Fundação de Amparo a Pesquisa no Estado do Rio Grande do Sul / Extreme climatic events have been occurring with greater intensity and/or frequency over South America. Indicatives for these alterations encompass natural climate variability, land use (deforestation and urbanization), global warming, and increase of greenhouse gases and aerosols in the atmosphere. South America receives a great input of moisture from the Amazon rainforest, as well as a 37% contribution from the Atlantic Ocean. Considering the whole planet, some atmospheric events need to be analyzed when regarding moisture input towards a continent. Ocean circulation can interfere for example in sea surface temperature (SST), either influencing or not the input of moisture to the continent. The objective of the present study was to analyze the variability of atmospheric moisture in South America and its extreme values, as well as the relationships with the sea surface temperature of the adjacent oceans. The present study made use of ECMWF data, ERA-INTERIM reanalysis (pressure at sea level and surface pressure, evaporation, air and dew point temperatures at 2 meters, and zonal and meridional wind at 10 meters) and also sea surface temperature data from the MetOffice Hadley Centre (HADISST). The analysis period of the present study was between 1980 and 2009, encompassing a period of 30 years of data. First, climatology, trends and extremes of moisture and evaporation (frequency, intensity and reoccurrence of events) were calculated. These were followed by lagged compositions to assess the role of sea surface temperature anomalies during extreme moisture and evaporation events. The main results found were regarding an increase of the pressure at sea level gradient and SST in the southwestern Atlantic, increase evaporation in the eastern and northern coasts of South America, and its decrease in the center-southern region of the continent. Moreover, the center-southern region also demonstrated a decrease of dew point temperature and specific moisture, and an increase in the difference between air temperature and dew point temperature. Decrease in the moisture flow magnitude and intensification of dry events over the center-southern region of South America were also observed. Finally, results showed that an SST anomaly cycle during an extreme event in the continent lasted approximately five months and, at least one month prior to the event, signs of this SST anomaly were already observable. In summary, the most significant moisture alterations in South America were found in the center-southern sector of the continent and over the southwestern Atlantic Ocean, near the Brazil-Malvinas Confluence (BMC). Nevertheless, more studies are needed to understand the relationships between SST at the BMC and moisture extremes, particularly in the center-southern portion of South America. / Atualmente os eventos climáticos extremos têm ocorrido com maior intensidade e/ou frequência sobre a América do Sul. Os indicativos para essas alterações circundam a variabilidade natural do clima, uso da terra (desmatamento e urbanização), aquecimento global, aumento da concentração de gases do efeito estufa e aerossóis na atmosfera. A América do Sul recebe um grande aporte de umidade pela existência da floresta Amazônica em seu território e também cerca de 37% de contribuição oriunda do Oceano Atlântico. Considerando todo o globo terrestre, alguns dos eventos atmosféricos precisam ser analisados com relação ao aporte de umidade sobre o continente. Com relação ao oceano, a circulação dos oceanos podem interferir, por exemplo, na temperatura da superfície do mar (TSM), influenciando ou não no aporte de umidade para o continente. O objetivo do presente trabalho foi analisar a variabilidade da umidade atmosférica na América do Sul e de seus valores extremos e as relações com a temperatura da superfície do mar nos oceanos adjacentes. O presente trabalho utilizou dados do ECMWF, da reanálise do ERA-INTERIM (pressão ao nível do mar e pressão em superfície, evaporação, temperatura do ar e temperatura do ponto de orvalho a 2 metros e vento zonal e meridional a 10 metros) e também dados de temperatura da superfície do mar do MetOffice Hadley Centre (HADISST). O período de análise do presente trabalho foi de 1980 a 2009, compreendendo um período de 30 anos de dados. Primeiramente foram calculadas as climatologias, as tendências e os extremos de umidade e evaporação (frequência, intensidade e recorrência dos eventos). Posteriormente, foram realizadas as composições defasadas para verificar o papel das anomalias da temperatura da superfície do mar durante os eventos extremos de umidade e evaporação. Os principais resultados encontrados foram em relação a um aumento da pressão ao nível do mar e da TSM no Atlântico sudoeste, aumento também da evaporação na costa leste e norte da América do Sul, e sua diminuição na região centro-sul do continente. Além disso, a região centro-sul também demonstrou uma diminuição da temperatura do ponto de orvalho e da umidade específica, e um aumento na diferença entre a temperatura do ar e a temperatura do ponto de orvalho. Diminuição da magnitude do fluxo de umidade e intensificação de eventos extremos secos sobre a região centro-sul da América do Sul também foram observados. E por fim, os resultados mostraram que um ciclo de anomalia de TSM durante um evento extremo no continente durou aproximadamente cinco meses e, pelo menos um mês antes do evento, sinais da anomalia de TSM já era observada. Em suma, as alterações mais significativas na umidade sobre a América do Sul foram encontradas no setor centro-sul do continente e sobre o Oceano Atlântico sudoeste, próximo a Confluência Brasil-Malvinas (CBM).

Ces travaux de thèse s'intéressent à la variabilité océanique intrinsèque générée spontanément sous forçage atmosphérique saisonnier dans des simulations océaniques à haute-résolution (1/4 de degré et 1/12 de degré ), en présence de tourbillons de méso-échelle (environ 100 km). L'empreinte de la variabilité intrinsèque sur le niveau de la mer (SLA) et sur la température de surface (SST) est caractérisée dans plusieurs gammes d'échelles spatio-temporelles par des méthodes de filtrage. En particulier, il est montré que la variabilité petite-échelle inter-annuelle à décennale de SLA observée par les satellites altimétriques, a un caractère stochastique et est majoritairement intrinsèque. Aux échelles de temps multi-décennales, la variabilité intrinsèque de SLA dans les régions océaniques turbulentes est d'amplitude comparable à la variabilité interne simulée dans les modèles climatiques couplés (dénués de turbulence océanique), et pourrait constituer une source additionnelle d'incertitudes dans la détection de l'élévation régionale du niveau de la mer d'origine anthropique. Une analyse spectrale montre enfin que l'advection non-linéaire de vorticité relative transfère spontanément de l'énergie cinétique d'ondes frontales hautes-fréquences vers des tourbillons de méso-échelle plus lents, générant in fine de la variabilité intrinsèque basse-fréquence. Les diagnostiques ont été réalisés à l'aide d'outils développés pour traiter de façon optimale les données océaniques haute-résolution. Ces travaux témoignent plus généralement du caractère chaotique de l'océan turbulent, dont l'interaction avec l'atmosphère est encore mal comprise. / This work focuses on the intrinsic oceanic variability spontaneously generated under seasonal atmospheric forcing in high-resolution oceanic simulations (1/4 ? and 1/12 ? ) including mesoscale eddies (~ 100 km). The imprint of intrinsic variability on sea-level (SLA) and sea surface temperature (SST) is characterized in various spatio-temporal ranges using filtering methods. In particular, the small-scale interannual-to-decadal SLA variability observed by satellite altimetry, is stochastic and mostly intrinsic. At multi-decadal timescales, SLA intrinsic variability is comparable to the internal climate variability simulated in climate coupled models (devoid of oceanic turbulence), and may yield additional uncertainties in the detection of human-induced regional sea-level change. A spectral analysis eventually shows that non-linear advection of relative vorticity spontaneously transfers kinetic energy from high-frequency frontal waves to slower mesoscale eddies, ultimately generating low-frequency intrinsic variability. The analyses have been performed using tools developed for optimal processing of high-resolution oceanic dataset. This work generally provides evidence of the chaotic behavior of the turbulent ocean, whose interaction with the atmosphere is still poorly-known.

Philosophiae Doctor - PhD / The Table Mountain Group (TMG) Formation is the lowest member of the Cape Supergroup which consists of sediments deposited from early Ordovician to early Carboniferous times, approximately between 500 and 340 million years ago. The Table Mountain Group (TMG) aquifer system is exposed along the west and south coasts of South Africa. It is a regional fractured rock aquifer that has become a major source of bulk water supply to meet the agricultural and urban water requirements of the Western and Eastern Cape Provinces of South Africa. The TMG aquifer system comprises of an approximately 4000 m thick sequence of quartz arenite and minor shale layers deposited in a shallow, but extensive, predominantly eastwest striking asin, changing to a northwest orientation at the west coast. The medium to coarse grain size and relative purity of some of the quartz arenites, together with their well indurated nature and fracturing due to folding and faulting in the fold belt, enhance both the quality of the groundwater and its exploitation potential for agricultural and domestic water supply purposes and its hot springs for recreation. The region is also home to some unique and indigenous floral species (fynbos) of worldwide importance. These and other groundwater dependent vegetation are found on the series of mountains, mountain slopes and valleys in the Cape Peninsula. The hydrogeology of the TMG consists of intermontane and coastal domains which have different properties but are interconnected. The former is characterized by direct recharge from rain and snow melt, deep groundwater circulation with hot springs and low conductivity groundwater. The coastal domain is characterized by shallow groundwater occurrence usually with moderate to poor quality, indirect recharge from rainfall of shallow circulation and where springs occur they are usually cold. The sustainable utilization of the TMG aquifer addressed the issues of the groundwater flow dynamics, recharge and discharge to and from the aquifer; challenges of climate change and climate variability and their potential impact on the aquifer system. The concept of safe yield, recharge and the capture principle and the integration of sustainable yield provided the basis for sustainable utilization with the adaptive management approach. Methodology used included the evaluation of recharge methods and estimates in the TMG aquifer and a GIS based water balance recharge estimation. The evaluation of natural discharges and artificial abstractions from the TMG aquifer system as well as its potential for future development. The Mann-Kendal trend analysis was used to test historical and present records of temperature and rainfall for significant trends as indication for climate variability and change. The determination of variability index of rainfall and standard precipitation index were additional analyses to investigate variability. The use of a case study from the Klein (Little) Karoo Rural Water Supply Scheme (KKRWSS) within the TMG study area was a test case to assess the sustainable utilization of TMG aquifers. Results show that recharge varies in time and space between 1% and 55% of MAP as a result of different hydrostratigraphic units of the TMG based on geology, hydrology, climate, soil, vegetation and landuse patterns however, the average recharge is from 1% to 5% of MAP. The TMG receives recharge mainly through its 37,000 km2 of outcrop largely exposed on mountainous terrain. Natural discharges from the TMG include 11 thermal and numerous cold spring discharges, baseflow to streams and reservoirs, and seepage to the ocean. Results from this study also show increasing temperature trend over the years while rainfall trend generally remain unchanged in the study area. Rainfall variability persists hence the potential for floodsand droughts in the region remain. Global and Regional Models predict about 10% to 25% reduction in rainfall and increase in variability in future. Impacts of his change in climate will affect the different types of aquifers in various ways. Increase in temperature and reduction in rainfall will increase evapotranspiration, reduce surface flows and eventually reduce shallow aquifer resources. Coastal aquifers risk upsurge in salinisation from sea level rise and increase in abstractions from dwindling surface water resources. While floods increase the risk of contamination to shallow aquifers droughts put pressure on all aquifers especially deep aquifers which are considered to be more reliable due to the fact that they are far removed from surface conditions. Future population growth and increase in freshwater demand will put more pressure on groundwater. Recharge to groundwater have been over-estimated in certain areas in the past leading to high abstraction rates from boreholes causing extensive groundwater storage depletion evident by high decline in groundwater levels in these areas and hampering sustainable management of the aquifer resources. Over-abstraction have resulted in loss of stream flow and baseflow reduction to streams during summer, complete loss of springs and reduction of flow to others. Flow to wetlands, riparian vegetation, and sometimes loss and shifts in dependent ecosystems have also resulted from over-abstraction. Sustainability has spatial and temporal implications due to changing climate and demand. The study recommends adaptive management practices in which several factors are considered in managing groundwater together with surface water resources in order to maintain ecological and environmental integrity. The KKRWSS and other groundwater supply schemes in the Western and Eastern Cape Provinces demonstrate the huge potential of the TMG to provide freshwatersupply for domestic and irrigation water needs however, the huge decline in groundwater levels due to over-abstraction in the KKRWSS and other groundwater schemes underscores the need for sustainable utilization of the TMG groundwater resources for present and future generations with minimal impacts on the quality, dependent hydrological and ecosystems as well as the environment. / South Africa

Assessing the impact of climate variability on water resources is one of the difficult tasks in planning the future growth of North-Central Texas. This study defined twelve extreme climate scenarios. Data from each scenario was input to a hydrological model (HEC-HMS) to calculate watershed runoff to Lake Ray Roberts. Model parameters are determined using Geographic Information System (GIS). The water balance was calculated for current and future water demand and resulting change in the volume and level of this reservoir. The results indicate certain climate scenarios decrease in volume. Thus, local governments should plan alternative water management strategies during droughts.

No description available.

MENVSC (Geography) / Department of Geography and Geo-Information Sciences / Climate variability and change directly affect agricultural production. This is because the agricultural sector is inherently sensitive to climatic conditions and is one of the most vulnerable sectors to risks and impact of global climate change. The aim of this study was to determine maize producer's vulnerability and assess the impact of climate variability and change on maize production in the Makhuduthamaga Local Municipality, of Limpopo Province, South Africa. Climatic and maize yields data utilized in the study are for the period 1985 - 2015). Interviews were also conducted with the producers and various officials from government and non-governmental sectors. The results illustrate significant rainfall and temperature variations both spatially and temporally. The variations observed in the average rainfall and rain days for the period under consideration were not related to the variation in yield of maize for the same period. The regression results revealed low R² values, indicating a weak relationship between maize yields, rain days and rainfall. Furthermore, the results revealed a significant positive relationship between annual rainfall and temperature (r²<0.05 and P<0.05) but not a significant relationship with maize yields. The results of the qualitative data showed that the producers’ perception of the occurrence of climate variability was high, as 65.7% of the respondents indicated that the state of climate is increasingly variable. About 61.5% of the producers implemented or adopted an adaptation strategy to cope with the perceived climate variability and change. Age, gender and access to extension services were determined as important factors that determine the adoption of adaptation strategies. The vulnerability assessment revealed that producers were highly vulnerable to changing climate; this exposes producers to the risks of crop failure, loss of income and food insecurity. The study recommended (a) intervention and adaptation strategies that target mitigation of decreased rainfall impacts (b) increased access to extension service (c) empirical research around the impacts of climate change to increase producers’ level of awareness. / NRF

Piura ha sido una de las regiones más afectadas por inundaciones a causa de los eventos de lluvias extremas. En los años de 1982-1983,1998 y 2017 se registraron innumerables pérdidas en infraestructura como consecuencias del fenómeno de "El Niño”, siendo este último producto del incremento inusual de la temperatura superficial del mar (TSM). El análisis de la asociación entre las anomalías de temperatura superficial del mar (ATSM) y las precipitaciones máximas (PPmáx) que ocurrieron en la zona norte del Perú (Región Piura) tiene como fin describir el comportamiento de ATSM en relación con las lluvias de gran escala. Para esto se utilizaron correlaciones cruzadas con aplicación de desfases temporales a fin de encontrar la intensidad en la que se asocian dichos parámetros. Para las PPmáx se extrajeron datos del producto grillado Piscop, el cual usa como base de información y calibración los registros de las estaciones meteorológicas. En tanto que, para las ATSM se extrajeron datos de ERA5-ECMWF calibrado mediante estaciones oceanográficas. Del análisis se observó que las precipitaciones máximas que se registran en la región Piura presentan mayor asociación y significancia menor o igual a 5% cuando se aplican desplazamientos temporales a las ATSM, de 1 mes para puntos ubicados en las regiones NIÑO 1 y NIÑO 2, y de 2 meses para puntos ubicados en las regiones NIÑO 3 y NIÑO 4. Finalmente, la mayor asociación se origina entre las variaciones inusuales de TSM producidas en el punto 3.3 y las PPmáx con desplazamientos temporales de 3 meses. / Piura has been one of the most affected regions by floods due to extreme rain events. In the years of 1982-1983, 1998, and 2017 innumerable losses in infrastructure were registered as a consequence of the "El Niño" effect, the latter being considered as a product of the unusual increase in sea surface temperature. Analysis of the association between sea surface temperature anomalies (SSTA) and extreme rainfall (ER) which occurred in the north of Peru (Piura región) to describe the behavior of SSTA in relation to large-scale rainfalls. For this, cross-correlations with the application of time lags were used in order to find the intensity in which SSTA and ER are associated. For ER, data were extracted from the Piscop grilled product, which is based on information and calibration of records of meteorological stations. While data for the SSTA was extracted from ERA5-ECMWF calibrated by oceanographic stations. From the analysis was observed that maximum precipitations that are recorded in the Piura region present a greater association and significance less than or equal to 5% when time-lag are applied to SSTA, for 1 month for points ubicated in the regions NIÑO 1 and NIÑO 2, and for 2 months points ubicated in the regions NIÑO 3 and NIÑO 4. Finally, the greatest association originates between the unusual variation of SST produced in the 3.3 SSTA point and the ER whit time-lag of 3 months. / Trabajo de investigación

This thesis contributes to research on climate change and violent conflict by testing the theory of a causal relationship between climate variability, agricultural production and political violence in the case of Vietnam 2010-2019. Climate-related negative shocks to agricultural production in developing countries are expected to lower the opportunity cost of violence through an income effect. This increases the risk of violent conflict. The thesis draws on a framework that combines climate-conflict research, civil war theory and research on how climactic factors affect rice cultivation in Southeast Asia. It tests the hypotheses emerging from the framework using mixed-effect models and a counterfactual comparison. Minimum temperature increases in the growing season for rice have been found to decrease rice yields, while maximum temperature increases have a positive effect on yield.The results show that minimum temperature increases are averse to Vietnamese rice production and have a positive relationship with political violence in the following year. Maximum temperature however is not significantly related to either rice production or violence. These results are in line with the hypotheses drawn from the framework. The minimum temperature effect on political violence is small compared to some of the covariates but robust to several different model specifications. The results provide evidence of a climate-conflict link through agricultural production in contemporary Vietnam which is similar to the findings in existing case studies in Southeast Asia. However, more research will be needed to decisively identify the causal mechanism and the specifics of how it works. / <p>The seminar was held digitally. </p>

This dissertation presents the results of an investigation of rural households’ ability to adapt to changing environmental and climatic conditions. It presents soil degradation arising from worsening soil erosion, leaching, depletion of nutrients due to years of uninterrupted cultivation and low levels of use of fertilizers; uncontrolled deforestation leading to loss of biodiversity; and climate variability seen through longer dry seasons as well as delayed and falling levels of precipitation as key issues leading to the vulnerability of households in Kakemega District in Western Province of Kenya. An enquiry has been made into the adaptation strategies of the rural households and a composite household adaptive capacity index (HACI) developed which is then used in hypothesis testing. Despite a situation laden with serious soil degradation and fears that credit taken by rural households often end up in low-return necessity-based enterprises or in consumption expenditure, the dissertation shows that the use of credit positively contributes to the HACI as does regular and optimal use of farm inputs. Diversification into non-agricultural activities, on-farm planting of trees and migration with remittances were some of the adaptation strategies observed among households with relatively high adaptive capacity indices while a secondary school level of education alongside the possession of non-land and non-livestock assets were key factors clearly associated with high adaptive capacity indices. Regarding adaptation decision making, the household head was observed to be the single most important actor in a process which was often characterized by authoritarianism. The household head’s level of information or awareness of environmental changes and open options proved to be important for adaptation. It was revealed that membership to groups and networks as well as government and NGO-activities were the most important factors in informing the household heads. Given small land sizes and a high incidence of other negative shocks, household heads tended to adopt and implement only tried and tested adaptation actions. During the study behind this dissertation, pioneers in the implementation of new strategies were observed to be better informed household heads or beneficiaries of incentives from the promoters of such strategies. Newer efforts aimed at the promotion of adaptability would therefore gain wider acceptance and adoption if preceded by a pilot phase carefully designed to include committed opinion shapers who would provide a demonstration effect.:Acknowledgment......................................................................................i Dedication................................................................................................ii Summary.................................................................................................iii Zusammenfassung (summary in the German language).........................iv List of Tables....................................................................................................vii List of Figures.........................................................................................ix List of Abbreviations...............................................................................xi 1.0 Introduction: Structure and Objectives.............................................1 1.1 Background.................................................................................5 1.2 Problem Statement.....................................................................7 1.3 Theoretical and Methodological Contribution..............................8 1.4 Objectives...................................................................................9 1.5 Research Questions..................................................................10 1.6 Hypothesis................................................................................10 1.7 Scope and Limitations of the Study...........................................11 1.8 Structure of the Dissertation.....................................................12 2.0 Environmental and Climate Change................................................13 2.1 Climate Change.........................................................................13 2.2 Environmental Changes............................................................15 2.3 Vulnerability..............................................................................22 2.4 Adaptation and Coping Strategies............................................32 2.5 Household Adaptability.............................................................40 3.0 Study Design and Setting................................................................57 3.1 Study Area................................................................................76 3.2 Sampling and Data Collection....................................................85 4.0 Rural Households and their Environment........................................87 4.1 General Descriptive Statistics....................................................87 4.2 Observed Vulnerability Causes and Coping Strategies.............92 4.3 Role of the Government............................................................98 5.0 Rural Household Adaptive Capacity...............................................101 5.1 HACI without External Sub-index................ ............................101 5.2 HACI including External Sub-index..........................................167 5.3 Hypothesis Testing..................................................................171 5.4 Towards Enhanced Adaptability: Factors and Strategies........180 6.0 Conclusion and Recommendations................................................185 7.0 Appendix.......................................................................................197 / In dieser Dissertation wurden ländliche Haushalte bezüglich ihrer Anpassungsfähigkeit an den Umwelt- und Klimawandel untersucht. Desweiteren geht die Dissertation unter anderen der Frage über Strategien nach, die von ländlichen Haushalten angesichts der Auswirkungen von Umweltproblemen eingesetzt werden. Die Feldforschung wurde unter den Haushalten im Kakamega Distrikt in Kenia getätigt. Eine Abnahme der Bodenproduktivität ist durch Erosion, einem Auslaugen und einer ununterbrochenen Kultivierung in Kakamega entstanden. Desweiteren führt eine unkontrollierte Abholzung mit resultierendem Verlust von heimischer Flora und Fauna sowie längeren Trockenperioden mit verspätetem Einsatz von Regenfällen und einer damit verbundenen Niederschlagsminimierung zu einer schwierigen Lebenssituation für die ländlichen Haushalte, die hauptsächlich durch Landwirtschaft ihre Existenz sichern. Diese Situation (gekennzeichnet durch Abholzung, Verlust der Artenvielfalt, Verminderung der Bodenqualität und unregelmäßige und wechselhafte Niederschlag) wird in dieser Arbeit als Umweltwandel (Environmental Change oder Environmental Stress) bezeichnet. Es konnte unter anderem als eines der Ergebnisse der Arbeit festgestellt werden, dass die ländlichen Haushalte aufgrund schlechten Bodens, unkontrollierten Abholzungen, längeren Trockenzeiten und sinkenden Niederschlagsmengen sehr anfällig sind. Durch den Einsatz des zusammengesetzten Haushalt-Anpassungsfähigkeitsindex (Household Adaptive Capacity Index = HACI), der im Rahmen dieser Dissertation entwickelt wurde, konnten die Bedenken gemindert werden, dass Kredite, die an ärmeren ländlichen Haushalten vergeben werden, oft für Notgründungen und Konsumausgaben eingesetzt werden. Es hat sich herauskristallisiert, dass die optimale und regelmäßige Nutzung von Düngemitteln sowie der Einsatz von Krediten, die HACI positiv beeinflusst. Als weitere Ergebnisse konnte beobachtet werden, dass Haushalte mit höheren Anpassungsfähigkeitsindexen Anpassungstrategien wie Diversifizierung in nicht-agra Aktivitäten, Aufforstung und Migration verwenden, und, dass ein Sekundarschulabschluss und der Besitz von Wirtschaftsgütern mit hohen Haushalt-Anpassungsfähigkeitsindexen assoziiert sind. Zum Anpassungsentscheidungspozess konnte festgestellt werden, dass Haushaltoberhäupter, die wichtigste Akteure sind. Entscheidungsweisen dieser Haushaltoberhäupten lassen oftmals autoritäre Züge erkennen. So entscheiden die Haushaltoberhäupter häufig auch, in welcher Art und Weise Haushalte sich anpassen dürfen. Von daher ist das Wissen des Haushaltoberhauptes über die herrschenden Umweltbedingungen und die offenen Strategien oder Handlungspielräume von Bedeutung. Die Feldforschung zeigte, dass die Zugehörigkeit zu einzelnen Gruppen sowie die Bemühungen von der Regierung und den Nichtregierungsorganisationen wichtig für die Erhöhung des Wissens von Haushaltoberhäupten sind. Da der durchschnittliche Haushaltgrundstückbesitz sinkt und andere negative Ereignisse wie Krankheit und Tod zunehmend Angst verbreiten, setzen Haushaltsoberhäupter häufig nur dann empfohlene Strategien zur Anpassung ein, wenn sie beispielsweise einen Erfolg bei einem Nachbar verzeichnen können. Oftmals werden Anpassungsstrategien auch bei finanziellen Anreizen, zum Beispiel von Förderern, umgesetzt. Es würden mit hoher Wahrscheinlichkeit mehr Anpassungstrategien von ländlichen Haushalten umgesetzt werden, wenn diese Strategien Pilotprojekte beinhalten würden, die Haushalten das Zusammenspiel von Anpassung und Ernteertrag präsentieren.:Acknowledgment......................................................................................i Dedication................................................................................................ii Summary.................................................................................................iii Zusammenfassung (summary in the German language).........................iv List of Tables....................................................................................................vii List of Figures.........................................................................................ix List of Abbreviations...............................................................................xi 1.0 Introduction: Structure and Objectives.............................................1 1.1 Background.................................................................................5 1.2 Problem Statement.....................................................................7 1.3 Theoretical and Methodological Contribution..............................8 1.4 Objectives...................................................................................9 1.5 Research Questions..................................................................10 1.6 Hypothesis................................................................................10 1.7 Scope and Limitations of the Study...........................................11 1.8 Structure of the Dissertation.....................................................12 2.0 Environmental and Climate Change................................................13 2.1 Climate Change.........................................................................13 2.2 Environmental Changes............................................................15 2.3 Vulnerability..............................................................................22 2.4 Adaptation and Coping Strategies............................................32 2.5 Household Adaptability.............................................................40 3.0 Study Design and Setting................................................................57 3.1 Study Area................................................................................76 3.2 Sampling and Data Collection....................................................85 4.0 Rural Households and their Environment........................................87 4.1 General Descriptive Statistics....................................................87 4.2 Observed Vulnerability Causes and Coping Strategies.............92 4.3 Role of the Government............................................................98 5.0 Rural Household Adaptive Capacity...............................................101 5.1 HACI without External Sub-index................ ............................101 5.2 HACI including External Sub-index..........................................167 5.3 Hypothesis Testing..................................................................171 5.4 Towards Enhanced Adaptability: Factors and Strategies........180 6.0 Conclusion and Recommendations................................................185 7.0 Appendix.......................................................................................197

La variabilité du système climatique influence la productivité et la distribution des espèces marines sur toutes les échelles de temps, de la variabilité saisonnière et inter-annuelle aux cycles glaciaires-interglaciaires. Mais ces liens entre climat et écosystèmes marins sont encore largement méconnus, de telle sorte que les prévisions des changements à venir sont difficiles. De plus, parce que les indicateurs paléoclimatiques issus des archives marines sont souvent liés au fonctionnement de l’écosystème, cette méconnaissance limite la fiabilité de la reconstruction de la variabilité climatique passée.Ce travail de thèse vise à améliorer notre connaissance de ces liens entre climat et écosystèmes marins : nous nous sommes intéressés aux changements de productivité marine au cours du dernier cycle glaciaire-interglaciaire, et nous nous sommes aussi penchés sur la réponse de l’écosystème, incluant l'ensemble des niveaux de la chaine trophique, à la variabilité inter-annuelle à décennale en climat pré-industriel. Ce travail est basé sur l’utilisation d’un modèle climatique (IPSL-CM), d’un modèle de biogéochimie marine (PISCES) et d’un modèle de niveaux trophiques supérieurs (APECOSM).Dans un premier temps, nous montrons que le lien entre l’intensité de la mousson indienne et la productivité primaire marine, en été boréal dans la mer d’Arabie, n’est pas direct. En effet, il apparait indispensable pour comprendre les changements de productivité de considérer, en plus de l'intensité de la mousson, la structure de la mousson. En particulier, la position du Jet de Findlater par rapport à la côte de la péninsule arabique est un paramètre important puisqu'elle conditionne la dynamique d'Ekman dans la région.Dans un second temps, nous avons étudié les variations de la productivité marine au large de l'embouchure du fleuve Congo et leurs liens avec le fleuve et les changements de dynamique atmosphérique africaine. Ce travail a mis en évidence que la relation entre l'intensité de la mousson et l'intensité des alizés, souvent utilisée dans les reconstructions climatiques, n'est pas toujours vérifiée. Selon le climat étudié, l'importance des effets thermiques ou dynamiques sur les changements de précipitations et de vents simulés est différente.Dans un troisième temps, nous avons étudié l'effet de la variabilité inter-annuelle sur les changements de productivité passés et sur le signal climatique potentiellement enregistré par des indicateurs climatiques biologiques.Enfin, la dernière partie de cette thèse se focalise sur la réponse des organismes marins des haut-niveaux trophiques à la variabilité climatique à différentes fréquences. Ce travail a révélé que les organismes marins répondent de façons différentes aux variations environnementales en fonction de leur taille et de leur habitat. / Climate variability influences marine primary productivity and marine species distribution over all timescales, from seasonal to interannual variability and glacial-interglacial cycles. The links between climate and marine ecosystems are still sparsely known so that the predictions of futur changes are difficult. Moreover, because paleoclimate recorders extracted from marine archives are often linked to the functionning of the ecosystem, this lack of knowledge limits our ability to reconstruct past climate variability.This thesis work aims at improving our knowledge of these links between climate and marine ecosystems : we have looked into marine productivity changes during the last glacial-interglacial cycle, but we also examined the "end-to-end" ecosystem response to inter-annual to decadal variability in a pre-industrial climate. This work uses a climate model (IPSL-CM), a bio-geochemical model (PISCES) and a model of high trophic levels (APECOSM).First, we show that the link between Indian summer monsoon intensity and marine primary productivity in the Arabian Sea is indirect. Indeed, it appears necessary to consider the monsoon pattern, such as the Findlater Jet position, which drives the Ekman dynamics in the region, as well as its intensity to understand the productivity changes.Second, we study the marine productivity changes off the Congo river mouth and their links with the river runoff and the African atmospheric dynamics. This work shows that the relationship between monsoon intensity and trade winds intensity, often used to reconstruct past changes, is not always verified. Depending on the climate, thermal or dynamical effects are more or less prominent drivers of the simulated changes in precipitation and winds. Productivity off the Congo river mouth, which is mainly located in the subsurface, seems more affected by the ocean and atmosphere dynamics than by the river supply in nutrients.Third, we study the inter-annual variability effects over past productivity changes and over the climatic signal potentially recorded in the biological climate proxies.Finally, the last part of the thesis focuses on high trophic levels marine organisms response to climate variability at different frequencies. This study shows that marine organisms response to environmental changes varies with the organism' size and habitat.