<p> Ocean tides worldwide have exhibited secular changes in the past century, simultaneous with a global secular rise in mean sea level (MSL). The combination of these two factors contributes to higher water levels, and may increase threats to coastal regions and populations over the next century. Equally as important as these long-term changes are the short-term fluctuations in sea levels and tidal properties. These fluctuations may interact to yield locally extreme water level events, especially when combined with storm surge. This study, presented in three parts, examines the relationships between tidal anomalies and MSL anomalies on yearly and monthly timescales, with a goal of diagnosing dynamical factors that may influence the long-term evolution of tides in the Pacific Ocean. Correlations between yearly averaged properties are denoted tidal anomaly trends (TATs), and will be used to explore interannual behavior. Correlations of monthly averaged properties are denoted seasonal tidal anomaly trends (STATs), and are used to examine seasonal behavior. Four tidal constituents are analyzed: the two largest semidiurnal (twice daily) constituents, M2 and S2, and the two largest diurnal (once daily) constituents, K1 and O1. </p><p> Part I surveys TATs and STATs at 153 Pacific Ocean tide gauges, and discusses regional patterns within the entire Pacific Ocean. TATs with statistically significant relations between MSL and amplitudes (A-TATs) are seen at 89% of all gauges; 92 gauges for M2, 66 for S2, 82 for K1, and 59 for O1. TATs with statistically significant relations between tidal phase (the relative timing of high water of the tide) and MSL (P-TATs) are observed at 55 gauges for M2, 47 for S2, 42 for K1, and 61 for O1. Significant seasonal variations (STATs) are observed at about a third of all gauges, with the largest concentration in Southeast Asia. The effect of combined A-TATs was also considered. At selected stations, observed tidal sensitivity with MSL was extrapolated forward in time to the predicted sea level in 2100. Results suggest that stations with large positive combined A-TATs produce total water levels that are greater than those predicted by an increase in MSL alone, increasing the chances of high-water events. </p><p> Part II examines the mechanisms behind the yearly (TAT) variability in the Western Tropical Pacific Ocean. Significant amplitude TATs are found at more than half of 26 gauges for each of the two strongest tidal constituents, K1 (diurnal) and M2 (semidiurnal). For the lesser constituents analyzed (O1 and S2), significant trends are observed at ten gauges. </p><p> Part III analyzes the seasonal behavior of tides (STATs) at twenty tide gauges in the Southeast Asian waters, which exhibit variation by 10 &ndash; 30% of mean tidal amplitudes. A barotropic ocean tide model that considers the seasonal effects of MSL, stratification, and geostrophic and Ekman velocity is used to explain the observed seasonal variability in tides due to variations in monsoon-influenced climate forcing, with successful results at about half of all gauges. The observed changes in tides are best explained by the influence of non-tidal velocities (geostrophic and Ekman), though the effect of changing stratification is also an important secondary causative mechanism. </p><p> From the results of these surveys and investigations, it is concluded that short-term fluctuations in MSL and tidal properties at multiple time scales may be as important in determining the state of future water levels as the long-term trends. Global explanations for the observed tidal behavior have not been found in this study; however, significant regional explanations are found at the yearly time scale in the Solomon Sea, and at the seasonal time scale in Southeast Asia. It is likely that tidal sensitivity to annual and seasonal variations in MSL at other locations also are driven by locally specific processes, rather than factors with basin-wide coherence. (Abstract shortened by ProQuest.)</p>

According to the recently released National Climate Assessment (NCA), climate change will disproportionally impact the health of the most vulnerable communities in Central Texas (Melillo, 2014). Exactly how climate change will impact these populations is unclear (Measham, 2011; Martens, 2014). Nationwide, there are few examples of cities looking at the impacts of climate change on existing public health issues and vulnerable communities. The NCA, Austin/Travis County Community Health Assessment (CHA) and Community Health Improvement Plan (CHIP), broadly identifies vulnerable communities as children, the elderly, the sick, the poor, and some communities of color (Melillo, 2014: Luber, 2009). The 2014 release of the NCA, in addition to the 2013 completion of the CHA and CHIP, provides an opportunity to compare current public health issues with projected changes in climate. The deductive process starts with a review of the CHA and CHIP to identify issues that are directly impacted by hotter and longer heat waves including a lack of physical activity, a decrease in mobility, and greater social isolation. These issues are then compared to likely climate scenarios for Austin in the coming century. For Austin, climate scientists project longer and hotter heat waves and higher overnight average temperatures. The results of the process are a hypothetical framework and specific actions to incorporate increasing temperatures into short-term and long-term health improvement planning. Comparing the NCA and CHA/CHIP reveals that an increase in intensity and duration of heat waves will make it especially dangerous for vulnerable communities who already struggle with health issues sensitive to heat such as obesity, respiratory ailments, and social isolation (Martens, 2014). Further analysis finds that the health implications of climate change come down to three broad topics: outdoor physical activities, lack of access to healthcare facilities, and isolation. Austin’s increasing temperatures and growing population means that more resources and efforts are needed to ensure the safety of all Austin residents. In this thesis, I put forth a hypothetical decision-making framework that prioritizes the allocation of resources to advance Austin’s pathway to climate resiliency. In addition, tools and actions are proposed to increase the climate resilience of the most vulnerable community members in Austin. / text

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This thesis tests and applies a new, physically based snow distribution and melt model at spatial scales of tens of metres and temporal scales of days across sub-arctic landscapes, in order to assess the significance of snow variability in sub-arctic human ecodynamics at resolutions relevant to human activities. A wider goal is to contribute to planning in the face of future climate change. Model tests are undertaken based on original field data collected in Sweden and Norway, and secondary data from Idaho, France and Greenland. Model applications focus on the ‘completed experiment’ of the medieval Norse in Greenland, a comparatively isolated population that relied on a combination of pastoralism and hunting for survival. A combination of local calibration based on contemporary meteorological data, customised climate reconstructions based on GCM data, new archaeological survey and new DEM are used in order to apply the model. This thesis shows, for the first time, the likely range of snow depth and duration experienced across the medieval Norse Greenland landscape as a result of climate and vegetation change. Results show that increases in snow cover could have been significant drivers of transformative change in Norse Greenland, and are therefore likely to be key in understanding the potential impact of future climate changes on similar sub-arctic and relatively marginal communities. Selected model analyses simulate the total spring (April-June) snow cover at the homefields to range from 32% cover lasting 6 days in the most favourable climate to 100% cover lasting 45 days in the most unfavourable climate at key elite inner fjord farms. At the more isolated outer fjord farms, total spring snow cover ranges from 33% cover lasting 10 days in the most favourable climate to 100% cover lasting 60 days in the most unfavourable climate. Increased climate variance and recovery times, as experienced by the Norse, are potential early warning signals of threshold-crossing change. Model results show that these signals could have been masked for the Norse decision making elite because they were located in the most favourable and least snow covered locations. Masking could have been further increased through the intensified seal hunting implemented by the Norse as an adaption strategy, and these actions could have developed into a rigidity trap. When the conjunctures of the 15th century developed in terms of increased sea ice, snow cover, storminess, culture contact, changing trade and sea level rise, it was too late to develop different responses. Whilst current populations have improved technology and knowledge relative to the Norse Greenlanders, there is a risk that adaptations will lack long-term utility, spatially restricted indications of change may be ignored, and rigidity traps develop. This thesis provides an additional tool for understanding a key element of both the past and possible futures of subarctic human ecodynamics.

The Lake Heron basin is an intermontane basin located approximately 30 kms west of Mount Hutt. Sediments within the basin are derived from a glacier that passed through the Lake Stream Valley from the upper Rakaia Valley. The lack of major drainage in the south part of the basin has increased the preservation potential of glacial phenomena. The area provides opportunities for detailed glacial geomorphology, sedimentology and micropaleontogical work, from which a very high-resolution study on climate change spanning the Last Glacial Maximum (LGM) through to the present was able to be reconstructed. The geomorphology reveals a complex glacial history spanning multiple glaciations. The Pyramid and Dogs Hill Advance are undated but possibly relate to the Waimaungan and Waimean glaciations. The Emily Formation (EM), previously thought to be MIS 4 (Mabin, 1984), was dated using Be10 to c. 25 ka B.P. The EM was largest advance of the Last Glacial Maximum (LGM). Ice during the LGM was at least 150m thicker than previously thought, as indicated by relatively young ages of high elevation moraines. Numerous moraine ridges and kame terraces show a continuous recession from LGM limits, and, supported by decreasing Be10 ages for other LGM moraines, it seems ice retreat was punctuated by minor glacial readvances and still-stands. These may be associated with decadal-scale climate variations, such as the PDO or early ENSO-like systems. There are relatively little sedimentological exposures in the area other than those on the shores of Lake Heron. The sediment at this location demonstrates the nature of glacial and paraglacial sedimentation during the later stages of ice retreat. They show that ice fronts oscillated across several hundred metres before retreating into Lake Heron proper. Vegetation change at Staces Tarn (1200m asl) indicates climate amelioration in the early Holocene. The late glacial vegetation cover of herb and small shrubs was replaced by a low, montane forest about 7,000 yrs B.P, approximately at the time of the regional thermal maxima. From 7,000 and 1,400 yrs B.P, temperatures slowly declined, and grasses slowly moved back onto the site, although the montane forest was still the dominant vegetation. Fires were frequent in the area extending back at least 6,000 years B.P. The largest fire, about 5,300 yrs B.P, caused major forest disruption. But full recovered occurred within about 500 years. Beech forest appears at the site about 3,300 yrs B.P and becomes the dominant forest cover about 1,400 yrs B.P. Cooler, cloudier winters and disturbance by fire promoted the expansion of beech forest at the expense of the previous low, montane forest. Both the increased frequency of fire events and late Holocene beech spread may be linked to ENSO-related variations in rainfall. The youngest zone is characterised by both a dramatic decline in beech forest and an increase in grasses, possibly representing human activity in the area.

Agricultural production is affected by a range of policy and climatic variables. This research explored the impacts of cap and trade, climate change and agricultural policy scenarios on water resource use and allocation in agricultural production. The research is organized into three separate studies, one for each set of scenarios.The first study focused on cap and trade policy for controlling greenhouse gas emissions, combining cost of production estimates with output price projections to determine the overall economic impact of cap and trade legislation, as well as its impact on agricultural water consumption. Price projections that included carbon offsets were higher than projections that did not, due to land being taken out of production and prices being bid up. HR2454 will increase production costs, particularly energy intensive inputs. Output prices increase as producers reduce production in response to cost increases. If agricultural offsets are allowed, output prices will be bid up further. Offsets allow producers to receive payments for cutting emissions. Producers benefit due to indirect price effects. Since water is quantity limited, total water use is unchanged.The next study looked at the physical impacts of climate change on production, particularly rising temperatures and carbon dioxide concentrations. By analyzing the anticipated yield effects, it was found that overall net incomes would decrease and the water constraint would remain binding - meaning total water use is unchanged.The third paper analyzed the effects of agricultural policy on land and water resource allocation. Cotton is directly subsidized. Corn and grain sorghum are subsidized indirectly through ethanol subsidies. Sugar cane prices are artificially high due to tariff rate quotas on sugar imports. Removal of any of these interventions decreased net profits to producers, but water use remains unchanged. Removing all farm programs significantly decreases acres under cultivation, and reduces water use below the water constraint. It comes at a great cost to producers however, given the small amount of water saved.

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