Harbor in the western Taiwan. ¡@¡@We rearranged the records format, filtered out error data, and then sorted the data by the logged time. Three kinds of analysis method were applied to investigate the trend of water level change. The first one was harmonic analysis which was used to eliminate the effects of astronomical tide. The second method was spectrum analysis and it assisted to obtain the amplitudes and phases of tidal component. Finally, we used the moving average method to smooth data and discussed the tendency of water level change. ¡@¡@The result showed no evidence of sea level rising along the western coast of Taiwan. The average water level raised and declined evenly in the duration of forty years, and the general trends of water level varied near the zero level. The result also showed the variation of water level that affected by the measurement instruments was more over the physical effects.

In 2005 the highest global surface temperature ever was recorded. A virtual consensus exists today among scientists that global warming is underway and that human greenhouse gas (GHG) emissions are a significant cause. Possible mitigation of climate change through reduction of net GHG emissions has become a worldwide concern. Under the United Nation’s Framework convention on Climate Change, the Kyoto Protocol was formed in 1997 and required ratifying countries to co-operate in stabilizing atmospheric GHG concentrations. The protocol took effect on February 16, 2005. The mitigation cost for reducing GHG emissions for the US economy has been argued to be high particularly through the energy sector. Agriculture and Forestry (AF) can provide some low cost strategies to help with this mitigation principally through carbon sequestration but must be competitive with mitigation costs in the rest of the economy. A general equilibrium approach is used herein to evaluate the role of AF mitigation in an economy wide setting. The results show that the AF sectors have significant mitigation potential. Higher carbon prices lead to more sequestration, less emissions, reduced consumer and total welfare, improved environmental indicators and increased producer welfare. AF mitigation increases as the carbon price increase over time. In the earlier periods, while the carbon price is low, AF emissions and sink are quite small compared to the energy sector. As carbon prices increase over time, the AF sectors mitigate about 25% of the net emissions. This verifies McCarl et al's (2001) argument that the AF sectors “may be very important in a world that requires time and technological investment to develop low-cost greenhouse gas emission offsets.” AF GHG emission mitigation is sensitive to saturation of sequestration sinks. This research finds that ignoring saturation characteristics leads to a severe overestimate of mitigation potential with estimates being inflated by as much as a factor of 6.

The present work examines the potential impact of changes in climatic conditions on the long-term functioning of nuclear power plants. Nuclear power plants are potentially susceptible to changes both in acute risks, such as severe storm events, and chronic risks, such as detrimental changes in the thermodynamics of plant operation. Extending plant lifetimes well beyond the lengths of operation for which they were originally designed suggests the necessity of studying the impacts such changes might have. Potential threats are examined in light of earlier work performed by Business Continuity Consulting on commission for Enteritgy Nuclear. The fourteen risk drivers identified in that work as threats warranting additional investigation are studied individually, and their relevance and likely impact extrapolated for regions covered by the ten selected sites under examination. Thermodynamic eff ects are simulated with a plant analysis program known as PEPSE (Performance Evaluation of Plant Systems Efficiencies), with which a broad range of modeled environmental and plant conditions are analyzed for potential impacts to plant functioning. Of the fourteen climatic risk drivers considered, changes in drought and ood severity and frequency resulting from climate change were determined to be the most likely detriments to plant operations. Precipitation gures indicate that plants located in the Midwest are particularly susceptible to future drought conditions while those in the Northeast are likely to experience more frequent ooding. Many of the risk drivers specifi ed by the earlier work were only cursorily examined in light of the complex nature of these phenomena and lack of well defi ned correlation to climate change. Other risks were analyzed using the gathered data, but were determined not to pose signi ficant threats to plant operations. In addition to large scale climatic e ffects, changes related to coolant uid temperature rise and plant component efficiency were examined to qualify their e ect on the thermodynamics of the model plant. Plant operating conditions were modeled for a wide range of conditions related to theoretical environmental changes. These examinations showed negligibly small impacts caused by increased coolant water temperature and moderate impact caused by changes in air humidity.

The effects of water vapor and carbon dioxide on temperature and heat transfer in the troposphere layer, which is less than the altitude of 10 km, in the atmosphere are presented in this work. Accounting for realistic temperature- and pressure- or concentration-dependent radiative properties, this work systematically evaluates heat transfer encountered in atmosphere. For simplicity, the heat transfer is assumed to be one-dimensional and pure conduction and radiation modes. The solar irradiation penetrates through the atmosphere within its short wavelength range near around visible range between 0.4-0.7 £gm , and absorbed and reflected by the earth ground with a black body property. The ground emits radiation in longwave range. Water vapor is transparent to longwave range 8-12 £gm , whereas carbon dioxide is absorbed in three long wavelength bands centered at 15, 10.4 and 9.4 £gm , respectively. The computed results quantitatively show that water vapor and carbon dioxide are the most important factors affecting temperature difference around 2 and 5 Celsius degrees.

Accurate forecasts of future regional temperature and rainfall patterns in many regions largely depend on characterizing anthropogenic trends in tropical Pacific climate. However, strong interannual to decadal-scale tropical Pacific climate variability, combined with sparse spatial and temporal coverage of instrumental climate datasets in this region, have obscured potential anthropogenic climate signals in the tropical Pacific. In this dissertation, I present sea-surface temperature (SST) and salinity proxy records that span over the 20th century using living corals from several islands in the central tropical Pacific. I reconstruct the SST proxy records via coral Sr/Ca, that are combined with coral oxygen isotopic (d18O) records to quantify changes in seawater d18O (hereafter d18Osw) as a proxy for salinity. Chapter 2 investigates the spatial and temporal character of SST and d18Osw-based salinity trends in the central tropical Pacific from 1972-1998, as revealed by corals from Palmyra (6ºN, 162ºW), Fanning (4ºN, 159ºW) and Christmas (2ºN, 157ºW) Islands. The late 20th century SST proxy records exhibit warming trends that are larger towards the equator, in line with a weakening of equatorial Pacific upwelling over this period. Freshening trends revealed by the salinity proxy records are larger at those sites most affected by the Inter-Tropical Convergence Zone (ITCZ), suggesting a strengthening and/or an equatorward shift of the ITCZ. Taken together, the late 20th century SST and salinity proxy records document warming and freshening trends that are consistent with a trend towards a weakened tropical Pacific zonal SST gradient under continued anthropogenic forcing. Chapter 3 characterizes the signatures of natural and anthropogenic variability in central tropical Pacific SST and d18Osw-based salinity over the course of 20th century using century-long coral proxy records from Palmyra. On interannual timescales, the SST proxy record from Palmyra tracks El Niño-Southern Oscillation (ENSO) variability. The salinity proxy record tracks eastern Pacific-centered ENSO events but is poorly correlated to central Pacific-centered ENSO events - the result of profound differences in precipitation and ocean advection that occur during the two types of ENSO. On decadal timescales, the coral SST proxy record is significantly correlated to the North Pacific Gyre Oscillation (NPGO), suggesting that strong dynamical links exist between the central tropical Pacific and the North Pacific. The salinity proxy record is significantly correlated to the Pacific Decadal Oscillation (PDO), but poorly correlated to the NPGO, suggesting that, as was the case with ENSO, these two modes of Pacific decadal climate variability have unique impacts on equatorial precipitation and ocean advection. However, the most striking feature of the salinity proxy record is a prominent late 20th century freshening trend that is likely related to anthropogenic climate change. Taken together, the coral data provide key constraints on tropical Pacific climate trends, and when used in combination with model simulations of 21st century climate, can be used to improve projections of regional climate in areas affected by tropical Pacific climate variability.

We study timing effects of carbon mitigation and solar radiation management (SRM) policies for correlated pollutants, CO₂ and SO₂. We show that national levels of carbon and sulfur emissions quotas and SRM implementation are positively correlated with each other. First-mover advantages exist when deciding both carbon quotas and SRM levels. Moreover, we use an example to illustrate that if international equity is considered, governments would be willing to choose SRM levels before carbon quotas since it yields higher payoffs and less acid rain and droughts damages. This timing was neglected by all previous theoretical economic models on geoengineering.

Univ., Diss.--Utrecht, 2005.

Thesis (M Arch)--Montana State University--Bozeman, 2008. / Typescript. Chairperson, Graduate Committee: John Brittingham. Includes bibliographical references (leaves 90-92).