Tesi sul tema "Climate Response Change"

Climate change associated with increasing concentrations of the greenhouse gas, carbon dioxide(CO2), is expected to lead to an increase in global mean temperature of between 1 and 3.5 deg C by the end of the 21st century, with regional changes in rainfall and humidity. This thesis is concerned with modelling the effects of a changing climate and atmospheric C02 concentration on global vegetation. The process-based model, DOLY (Dynamic glObal phtogeographY), is used. It is able to operate using three climate variables, two soil variables and an atmospheric CO2 concentration. Its outputs are leaf area index (LAI), and net primary productivity (NPP). The LAI and NPP values predicted by DOLY were used to run a life-form model with a climate change scenario. It was found that warming led to the spread of trees into the tundra region. The DOLY model was also coupled with the Hadley Centre general circulation model to determine the feedbacks of vegetation on climate. With a global warming of 2◦C, the global feedback of vegetation on temperature was a decrease of 0.1 deg C. However at the regional scale the feedback was +/-2 ◦C, of similar magnitude to the driving temperature change. Finally, the DOLY model was run with transient climate data from the Hadley Centre. The boreal forest moved north, and the Gobi desert and the southern steppes in the former Soviet Union shrank in area. The sensitivity of the model to its soil and climate inputs have also been analysed over a range of environments and the model has been validated with reference to satellite data and experimental data. It was found to perform well. This thesis has shown that it is possible to predict current and possible future distributions of vegetation with climate change using a vegetation model.

80% of Volatile Organic Compounds (VOCs) that are emitted every year to the atmosphere come from biogenic sources (BVOCs), where many different families are included, such as isoprenoids. The production and emission of those compounds is influenced by environmental variables such as light and temperature. Those environmental variables will be affected by global change which has been predicted for the next decades. The main objective of this thesis was to study the effect of global change, and specifically climate change, global warming and eutrophication, on isoprenoid, mono and sesquiterpene contents and emission rates. Moreover, we tested those effects in different families and genotypes, due to the intra and interespecific variability. In order to answer those questions we carried out different experiments, from seminatural conditions to more controlled conditions (lab), because the more control of the environmental sampling parameters the better conditions to study isolated factors. Identification and quantification of both contents and emission was carried out using gas chromatography with mass spectrometry. The main conclusions of the present thesis are: warming and drought increase both terpene content and emission independently of the specie (storing and non-storing species). However, different species responded differently to eutrophication: these responses depended on the species and on the sampling time. Finally, intra and interspecific differences where shown: different genotypes and different species behaved differently in both storing and non-storing species.<br>Un 80% dels Compostos Orgànics Volaltils (COVs) que s’emeten anualment a l’atmosfera provenen de fonts biogèniques (COVBs), entre els que destaquen diferents famílies com per exemple els isoprenoids. La producció i emissió d’aquests compostos està influenciada per variables ambientals com la llum i la temperatura. Aquestes variables ambientals es veuran afectades pel canvi global que s’ha predit per les properes dècades. L’objectiu de la present tesi va estar estudiar l’efecte del canvi global i específicament canvi climàtic, escalfament i eutrofització, sobre el continguts i les emissions de les famílies isoprenoids, mono i sesquiterpens. A més, varem testar aquests efectes en diferents famílies i genotips, donades les variacions intra i interespecífiques. Per aconseguir resoldre aquestes preguntes varem realitzar diferents experiments, des de condicions seminaturals fins a condicions més controlades (de laboratori), on un major control de les condicions ambientals de mostreig permet estudiar efectes de forma aïllada. La identificació i quantificació dels compostons, tant continguts com emesos, es va fer mitjançant cromatografia de gasos i espectrometria de masses. Les principals conclusions d’aquesta tesis són: l’escalfament i la sequera van incrementar tant el contingut com les emissions de terpens en espècies acumuladores i en espècies no acumuladores. No obstant, les respostes de les diferents espècies a l’eutrofització van ser diverses, depenent de l’espècie i de les condicions ambientals del moment de mostreig. Finalment, es van constatar les diferències intra i interespecífiques: espècies diferents i genotips diferents es van comportar de diferent manera, tant en espècies acumuladores com en espècies no acumuladores.

Australia has experienced pronounced climate change since 1950, especially in forested areas where a reducing trend in annual precipitation has occurred. However, the interaction between forests and water at multiple scales, in different geographical locations, under different management regimes and in different forest types with diverse species is not fully understood. Therefore, some interactions between forests and hydrological variables, and in particular whether the changes are mediated by management or climate, remain controversial. This thesis investigates the responses of Australia’s terrestrial ecosystems to both historical and projected climate change using remote sensing data and ecohydrological models. The thesis is structured in seven chapters, and contains five research chapters. Vegetation dynamics and sensitivity to precipitation change on the Australian continent for the past long drought period (2002-2010) are explored in Chapter 2 using multi-resource vegetation indices (VIs; normalized difference vegetation index (NDVI) and leaf area index (LAI)) and gridded climate data. During drought, precipitation and VIs declined across 90% and 80% of the whole continent, respectively, compared to the baseline period of 2000-2001. The most dramatic declines in VIs occurred in open shrublands near the centre of Australia and in southwestern Australia coinciding with significant reductions in precipitation and soil moisture. Overall, a strong relationship between water (precipitation and soil moisture) and VIs was detected in places where the decline in precipitation was severe. For five major vegetation types, cropland showed the highest sensitivity to water change, followed by grassland and woody savanna. Open shrublands showed moderate sensitivity to water change, while evergreen broadleaf forests only showed a slight sensitivity to soil moisture change. Although there was no consistent significant relationship between precipitation and VIs of evergreen broadleaf forests, forests in southeastern Australia, where precipitation had declined since 1997, appear to have become more sensitive to precipitation change than in southwestern Australia. The attribution of impacts from climate change and vegetation on streamflow change at the catchment scale for southwestern Australia are described in Chapter 3. This region is characterized by intensive warming and drying since 1970. Along with these significant climate changes, dramatic declines in streamflow have occurred across the region. Here, 79 catchments were analyzed using the Mann-Kendall trend test, Pettitt’s change point test, and the theoretical framework of the Budyko curve to study changes in the rainfall-runoff relationship, and effects of climate and vegetation change on streamflow. A declining trend and relatively consistent change point (2000) of streamflow were found in most catchments, with over 40 catchments showing significant declines (p < 0.05, -20% to -80%) between the two periods of 1982-2000 and 2001-2011. Most of the catchments have been shifting towards a more water-limited climate condition since 2000. Although streamflow is strongly related to precipitation for the period of 1982 to 2011, change of vegetation (land cover/use change and growth of vegetation) dominated the decrease in streamflow in about two-thirds of catchments. The contributions of precipitation, temperature and vegetation to streamflow change for each catchment varied with different catchment characters and climate conditions. In Chapter 4, the magnitude and trend of water use efficiency (WUE) of forest ecosystems in Australia, and their response to drought from 1982 to 2014, were analyzed using a modified version of the Community Atmosphere Biosphere Land Exchange (CABLE) land surface model in the BIOS2 modelling environment. Instead of solely relying on the ratio of gross primary productivity (GPP) to evapotranspiration (ET) as WUE (GPP/ET), the ratio of net primary productivity (NPP) to Transpiration (ETr) (NPP/ETr) was also adopted to more comprehensively understand the response of vegetation to drought. For the study period, national average annual forest WUE was 1.39 ± 0.80 g C kg−1 H2O for GPP/ET and 1.48 ± 0.28 g C kg−1 H2O for NPP/ETr. The WUE increased in the entire study area during this period (with a rate of 0.003 g C kg−1 H2O yr-1 for GPP/ET; p < 0.005 and a rate of 0.0035 g C kg−1 H2O yr-1 for NPP/ETr; p < 0.01), whereas different trends were detected in different biomes. A significantly increasing trend of annual WUE was only found in woodland areas due to higher magnitudes of increases in GPP and NPP than ET and ETr. The exception was in eucalyptus open forest area where ET and ETr decreased more than reductions in GPP and NPP. The response of WUE to drought was further analyzed using 1-48 month scales standardised precipitation-evapotranspiration index (SPEI). More severe (SPEI < -1) and frequent droughts (over ca. 8 years) occurred in the north than in the southwest and southeast of Australia since 1982. The response of WUE to drought varied significantly regionally and across forest types. The response of WUE to drought varied significantly regionally and across forest types, due to the different responses of carbon sequestration and water consumption to drought. The cumulative lagged effect of drought on monthly WUE derived from NPP/ETr was consistent and relatively short and stable between biomes (< 4 months), but notably varied for WUE based on GPP/ET, with a long time lag (mean of 16 months). As Chapters 2-4 confirmed that climate change has been playing an important role in the water yield and vegetation dynamics in Australia, the response of water yield and carbon sequestration to projected future climate change scenarios were integrated using the Water Supply Stress Index and Carbon model (WaSSI-C) ecohydrology model in Chapter 5. This model was calibrated with the latest water and carbon observations from the OzFlux network. The performance of the WaSSI-C model was assessed with measures of Q from 222 Hydrologic Reference Stations (HRSs) in Australia. Across the 222 HRSs, the WaSSI-C model generally captured the spatial variability of mean annual and monthly Q as evaluated by the Correlation Coefficient (R2 = 0.1-1.0), Nash-Sutcliffe Efficiency (NSE = -0.4-0.97), and normalized Root Mean Squared Error by Q (RMSE/Q = 0.01-2.2). Then 19 Global Climate Models (GCMs) from the Coupled Model Intercomparison Project phase 5 (CMIP5), across all Representative Concentration Pathways (RCPs) (RCP2.6, RCP4.5, RCP6.0 and RCP8.5), were used to investigate the potential impacts of climate change on water and carbon fluxes. Compared with the baseline period of 1995-2015 across the 222 HRSs, the temperature was projected to rise by an average of 0.56 to 2.49 ˚C by 2080, while annual precipitation was projected to vary significantly. All RCPs demonstrated a similar spatial pattern of change of projected Q and GPP by 2080, however, the magnitude varied widely among the 19 GCMs. Overall, future climate change may result in a significant reduction in Q but may be accompanied by an increase in ecosystem productivity. Mean annual Q was projected to decrease by 5 - 211 mm yr-1 (34% - 99%) by 2080, with over 90% of the watersheds declining. On the contrary, GPP was projected to increase by 17 - 255 g C m-2 yr-1 (2% - 17%) by 2080 in comparison with 1995-2015 in southeastern Australia. A significant limitation of WaSSI-C model is that it only runs serially. High resolution simulations at the continental scale are therefore not only computationally expensive but also present a run-time memory burden. In Chapter 6, using distributed (Message Passing Interface, MPI) and shared (Open Multi-Processing, OpenMP) memory parallelism techniques, the model was parallelized (and renamed as dWaSSI-C), and this approach was very effective in reducing the computing run-time and memory use. By using the parallelized model, several experiments were carried out to simulate water and carbon fluxes over the Australian continent to test the sensitivity of the model to input data-sets of different resolutions, as well as the sensitivity of the model to its WUE parameter for different vegetation types. These simulations were completed within minutes using dWaSSI-C, and this would not have been possible with the serial version. Results show that the model is able to simulate the seasonal cycle of GPP reasonably well when compared to observations at 4 eddy flux sites in Australia. The sensitivity analysis showed that simulated GPP was more sensitive to WUE during the Australian summer as compared to winter, and woody savannas and grasslands showed higher sensitivity than evergreen broadleaf forests and shrublands. With the parallelized dWaSSI-C model, it will now be much easier and faster to conduct continental scale analyses of the impacts of climate change and land cover change on water and carbon. Overall, vegetation and water of Australian ecosystems have become very sensitive to climate change after a considerable decline in streamflow. Australian ecosystems, especially in temperate Australia, are projected to experience warmer and drier climate conditions with increasing drought risk. However, the prediction from different models varied significantly due to the uncertainty of each climate model. The impacts of different forest management scenarios should be studied to find the best land use pattern under the changing climate. Forest management methods, such as thinning and reforestation, may be conducted to mitigate the impacts of drought on water yield and carbon sequestration in the future.

Large areas of the world’s oceans experience a significant seasonal cycle in phytoplankton biomass. Variability in the phenology of these phytoplankton blooms affect ecosystem dynamics with implications for carbon export production and food availability at higher trophic levels. Climate change is expected to alter phytoplankton seasonality through changes to the underlying physical drivers controlling bloom timing. This thesis focusses on the drivers of contemporary variability and climate change-driven trends in phytoplankton phenology. Satellite-derived chlorophyll data (GlobColour) are used to examine phenological characteristics on a global scale. This dataset is complimented by remotely sensed photosynthetically active radiation (PAR; MODIS), net heat flux (remotely sensed and reanalysis products) and Argo float-derived mixed layer depth datasets in addition to global biogeochemical model output. Four bloom timing metrics are developed to quantify the timing of bloom initiation and termination in a consistent manner. The advantages and limitations of each metric are discussed in the context of the required criteria for a suitable metric definition. The choice of metric definition is based on the performance of the metrics against these criteria. The impact of missing data in the time series on the accuracy of the bloom timing metrics is investigated using the global biogeochemical model NOBM. It is found that missing data cause errors of approximately 30, 15 and 50 days in the date of bloom initiation, peak and termination respectively. The exact cause and implications for phenological studies of these errors is discussed. The physical drivers of interannual variability are examined using global datasets of mixed layer depth, net heat flux and mean mixed layer PAR. The date the net heat flux becomes positive is seen to be a strong predictor for the onset of the subpolar spring bloom, especially in the North Atlantic. This finding is the first to support the critical turbulence hypothesis over Sverdrup’s critical depth theory using satellite observations on a global scale. Physical drivers are only weakly related to interannual variability in bloom timing in the subtropics. The reasons for these relationships and other potential drivers of bloom timing are discussed. Finally, the climate change-driven trends in phytoplankton phenology are investigated using a suite of global biogeochemical models. The ability of the models to capture contemporary seasonality is discussed. The climate change response is found to be strongest at higher latitudes and the phenological changes are consistent with longer periods of strong stratification and earlier onset of ocean warming. Furthermore, it is found that using higher temporal resolution may enable the earlier detection of climate change-driven trends but only at high latitudes.

The land surface is important to the climate system for the exchanges of moisture, momentum and heat. Momentum, radiation, and sensible and latent heat fluxes between the atmosphere and the surface will likely affect atmospheric dynamics, temperature, precipitation and humidity fields (Sato et ai., 1989). These may subsequently feed back into the land surface processes as part of a cyclical system. Therefore it is evident that our livelihood is largely dependent on interactions and exchanges between the land surface and climate system (Henderson-Sellers et ai., 1993) and it is thus essential that we gain a better understanding of the interactive sensitivity. This is of particular relevance in the context of the portended future global climate change. In the present study the interactions between the land surface and the atmosphere are considered over the southern African region. This region has a climate showing a high degree of spatial and temporal variability, most notably with rainfall. Regional climates are characterised by summer, winter and all-year-round rainfall. There are steep vegetation gradients and a wide range of vegetation types adapted to suit the variable climate. These factors, combined with the societal implications of changes in the climate and land surface systems, make southern Africa a challenging and important study domain for examining the sensitivity between the different elements of the atmosphere and biosphere. This research makes use of a biosphere model driven by climate change data derived from a general circulation model (GCM). Regions susceptible and sensitive to changes on an annual and seasonal basis are identified and examined. The thesis comprises 8 chapters. The first chapter, Chapter 1, provides some background information on climate change, biosphereatmosphere interactions, GCMs and transient simulations, vegetation models and vegetation representation over southern Africa. This chapter also sets out the research objectives. The following chapter, Chapter 2, introduces the atmospheric GCM model data from the Hadley Centre Model (HadCM2) used in the analysis. The chapter additionally provides a detailed description of the biosphere model, the Integrated Biosphere Simulator (IBIS). Chapter 3 examines the Hadley Centre HadCM2 GCM input data used in driving the biosphere model, while Chapter 4 presents the input forcing data and configuration of the IBIS model. In Chapter 5 the results of the IBIS model simulation are examined on the annual scale and in Chapter 6 the results are examined on the seasonal scale. Some of the implications of climate change are considered in Chapter 7. This chapter also places the HadCM2 GCM model data used in driving IBIS into the context of the latest emissions scenarios. In the final chapter, Chapter 8, an overview summary is provided and conclusions are drawn.

A thermal model is developed to find the distribution of stable near-surface ground ice on Mars that is in diffusive contact with the atmosphere for past and present epochs. Variations in the orbit of Mars are able to drive climate changes that affect both surface temperatures and atmospheric water content so the distribution of ground ice will vary significantly in past epochs. A technique is developed to correct the average water vapor density above the surface for depletion due to diurnal frost formation. Also presented is a simple model to estimate the atmospheric water content, based on the water vapor carrying capacity of the atmosphere over water ice on the martian surface.Maps of the distribution of ground ice are generated for the present epoch of Mars with varying amounts of water vapor in the atmosphere. The water vapor depletion scheme restricts the extent of stable ground ice as more water is put into the atmosphere so that ice never becomes stable at low latitudes. As the position of the perihelion varies, the extent of ground ice changes several degrees in the latitudinal extent, primarily in the northern hemisphere. The extent of ground ice is sensitive to the obliquity of Mars, however high obliquities are still not able to make ground ice stable at low latitudes. Finding ice is never stable at low latitudes is consistent with the lack of terrain softening at low latitudes and models that indicate Mars had high obliquities for much of its history.Also presented is the first L-band spectrum of an irregular satellite from the outer Solar System. Spectra of Himalia were obtained with the Visual and Infrared Mapping Spectrometer onboard the Cassini spacecraft. The Himalia spectrum is essentially featureless, showing a slight red slope and a suggestion of an absorption feature at 3 microns that would indicate the presence of water. Better measurements of the spectrum of Himalia, particularly in the region of the apparent 3-micron band, could help determine whether water is present, and if so, in what form.

Climate change is predicted to impact organismal nutritional ecology. Increased temperatures can directly accelerate physiological rate processes, which in turn, impact nutritional requirements. Climate change can also impact organisms indirectly by altering the quality and quantity of nutritional resources, creating the potential for nutritional mismatch between what nutrients are available in the environment and what organisms require. Investigation of organismal stoichiometry, particularly the balance of carbon, nitrogen, and phosphorus content of organisms, can help illuminate the extent to which changes in climate may impact organism nutritional ecology. Ants represent an excellent system to examine stoichiometry because they occur across a broad range of environmental conditions and perform important ecosystem services, such as seed dispersal, which may impact ecosystem functioning. In this thesis, I examined how climate variables influence ant stoichiometry across a broad latitudinal gradient in natural populations of three closely-related ant species in the genus Aphaenogaster. In a common garden study, I tested the extent to which such stoichiometric variation was due to plastic or evolved variation. I found significant species-specific differences in how ant stoichiometry responded to climate gradients. The northern species, A. picea contained more C, and less N and P at higher latitudes and elevation, consistent with increased winter lipid storage. In contrast, the more southern species, A. rudis, showed the opposite pattern, which may reflect N and P limitation at southern extremes. Aphaenogaster fulva, whose range is intermediate in latitude and partially overlaps with both congeners, contained more C in environments with more seasonal precipitation. Thus, these species appear to use different nutrient storage strategies in response to the variation in abiotic and trophic conditions across their range. When reared under the same feeding regime and thermal conditions, site-level differences in nitrogen storage between a northern and a southern ant population were retained over time and across years, suggesting that adaptive divergence in elemental composition is at least partially responsible for clinal patterns in the field. To connect latitudinal patterns to temporal changes projected under climate change, I evaluated how increases in temperature impact ant stoichiometry and associated functional traits at the individual and colony level using an experimental field mesocosm experiment at two sites, Harvard Forest (HF) and Duke Forest (DF). I examined how experimental increases in temperature impacted ant body size, colony demography, and nutritional status of two Aphaenogaster ant species. I found that Aphaenogaster ants at the northern site, HF, responded positively to direct increases in temperature, with increases in colony biomass, colony size, total reproductive output, and shifts toward increased nitrogen content with increases in temperature. In contrast, Aphaenogaster ants at the southern site, DF, were generally unaffected by temperature except for a decrease in maximum colony size with increases in temperature. Together, my findings provide evidence that both climate variables and evolutionary history impacts ant stoichiometry, which in turn, may impact ant colony fitness. Examination of the biochemical basis of stoichiometric trait variation is needed to ascertain the role stoichiometry may play in how ant species adapt to changing environmental conditions.

Climate change is the first anthropogenic alteration of a global Earth system. It is globally catastrophic in terms of food production, sea level rise, fresh water availability, temperature elevation, ocean acidification, species disturbance and destruction to name just a few crisis concerns. In addition, while those changes are occurring now, they are amplifying over decadal periods and will last for centuries and possibly millennia. While there are a number of pollutants involved, carbon dioxide (CO2) which results from the combustion of any fossil fuel is the primary pollutant. It has not been considered a pollutant until recently because of its natural dissociation into oxygen and carbon compounds like wood. However, because of its molecular durability and ability to acidify water, it has become the primary pollutant as a result of the exponential increase in fossil fuel use for the production of energy by Earth’s population that has doubled over the last six decades. That increase has exceeded Earth’s ability to handle humanity’s waste CO2. Obviously, the involved changes detrimentally affect all life on Earth. Because of the evolving nature of the changes, climate change is presently denied primarily in the United States because of the costs of eliminating our carbon addiction. Because no similar global natural or anthropogenic situation has previously occurred during the lifetime of Homo sapiens, our extant ethical theories are incapable of confronting the crisis. Consequently, new ethical paradigms are necessary. This dissertation attempts to provide thoughts about the use of Aristotelian ethical theory, the aidōs feeling, Aquinian psychology and a possible new virtue of proper primility in an effort to further nurture the growth of the new climate change ethics.

The climate of the Earth is expected to warm due to increasing atmospheric concentrations of greenhouse gases, particularly carbon dioxide (CO 2). The impact of this change on terrestrial ecosystems is uncertain, yet these ecosystems contain three times more carbon (C) than the atmosphere and could considerably augment anthropogenic CO2 emissions. This thesis aimed to quantify the terrestrial C stored in an area of Pennine moorland and predict its response to changes in climate and management. The area of soil and vegetation types was determined using existing maps of the study site and a geographical information system. Vegetation C was assessed using results from published productivity studies, and soil C was evaluated from a programme of field sampling. Most C was contained in peat soils and comparison of the results with the UK's national C inventory identified inaccuracies in the national values. The impact of sheep grazing and moorland burning on C storage was investigated by utilising long-term experiments at the site. Areas where sheep had been excluded for forty years were compared to grazed areas and burning was investigated using a randomised block experiment. Grazing had little impact on terrestrial C storage, but regular burning significantly reduced C sequestration in peats. The response of the C store to climate change was investigated by i) determining the impact of past climate on C storage and ii) developing a predictive model by measuring the underlying processes of C input and output in the ecosystem. Both approaches illustrated the sensitivity of the ecosystems C balance to climate, suggesting that global warming will reduce C accumulation at the site and, therefore, augment atmospheric CO 2 concentrations. The novel use of near infrared reflectance spectroscopy to characterise peat samples was also demonstrated, indicating opportunities for application of this technique in palaeoecological studies of peats.

Climate change is one of the most pressing issues facing civil society. Scientific evidence indicates the likelihood of greater variability and more frequent extremes of temperature and precipitation which will result in increased flood risk and corresponding social, economic and environmental impacts. Complementing more traditional structurally-based engineering interventions, an important additionaladaptation strategy is through natural flood management (NFM). NFM seeks to utilise natural processes (i.e. by promoting higher infiltration through land management practices) to attenuate flood peaks. Such measures have wider significance in the context of Ecosystem based Adaptation (EbA), to deliver highly beneficial solutions as they provide important benefits in relation to runoff rates but also in terms of wider environmental aspects (e.g. water quality, biodiversity). The present study used a holistic approach to evaluate the effectiveness of NFM options in reducing the flood risk for the current and future climate with a consideration also for the wider delivery of ecosystem services. Tarland Burn catchment (NE Scotland) was used as a platform to explore individual adaptation options through woodland expansion (distinguishing between coniferous and deciduous) and drainage schemes, together with land use scenarios that explore emergent socio-economic contexts. The distributed hydrological model WaSiM-ETH was utilised for the analysis linking land management options with climate projections obtained from UK Climate Projections (UKCP09). Modelling results showed that the magnitude of extreme weather events is expected to increase up to the end of the century with important implications for climate adaptation strategies. Woodland expansion could help attenuate the high flows, with the benefit for flood protection significantly higher for coniferous woodland compared to deciduous woodland and up to 1.5 more if woodland is located in lowland areas. However, modelling results suggested that there are potential negative impacts of afforestation on low flows (and hence water quality) which could exacerbate existing vulnerabilities. This may become an even greater issue in the future as summers are predicted to be drier and warmer. Improving the efficiency of the drainage network was seen to reduce the high flows, though the results are marginal for the winter when most floods occur. Modelling results suggested that climate change will eventually exceed the capacity of beneficial land use change by itself (through NFM measures) to avoid significant changes on catchment hydrology. This has important implications as other complementary engineered solutions may therefore be required to counteract the adverse impacts of climate change on flood risk. Moreover, the EbA assessments results indicated that NFM options may not always be ‘win-win’ solutions as commonly advertised (McShane et al., 2011). Instead trade-offs between the delivery of different services may be required and decisions should be aimed at maximizing benefits whilst minimizing the disbenefits. This novel approach highlighted that land use change should be carefully managed and the choices about land use and flood risk should always have at their core an enhancement of landscape resilience, particularly at the catchment scale.

This thesis presents an assessment of farmers' behaviour in response to current changes in climate and policy in the UK. At present, many catchments in England are considered as over licensed or over abstracted and although water licence trading is regarded as a potential solution to the problem, and is currently possible, high transaction costs and institutional barriers deter farmers from trading. In response, two new water allocation systems have been proposed to provide farmers with the ability to adapt to climate and demand change pressures (i.e. basic and enhanced systems). A review of the current literature suggested farmers' behaviour very much influences the success of policy interventions. Therefore, this study sought to understand the behavioural intentions of farmers in England, and the underlying factors which drive their decision-making, under different climate and policy scenarios. Furthermore, this study examined whether farmers with different behavioural intentions lead to different patterns of abstraction behaviour at the system level, thus providing a means of assessing the current and proposed water allocation systems. An empirical survey was conducted within the Great Ouse catchment in eastern England, UK, where freshwater availability for crop irrigation is considered highly vulnerable to climate change. The questionnaire, and subsequent interpretation of behaviours, was developed under the theoretical framework of the Theory of Planned Behaviour (TPB) (Ajzen, 1991). Farmers' preferred behavioural intentions were identified under different strategic (long-term) and in-season (short-term) water shortage and surplus scenarios. Furthermore, the TPB explained between 29-65 % of the variance in intention, based on Nagelkerke's R2, and was similar to the range found by meta-analytical reviews (i.e. 40-49 % based on R2). In addition, attitude and subjective norm were found to be significant predictors of intention in three of the four scenarios. Overall, farmers believed they have greater volitional control with regards to decision-making in the long-term but less in the short-term. Furthermore, a behavioural farm typology based on farmers' preferred behavioural intentions was used in the development of an Agent-Based Model (ABM) to simulate system level patterns of abstraction behaviour which emerge from individual farm level decision-making. The scenario simulation results indicated the proposed enhanced water allocation system was likely to provide the greatest utility to balance the needs of licence users, at least farmers, whilst protecting the environment.

Mestrado em Ciências do Mar e das Zonas Costeiras<br>Estuaries are highly dynamic systems which may be modified in a climate change context. These changes can affect the biogeochemical cycles. Among the major impacts of climate change, the increasing rainfall events and sea level rise can be considered. This study aims to research the impact of those events in biogeochemical dynamics in the Tagus Estuary, which is the largest and most important estuary along the Portuguese coast. In this context a 2D biophysical model (MOHID) was implemented, validated and explored, through comparison with in-situ data. In order to study the impact of extreme rainfall events, which can be characterized by an high increase in freshwater inflow, three scenarios were set by changing the inputs from the main tributaries, Tagus and Sorraia Rivers. A realistic scenario considering one day of Tagus and Sorraia River extreme discharge, a scenario considering one day of single extreme discharge of the Tagus River and finally one considering the extreme runoff just from Sorraia River. For the mean sea level rise, two scenarios were also established. The first with the actual mean sea level value and the second considering an increase of 0.42 m. For the extreme rainfall events simulations, the results suggest that the biogeochemical characteristics of the Tagus Estuary are mainly influenced by Tagus River discharge. For sea level rise scenario, the results suggest a dilution in nutrient concentrations and an increase in Chl-a in specific areas.For both scenarios, the suggested increase in Chl-a concentration for specific estuarine areas, under the tested scenarios, can lead to events that promote an abnormal growth of phytoplankton (blooms) causing the water quality to drop and the estuary to face severe quality issues risking all the activities that depend on it.<br>Os estuários são sistemas altamente dinâmicos que se encontram em risco devido a eventos relacionados com as alterações climáticas. Estas alterações podem ter impactos nos ciclos biogeoquímicos. Entre esses efeitos podem considerar-se o aumento de períodos de chuvas torrenciais e o aumento do nível médio do mar. Assim, o objetivo deste trabalho é o estudo do impacto destes eventos na dinâmica biogeoquímica do Estuário do Tejo, que se trata do maior sistema estuarino da Península Ibérica. Neste contexto, foi implementado, validado e explorado através de comparação com dados in-situ, um modelo biofísico 2D (MOHID). De forma a avaliar a resposta biogeoquímica do estuário a períodos de chuvas torrenciais, caracterizadas por variações abruptas nas descargas fluviais dos principais tributários, Tejo e Sorraia, foram considerados três cenários. O primeiro considerando um dia de descarga extrema para os rios Tejo e Sorraia. O segundo, considerando uma descarga extrema apenas para o Rio Tejo e por último, considerando uma descarga apenas para o Rio Sorraia. Relativamente ao aumento do nível médio do mar, foram estabelecidos dois cenários, o primeiro com o nível médio do mar atual e o segundo considerando um aumento de 0.42 m, conforme estimado em estudos anteriores. Os resultados para a simulação das chuvas torrenciais indicam que as modificações previstas para os padrões biogeoquímicos dependem essencialmente da descarga do Rio Tejo. Para o cenário de aumento do nível médio do mar os resultados sugerem uma diminuição da concentração de nutrientes e um aumento de clorofila em áreas específicas. Em ambos os cenários, o aumento de clorofila em determinadas zonas do estuário, sugerido pelos resultados, pode levar a eventos que promovam um crescimento anormal de fitoplâncton fazendo com que a qualidade da água diminua e colocando em risco todas as atividades que dependem no Estuário do Tejo.

While climate change mitigation has been on the agenda of spatial planning practitioners for over two decades, adaptation has only become influential in spatial planning practice in recent years. This trend is evident not only at the municipal levelbut also at the regional and national levels. The revised planning and building law from 2011 states that municipalities must consider climate change. In parallel, a body of research focusing on the relationship between gender and concern for environmental and climate change and arguing that women are more concerned and proactive with respect to environmental issues has emerged. However, this research has been criticized for being essentialist and for stigmatizing women and men. The long-term aim of the present dissertation is to contribute to knowledge on how a gender perspective on municipal spatial planning can contribute to efficient and well-informed climate change response, as well as on how a gender perspective, as an analytical framework, can be developed to analyze, on the one hand, spatial planning related to climate change and, on the other, spatial planning more generally. One of the main contributions of my dissertation is to demonstrate that, by including a gender perspective in municipal climate change response, aspects that may be important for achieving efficient and well-informed spatial planning related to climate change response that are not typically prioritized can be afforded prominent places on the agenda. In this dissertation, I refer to these aspects as feminine values and perspectives—or attributes. I also contribute to the development of an analytical framework that can be used by policy makers and scientists to assess how a gender perspective is and can be integrated within municipal spatial planning processes related to climate change response, as well as spatial planning more generally. Furthermore, in addition to the development of efficient and well-informed responses, a dimension of gender equality must be considered. My dissertation contributes to the understanding that planners who adopt a gender perspective must consider the general level of gender equality in a country. Although the primary objective of this dissertation is to contribute to the development of efficient and well-informed policy, issues of equality and democracy cannot be overlooked. As I argue in my dissertation, participatory approaches to spatial planning are imperative for municipal efforts related to climate change. Nonetheless, participatory approaches require spatial planners to ensure that democracy and equality, on the one hand, and efficient and well-informed policy delivery, on the other, do not conflict.<br><p>QC 20140214</p>

This study examines the importance of short-term climate variability when simulating forest succession using ecological process models. A version of the FORSKA2 forest gap model was modified for use with daily climate data and applied along a transect of sites crossing the boreal region in central Canada, including the aspen-parkland and forest-tundra ecotones where impacts of climatic change on forest ecosystems could be particularly significant. The model's sensitivity to forcing with daily climate observations compared to monthly mean and long term averages of monthly mean climate data was investigated. Inclusion of daily climate (minimum and maximum temperature and total precipitation) improved the simulations of key characteristics of present-day forest along the transect, and was particularly important at the ecotones. The results demonstrate that changes in variability associated with future change in mean climate are likely to be important when trying to predict boreal forest responses to projected future climate change. Ideally, the use of projected daily climate data or data based on the statistical characteristics of daily climate is highly recommended for future impact studies. A number of approaches to further improve the functioning of the model are also presented.

<p> Severe drought plays a critical role in altering the magnitude and interannual variability of the net terrestrial carbon sink. Drought events immediately decrease net primary production (NPP), and drought length and magnitude tend to enhance this negative impact. However, satellite and in-situ measurements have also indicated that ecosystem recovery from extreme drought can extend several years beyond the return to normal climate conditions. If an ecosystem&rsquo;s drought recovery time exceeds the time interval between successive droughts, these legacy effects may reinforce the impact of future drought. Since the frequency and severity of extreme climate events are expected to increase with climate change, both the immediate and prolonged impact of drought may contribute to amplified climate warming by decreasing the strength of the land carbon sink. However, it is unknown whether terrestrial biosphere models capture the impact of drought legacy effects on carbon stocks and cycling. Using a suite of twelve land surface models from the Multi-scale Synthesis and Terrestrial Model Intercomparison Project (MsTMIP), we assessed model ability to simulate drought legacy effects by analyzing the modeled NPP response to drought events across forested regions of the US and Europe. We found that modeled drought legacy effects last about one year (2% reduction in NPP), with complete NPP recovery in the second post-drought year. Since observations suggest that legacy effects extend up to four years post-drought, with a 9% growth reduction in the first post-drought year, models appear to underestimate both the timescales and magnitude of drought legacy effects. We further explored vegetation sensitivity to climate anomalies through global, time-lagged correlation analysis of NPP and climatic water deficit. Regional differences in the lag time between climate anomaly and NPP response are prevalent, but low sensitivities (correlations) characterize the entire region. Significant correlations coincided with characteristic lag times of 0 to 6 months, indicating relatively immediate NPP response to moisture anomalies. Model ability to accurately simulate vegetation&rsquo;s response to drought and sensitivity to climate anomalies is necessary in order to produce reliable forecasts of land carbon sink strength and, consequently, to predict the rate at which climate change will progress in the future. Thus, the discrepancies between observed and simulated vegetation recovery from drought points to a potential critical model deficiency.</p><p>

Recent (post-1950s) climate change impacts on society and ecosystems have been recognised globally. However these global impacts are not uniform at regional or local scales. Despite research progress on such scales there are still gaps in the knowledge as to 'what' is happening and 'where'? The goal of this study addresses some of these gaps by analysing climate variability and vegetation response at the furthest south westerly peninsula of the United Kingdom. This research is focused on West Cornwall (South West England) - an area dominated by a strong maritime influence. The first part of this PhD research analysed archive and contemporary instrumental data in order to detect any trends in climate variability. The weather data was retrieved from the Met Office archive for Camborne 1957-2010 and Culdrose 1985-2011 stations; Trengwainton Garden (1940-2010), and from the Royal Cornwall Polytechnic Society, for Falmouth (1880-1952) and Helston (1843-1888). The data showed positive trends in mean annual and maximum temperature with the largest trend magnitude in the 20th and 21st century. Seasonal temperature change varies locally with the highest increase in autumn spring and summer. Precipitation trends were only positive for the 19th century for Helston. Correlation between precipitation data and North Atlantic Oscillation (NAO index) was negative, however the opposite result was detected when the NAO index was correlated with temperatures. Surprisingly, return period analysis showed a decrease in the frequency and intensity of extreme precipitation events post 1975 for Camborne and Trengwainton Garden stations. The second part of this study analysed changes in vegetation distribution in West Cornwall using historical and contemporary vegetation records. Historical vegetation records were used from the Flora of Cornwall collection of herbarium records and contemporary vegetation records which were available online, containing mainly the 'New Atlas of British and Irish flora'. Data sets were geo-referenced using ArcGIS in order to analyse changes in species geographical distribution pre and post-1900. Analysis showed that historical vegetation records can be used to assess any changes in geographic distributions of vegetation. Analysis for the area of West Cornwall showed a loss of range for 18 species, for 6 species this loss was larger than 50% of the area, and there was no change in overall range area for 10 species. Ellenberg values and environmental indicator values showed that they can be used as an indicator of environmental change, showing a decrease in species with lower January temperatures. Analysis also showed an increase in moderate wetter species, where species with extreme low and high precipitation environmental indicator values showed a greater loss. Furthermore species with a higher requirement for light showed a loss as well as species with lower nitrogen values. To analyse the loss of species at the local scale, West Cornwall was divided into three areas (North Border Cells, Central West Cornwall Cells and South Border Cells). The highest loss of 11 species was detected for South Border Cells, where the loss for Central West Cornwall Cells was 6 and for North Border Cells 8 species. It was found that 17 species were experiencing loss on different local sites. For 9 of these 17 species, change at the local scale was different to the national scale change at the individual species level, group level and habitat level. Furthermore, the whole area of West Cornwall lost two species post-1900, with a different loss locally. This showed that species could be protected locally in appropriate microclimate refugia, which will be of benefit for the preservation of regional identity ecosystem services and overall genetic pool of the species.

The thesis asks two crucial questions, (a) what are the normative frameworks available for protecting the rights and status of a person migrating due to climate change related hydro-metrological changes? (b) why is there a non-uniformity and inadequacy in the deliverance of assistance from the state? To address these questions, I have analysed the perception, framing and assistance a climate change migrant receives from the state of Assam in India, while also explaining the reasons for the differential nature and deficits in protection. Based on interviews with senior bureaucratic officials (elite actors), group-discussions, field surveys, and engagements at the block and village level, the thesis makes three critical arguments. First, the sub-national government perceive climate-induced migrations as a developmental issue. Second, the way in which climate change migration is framed as a developmental issue by elite actors does not correspond with how the issue is understood by street-level bureaucratic actors. Instead, the routine judgements and discretions exercised by street-level actors are complexly tied to the political and social circumstances of local areas. Finally, while it is known that socio-political and demographic factors (such as gender, membership of a social group, and religion) contribute to forced forms of migration, the thesis argues that these demographic factors also adversely affect the performance of the programs meant to reduce climate vulnerabilities.

Recent concern over the effects of ocean acidification upon calcifying organisms in the modern ocean has highlighted the aragonitic shelled thecosomatous pteropods as being at a high risk. Laboratory studies have shown that increased pCO2, leading to decreased pH and low carbonate concentrations, has a negative impact on the ability of pteropods to calcify and maintain their shells. This study presents the micropalaeontological analysis of marine cores from the Caribbean Sea, Mediterranean Sea and Indian Ocean. Pteropods, heteropods and planktic foraminifera were picked from samples to provide palaeoenvironmental data for each core. Determination of pteropod calcification was made using the Limacina Dissolution Index (LDX) and the average shell size of Limacina inflata specimens. Pteropod calcification indices were compared to global ice volume and Vostok atmospheric CO2 concentrations to determine any associations between climate and calcification. Results show that changes in surface ocean carbonate concentrations throughout the Late Pleistocene did affect the calcification of thecosomatous pteropods. These effects can be detected in shells from marine sediments that are located well above the aragonite lysocline and have not undergone post-depositional dissolution. The results of this study confirm the findings of laboratory studies, showing a decrease in calcification during interglacial periods, when surface ocean carbonate concentrations were lower. During glacial periods, calcification was enhanced due to the increased availability of carbonate. This trend was found in all sediments studied, indicating that the response of pteropods to past climate change is of global significance. These results demonstrate that pteropods have been negatively affected by oceanic pH levels relatively higher and changing at a lesser rate than those predicted for the 21st Century. Results also establish the use of pteropods and heteropods in reconstructing surface ocean conditions. The LDX is a fast and appropriate way of determining variations in surface water carbonate saturation. Abundances of key species were also found to constrain palaeotemperatures better than planktic foraminifera, a use which could be further developed.

This thesis examines the response of Taiwanese hotels to climate change. Climate change is increasingly recognised by industry, governments and researchers as one of the most substantial challenges to the sustainability of tourism at both a destination and business level in both the short and long-term. Hall (2008) observed that tourism was explicitly recognised by the IPCC as one of the most important industries in Asia, yet the lack of research on tourism and climate change in an Asian context was identified, with especially little explicit research on the climate change response of the hospitality and accommodation sector. This is also despite the accommodation sector being the most significant tourism sector contributor to emissions after aviation (United Nations World Tourism Organisation [UNWTO] and United Nations Environment Programme [UNEP] 2008; World Economic Forum [WEF] 2009; Scott et al. 2012). Therefore this research seeks to explicitly respond to this knowledge gap by examining the response of the Taiwanese hotel sector to climate change. It is also the first known study that explores the extent to which the hotel sector meets the specific recommendations of the UNWTO-UNEP (2008) with respect to accommodation sector measures in relation to climate change. In order to provide a firm basis of methodological comparison with the previous international literature on environmental studies of the accommodation sector, this thesis conducted a baseline survey to investigate the response of Taiwanese hotels towards environment and climate change with respect to four main dimensions, including perception, attitudes, actions, and influencing factors for environmental and climate change practices. Overall, 270 hotel participants answered the email-based questionnaire survey of the total population of Taiwanese hotels, reflecting a response rate of approximately 10%. Taiwanese hotel respondents acknowledged the existence of climate change, but rarely related this phenomenon to their daily business operations. Their attitude towards their own hotel’s contribution to climate change was especially reserved. In addition to waste management, energy-saving practice, and the offer of local-produced cuisine, the level of implementation of environmental practices in Taiwanese hotels was relatively limited. There were also low compliance rates with existing environmental policy, although they were aware of environmental schemes. The factors of size and extreme weather event experience were identified as the more significant variables to differentiate Taiwanese hotel response to environment and climate change. The significance of hotel size, standard, and experience of weather extreme variables were also examined. Finally, this research discussed the prospective contributions and issues of the results of this study, and argues for their application in the fields of climate change research, benchmarking development, education and and training, government regulation and policy, and hotel management.

Tall fescue is the most common cool-season grass in the eastern USA, with broad economic and ecological importance to the region. Tall fescue is known to associate with a fungal endophyte, Neotyphodium coenophialum, whose presence can decrease biotic and abiotic stress experienced by the plant. This thesis evaluates the response of tall fescue and the fungal endophyte symbiosis to predicted climate change. I participated in two multi-factor climate change projects where I investigated the response of tall fescue tissue chemistry and growth to various climate change factors. Endophyte-infected (E+) tall fescue had decreased alkaloid production under elevated CO2 but increased alkaloid production under elevated temperatures. Significant differences between E+ and E- (endophyte-free) tall fescue tissue chemistry were also found, suggesting the endophyte interacts with the plant response to abiotic stress. Although several studies have reported benefits of endophyte infection for tall fescue growing under drought stress, my research found no differences between E+ and E- total growth and surprisingly showed increased mortality of E+ individuals under elevated temperature. Taken together, my research indicates that this grass-fungal relationship will respond to climate change, and may produce dramatic and unforeseen results that question the widely believed mutualistic nature of the symbiosis.

Tropical cyclones can cause substantial loss of life and an improved understanding of storm variability and their response to climate change can help inform preparation and future adaptation. The influence of the El Nino Southern Oscillation (ENSO) on global tropical cyclone activity is investigated in a high-resolution coupled climate model (Hi GEM) compared to an atmosphere-only simulation using the atmospheric component of Hi GEM (Hi GAM). HiGEM is able to capture the shift in tropical cyclone locations to ENSO in the Pacific and Indian Oceans but not in the North Atlantic. The vertical wind shear response over the Caribbean is not captured in HiGEM compared to HiGAM and ERA-Interim. Precipitation biases in HiGEM remain in HiGAM over the Western North Pacific, however HiGAM simulates a more accurate representation of the ENSO-tropical cyclone teleconnection. Model experiments are subsequently undertaken to investigate a contemporary issue on how different types ofEl Nino influence tropical cyclone activity in the Western North Pacific. The Hi GEM-Hi GAM central Pacific El Nino experiment simulates an increase of tropical cyclones that move towards South East Asia. This response is attributed to a large-scale anti-cyclonic anomaly over east China. In contrast, the low SST in the West Pacific during east Pacific El Nino reduces tropical cyclone activity. How tropical cyclone activity might change due to the influence of increased atmospheric carbon dioxide concentrations using HiGEM is finally investigated. Tropical cyclones are shown to decrease in frequency globally by 9 % in the 2XC02 (2C02) simulation and 26 % in the 4 x C02 (4C02) simulation. Tropical cyclones only become more intense in the 4C02. A decrease in mean ascent at 500 hPa contributes to the reduction of tropical cyclones in the 2C02 in most basins. The larger reduction of tropical cyclones in the 4C02 arises from further reduction of mean ascent at 500 hPa and a large enhancement of vertical wind shear.

Interactions between climate, fire and CO2 are believed to play a crucial role in controlling the distributions of tropical woodlands and savannas, but our understanding of these processes is limited by the paucity of data from undisturbed tropical ecosystems. Here we use a 28,000-year integrated record of vegetation, climate and fire from West Africa to examine the role of these interactions on tropical ecosystem stability. We find that increased aridity between 28-15 kyr B.P. led to the widespread expansion of tropical grasslands, but that frequent fires and low CO2 played a crucial role in stabilizing these ecosystems, even as humidity changed. This resulted in an unstable ecosystem state, which transitioned abruptly from grassland to woodlands as gradual changes in CO2 and fire shifted the balance in favor of woody plants. Since then, high atmospheric CO2 has stabilized tropical forests by promoting woody plant growth, despite increased aridity. Our results indicate that the interactions between climate, CO2 and fire can make tropical ecosystems more resilient to change, but that these systems are dynamically unstable and potentially susceptible to abrupt shifts between woodland and grassland dominated states in the future.

Cette recherche est axée sur les relations entre les changements climatiques actuels et futurs et l'activité des laves torrentielles à l'échelle régionale dans les Alpes françaises à partir des données historiques pour la période 1970-2005. 565 événements documentés pour cette période ont été intégrés dans une base de données SIG. Les Alpes françaises sont constituées de deux secteurs géographiques contrastés : une zone humide au nord, subissant l'influence de masses d'air atlantique, avec des vallées escarpées et étroites, et une zone sèche au sud, sous influence climatique méditerranéenne, avec des massifs montagneux étendus et à faible pente. Pour ces deux zones géographiques on a repéré une activité spécifique des laves torrentielles. Des analyses statistiques ont de plus révélé dans ces deux régions une relation entre les déclenchements des laves torrentielles et des variables climatiques différentes. Par ailleurs, des analyses hiérarchiques, utilisant des variables climatiques régionales et des caractéristiques géomorphologiques des bassins versants, viennent confirmer ce contraste. Pour détecter les changements potentiels de l'activité future, quatre modèles climatiques régionaux ont été utilisés. Quel que soit le modèle, une double augmentation de la probabilité annuelle est prévue dans les deux régions, à la fois pour le futur proche (2020-2050) et pour le futur lointain (2070-2100). La principale raison de ces augmentations spectaculaires est l'augmentation significative de la température de l'air entre mai et octobre, période principale d'activité des laves torrentielles.

Thesis: Ph. D. in Physical Oceanography, Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2019<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 121-133).<br>Global patterns of ocean salinity arise from the exchange of freshwater between the sea surface and the atmosphere. For a quasi-steady state system, these surface fluxes are balanced by compensating transports of salt in the ocean interior. In a warming climate, the atmosphere holds additional water vapor which acts to intensify the global water cycle. Amplified freshwater fluxes are then absorbed at the surface and propagate along ocean circulation pathways. Here, we use coupled model results from the CMIP5 experiment to identify coherent responses in the atmospheric water cycle and in ocean salinity patterns. Some aspects of the response are consistent across models, while other regions show large inter-model spread. In particular, the salinity response in the North Atlantic subpolar gyre, where the mean salinity plays a role in maintaining high surface density for deep-water formation, has low confidence in CMIP5 models.<br>To understand how differences in ocean circulation may affect this response, we use two techniques to diagnose the role of salt transports in the present-day climate. The first is a salt budget within the surface mixed layer, which identifies major transport processes. The second is a Lagrangian particle tracking tool, used to understand the regional connectivity of water masses. From this analysis, we find that anomalous freshwater signals become well mixed within the ocean gyres, but can be isolated on larger scales. The subpolar Atlantic salinity response generally shows freshening at the surface, but is sensitive to the transport of anomalously salty water from the subtropics, a largely eddy-driven process. As CMIP5 models use a range of eddy parameterizations, this is likely a source of uncertainty in the salinity response.<br>Finally, we investigate the effect of salinity changes on the deep overturning cells and other circulations, and find a complex influence that also depends on the details of advective pathways. In a warming scenario, water cycle amplification actually works to strengthen the Atlantic meridional overturning circulation due to the influence of enhanced subtropical evaporation.<br>by Samuel J. Levang.<br>Ph. D. in Physical Oceanography<br>Ph.D.inPhysicalOceanography Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution)

On-going climate change through the 21st century projects increasingly warmer and drier conditions for Mediterranean-type ecosystems (MTEs), creating threats to species persistence in these biodiversity hotspots. For the highly biodiverse kwongan of southwest Australia, this means a climate shifting towards semi-arid conditions, yet how this unique vegetation type will respond to a novel hotter and drier climate is largely unknown. Therefore, this study examined the effects of altered rainfall and temperature on demographic processes of woody kwongan in post-fire (0 - 3 years since last fire) and mature (12 - 15 years since last fire) stands across a soil depth gradient in the northern sandplains of southwestern Australia, seeking to identify the consequences for plant species and functional trait composition. To achieve this, a selection of commonly occurring species (Banksia attenuata, Banksia hookeriana, Melaleuca leuropoma and Beaufortia elegans as primary focal species) were used to form a plant functional trait scheme, with fire-response strategy (resprouter, non-resprouter) as a trait of key interest due to the fire prone nature of MTEs, and leaf type (broad, needle, small), growth form (shrub, subshrub) and seed size (large, medium, small) as traits of interest due to their potential roles in drought and temperature responses. Passive rainout shelters were used to reduce rainfall, and drip irrigation to increase rainfall, by ~ 30 %. Open top chambers were used to increase temperature, with daytime temperature increased by an average of 2.9˚C. Seedling germination, survival and growth, and adult survival, health, flowering and fruiting were reduced by drought and warming, with increased rainfall producing little change. Greater magnitude of reduction was observed under experimental warming, however experimental drought resulted in greater level of change in functional trait composition. Despite the general higher resistance of adult resprouters, it was non-resprouters that showed potential to become the dominant fire-response strategy in a drier environment, through higher seedling resilience and similar resistance as adults to resprouters. With a decline in survival for both post-fire resprouts and seedlings, resprouters could be at risk of population decline in the long term. Subshrub and small leaf traits were the most successful in drought conditions due to their drought tolerant nature, while broad leaf and shrub traits will likely suffer population decline. In warmer conditions, significant decline in resprouter seedling survival was matched by equally large decline in non-resprouter adult survival, indicating little change in dominance of non-resprouters at the seedling stage and resprouters at the adult stage, and thus little change in their relative abundances. The needle leaf trait was most competitive in warmed conditions performing well relative to other traits both in seedlings and adults. Shallow soil profiles, reflecting lower water availability, negatively affected demographic rates, suggesting decreases in diversity and density on shallow soils as less drought tolerant species retreat to deeper soil profiles with greater water stores. Results here show potential for large scale change in MTEs in projected warmer and drier climates, through decline in vulnerable functional traits, and thus reduced density of woody species and losses to biodiversity. Further investigation is needed into the combined effect of warming and drought, in addition to impact of altered fire regime, with changes in fire behaviour projected for MTEs as a result of warmer and drier conditions. Investigation that encompasses a broader range of Mediterranean species is also necessary to provide greater accuracy to conclusions drawn here on functional trait responses.

Scientist and decision-makers on the international and national arena agree that the climate is changing and will continue to change over this century. In fact, even if greenhouse gas emissions are brought to a halt today, the earth is already, to an extent, locked in towards climate change over the next 30-40 years, as a result of the emissions that have been released during the development of the modern society. The next 20 to 30 years efforts to respond to climate change will decide the long-term effects of global warming (IPCC, 2007). Sweden and the Swedish business sector have now the opportunity to set an example for other countries, also concerned with sustainable development, by taking advantages of the possibilities to “climate-proof” business activities within commercial boarders. This qualitative study has examined the Swedish businesses’ understanding of the need to respond to climate change, with focus on mitigation and adaptation strategies. The study is based on eleven in-depth interviews with respondents that represent businesses within the sectors housing (including infrastructure), forestry industry (including paper and pulp production) and transport (including public transportation). The sectors were selected on the basis as they were particularly exposed to climatic impacts, but also with the aim to cover a large span of business activities. By applying a conceptual model of how a response process can take place in an organizational context (based on the parameters awareness and concern, idea of response strategy and response options), the understanding of the respondents was analyzed and assessed. The result indicates that the awareness of climate change is now high among the respondents, while the concern of its impacts varies in the sectors. In general, climate change is perceived as a wide-ranging external threat, that foremost changes conditions in the external context. Hence, in the perspective of the respondents, the largest reverse climate effects will not take place in “their backyard”, but will impact others directly and business indirectly. For that reason they do not consider themselves as exposed to direct impacts, but connect climate change to a need to reduce energy consumption and fossil fuel dependency. Hence, in many cases, the climate change issue has transcended from being treated as an environmental issue to an energy issue. Finally, the results indicate that there is a strong link between adaptation and mitigation in a business context. As climate change is perceived as one by many external factors that can impact activities, businesses will not handle it differently from any other external challenges. For this reason, the concept of examining a systems’ totally response capacity, as has been the focus in this study, could improve further studies on businesses’ perspectives on dealing with climate change.

Doutoramento em Engenharia Florestal e dos Recursos Naturais - Instituto Superior de Agronomia / UL<br>To anticipate European climate scenarios for the end of the century, we explored the climate gradient within the REINFFORCE (RÉseau INFrastructure de recherche pour le suivi et l’adaptation des FORêts au Changement climatiquE) arboreta network, established in 38 sites between latitudes 37◦ and 57◦, where 35 tree species are represented. Understanding how climate affects tree phenology, biotic and abiotic vulnerability, is a most important research subject under Climate Change. We focused on determining which climatic variables best explain their survival and growth, and identify which species that are more tolerant to climate variation and those whose growth and survival future climate might constrain. We used empirical models to determine the best climatic predictor variables that explain tree survival and growth, to predict the impact on the specific response of tree species to changing climate scenarios, to evaluate the loss and assess the risk of maintaining or changing species, under each scenario. Considering the scenarios described on IPCC’s Fifth Assessment Report, predictions were run under two main Representative Concentration Pathways (RCP) 4.5 and 8.5. Precipitation-transfer distance was most important for the survival of broadleaved species, whereas growing-season-degree days best explained conifer-tree survival. Growth (annual height increment) was mainly explained by a derived annual dryness index (ADI) for both conifers and broadleaved trees. Species that showed the greatest variation in survival and growth in response to climatic variation included Betula pendula Roth, Pinus elliottii Engelm., and Thuja plicata Donn ex D.Don, and those that were least affected included Quercus shumardii Buckland and Pinus nigra J.F.Arnold. We also demonstrated that provenance differences were significant for Pinus pinea L., Quercus robur L., and Ceratonia siliqua L. A higher survival risk is expected for conifer species, especially for species like Calocedrus decurrens, Pseudotsuga menziesii, and Pinus nigra. For growth, high risk is indicated for Larix decidua, Pinus pinaster, and Betula pendula. Risk distribution points to higher risk at southern sites, and higher production potential for northern sites. Here, we demonstrate the usefulness of infrastructures along a climatic gradient like REINFFORCE to determine major tendencies of tree species responding to climate changes<br>N/A

Amazonia contains the largest expanse of tropical forest in the world and is globally significant as a store of carbon, a regulator of climate and an area of high species diversity. The ability of the Amazonian forests to maintain these important ecological functions is however, increasingly under question in light of recent predictions of climate change. There is currently significant uncertainty in model predictions of how Amazonian forests will respond to predicted future climate change. This thesis reports the finding of two field studies, targeted at understanding the responses of two tropical forest carbon fluxes which are poorly simulated in vegetation models, and two modelling studies, which aim to better quantify uncertainty on model predictions of the effects of current and future climate change on the ecological function of Amazonian forests. The responses of forests to varying magnitudes of seasonal changes in climate which occur across Amazonia can give an important insight into the sensitivity of these forests to climate perturbations and changes. Testing the sensitivity of an Amazonian forest in Tambopata, Peru, to seasonal variations in precipitation and temperature, I find that the stem diameter growth of tropical trees is more sensitive to water availability than temperature changes. The vulnerability of trees to reduced soil water varied between tree classes with different functional traits, including wood density, tree height, tree diameter and tree growth rate. Similarly, I find that the respiration flux from tropical dead wood, at a second site in French Guiana, is highly sensitive to variations in water content. I show that these variations in respiration fluxes can be modelled successfully using seasonal variations in soil water content. To date there are few studies which have comprehensively tested vegetation models using ecological data from Amazon forests. Using data assimilation and nine sources of ecological data I estimate the certainty with which we can parameterise a carbon cycle model to represent the effects of a strong dry season on tropical forests. Using this technique I find, that the carbon balance of Amazonian forests can be very sensitive to reductions in water availability, and that these seasonal changes need to be accurately simulated across models to correctly predict annual carbon budgets. The variability in model responses caused by differences in the way processes are structured and parameterised in vegetation models requires better quantification. Using a model inter-comparison I demonstrate that the relative sensitivity of modelled climate-vegetation feedbacks to changes in ambient air temperature and precipitation is highly variable. I find that although the models showed similar directional responses at both the leaf and canopy scale some models showed a greater sensitivity to temperature and others to drought. I therefore demonstrate the need for greater constraint on modelled responses of Amazonian forests to changes in temperature and precipitation. The impact of climate change on Amazonian forests is an important global issue, yet our knowledge is reliant on our ability to understand the uncertainties on our predictions. Using field data to evaluate and to develop model predictions is a valuable way to reduce the uncertainty associated with modelling future change. This thesis presents an investigation of how tropical forests respond to changes in climate and with what certainty we can model these changes in order to predict the response of Amazon forests to predicted future climate change.

This thesis examines how climate change is being integrated within India's national and state government water policy and management practices. Climate change poses significant challenges to the management of non-stationary hydro-meteorological conditions, whilst meeting rising water demand. The nature and orientation of the Indian government's water institutional approach compounds this challenge, due to the1r focus on large-scale infrastructure-based supply-side water management. This research takes an interdisciplinary political ecology approach to examine the Indian hydrocracy's response, namely, the Ministry of Water Resources' (MWR) policy response to climate change, and the state level response by the Andhra Pradesh (AP) Irrigation Department. The analysis is based on policy documents and other government reports, interviews with policy makers and water managers, and non-government water experts 1n India, conducted between 2008 and 2011. The research draws on theoretical groundings of the linear and interactive models to understand public policy processes, water management paradigms including the hydraulic mission, river basin trajectory and institutional reform theory to understand the process and pace of government change. The Indian water policy experience will generate insights into the use of water policy to respond to climate change. The results indicate that climate change is being integrated within policy and water management practices as a continuation of infrastructure-based supply approaches to water management. This approach is facilitated by the uncertainty of climate change projections and impacts, which provide plasticity for it to be used to strengthen a sanctioned 'water for food' government discourse and hence continue India's hydraulic mission. The MWR and AP Irrigation Department appear resistant to change their strategic approach to water management. However, certain reformist actors within the margins of government are endeavouring to operationalise demand management strategies and institutional reform measures, broadly representing a reflexive modernity stage of water management. Insights into the Indian water policy process highlight numerous challenges to implementation, consistent with an interactive theoretical model of public policy. Implementation challenges of paramount importance include the politically contested nature of water management which serves vested political and financial interests, and the inertia of government, characterised by centralised and hierarchical structures and procedures. The government appears to be operating within the limits of a linear theoretical model of public policy, recommending demand management and institutional reform 'statements of policy intent', but without offering a suitable institutional approach to address implementation challenges. The hydrocracy is largely permitted to continue its approach within the wider political context in India, with other actors implicitly supporting and benefiting from large-scale water infrastructure. In conclusion, this research finds that both continuity and change co-exist within government water management in India. Resistance to change endures, whilst at the same time, certain reformist actors are intent to navigate the complex and uncertain nature of institutional reform.

The current cycle of climate change along with increases in hurricane activity, changing precipitation patterns, glacial melt, and other extremes of weather has led to interest and research into the global correlation or teleconnection between these events. Examination of historical climate records, proxies and observations is leading to formulation of hypotheses of climate dynamics with modeling and simulation being used to test these hypotheses as well as making projections. Ocean currents are believed to be an important factor in climate change with thermohaline circulation (THC) fluctuations being implicated in past cycles of abrupt change. Freshwater water discharge into high-latitude oceans attributed to changing precipitation patterns and glacial melt, particularly the North Atlantic, has also been associated with historical abrupt climate changes and is believed to have inhibited or shut down the THC overturning mechanism by diluting saline surface waters transported from the tropics. Here we analyze outputs of general circulation model (GCM) simulations parameterized by different levels of freshwater flux (no flux (control), 0.1 Sverdrup (Sv) and 1.0 Sv) with respect to tropical cyclone-like vortices (TCLVs) to determine any trend in simulated tropical storm frequency, duration, and location relative to flux level, as well as considering the applicability of using GCMs for tropical weather research. Increasing flux levels produced fewer storms and storm days, increased storm duration, a southerly and westerly shift (more pronounced for the 0.1 Sv level) in geographic distribution and increased activity near the African coast (more pronounced for the 1.0 Sv level). Storm intensities and tracks were not realistic compared to observational (real-life) values and is attributed to the GCM resolution not being fine enough to realistically simulate storm (microscale) dynamics.<br>Ph.D.<br>Other<br>Sciences<br>Modeling and Simulation PhD

Climate change is likely to alter plant species composition and interactions between plants and soil microbes that together dictate the quantity and quality of forage produced in pastures, the base of animal production in central Kentucky. This study assessed the seasonal dynamics of soil microbes and their response to increased temperature (+3oC) and growing season precipitation (+30% of the mean annual). Total soil microbial biomass, community composition, enzyme activities, potential carbon mineralization, and catabolic responses to selected substrates were measured seasonally in the different climate treatments. In this system, seasonal variability was a dominant driving factor for all the soil microbial characteristics that I investigated. Summer maxima and winter minima were identified in the active microbial biomass, while soil microbial community structure differed between each season. Extracellular enzyme activities were generally highest in either the spring or summer, while seasonal patterns for each substrate were unique across catabolic response profiles. Climate treatments produced few significant main or interactive effects on the soil microbial biomass and function. This resiliency, coupled with evidence of functional redundancy, suggests that central Kentucky pasture ecosystems may be well-equipped to handle future environmental stress associated with climate change and to maintain critical ecosystem services.