<p>The destruction of the ozone layer, concomitant with a projected enhancement in ocean stratification, will increase the dosage of ultraviolet radiation (UVR), as well as sea surface temperature and incident light level. The diatom <i> Fragilariopsis cylindrus</i> and other Antarctic phytoplankton will therefore be exposed to, and require protection from, increasing levels of damaging UVR, under elevated temperatures and light conditions. It has been hypothesized that phytoplankton utilize photoprotective pigments and the production of mycosporine-like amino acids as strategies against UVB-induced production of reactive oxygen species (ROS). The goal of this research was to investigate photoprotective mechanisms employed by <i>F. cylindrus</i>, following exposure to enhanced UVB. Interactive effects of temperature and light level were explored, as cultures were subjected to temperatures of 0&deg;C or 4&deg;C and light levels of 15 &micro;E m^&minus;2 s^&minus;1 or 100 &micro;E m^&minus;2 s^&minus;1, in order to approximate current and future Southern Ocean stratification conditions. Growth rate and photosynthesis significantly declined by 40&ndash;80% and 50-90%, respectively, following exposure to high UVB relative to control conditions. This decline in physiological health was accompanied by a 50&ndash;300% increase in photoprotective mechanisms. Exposure to high UVB under current climate conditions resulted in the least amount of photodamage and photoprotection. Conversely, elevated light level resulted in the greatest decrease in growth and photosynthesis, accompanied with the greatest increase in photoprotection when exposed to high UVB. Under both light levels, the elevated temperature appeared to mitigate damage caused by high UVB exposure. The results of this study shed light on the mechanisms utilized by <i>F. cylindrus</i> in response to oxidative stress induced by UVB, and how these mechanisms may be expected to change under future ocean stratification conditions. </p>

Climate change research is undergoing a monumental shift, from an almost exclusive focus on mitigation, and the reduction of greenhouse gases, to adaptation, and identifying the ways in which nations, communities and sectors might best respond to the reality of a changing climate. Vulnerability assessments are now being employed to identify the conditions to which socio ecological systems are exposed-sensitive and their capacity to adapt. Work has been conducted across a range of geographical locations and systems as diverse as healthcare and mining. There are however, few examples of analyses incorporating an assessment of the multiple climatic and non-climatic stressors to which agricultural producers are exposed. This thesis examines farm-level vulnerability to climate change of agricultural producers from the Eastern Bay of Plenty, New Zealand. The study area has a diverse agricultural economy, founded upon pastoral farming (dairy and drystock) and kiwifruit. This dependence on agricultural production, and the likely influence of expected changes in climatic conditions in the future provided a unique setting in which to develop a place-based case study exploring vulnerability to future climatic variability and change. Using a mixed methods approach, including semi-structured interviews and temporal analogues, a conceptual framework of farm-level vulnerability was developed and applied. The application of the framework was conducted through an empirical study that relied on engagement with and insights from producers who identified current exposure-sensitivity and adaptive capacity. It is shown that pastoral farmers and kiwifruit growers are exposed-sensitive to a range of climatic and non-climatic conditions that affect production, yields and farm income and returns. It demonstrates that producers have in turn, developed a range of short- and long-term adaptive strategies in order to better manage climatic conditions. It shows that these responses are varied, and are not made in response to climatic conditions alone, illustrating the need to consider other, multiple stimuli. An assessment of future vulnerability is presented, based on the empirical work and the identification of those drivers of vulnerability that are likely to be of concern and that will shape the capacity of farmers and growers to respond to climatic variability and change. The thesis as a whole not only provides a place-based case study on the vulnerability of farmers and kiwifruit growers in eastern New Zealand, but also demonstrates the need to engage with producers in order to develop an understanding of the complex ways in which climatic conditions interact with non-climatic stimuli beyond the farm-gate to influence vulnerability to climatic variability and change, both now and in the future.

The purpose of this study is to 1: Get an updated population estimate for the regionally endangered alpine specialist plant Phippsia concinna in Sweden and 2: Explore the ecological dependencies that limits the distributions of this species to late melt-out alpine snowbeds on calcareous soils, and 3: Explore if climate change in the southern part of the Scandes mountain range is causing a decline in the population numbers of P. concinna. The majority of the sites in Sweden where P. concinna occurred historically was inventoried in 1992. This study presents the results of a re-inventory of the same snowbeds after 22 years, along with measurements of abiotic soil factors and records of abundance and composition of associated vegetation at the sites. The main findings are 1: Population number of P. concinna has increased but one third of the original populations has disappeared since 1992, and 2: Soil pH appears to limit the distributions of P. concinna while slope aspect and soil Nitrogen concentrations affects this species competitive abilities in the Swedish Scandes. 3: Presence of P. concinna is negatively correlated to cover of other graminoids and bryophytes. These results suggests that snowbeds are melting earlier following increased temperatures and precipitations in summer, resulting in longer vegetation periods that favours plant species with stronger competitive abilities over specialised snowbed species. The observed rate of change in P. concinna populations during 22 years is evidence of fast occurring vegetation changes and highlights the need to monitor rare plant species in alpine environments.

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<p> In the United States public discourse, climate change is often framed as a polarized and intractable issue. The purpose of this dissertation was to explore deliberation about climate action, and to evaluate whether effective responses to climate change can be facilitated through new structures and processes that enable and encourage dialogue on the subject of how to reduce greenhouse gas emissions. Working with sustainability leaders at the University of Montana and in the community of Missoula, Montana, the author convened three public deliberations, in which a variety of solutions to climate change were discussed. Three questions guided this study: 1) what motivated individuals to engage in deliberation about climate action; 2) how did individual engagement vary and affect the quality of the deliberation; and 3) how effective were the deliberations in building a sense of individual agency and generating collaborative action strategies to address climate change. Based on a rigorous statistical analysis of survey responses combined with qualitative data, this action research study offers a holistic exploration of the three deliberative events convened. The deliberative processes generated collaborative action strategies and increased participants' sense of agency to take action on climate change; the findings also revealed differences in the ways individuals engaged and affected the quality of the overall group deliberation. This dissertation contributes to the literature on collaborative responses and collective action on climate change, broadens understanding of deliberative processes, and provides new insight into opportunities for leading deliberation about climate action.</p>

The global climate is predicted to go through great changes in the 21st century, which will have impacts on ecosystems all over the world. Aquatic ecosystems will be affected by higher annual temperatures and increased runoff from surrounding terrestrial areas. The increased runoff will cause more terrestrial organic matter (TOM) to reach the waters, which will elevate levels of dissolved organic carbon and nutrients. The higher temperature, changed water color and increased nutrient concentration are together bound to affect aquatic systems, but exactly how the systems will respond is yet unclear. The aim of this study was to investigate how periphyton and benthic grazers will react to higher temperatures and elevated amounts of TOM in the water. This was done by measuring production of periphyton and growth rates of the snail species Gyraulus acronicus when placed in treatments with higher temperature, more TOM or a combination of these two. Higher temperature was found to have a negative effect on periphyton production, while increased amounts of TOM alone had a positive effect, and the combination of these two lowered production. The results on snail performance were in most cases non-significant, but the results still suggest that possible future effects of more TOM and higher temperature on the snails will be negative.

<p> This thesis examines resilience among the Point Lay I&ntilde;upiat in the context of climate change. Resilience is manifest in the ability of community members to maintain meaningful subsistence practices and activities despite ongoing changes in weather, ice, and resource conditions. Twenty-one Point Lay I&ntilde;upiat were interviewed for this thesis. Respondents were divided into three cohorts: youths (ages 18-29), adults (ages 30-49), and elders (ages 50-70+). Respondents shared changes in weather, ice, and resource conditions. Respondents also shared community concerns, including concerns not attributable to climate change. Received responses were sorted and compared by cohort to identify trends in weather, ice, and resource conditions, as well as to identify adaptive and maladaptive strategies for coping with climate change and other stressors impacting the community. Whether the community can maintain meaningful subsistence practices and activities if local changes in weather, ice, and resource conditions remain unchanged or intensify is also questioned.</p>