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This thesis draws on the climate-conflict research field to explore the question how does climate variability affect interstate conflict? This thesis contributes to various gaps in previous research by studying interstate conflict while most climate-conflict research investigates internal conflict, by using a new operationalization of climate variability as sea ice extent, and by studying an understudied case, the Arctic region. The theoretical argument consists of two parallel processes, a background mechanism focused on long-term climate change and a main mechanism focused on short-term climate variability. Increased climate variability is theorized to increase access to rivalrous resources, thereby increasing their saliency and leading to interstate competition. This increases each state’s utility of fighting, increasing the risk of bargaining failure and hence interstate conflict. The background mechanism theorizes that increased climate change will increase the risk of commitment problems, thereby contributing to bargaining failure and interstate conflict. I test the hypothesis that decreased sea ice extent increases the likelihood of militarized interstate incidents through a large-N quantitative study. Overall, the findings are inconclusive but with a low degree of support for the hypothesis.

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Die Gletscherschmelze in den südlichen Anden trägt maßgeblich zum Anstieg des Meeresspiegels der letzten Jahrzehnte bei und beeinflusst regional die saisonale Wasserverfügbarkeit. In jüngster Zeit wurde eine rapide Zunahme der Massenverluste insbesondere einzelner großer Auslassgletscher des Südlichen Patagonisches Eisfeldes beobachtet. Im Rahmen der Dissertation wurden die rezente Variabilität des Klimas und der klimatischen Massenbilanz für ausgewählte vergletscherte Gebiete in Patagonien und Feuerland untersucht. Die Verbesserung unseres Verständnisses über räumliche und zeitliche Muster der klimatischen Massenbilanz, ihrer atmosphärischen Antriebsfaktoren und ihres Einflusses auf das in jüngster Vergangenheit beobachtete individuelle Gletscherverhalten, sind weitere wichtige Ziele. Da die Klimavariabilität die Hauptursache für lokale Veränderungen in der Kryosphäre der südlichen Anden ist, wurden langjährige meteorologische Beobachtungen im Gebiet der Gran Campo Nevado-Eiskappe im südlichsten Patagonien im Hinblick auf räumliche und zeitliche Variabilität untersucht und der Einfluss mesoskaliger Wettermuster und Modi atmosphärischer Oszillationen auf die Ausprägung des Klimas analysiert. Darüber hinaus wurde die rezente Variabilität der klimatischen Massenbilanz für ausgewählte Gletscher in Südpatagonien und Feuerland durch die Implementierung des Energie- und Massenbilanzmodells COSIMA simuliert. Eine unterschiedliche Ausprägung der Oberflächenmassenbilanz und geodätischer Massenbilanz unterstreicht wie wichtig ein besseres Verständnis über die Prozesse der klimatischen Massenbilanz und Eisdynamik ist. Des Weiteren wurden Simulationen der klimatischen Massenbilanz eingesetzt, um eine ausgeglichene Massenbilanz für rezente und vergangene Ausdehnungen des Gletschers Schiaparelli abzuleiten. Ziel war es, eine modellgestützte Annäherung an die klimatischen Bedingungen während der Kleinen Eiszeit zu simulieren. / Glacier mass loss of the Southern Andes contributes largely to sea-level rise during recent decades and also affects the regional water availability. Despite the overall glacier retreat of most glaciers in Patagonia and Tierra del Fuego, a recent increase in mass loss of individual glaciers has been observed. The recent variability of climate and climatic mass balance for selected glaciated study sites in Patagonia and Tierra del Fuego are investigated in this thesis. Improving our understanding on the spatial and temporal variations of climatic mass balance processes, its atmospheric drivers, and their impact on the recently observed individual glacier behavior are further important aims. Since climate variability is the key driver of local changes in the cryosphere in the Southern Andes, a unique record of meteorological observations across the Gran Campo Nevado Ice Cap in Southernmost Patagonia was analyzed with regard to main climate features and the relationship between the in-situ observations, large-scale climate modes and mesoscale weather patterns. Furthermore, recent climatic mass balance variability was simulated for selected glaciers in Southern Patagonia and Tierra del Fuego by implementing the ’COupled Snow and Ice energy and MAss balance model’ COSIMA. Contrasting patterns of positive simulated annual climatic mass balance and clearly negative geodetic mass balance were found for two neighboring glaciers of the Southern Patagonia Icefield between 2000 and 2014. This highlights the importance of understanding of both, the climatic mass balance, and the ice-dynamical processes. Climatic mass balance simulations were further used to derive glacier steady-state conditions for recent and past glacier extents of Schiaparelli Glacier, aiming for a model-based approximation of climate conditions during the Little Ice Age.

Seit der industriellen Revolution haben Menschen durch Verbrennung von fossilen Energieträgern die Treibhausgaskonzentration in der Atmosphäre erhöht. Die daraus folgende Erderwärmung hat weitreichende Folgen für das Klima, unter anderem häufigere und intensivere Wetterextreme. Wegen ihrer gravierenden Auswirkungen auf die Gesellschaft, ist es von allgemeinem Interesse zu verstehen, wie der menschengemachte Klimawandel diese Wetterextreme beeinflusst. In dieser kumulativen Dissertation analysiere ich erst zwei komplexe Wettereignisse, die die Nahrungsmittelproduktion in Europa beeinträchtigen: Frosttage nach dem Beginn der Apfelblüte und Feuchte Frühsommerperioden nach warmen Wintern. In einer dritten Studie untersuche ich wie dynamische Klimaveränderungen in den mittleren Breiten der Nordhalbkugel zu beständigerem Sommerwetter beitragen. Schließlich beschäftige ich mich mit tropischen Stürmen im Nordatlantik und damit, wie sie von der globalen Erwärmung beeinflusst werden. Eine zentrale methodische Herausforderung in diesem Forschungsfeld ist, dass Wetterextreme per Definition selten sind und dass es aufgrund der starken internen Klimavariabilität schwierig ist, die Veränderungen zu quantifizieren, die auf den menschgemachten Klimawandel zurück zu führen sind. In dieser Arbeit verfolge ich zweigegenläufige Ansätze um mit dieser Herausforderung um zu gehen: 1) Ich verwende große Klimasimulationsensembles um den Effekt der internen Klimavariabilität aus zu glätten und dadurch die erzwungenen Veränderungen beim Apfelfrost und in der Persistenz zu ergründen. 2) Mit Methoden, die auf Beobachtungsdaten beruhen, quantifiziere ich den Einfluss der internen Klimavariabilität auf tropische Zyklone um dann einschätzen zu können, in welchem Maß der beobachtete Anstieg der tropischen Zyklonaktivität im Atlantik der internen Klimavariabilität oder erzwungenen Veränderungen zugeschrieben werden kann. / Since the industrial revolution, humans have increased the greenhouse gas concentration of the atmosphere by burning fossil fuels. The resulting global warming has far reaching impacts on the climate system including increasingly frequent and intense weather extremes. Due to the severe impacts these weather extremes cause to societies, there is a strong interest in understanding how anthropogenic climate change affects weather extremes. In this cumulative thesis I first study two compound weather extremes that affect food production in Europe: frost days after apple blossom and wet early summers after warm winters. In a third study I quantify how dynamic changes in the climate system contribute to more persistent summer weather extremes in the northern hemispheric mid-latitudes. Finally, I analyze tropical cyclones in the Atlantic basin and changes in tropical cyclone activity as a result of global warming. One central methodological challenge in the research field is that weather extremes are rare by definition and that due to the strong internal climate variability it is difficult to quantify changes that are forced by anthropogenic climate change. In this thesis I explore two divergent approaches to this challenge: 1) Using large ensemble climate simulations I smooth out the effect of internal variability thereby exposing the forced change in apple frost and weather persistence. 2) Using observation based approaches, I quantify the contributions of internal climate variability on tropical cyclones in order to subsequently estimate to which extent the observed increase in tropical cyclone activity in the Atlantic can be attributed to internal climate variability or forced changes.

The main objective of this dissertation was to investigate the impacts of human activities and climate control on hydrologic responses using the Integrated Hydrologic Model (IHM), which dynamically couples HSPF and MODFLOW. The study first evaluated the impacts of land use change and rainfall variability on hydrologic responses—such as streamflow, evapotranspiration (ET), groundwater ET, recharge, and groundwater heads—in the Anclote River basin (ARB), Florida. The results provided insights into the uncertainties in hydrologic responses due to rainfall variability. Secondly, hydrologic response flux changes were partitioned into anthropogenic causes, including groundwater pumping, irrigation, and land use change, by the IHM in the Trout Creek Watershed, Florida. Hydrologic response flux changes per unit of human stress flux change were calculated and assessed at mean annual and monthly scales, offering insights for projecting hydrologic changes due to anthropogenic stressors. For climate control, a three-stage precipitation partitioning framework was proposed to study climate impacts on mean annual groundwater ET across 33 gauged watersheds in west-central Florida using the IHM. The roles of groundwater ET in long-term water balance were quantified through four ratios, and the contributions of various climate variabilities to groundwater ET were determined, providing new insights into sustainable groundwater management. Moreover, the dissertation explored the development and application of a multi-scale framework for the IHM, enhancing simulation accuracy and efficiency across different spatial scales and facilitating better water resource management. Applied to the ARB, this framework demonstrated improved model performance in capturing hydrologic changes due to local human activities and climate variability. This research underscored the significance of integrated surface-groundwater models in accurately assessing hydrologic impacts for water resource management, especially in regions with shallow water tables. It advanced the understanding of human and climate impacts on hydrologic systems, offering valuable tools and methodologies for integrated water resource management.

Climate change and variability have great impact on the hydrological cycle and consequently on the availability of water resources. Variations in temperature and precipitation trends that are occurring are a consequent of the increase in the concentrations of greenhouse gases, which are subsequently affecting the hydrological cycle. This in turn affects water quantity and quality, which is essential for agriculture, domestic and industrial uses. This study, done in Elliot Town and the surrounding areas of Sakhisizwe Municipality in the Eastern Cape Province of South Africa, evaluates how climate change and variability is affecting water availability and its quality in the town. The impact climate change and variability on agricultural production is also assessed. Remote Sensing, Geographic Information Systems (GIS), databases and some statistical packages have been used to collect, analyse and create spatial maps used to derive concrete conclusions. The methods used aided in spatially analysing the changes in temperature and rainfall along the years and make a comparative analysis. The study has shown that the spatial changes in the amount, intensity and frequency of rainfall affects the magnitude and frequency of stream flows; consequently, increasing the intensity of floods and droughts that have been recurring in the last few decades. The municipality is more affected by climate variability than change, and the resultant extreme climate events are affecting the water resources resulting in domestic water cuts, poor water quality and low agriculture productivity. This study recommends the importance of an awareness campaigns on climate change and variability and their effect directed towards the community, especially on novel water harvesting technologies. The study also highlights the importance of a robust early warning system to prepare the community in case of a climate shock, which is an area that needs further research. / Environmental Sciences

Au-delà des variables climatiques, d’autres facteurs non climatiques sont à considérer dans l’analyse de la vulnérabilité et de l’adaptation au changement et variabilité climatiques. Cette mutation de paradigme place l’agent humain au centre du processus d’adaptation au changement climatique, notamment en ce qui concerne le rôle des réseaux sociaux dans la transmission des nouvelles idées. Dans le domaine de l’agriculture, le recours aux innovations est prôné comme stratégie d’adaptation. L’élaboration et l’appropriation de ces stratégies d’adaptation peuvent être considérées comme des processus d’innovation qui dépendent autant du contexte social et culturel d’un territoire, de sa dynamique, ainsi que de la stratégie elle-même. Aussi, l’appropriation et la diffusion d’une innovation s’opèrent à partir d’un processus décisionnel à l’échelle de l’exploitation agricole, qui à son tour, demande une compréhension des multiples forces et facteurs externes et internes à l’exploitation et les multiples objectifs de l’exploitant. Ainsi, la compréhension de l’environnement décisionnel de l’exploitant agricole à l’échelle de la ferme est vitale, car elle est un préalable incontournable au succès et à la durabilité de toute politique d’adaptation de l’agriculture. Or, dans un secteur comme l’agriculture, il est reconnu que les réseaux sociaux par exemple, jouent un rôle crucial dans l’adaptation notamment, par le truchement de la diffusion des innovations. Aussi, l’objectif de cette recherche est d’analyser comment les exploitants agricoles s’approprient et conçoivent les stratégies d’adaptation au changement et à la variabilité climatiques dans une perspective de diffusion des innovations. Cette étude a été menée en Montérégie-Ouest, région du sud-ouest du Québec, connue pour être l’une des plus importantes régions agricoles du Québec, en raison des facteurs climatiques et édaphiques favorables. Cinquante-deux entrevues ont été conduites auprès de différents intervenants à l’agriculture aux niveaux local et régional. L’approche grounded theory est utilisée pour analyser, et explorer les contours de l’environnement décisionnel des exploitants agricoles relativement à l’utilisation des innovations comme stratégie d’adaptation. Les résultats montrent que les innovations ne sont pas implicitement conçues pour faire face aux changements et à la variabilité climatiques même si l’évolution du climat influence leur émergence, la décision d’innover étant largement déterminée par des considérations économiques. D’autre part, l‘étude montre aussi une faiblesse du capital sociale au sein des exploitants agricoles liée à l’influence prépondérante exercée par le secteur privé, principal fournisseur de matériels et intrants agricoles. L’influence du secteur privé se traduit par la domination des considérations économiques sur les préoccupations écologiques et la tentation du profit à court terme de la part des exploitants agricoles, ce qui pose la problématique de la soutenabilité des interventions en matière d’adaptation de l’agriculture québécoise. L’étude fait ressortir aussi la complémentarité entre les réseaux sociaux informels et les structures formelles de soutien à l’adaptation, de même que la nécessité d’établir des partenariats. De plus, l’étude place l’adaptation de l’agriculture québécoise dans une perspective d’adaptation privée dont la réussite repose sur une « socialisation » des innovations, laquelle devrait conduire à l’émergence de processus institutionnels formels et informels. La mise en place de ce type de partenariat peut grandement contribuer à améliorer le processus d’adaptation à l’échelle locale. / Other than climatic variables, non-climatic factors should be considered in the analysis of vulnerability and adaptation to climate change and variability. This shift in paradigm places the human agent at the centre of the process of adaptation to climate change, particularly with regard to the role of social networks in the transmission of new ideas. In agriculture, the use of innovations is advocated as a coping strategy. The development and adoption of these coping strategies can be considered innovative processes that depend as much on the social and cultural context of a country, its dynamics, and the strategy itself. Also, the ownership and dissemination of an innovation are taking place from a decision-making across the farm, which in turn requires an understanding of the multiple forces and external and internal factors in operation and the multiple objectives of the operator. Thus, understanding of the farmer’s decision- making environment at the farm level is vital because it is a prerequisite for the success and sustainability of any agricultural adaptation policy. However, in a sector like agriculture, it is recognized that social networks for example, play a crucial role in adaptation in particular, through the diffusion of innovations. Therefore, the objective of this research is to analyze how farmers take ownership and design strategies to adapt to climate change and variability from the perspective of diffusion of innovations. This study was conducted in Montérégie- West, a region located in the southwestern part of Quebec and which is known to be one of its most important agricultural regions, due to favorable climatic and soil factors. Fifty-two interviews were conducted with various stakeholders in agriculture at local as well as regional levels. The grounded theory approach is used to analyze and explore the contours of farmers’s decision-making environment regarding the use of innovation as a coping strategy. The results show that innovations are not implicitly designed to cope with climate change and variability even if climate change affects their emergence. The decision to innovate is largely determined by economic considerations. Moreover, the study also shows a weakness of social capital within farmers groups related to the overriding influence of the private sector, which are the main supplier of materials and agricultural inputs. The influence of the private sector has resulted in the dominance of economic considerations over environmental concerns and the temptation of short-term profit from the farmers, which raises the issue of sustainability of interventions in adaptation of Quebec’s agriculture. The study also highlights the complementarity between informal social networks and formal structures of support for adaptation, as well as the need to build partnerships. In addition, the study places the adaptation of Quebec’s agriculture from the perspective of private adaptation whose success is based on a "socialization" of innovations, which should lead to the emergence of formal and informal institutional processes. The establishment of such partnerships can greatly help improve the adaptation process at the local level.

A Thesis Submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy May, 2015. / There is sufficient evidence supporting that climate change and variability are pervasive realities that are strongly impacting on smallholder farmers in the Great Ruaha River sub-Basin of Tanzania. This PhD study examines smallholder farmers’ vulnerability, coping and adaptation strategies to climate change and variability (including non-climatic stresses), and investigates how such coping and adaptation may be constrained or enhanced given climate variability and change. Both quantitative and qualitative data collection methods were used when engaging with smallholder farmers and government officials. Primary data collection was undertaken in two phases, with phase one using participatory tools (e.g. focus group discussions, wealth ranking, community mapping and transect walk, and historical time lines). Data collected include climatic and non-climatic extreme events, farmers’ perceptions, coping and adaptation strategies. Phase two involved detailed individual interviews (questionnaire surveys) and key informant interviews (case studies), so as to obtain in-depth information on issues of interest. Secondary data were collected from existing statistical sources, literature surveys in archives, libraries and documentation centres, and from governmental agencies (e.g. TMA). Demographic, agricultural production and livestock statistics, and rainfall and temperature records were collected. Results from selected meteorological stations and farmers’ perceptions (74%) indicate that there has been an increase in average maximum temperatures, and both dry and wet years with varying magnitudes during the past four decades. Other climatic stresses include delayed onset and later cessation of the rain seasons. The agreement between farmers’ perceptions and rainfall trends provides good evidence that the climate has become increasingly variable in the GRRB during the past four decades. Achieving sustainable livelihoods is further compounded by non-climatic stresses such as access to markets and coordinating institutions. Results indicate that vulnerability is a complex phenomenon that entails two approaches (end-point and starting-point perspectives). The end-point perspective views vulnerability as the net projected climate change impacts after adaptation has taken place, whilst the starting-point perspective looks at both the current and future multiple stresses and places much emphasis in improving the adaptive capacity. In the study villages, such a nuanced picture highlighted areas for enhanced adaptation strategies. Farmers respond by using various strategies to deal with droughts, floods and other stresses when they occur. During droughts, they mostly use irrigation (canal, pumping and cans), or plant short-term maturing crops. During food shortages, farmers use strategies such as buying food, borrowing money, temporary migration, working in other people’s farms for cash, and reducing consumption. Moreover, the farmers’ choice of adaptation and coping strategies is influenced by factors such as location, access to resources, education levels and institutions. This calls for a whole system approach, which entails defining vulnerability of smallholder farmers to climatic and non-climatic stresses and thus designing appropriate response strategies. For example, mainstreaming adaptation to such stresses when considering development plans, projects, programmes and policies at all scales.