Climate change is one of the most important and urgent issues of our time. Since 2006, China has overtaken the United States as the world’s largest greenhouse gas (GHG) emitter. China’s role in an international climate change solution has gained increased attention. Although much literature has addressed the functioning, performance, and implications of existing climate change mitigation policies and actions in China, there is insufficient literature that illuminates how the national climate change mitigation policies have been formulated and shaped. This research utilizes the policy network approach to explore China’s climate change mitigation policy making by examining how a variety of government, business, and civil society actors have formed networks to address environmental contexts and influence the policy outcomes and changes. The study is qualitative in nature. Three cases are selected to illustrate structural and interactive features of the specific policy network settings in shaping different policy arrangements and influencing the outcomes in the Chinese context. The three cases include the regulatory evolution of China’s climate change policy making; the country’s involvement in the Clean Development Mechanism (CDM) activity, and China’s exploration of voluntary agreement through adopting the Top-1000 Industrial Energy Conservation Program. The historical analysis of the policy process uses both primary data from interviews and fieldwork, and secondary data from relevant literature. The study finds that the Chinese central government dominates domestic climate change policy making; however, expanded action networks that involve actors at all levels have emerged in correspondence to diverse climate mitigation policy arrangements. The improved openness and accessibility of climate change policy network have contributed to its proactive engagement in promoting mitigation outcomes. In conclusion, the research suggests that the policy network approach provides a useful tool for studying China’s climate change policy making process. The involvement of various types of state and non-state actors has shaped new relations and affected the policy outcomes and changes. In addition, through the cross-case analysis, the study challenges the “fragmented authoritarianism” model and argues that this once-influential model is not appropriate in explaining new development and changes of policy making processes in contemporary China.

Habitat loss is the leading cause of species extinction. Protecting and managing habitat quality is vital to an organism’s persistence, and essential to endangered species recovery. We conducted an investigation of habitat quality and potential impacts from climate change to piping plovers (Charadrius melodius) breeding on the barrier island ecosystem of New York, during 2003-2005. Our first step in this analysis was to examined the relationship between two common measures of habitat quality: density and productivity (Chapter 1). We used both central and limiting tendency data analysis to find that density significantly limited productivity across many spatial scales, especially broader scales. Our analysis of plover habitat quality (Chapter 2) focused on (1) identifying the spatial scaling of plovers to their environment; (2) determining the relative importance of four aspects of the environment (land cover, predation, management, and disturbance); and (3) determining the key environmental variables that influence productivity. We found that plover habitat selection occurred within a narrow range of spatial scales that was unique to each environmental variable. Further, we found that management and predation variables influenced population-level productivity relatively more than land cover and disturbance. Environmental variables with a significant positive influence on habitat quality were land management units, plover conservation educational signs, and symbolic string fencing erected around plover nesting areas. We found a significant negative relationship among density of people on ocean beaches, herring gull density, and land cover degradation. To quantify possible impact to plover habitat from future climate change (Chapter 3), we examined the extent of habitat change resulting from different estimates of sea-level rise (SLR) and storminess over the next 100 years. We found that the particular SLR estimate, habitat response, and storm type used to model climate changes influenced the amount of potential habitat available. Importantly, we observed synergy between SLR and storms resulting in the increasing impact of SLR and storms on plover habitat over the next 100 years. Finally, we found that coastal development contributed considerably to habitat loss when combined with climate changes. Our findings raise concerns regarding current plover recovery goals and management strategies. Density-dependent productivity may threaten the goal of a joint increase in both plover population and productivity. We advocate density monitoring and allocation of alternative nesting areas to provide the relief of possible high-density limitations. Based on our analysis of habitat selection and climate change threats, we call for a shift in management focus away from known breeding areas, towards ecosystem processes. Long-term conservation of piping plover habitat quality is more likely through protecting and promoting natural barrier island dynamics (i.e. overwash and migration) and minimizing human development on the barrier islands of New York State.

The cryosphere and its interactions with other components of the climate system are considered to be major influences on global climate change through the Cenozoic and into the future. However, fundamental dynamics and secondary feedbacks that drive long-term ice sheet variability on Greenland remain poorly understood. Here, a numerical climate-ice sheet modeling study is conducted with the aim of reconstructing most likely locations, timing and variability of continental ice in the mid to late Pliocene and the transition into the Pleistocene. Simulations using the GENESIS v3 General Circulation Model coupled to the Penn State Ice Sheet-Shelf Model are compared with a range of independent numerical ice sheet model simulations under Pliocene boundary conditions and validated against available proxy reconstructions. This study aims at investigating the sensitivity of an ice-free and glaciated Greenland to changes in climate forcings, and the modulation of those forcings through internal feedbacks with focus on the dynamical thresholds involved in the growth and retreat of continental ice on Greenland. Orbital changes of latitudinal and seasonal solar radiation, in combination with prevalent atmospheric pCO2 levels, are found to pace the timing of the cryospheric response. Internal feedbacks invoked though local surface characteristics on Greenland in concert with far field changes in Arctic sea surface temperature and sea ice conditions control the energy and moisture budget on Greenland with consequences for its mass balance. In the Pliocene, inception of Greenland ice is inhibited during interglacials and ice volume is limited even when orbits are favorable for ice sheet growth. During Pliocene warmth, a present-day Greenland Ice Sheet cannot be maintained and ice was most likely restricted to the highest elevations in the East and South, contributing ∼6m of equivalent sea level rise. This assessment of the sensitivity and survivability of Greenland Ice Sheet in a warmer-than-modern world implies the potential for a long-term commitment to future sea level rise from a smaller Greenland Ice Sheet.

Uncertainty in climate change plays a major role in watershed systems. The increase in variability and intensity in temperature and precipitation affects hydrologic cycle in spatial and temporal dimensions. Predicting uncertainty in climate change impacts on watershed systems can help to understand future climate-induced risk on watershed systems and is essential for designing policies for mitigation and adaptation. Modeling the temporal patterns of uncertainties is assessed in the New England region for temperature and precipitation patterns over a long term. The regional uncertainty is modeled using Python scripting and GIS to analyze spatial patterns of climate change uncertainties over space and time. The results show that the regional uncertainty is significant in variation for changes in location and climatic scenarios. Watershed response to climate change under future scenarios is assessed using hydrologic simulation modeling for the Connecticut River watershed. Changes in water budgets are assessed for each of the subbasins using spatial analysis and process modeling using GIS and Soil and Water Assessment tool (SWAT). The results show that climate change uncertainty in precipitation and temperature can lead to uncertainty in both quantity and quality in the watershed system. A spatiotemporal, dynamic model was applied to subbasins within the Chicopee River Watershed to estimate climate change uncertainty impacts at a micro scale. These changes were assessed relative to changes in land use and climatic change. The results show that there is a significant potential for climate change to increase evaporation, watershed runoff and soil erosion rates and this varied with climate change uncertainty. Finally, water sustainability gradient analysis was applied to the Volga River watershed in Russia to assess potential climate change impacts by combining with downscaled Global Circulation Model estimates and spatial assessment. Results show that runoff and evapotranspiration are projected to increase with potential for more localized floods and drought events effecting both water resources and food supply. Overall results show that climate change uncertainty can impact watershed systems and spatial and temporal assessments is important for developing strategies for adaptation to climatic change conditions at local and regional scales.

In addition to being one of the poorest countries in Africa, Tanzania is considered the 13th most vulnerable nation in the world to climate change and climate variability. Currently over 63% of Tanzanians have no access to the national power grid. Instead they rely on biomass and kerosene lamps to provide energy in their homes. In addition, rural youth in Tanzania have limited occupational pursuits other than subsistence farming (both formal and informal). Utilizing a case study approach, this research qualitatively explores the effects of energy access in the form of solar PV for those seeking to secure this public good at a household-level. Face-to-face interviews conducted in the coastal region of Tanzania concentrated on understanding rationales for adopting off-grid energy (adoption rationales), particularly respondent's 'Awareness', 'Motivation' and selected 'Pathways' (the AMP Framework). High rates of rural poverty highlight systemic lack of energy access in Tanzania. In contrast, livelihood transformations through solar PV were observed in the case to couple with energy access. Indicators of improvement in living standards were observed to have cascading influence on other adopters which, in turn, encouraged further uptake. This innovative adoption lead to decreased pressure on the surrounding ecosystems, but environmental factors did not influence initial adoption rationales. Reflecting on the findings, the author develops a framework for better understanding of the role private actors take in transitions from to off-grid energy access in Africa. Reflecting on the case observations, particularly how respondents sought shape the flow of events independent, and sometimes in spite of, the State, the framework extends current understandings of nodes of change in rural communities and provides a more extensive exploration of behavioural theories (the AMP Framework and Diffusion Theory). Novel connections are made conceptually with emerging nodes of change and decision-making theories of change to provide fresh extension of these approaches to understanding poverty arrangements in Africa and what researchers and decision makers might need to consider for targeted interventions towards universal energy access on the continent. The thesis concludes with a range of principles for energy access in Africa distilled from the observations and framework developed. They include environmental principles of sustainable resource management and socioecological balance, social principles of equality and participation, and economic principles of access and stability.

The continuous operation of civil and marine structures is essential for maintaining the flow of people and goods. However, structures are exposed to extreme or progressive events during their service time. The uncertainties associated with the occurrence and the magnitude of extreme events (e.g. flooding and scour) may change, leading to unprecedented loading conditions, while the progressive events (e.g. corrosion and fatigue) may jeopardize the structural capacity to resist loads. In order to maintain or improve the structural capacity, repair and maintenance actions need to be applied to structures. However, the determination of these actions may be challenging for decision makers due to (a) limited financial resources to be allocated for a group of structures, (b) uncertainties associated with current structure conditions and future loading conditions, and (c) various decision-making factors (e.g. reliability threshold, decision time, and risk attitude). In order to address these issues, the focus of the research in this dissertation is to enhance the development of management strategies with the application in (a) management of bridge networks under hydraulic events and climate changes, (b) service life extension of ships considering financial feasibility and decision-making factors, and (c) determination of reliability threshold in the decision-making process. The management of bridge networks involves the quantification of regional hazards imposed on the network, performance assessment of structures, and consequence evaluation of potential bridge failure. Regional hazards such as floods may be affected by the changes in the intensity of precipitation due to anticipated climate changes. These hazards may cause extensive damage to bridges, and failure may cause significant costs to bridge managers and result in inconvenience on the daily traffic commute. This research focuses on enhancing the assessment and management of bridges networks vulnerable to regional hydraulic events and climate changes. The integration of transportation network analysis, which reflects the redistribution of traffic flow in the event of bridge failure, is shown to be essential when determining the risk level of bridges. Furthermore, this work includes proposed methodologies for determining optimal management strategies that account for the connection between global climate predictions and regional hydrologic conditions. The crux of determining management strategies, especially for extending ship service lives, is to ensure an adequate safety margin within and beyond the design life. In addition to the loading effect and structural capacity, the safety margin of ships is related to the deterioration acting on the structure. During ship operation, in-service condition surveys are conducted on ship details to assess structural conditions and to inform maintenance actions. This research focuses on the integration of condition surveys of ship details, as well as the timing of conducting surveys, to improve the service life extension for ship structures. While decision makers strive to maintain the safe operation of ships, they should also identify the management strategy that can deliver the best return given the limited budget. This research, from the perspective of cost-effectiveness and profitability, proposes optimization frameworks to clarify the financially feasible life expectancy of different management strategies as well as identify the optimal duration of extended service life for different categories of commercial ships. The last focus of this research emanates from the reliability threshold when determining management strategies. In addition to facilitating decision-making on the management of civil and marine structures, the reliability threshold in terms of target reliability index has been extensively used in design guidelines to ensure adequate safety margin for structures. The level of safety is typically related to the failure mode and severity of failure consequences (e.g. number of potential fatalities). Driven by the emerging application of unmanned ships where there are fewer or no crew members on board, this research specifically focuses on the integration of different acceptance criteria for human safety into the determination of the target reliability index.

Assessments of the anthropogenic threats to savanna ecosystems are primarily focussed on land use change, bush encroachment, and biological invasions. There is, however, very little understanding as to the threats from atmospheric pollution. South Africa is the major emitter of CO2 on the African content while the Mpumalanga region bordering the Kruger National Park (KNP) is among the leading regions for nitrous oxide pollution in the world. It is not only increasing atmospheric pollution, but rainfall intensity is also predicted to increase for southern Africa. As savannas are nutrient limited, an increase in nitrogen deposition will have major consequences for vegetation structure and this can only be exacerbated by increased rainfall amounts. Current research suggests that these predicted increases in water and nutrients will result in increasing grass biomass and decreasing herbaceous species richness. The effects of global change drivers on savanna vegetation are also likely to propagate through to multiple trophic levels, with changes in vegetation structure cascading down to invertebrate assemblages. As invertebrates are ubiquitous, form the bulk of metazoan species diversity and biomass on earth, and play a pivotal role in many ecosystems, I discuss in the introductory chapter of this thesis why the influence of global change on these assemblages should not be ignored. In my first data chapter, Chapter 2, I examine the effect that increases in available nutrients and water may have on vegetation structure, and how this may cascade down to grasshopper and ant assemblages. I do this using a fully factorial experiment in KNP with nutrient and water additions where I assessed both herbaceous (forb and grass) and insect (ant and grasshopper) assemblages five years after resource additions began. My results show that there was a substantial increase in grass biomass while plant and insect species richness declined with water addition alone and that a combination of nutrients and water resulted in the greatest increases in grass biomass and concomitant decreases in plant and insect species richness. The effects of nutrient and water additions on the insect community assembly was primarily driven by a decrease in grasshopper species and ant abundance respectively. An analysis of ant functional traits showed that the rare ant species mediated the impact of the resource additions on the ant assemblage. Fire is inherent to savanna systems with profound effects on vegetation structure. There has, however, been relatively little research on the effects of fire on savanna invertebrate fauna. In Chapter 3 I look at the effect that fire may have on the vegetation and insect community assembly at my study site between five and eight months after the site had been burned. These results show an increase in grass biomass and decrease in plant and insect species richness with a combination of nutrients and water. My results also show that grasshopper biomass, abundance, and species richness decreased as herbaceous biomass decreased. While ant species richness decreased, ant abundance increased post-fire, primarily related to an increase in patches of bare ground. With global change, drought frequency is also expected to increase. The insect and grass assemblages, both on and off Macrotermes mounds, at two sites in the southern section of KNP had been sampled in a separate study in 2012. In Chapter 4 I describe a study where I resampled these mounds during the peak of the most severe drought in 30 years. The two sites differed in drought severity, one where the drought severity was very high and the other where severity was much lower. The objective was to determine the effects that drought may have on the grass and associated insect assemblages both on and off termite mounds. My results show that at the high severity site grass cover and biomass and grasshopper abundance decreased both on and off mounds. The overall reduction in habitat structure resulted in an increase in both ant abundance and species richness but the mound and matrix ant assemblages diverged during drought. Where the drought was less severe there was an increase in large mammal herbivores as animals moved out of the more affected areas. This increase in mammal herbivory was more evident on rather than off mounds resulting in grass biomass being lower on rather than off mounds. The cascading effect saw grasshopper abundance decrease on and increase off mounds. The mound and matrix ant assemblages did not respond to the comparatively smaller change in habitat structure. Finally, in the synthesis chapter I discuss my results in the broader context of how global change drivers such as increased nitrogen deposition may cascade down from plant to insect community assembly. At present there is very little understanding of the amounts of nitrogen being deposited in KNP or the effect that this may have. The results of my study would suggest that this increase in nitrogen deposition will have major consequences for vegetation structure and that this will cascade down to the insect assemblage. In mitigating for this, it is therefore essential that management in KNP adapt a monitoring protocol for nitrogen deposition, especially when considering that where N deposition is really high fire may not volatilise everything to allow the system to reset itself back to its original state. It is not only nitrogen deposition, but drought frequency is also likely to increase. In mitigation for this there should also be monitoring programmes to consider the effects of drought as animals may move from areas of high drought severity to areas where severity is lower. Such movement will increase grazing pressure on both low and high nutrient environments with cascading effects on vegetation structure and insect assemblages.

CDOM (chromophoric dissolved organic matter) plays an important role in determining underwater light field and aquatic photochemical and biological processes. Knowing CDOM properties, origin, sink, content, and distribution is able to provide us not only a useful approach to evaluate, but also a new perspective to understand water quality, carbon cycle, as well as the climate change. Remote sensing inversion of CDOM bears the potential capability to assess CDOM at large scale, but it has not been fully investigated yet. Particularly, the previous approaches cannot meet the accuracy and spatial resolution requirement for analyzing complex waters in estuarine and coastal regions. Therefore, a new scheme, which combines a newly developed inversion algorithm and hyperspectral remote sensing, is proposed to solve problems encountered in CDOM evaluation. This research covers three study sites, in the estuarine and coastal regions of the Mississippi River, Hudson River, and Neponset River. Very high resolution in situ data were collected in these sites and EO-1 Hyperion satellite images were also acquired accordingly. Based on a quasi-analytical algorithm (QAA), a QAA-CDOM algorithm was developed, by which CDOM absorption coefficient ag(440) is separated from adg(440)(total absorption coefficient of CDOM and non-algal particles). Some QAA's parameters and functions were also optimized, using available datasets (in situ, IOCCG, and NOMAD). Result validation in the Atchafalaya plume has proved that QAA-CDOM is capable of estimating ag(440) in excellent accuracy (RMSE=0.11 m−1 and R2=0.73 in the Atchafalaya River plume region). More importantly, applying QAA-CDOM to other locations, including the Mississippi River, Amazon River, and Moreton Bay, also derived very reasonable and accurate ag(440), covering a wide range from 0.01 to 15 m −1. This confirms that our method is applicable to a wide range of estuarine regions. The uncertainties involved in CDOM inversion were also analyzed, aiming to know the origin, magnitude, and propagation of uncertainty in different inversion phases. This work strongly indicates that the proposed scheme, QAA-CDOM hyperspectral remote sensing inversion, is robust and reliable to quantify CDOM's concentration, distribution and dynamic for diverse waters, and hence can be applied to other regions.

Includes bibliographical references / Changes in precipitation extremes are projected by many global climate models as a response to greenhouse gas increases, and such changes will have significant environmental and social impacts. These impacts are a function of exposure and vulnerability. Hence there is critical need to understand the nature of weather and climate extremes. Results from an ensemble of regional climate models from the Coordinated Regional Downscaling Experiment (CORDEX) project are used to investigate projected changes in extreme precipitation characteristics over southern Africa for the middle (2036-2065) and late century (2069-2098) under the representative concentration pathway 4.5 (RCP4.5) and 8.5 (RCP8.5). Two approaches are followed to identify and analyze extreme precipitation events. First, indices for extreme events, which capture moderate extreme events, are calculated on the basis of model data and are compared with indices from two observational gridded datasets at annual basis. The second approach is based on extreme value theory. Here, the Generalized Extreme Value distribution (GEV) is fitted to annual maxima precipitation by a L-moments method. The 20-year return values are analyzed for present and future climate conditions. The physical drivers of the projected change are evaluated by examining the models ability to simulate circulation patterns over the regions with the aid of Self-Organizing Maps (SOM).

Coral reefs are crucial for the ecological sustainability of the oceans, yet, increasing sea surface temperature is threatening these ecosystems globally. Microbial communities associated with corals have become a recent research focus, as the associated microbiome may contribute to coral resilience to environmental stressors, e.g., heat stress. However, research in this area is hampered by the difficulty of working with corals. This study aims to use Aiptasia, a sea anemone, as a tractable laboratory model system to study the role of the coral microbiome. Analyses of the bacterial compositions associated with different Aiptasia strains across two temperatures (25 °C and 32 °C), based on 16S rRNA gene sequencing. This study aims also to identify a “core” microbiome associated with heat stress acclimation, as well as host-specific differences. In general, results showed that bacterial composition associated with Aiptasia strains differs significantly with temperature. Higher bacterial diversity and richness were observed when all Aiptasia strains were placed under heat stress. Moreover, results showed an increase in beta diversity and dispersion of bacterial communities in response to heat stress. These changes in the bacterial composition are in line with the recently described “Anna Karenina principle” for animal microbiomes, which suggests that the microbiomes of unhealthy individuals vary more than healthy and stable individuals. This study further shows that while temperature had the greatest effect on structuring the bacterial compositions, there were some variations better attributed to batch and host effects. This suggests that technical aspects have to be carefully addressed in the framework of microbiome studies. Members of a putative “core” microbiome associated with 32 °C Aiptasia have been identified as indicator species of heat stress (i.e., Francisella sp.,). Previous reports have shown that these indicator taxa are associated with saline environments and can tolerate high temperatures. Putative functional profiles based on taxonomic inference of associated bacterial taxa (i.e., enrichment and depletion of various metabolic processes) were also identified, implying functional differences of the microbiomes associated with Aiptasia strains in response to heat stress. Future studies should more specifically examine how the microbiome influences the animal ability to respond to environmental changes.