Understanding the interaction of multiple drivers and their compounded effects on ecosystem dynamics is a key challenge for marine resource management. The Baltic Sea is one of the world’s seas most strongly impacted by effects from both human activities and climate. In the late 1980’s changes in climate in combination with intensive fishing initiated a reorganization of the Central Baltic Sea (CBS) food web resulting in the current sprat-dominated state. In the future, climate change is projected to cause drastic changes in hydrodynamic conditions of the world oceans in general, and the Baltic Sea in particular.   In this thesis, CBS food web responses to the combined effects of fishing, nutrient loads and climate were tested for the past (1974-2006) and projected into the future (2010-2098). A new food web model for the CBS (BaltProWeb) was developed using extensive monitoring data across trophic levels. This model described the past food web dynamics well, and was hence also used for future (2010-2098) projections. Different ensemble modeling approaches were employed when testing the food web response to future scenarios. The results show that regardless the climate change, the management of nutrient loads and cod fishing are likely to determine the food web dynamics and trophic control mechanisms in the future Baltic Sea. Consequently, the variation in the food web projections was large, ranging from a strongly eutrophied and sprat-dominated to a cod-dominated CBS with eutrophication levels close to today’s values. The results also suggest a potential risk of abrupt ecosystem changes in the future CBS, particularly if the nutrient loads are not reduced. Finally, the studies illustrate the usefulness of the ensemble modeling approach, both from the perspective of ecosystem-based management as well as for studying the importance of different mechanisms in the ecosystem response. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 4: In press. Paper 5: Submitted.</p>

The purpose of this paper is to perform an exploratory analysis of the causalinteractions among global change drivers of regime shifts. Causal loops diagrams were usedto collect a set of feedback mechanisms underlying abrupt change dynamics in 11 regimeshifts. In order to prioritize drivers and to map out possible causal pathways we used networkanalysis. Agricultural processes, global warming, biodiversity loss, demographic andeconomic drivers are the main causes of regime shifts. Based on the analysis of 400pathways, we intuitively suggest five types of cascading effects between regime shifts.Regime shifts dramatically affect the provision of ecosystem services and might underminethe achievement of the first Millennium Development Goal: reduction of hunger and poverty.

京都大学 / 新制・課程博士 / 博士(農学) / 甲第24659号 / 農博第2542号 / 新制||農||1098(附属図書館) / 学位論文||R5||N5440(農学部図書室) / 京都大学大学院農学研究科森林科学専攻 / (主査)教授 北山 兼弘, 教授 北島 薫, 教授 柴田 昌三 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DGAM

We analyze the policy implications of aversion to Knightian uncertainty (ambiguity) about the possibility of tipping points. We demonstrate two channels through which uncertainty aversion affects optimal policy in the general setting. The first channel relates to the policy's effect on the probability of tipping, and the second channel to its differential impact in the pre- and post-tipping regimes. We then extend a recursive dynamic model of climate policy and tipping points to include uncertainty aversion. Numerically, aversion to Knightian uncertainty in the face of an ambiguous tipping point increases the optimal tax on carbon dioxide emissions, but only by a small amount.

A expansão do milho no Brasil é decorrente da mudança espaço-temporal da produção, que cria uma nova perspectiva de análise para a relação entre os preços do milho e da soja. Nesse contexto, este estudo objetiva analisar o transbordamento de risco entre esses mercados, por meio de três ensaios independentes, porém complementares. No primeiro ensaio, realiza-se uma revisão de literatura sobre a disseminação de riscos, com foco no mercado agrícola. Como estratégia de pesquisa realiza-se um levantamento de estudos publicados sobre os termos transmissão, transbordamento e contágio, que são utilizados de forma intercambiável pela literatura e que sintetizam os desdobramentos recentes no tocante à disseminação ou propagação de riscos entre mercados. No segundo ensaio, pretende-se identificar o contágio de preços dos mercados físicos e futuros de soja para o mercado de milho, com a utilização dos modelos de correlação condicional dinâmica. Os resultados indicam tanto a influência da crise financeira global de 2008 na relação entre os preços desses grãos, como mudanças nos padrões de correlação condicional entre o milho e a soja, principalmente em períodos de adversidades climáticas. Por fim, os maiores patamares de correlação condicional ocorrem na relação entre os preços físicos desses produtos, demonstrando que os agentes utilizam o conteúdo informacional presente nos preços de commodities correlatas em sua avaliação de risco. No terceiro ensaio, o transbordamento de risco é avaliado em termos de mudanças nos preços relativos de milho e soja em seus mercados físicos domésticos e futuros internacionais. Para esse fim, utiliza-se o modelo markoviano para identificar as mudanças de regime na relação de preços entre essas commodities e seu efeito sobre a estratégia de hedge. Os resultados sugerem que o comportamento das razões de preços no mercado físico doméstico e no mercado futuro externo divergem a partir de 2012. As mudanças nos regimes de preço no mercado doméstico refletem com mais intensidade o comportamento sazonal das duas safras de milho cultivadas ao longo do ano, enquanto que no setor externo, estão mais associadas às adversidades climáticas. Em termos de estratégias de hegde, a B3 consegue captar melhor o rearranjo de preços no mercado doméstico, apresentando uma elevação da razão ótima de hegde no regime de baixa (preços de soja e milho estão mais próximos). Resultado similar é obtido na CME, quando a mudança de regime de preços ocorre na razão de preços futuros. Em síntese, os resultados desse estudo evidenciam que a gestão de risco de preços não se limita apenas aos fundamentos e características de um mercado específico. Destaca-se assim a importância de se identificar fatores exógenos, presentes ou identificáveis em commodities correlatas, aperfeiçoando a estratégia de gestão de risco de preços. / The expansion of corn in Brazil is due to the spatio-temporal change in production, which creates a new perspective analysis for the price relationship between corn and soybeans. This study aims to analyze the risk of spillover between corn and soybeans markets, through three independent but complementary essays. In the first essay, a literature review on the spread of risks is carried out, focusing on the agricultural market. As a research strategy, carried out a survey of published studies on the subjects - transmission, spillover and contagion - which are used interchangeably in the literature, and summarizing the recent developments regarding the risk propagation across markets. In the second essay, we intend to identify the contagion of prices of spot and futures soybean prices for the corn market, with the use of dynamic conditional correlation models. The results indicate both the influence of the global financial crisis of 2008 on the relationship between prices of these grains and changes in the conditional correlation patterns between corn and soybeans, especially in periods of climatic adversity. Finally, the highest levels of conditional correlation occur in the relationship between the spot prices of these products, demonstrating that in their risk assessment, the agents use the informational content present in the prices of related commodities. In the third essay, risk of spillover is assessed in terms of changes in relative prices of corn and soybeans in the spot and futures markets. For this purpose, the Markov model is used to identify the regime change in the price relationship between these commodities and their effect on the hedging strategy. The results suggest that, as of 2012, the behavior of the price ratios in the domestic spot market differs from the behavior of the price ratio in the external futures market. Changes in price regimes in the domestic market respond more intensely to seasonal behavior of the two corn crops grown throughout the year, while in the external market, they are more associated with climatic adversities. In terms of hedge strategies, the B3 commodity exchange can better capture the rearrangement of prices in the domestic market, presenting an elevation of the optimal hegde ratio in the low regime (soybean and corn prices are closer). A similar result is obtained in CME, when the change in price regime occurs in the ratio of future prices. In summary, the results of this study show that price risk management is not limited to the fundamentals and characteristics of a specific market. This highlights the importance of identifying exogenous factors present or identifiable in related commodities, improving the strategy of price risk management.

In the Arctic, shallow sea-floor communities have been documented to shift abruptly from an invertebrate-dominated state to a state with high macroalgal abundance. Climate warming, resulting in increased water temperatures and decreased sea ice cover, could trigger such regime shifts in benthic ecosystems, but the underlying mechanisms are not clear. To gain a better understanding, a mechanistic model of algal growth and interspecific competition was applied in two marine ecosystems in northwestern Svalbard. Unravelling the effects of light and temperature on the model parameters, the current study showed that light is a key factor determining the algal dominance in the two ecosystems. Changes in sea-ice cover, which alters the underwater light regime, is therefore considered the most likely trigger for invertebratealgae regime shifts. A continued prolonging of the ice-free season in the Arctic is likely to occur in the upcoming years, considering the current climatic development. Thus, it is expected that macroalgal cover in shallow rocky-bottom communities will continue to increase, altering species composition and function in seasonally ice-covered arctic ecosystems. / I ekosystem på grunda havsbottnar i Arktis har snabba, kraftiga förändringar i artsammansättning och ekosystemstruktur dokumenterats. Organismsamhällen som tidigare främst utgjorts av ryggradslösa organismer och hårda kalkalger har plötsligt blivit dominerade av olika tångarter. Den globala uppvärmningen medför högre ytvattentemperatur och minskat havsistäcke i Arktis, vilket i sin tur innebär förbättrade ljusförhållanden. Dessa förändringar tros kunna utlösa regimskiften där de ekosystemen övergår från ett stadium dominerat av ryggradslösa djur, till ett stadium dominerat av tång. Mekanismerna bakom sådana regimskiften är emellertid inte kartlagda. Denna studie syftade därför till en bättre förståelse för regimskiften i Arktiska havsbottenekosystem. En mekanistisk modell för algtillväxt och konkurrens tillämpades på två marina organismsamhällen i nordvästra Svalbard, som genomgått sådana regimskiften. Temperatur- och ljusberoendet hos modellens parametrar uppskattades först utifrån kunskap från ett antal tidigare studier. Med hjälp av modellen testades sedan hur fördelningen av alger påverkades av temperatur- och ljusförändringar. Modelleringen indikerade att ljusförhållanden var avgörande för expansionen av tång i de två studerade organismsamhällena på Svalbard, och att ljusförändringar således kan vara en huvudsaklig orsak till regimskiften i Arktis. Med tanke på den nuvarande klimatutvecklingen är en fortsatt förlängning av den isfria säsongen mycket sannolik. Detta kommer troligen innebära en vidare expansion av tång samt förändrad artsammansättning och ekosystemfunktion i grunda, arktiska havsbottenekosystem.

There is increasing concern about potential climate-driven regime shifts– large abrupt shifts in social-ecological systems that could have large impacts onecosystems services and human well-being. This paper aims to synthesize the potentialpathways for building resilience to such regime shifts. Ten examples from the RegimeShift Database provided the cases for analysis. Causal loop diagrams were used toanalyze feedback mechanisms at different scales and identify “leverage points” –places to intervene in the system in order to build resilience. Sixteen of these leveragepoints were identified, most of which relate to agricultural management. Mostfeedback mechanisms include at least one leverage point highlighting the potential forbuilding resilience to climate-induced regime shifts. The most common leverage pointsidentified in our analyses were vegetation cover, algae volume and atmospherictemperature. These leverage points were compared to mitigation strategies discussedby the IPCC. This comparison indicates that current climate change mitigationstrategies do not alter most of the leverage points directly. This suggests that IPCCstrategies should be broadened in order to reduce the risk of regime shifts, and theassociated impacts on human well-being.

The 2006 Swedish parliamentary election was a historic election with the largest bloc transfer of voters in Swedish history. The 2002-2006 incumbent Social Democratic Party (S) received its lowest voter support since 1914 as roughly 150,000, or 8%, of the 2002 S voters went to the main opposition, the conservative Moderate Party (M). This became the most decisive factor in ousting S from power after 12 years of rule. As a result, the M-led Alliance (A) with the People's Party (FP), the Center Party (C), and the Christian Democrats (KD) won the election. Natural Disasters and National Election makes the novel contribution of proposing two natural disasters, the Indian Ocean’s 2004 Boxing Day Tsunami and 2005 Storm Gudrun (Erwin), which struck only two weeks following the tsunami, as major events that impacted government popularity in the 2006 election and contributed to the redistribution of voter support, within and across party-blocs. The core findings from this thesis show that the S government’s poor crisis response to Gudrun, which is the hitherto most costly natural disaster in Swedish history, alone has an estimated effect of a magnitude that likely contributed to the 2006 historic regime shift, while the tsunami also seems to have mattered. The tsunami is particularly interesting, as S’s poor international crisis response to the event constitutes the first natural disaster situation to knowingly have affected an election on the other side of the planet. Moreover, to some degree voters recognized the active opposition by C as effective representation and rewarded the party for its strong stance on the poor handling of both events by S. In fact, the active voice of C concerning these disasters likely helped move the party from the periphery of party politics to becoming the third-largest party in Swedish politics. In sum, this research investigates accountability and effective party representation via retrospective voting, which is an essential mechanism for the legitimacy of democracy. Findings suggest that the average Swedish voter indeed may be voting retrospectively to hold publically elected officials accountable, which suggest a healthy status of the retrospective voting mechanism and Swedish democracy.

Submitted by Mariana Dornelles Vargas (marianadv) on 2015-03-19T15:37:37Z No. of bitstreams: 1 analise_importacao.pdf: 945712 bytes, checksum: 6101bf28275e0f55c9b783cb13f2a508 (MD5) / Made available in DSpace on 2015-03-19T15:37:37Z (GMT). No. of bitstreams: 1 analise_importacao.pdf: 945712 bytes, checksum: 6101bf28275e0f55c9b783cb13f2a508 (MD5) Previous issue date: 2011-03-30 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O presente trabalho procurou avaliar o comportamento da função de demanda brasileira por arroz pós-Mercosul e sua relação com a variação na renda, nos preços internos e externos, na indústria e política comercial brasileira. Para a análise, foi desenvolvido um modelo teórico, o qual fundamentou a especificação dos modelos econométricos para o arroz em casca e beneficiado. Considerou-se na investigação estatística dados históricos de janeiro de 1995 a junho de 2010, tendo como objetivo geral testar a adequação de modelos lineares e não-lineares que representem as relações de curto e longo prazo das variáveis de comércio exterior brasileiro do setor. Além disso, pretende-se datar a cronologia dos ciclos das importações de arroz e verificar a relação desses com as idiossincrasias da condução das políticas econômicas, bem como com eventos climáticos. As elasticidades encontradas apresentaram sinais coerentes com o modelo econômico definido em sua maioria. Os resultados obtidos permitiram interpretar a dinâmica do mercado importador de arroz no Brasil. Em geral, os impactos de longo prazo da renda e preço doméstico foram os principais determinantes das importações e ressalta-se o comportamento de bem inferior de ambos os tipos de arroz nas equações trimestrais. Já o preço de importação contribui menos que proporcionalmente, ao passo que o importador parece ajustar a quantidade importada do período com certo grau de defasagem. Já a indústria, tendo como base dados trimestrais, manteve uma relação contra-cíclica com as importações de ambos os tipos de arroz, embora não tenha se mostrado significativa para a maioria dos modelos. A dinâmica de correção do modelo a choques no longo prazo foi atenuada nas estimativas não-lineares mensais, enquanto permaneceu praticamente estável nas estimativas trimestrais. Ainda, conforme os resultados é possível afirmar que os ciclos de expansão das importações de arroz beneficiado durante o período foram, em média, mais longos que as retrações. Finalmente, pode-se entender que os ciclos de importação se mostraram fortemente relacionados a eventos climáticos adversos e à alterações da política comercial. / This study tried to investigate the behavior of Brazilian demand for post-Mercosur rice and its relation with variation in income, in domestic and foreign prices, in industry and in Brazil?s trade policy. For the analysis, a theoretical model was developed, which based the specification of econometric models for rough and milled rice. The statistical investigation considered historical data from January 1995 through June 2010, aiming mainly to test the adequacy of linear and nonlinear relations that represent short and long-term variables of the Brazilian foreign trade in the sector. Furthermore, there is the goal of setting the chronology of the cycles of rice imports and verifying their relationship with idiosyncrasies of the conduct of economic policies, as well as of weather events. The elasticities estimated showed signs consistent with the economic model set in their majority. The results achieved allowed the interpretation of the rice import market dynamics in Brazil. In general, long-term impacts from income and domestic prices were the main determinants of imports; it should be pointed out the much lower behavior of both types of rice in quarterly equations. The price of imports contributes less than proportionately, while the importer seems to adjust the quantity imported in the period with some lag. The industry, based on quarterly data, sustained its counter-cyclical relation with the imports of both types of rice, although it has been not proved significant for most models. The correction dynamic of the model to long-term shocks was eased in monthly non-linear equations, while it remained nearly stable in quarterly estimates. Besides, still according to results, it is possible to say that expansion cycles of imports of milled rice are on average longer than the contractions. Finally, one can understand that import cycles were strongly related to adverse climatic events, as well as to alterations in trade policy.

<p>Seagrasses constitute the basis for diverse and productive ecosystems worldwide. In East Africa, they provide important ecosystem services (e.g. fisheries) but are potentially threatened by increasing resource use and lack of enforced management regulations. The major aim of this PhD thesis was to investigate effects of anthropogenic distur-bances, primarily seaweed farming and coastal fishery, in East African seagrass beds. Seaweed farming, often depicted as a sustainable form of aquaculture, had short- and long-term effects on seagrass growth and abundance that cascaded up through the food web to the level of fishery catches. The coastal fishery, a major subsistence activity in the region, can by removing urchin predators indirectly increase densities of the sea urchin <i>Tripneustes gratilla</i>, which has overgrazed seagrasses in several areas. A study using simulated grazing showed that high magnitude leaf removal – typical of grazing urchins – affected seagrasses more than low magnitude removal, typical of fish grazing. Different responses in two co-occurring seagrass species furthermore indicate that high seagrass diversity in tropical seagrass beds could buffer overgrazing effects in the long run. Finally, a literature synthesis suggests that anthropogenic disturbances could drive shifts in seagrass ecosystems to an array of alternative regimes dominated by other or-ganisms (macroalgae, bivalves, burrowing shrimp, polychaetes, etc.). The formation of novel feedback mechanisms makes these regimes resilient to disturbances like seagrass recovery and transplantation projects. Overall, this suggests that resource use activities linked to seagrasses can have large-scale implications if the scale exceeds critical levels. This emphasizes the need for holistic and adaptive management at the seascape level, specifically involving improved techniques for seaweed farming and fisheries, protection of keystone species, and ecosystem-based management approaches.</p>