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We document the individual willingness to act against climate change and study the role of social norms in a large sample of US adults. Individual beliefs about social norms positively predict pro-climate donations, comparable in strength to universal moral values and economic preferences such as patience and reciprocity. However, we document systematic misperceptions of social norms. Respondents vastly underestimate the prevalence of climate-friendly behaviors and norms. Correcting these misperceptions in an experiment causally raises individual willingness to act against climate change as well as individual support for climate policies. The effects are strongest for individuals who are skeptical about the existence and threat of global warming.
This paper studies the macro-financial implications of using carbon prices to achieve ambitious greenhouse gas (GHG) emission reduction targets. My empirical evidence shows a 0.6% output loss and a rise of 0.3% in inflation in response to a 1% shock on carbon policy. Furthermore, I also observe financial instability and allocation effects between the clean and highly polluted energy sectors. To have a better prediction of medium and long-term impact, using a medium-large macro-financial DSGE model with environmental aspects, I show the recessionary effect of an ambitious carbon price implementation to achieve climate targets, a 40% reduction in GHG emission causes a 0.7% output loss while reaching a zero-emission economy in 30 years causes a 2.6% output loss. I document an amplified effect of the banking sector during the transition path. The paper also uncovers the beneficial role of pre-announcements of carbon policies in mitigating inflation volatility by 0.2% at its peak, and our results suggest well-communicated carbon policies from authorities and investing to expand the green sector. My findings also stress the use of optimal green monetary and financial policies in mitigating the effects of transition risk and assisting the transition to a zero-emission world. Utilizing a heterogeneous approach with macroprudential tools, I find that optimal macroprudential tools can mitigate the output loss by 0.1% and investment loss by 1%. Importantly, my work highlights the use of capital flow management in the green transition when a global cooperative solution is challenging.
Climate change has become one of the most prominent concerns globally. In this paper, the authors study the transition risk of greenhouse gas emission reduction in structural environmental-macroeconomic DSGE models. First, they analyze the uncertainty in model prediction on the effect of unanticipated and pre-announced carbon price increases. Second, they conduct optimal model-robust policy in different settings. They find that reducing emissions by 40% causes 0.7% to 4% output loss with 2% on average. Pre-announcement of carbon prices affects the inflation dynamics significantly. The central bank should react slightly less to inflation and output growth during the transition risk. With optimal carbon price designs, it should react even less to inflation, and more to output growth.
Local climate change risk assessments (LCCRAs) are best supported by a quantitative integration of physical hazards, exposures and vulnerabilities that includes the characterization of uncertainties. We propose to use Bayesian Networks (BNs) for this task and show how to integrate freely-available output of multiple global hydrological models (GHMs) into BNs, in order to probabilistically assess risks for water supply. Projected relative changes in hydrological variables computed by three GHMs driven by the output of four global climate models were processed using MATLAB, taking into account local information on water availability and use. A roadmap to set up BNs and apply probability distributions of risk levels under historic and future climate and water use was co-developed with experts from the Maghreb (Tunisia, Algeria, Morocco) who positively evaluated the BN application for LCCRAs. We conclude that the presented approach is suitable for application in the many LCCRAs necessary for successful adaptation to climate change world-wide.
New particle formation in the upper free troposphere is a major global source of cloud condensation nuclei (CCN)1,2,3,4. However, the precursor vapours that drive the process are not well understood. With experiments performed under upper tropospheric conditions in the CERN CLOUD chamber, we show that nitric acid, sulfuric acid and ammonia form particles synergistically, at rates that are orders of magnitude faster than those from any two of the three components. The importance of this mechanism depends on the availability of ammonia, which was previously thought to be efficiently scavenged by cloud droplets during convection. However, surprisingly high concentrations of ammonia and ammonium nitrate have recently been observed in the upper troposphere over the Asian monsoon region5,6. Once particles have formed, co-condensation of ammonia and abundant nitric acid alone is sufficient to drive rapid growth to CCN sizes with only trace sulfate. Moreover, our measurements show that these CCN are also highly efficient ice nucleating particles—comparable to desert dust. Our model simulations confirm that ammonia is efficiently convected aloft during the Asian monsoon, driving rapid, multi-acid HNO3–H2SO4–NH3 nucleation in the upper troposphere and producing ice nucleating particles that spread across the mid-latitude Northern Hemisphere.
The calcareous substrate of spring-fed fens makes them unique islands of biodiversity, hosting endangered, vulnerable, and protected vascular plants. Hence, spring-fed fens ecosystems require special conservation attention because many of them are destroyed (e.g. drained, forested) and it is extremely difficult or even impossible to restore the unique hydrogeological and geochemical conditions enabling their function. The long-term perspective of paleoecological studies allows indication of former wetland ecosystem states and provides understanding of their development over millennia. To examine the late Holocene dynamics of a calcareous spring-fed fen (Raganu Mire) ecosystem on the Baltic Sea coast (Latvia) in relation to environmental changes, substrate and human activity, we have undertaken high-resolution analyses of plant macrofossils, pollen, mollusc, stable carbon (δ13C) and oxygen (δ18O) isotopes combined with radiocarbon dating (AMS) in three coring locations. Our study revealed that peat deposits began accumulating ca. 7000 cal. yr BP and calcareous deposits (tufa) from 1450 cal. yr BP, coinciding with regional hydrological changes. Several fire events occurred between 4000 and 1600 cal. yr BP, which appeared to have had a limited effect on local vegetation. The most significant changes in the forest and peatland ecosystems were at 3200 cal. yr BP associated with a dry climate stage and high fire activity, and then between 1400 and 500 cal. yr BP potentially associated with temperature changes during the Medieval Climate Anomaly (MCA) and Little Ice Age. Hydrological disturbances in the peatland catchment from 1400 cal. yr BP were most likely strengthened by human activity (deforestation) in this region. The relationship between the development of this peatland and changes in its catchment area, such as land cover changes or fluctuations in groundwater levels, suggest that protection and restoration of spring-fed fen ecosystems should also include the surrounding catchment. The presence of calcareous sediments, as well as appropriate temperature and local hydrological conditions appear to be the most crucial factors controlling Cladium marisus populations in our site - currently at the eastern limit of its distribution in Europe.
Global biodiversity is changing rapidly and contemporary climate change is an important driver of this change. As climate change continues, the challenge is to understand how it may affect the future of biodiversity. This is relevant to informing policy and conservation, but it requires reliable future projections of biodiversity. Biodiversity is the variety of life on Earth which includes the diversity of species. The species on Earth are linked in diverse networks of biotic interactions. Interacting species can respond differently to climate change. This can cause spatial or temporal mismatches between interacting species and result in secondary extinctions of species that lose obligate interaction partners. Yet, accounting for biotic interactions in biodiversity projections remains challenging. One way to address this challenge is the use of trait-based approaches because the impact of climate change on interacting species is influenced by species’ functional traits, i.e., measurable characteristics of the species that influence their abiotic and biotic interactions. First, species’ functional traits influence how species respond to climate change. Second, they influence whether the species find compatible interaction partners in reshuffled species assemblages under climate change. Thus, the overarching aim of this dissertation was to explore how trait-based approaches can increase our understanding of how climate change might affect interacting species. For this, I focussed on interactions between fleshy-fruited plants and avian frugivores along a tropical elevational gradient.
I investigated three principal research questions. First, I investigated how traits related to the sensitivity of avian frugivores to climate change and their adaptive capacity vary along elevation and covary across species. I combined estimates of species’ climatic niche breadth (approximating species’ sensitivity) with traits influencing species’ dispersal ability, dietary niche breadth and habitat niche breadth (aspects of species’ adaptive capacity). Species’ climatic niche breadth increased with increasing elevation, while their dispersal ability and dietary niche breadth decreased with increasing elevation. Across species, there was no significant relationship of the sensitivity of the avian frugivores to climate change and their adaptive capacity. The opposing patterns of species’ sensitivity to climate change and their adaptive capacity along elevation imply that species from assemblages at different elevations may respond differently to climate change. The independence between species’ sensitivity and adaptive capacity suggests that it is important to account for both sensitivity and adaptive capacity to fully understand how climate change might affect biodiversity.
Second, I assessed how climate change might influence the co-occurrence of interaction partners with compatible traits, i.e., the functional correspondence of interacting species. I integrated future projections of species’ elevational ranges considering different vertical dispersal scenarios with analyses of the functional diversity of interacting species assemblages. The functional correspondence of fleshy-fruited plants and avian frugivores was lowest if plant and bird species were projected to contract their ranges towards higher elevations in response to increasing temperatures. Contrastingly, if species were projected to expand their ranges upslope, the functional correspondence remained close. The low functional correspondence under a scenario of range contraction indicates that plant species with specific traits might miss compatible interaction partners in future assemblages. This could negatively affect their seed dispersal ability. These results suggest that ensuring the integrity of biotic interactions under climate change requires that species can shift their ranges upslope unlimitedly.
Third, I examined whether avian seed dispersal is sufficient for plants to track future temperature change along the elevational gradient. With a trait-based modelling approach, I simulated seed-dispersal distances avian frugivores can provide to fleshy-fruited woody plant species and quantified the number of long-distance dispersal events the plant species would require to fully track projected temperature shifts along elevation. Most plant species were projected to require several long-distance dispersal events to fully track the projected temperature shifts in time. However, the number of required long-distance dispersal events varied with the degree of trait matching and plant species’ traits. These findings suggest that avian seed dispersal is insufficient for plants to track future temperature change along the elevational gradient as woody plant species might not be able to undergo several consecutive long-distance dispersal events within a short time window, due to their long maturation times. These results also imply that the ability of bird-dispersed plant species to track climate change is associated with the specialization of the seed dispersal system and with plant species’ traits.
Trait-based approaches are promising tools to study impacts of climate change on interacting species. The trait-based approaches that I have developed in this thesis are applicable more widely, e.g., to other types of biotic interactions, or to assess the effects of other drivers of global change. Moreover, these approaches may be further developed to model changes in biotic interactions under global change more dynamically. Taken together, I have shown how a trait-based perspective could help to account for biotic interactions in biodiversity projections. The development of such approaches and the gained knowledge are urgently needed to facilitate the conservation of biodiversity in a rapidly changing world.
Research on collective resilience processes still lacks a detailed understanding of psychological mechanisms at work when groups cope with adverse conditions, i.e., long-term processes, and how such mechanisms affect physical and mental well-being. As collective resilience will play a crucial part in facing looming climate change-related events such as floods, it is important to investigate these processes further. To this end, this study takes a novel holistic approach by combining resilience research, social psychology, and an archeological perspective to investigate the role of social identity as a collective resilience factor in the past and present. We hypothesize that social identification buffers against the negative effects of environmental threats in participants, which increases somatic symptoms related to stress, in a North Sea region historically prone to floods. A cross-sectional study (N = 182) was conducted to analyze the moderating effects of social identification on the relations between perceived threat of North Sea floods and both well-being and life satisfaction. The results support our hypothesis that social identification attenuates the relationship between threat perception and well-being, such that the relation is weaker for more strongly identified individuals. Contrary to our expectations, we did not find this buffering effect to be present for life satisfaction. Future resilience studies should further explore social identity as a resilience factor and how it operates in reducing environmental stress put on individuals and groups. Further, to help communities living in flood-prone areas better cope with future environmental stress, we recommend implementing interventions strengthening their social identities and hence collective resilience.
Background: In the face of ongoing climate warming, vector-borne diseases are expected to increase in Europe, including tick-borne diseases (TBD). The most abundant tick-borne diseases in Germany are Tick-Borne Encephalitis (TBE) and Lyme Borreliosis (LB), with Ixodes ricinus as the main vector.
Methods: In this study, we display and compare the spatial and temporal patterns of reported cases of human TBE and LB in relation to some associated factors. The comparison may help with the interpretation of observed spatial and temporal patterns.
Results: The spatial patterns of reported TBE cases show a clear and consistent pattern over the years, with many cases in the south and only few and isolated cases in the north of Germany. The identification of spatial patterns of LB disease cases is more difficult due to the different reporting practices in the individual federal states. Temporal patterns strongly fluctuate between years, and are relatively synchronized between both diseases, suggesting common driving factors. Based on our results we found no evidence that weather conditions affect the prevalence of both diseases. Both diseases show a gender bias with LB bing more commonly diagnosed in females, contrary to TBE being more commonly diagnosed in males.
Conclusion: For a further investigation of of the underlying driving factors and their interrelations, longer time series as well as standardised reporting and surveillance system would be required.
This chapter argues that paying attention to the weather and its associated processes of geological, biological, and social weathering can destabilize knowledge traditions that insist on dichotomies. Looking to specific histories and current conditions in Guyana and Suriname, this chapter shows how notions of weathering can accommodate a wide range of referents, ranging from the weathering of rock to socio-political and historical afterlives of violent colonial displacements.
A list of authors and their affiliations appears at the end of the paper New-particle formation is a major contributor to urban smog, but how it occurs in cities is often puzzling. If the growth rates of urban particles are similar to those found in cleaner environments (1–10 nanometres per hour), then existing understanding suggests that new urban particles should be rapidly scavenged by the high concentration of pre-existing particles. Here we show, through experiments performed under atmospheric conditions in the CLOUD chamber at CERN, that below about +5 degrees Celsius, nitric acid and ammonia vapours can condense onto freshly nucleated particles as small as a few nanometres in diameter. Moreover, when it is cold enough (below −15 degrees Celsius), nitric acid and ammonia can nucleate directly through an acid–base stabilization mechanism to form ammonium nitrate particles. Given that these vapours are often one thousand times more abundant than sulfuric acid, the resulting particle growth rates can be extremely high, reaching well above 100 nanometres per hour. However, these high growth rates require the gas-particle ammonium nitrate system to be out of equilibrium in order to sustain gas-phase supersaturations. In view of the strong temperature dependence that we measure for the gas-phase supersaturations, we expect such transient conditions to occur in inhomogeneous urban settings, especially in wintertime, driven by vertical mixing and by strong local sources such as traffic. Even though rapid growth from nitric acid and ammonia condensation may last for only a few minutes, it is nonetheless fast enough to shepherd freshly nucleated particles through the smallest size range where they are most vulnerable to scavenging loss, thus greatly increasing their survival probability. We also expect nitric acid and ammonia nucleation and rapid growth to be important in the relatively clean and cold upper free troposphere, where ammonia can be convected from the continental boundary layer and nitric acid is abundant from electrical storms.
Global impact models represent process-level understanding of how natural and human systems may be affected by climate change. Their projections are used in integrated assessments of climate change. Here we test, for the first time, systematically across many important systems, how well such impact models capture the impacts of extreme climate conditions. Using the 2003 European heat wave and drought as a historical analogue for comparable events in the future, we find that a majority of models underestimate the extremeness of impacts in important sectors such as agriculture, terrestrial ecosystems, and heat-related human mortality, while impacts on water resources and hydropower are overestimated in some river basins; and the spread across models is often large. This has important implications for economic assessments of climate change impacts that rely on these models. It also means that societal risks from future extreme events may be greater than previously thought.
Background: Many fungal species occur across a variety of habitats. Particularly lichens, fungi forming symbioses with photosynthetic partners, have evolved remarkable tolerances for environmental extremes. Despite their ecological importance and ubiquity, little is known about the genetic basis of adaption in lichen populations. Here we studied patterns of genome-wide differentiation in the lichen-forming fungus Lasallia pustulata along an altitudinal gradient in the Mediterranean region. We resequenced six populations as pools and identified highly differentiated genomic regions. We then detected gene-environment correlations while controlling for shared population history and pooled sequencing bias, and performed ecophysiological experiments to assess fitness differences of individuals from different environments.
Results: We detected two strongly differentiated genetic clusters linked to Mediterranean and temperate-oceanic climate, and an admixture zone, which coincided with the transition between the two bioclimates. High altitude individuals showed ecophysiological adaptations to wetter and more shaded conditions. Highly differentiated genome regions contained a number of genes associated with stress response, local environmental adaptation, and sexual reproduction.
Conclusions: Taken together our results provide evidence for a complex interplay between demographic history and spatially varying selection acting on a number of key biological processes, suggesting a scenario of ecological speciation.
Background: Aedes albopictus and Ae. japonicus are two of the most widespread invasive mosquito species that have recently become established in western Europe. Both species are associated with the transmission of a number of serious diseases and are projected to continue their spread in Europe.
Methods: In the present study, we modelled the habitat suitability for both species under current and future climatic conditions by means of an Ensemble forecasting approach. We additionally compared the modelled MAXENT niches of Ae. albopictus and Ae. japonicus regarding temperature and precipitation requirements.
Results: Both species were modelled to find suitable habitat conditions in distinct areas within Europe: Ae. albopictus within the Mediterranean regions in southern Europe, Ae. japonicus within the more temperate regions of central Europe. Only in few regions, suitable habitat conditions were projected to overlap for both species. Whereas Ae. albopictus is projected to be generally promoted by climate change in Europe, the area modelled to be climatically suitable for Ae. japonicus is projected to decrease under climate change. This projection of range reduction under climate change relies on the assumption that Ae. japonicus is not able to adapt to warmer climatic conditions. The modelled MAXENT temperature niches of Ae. japonicus were found to be narrower with an optimum at lower temperatures compared to the niches of Ae. albopictus.
Conclusions: Species distribution models identifying areas with high habitat suitability can help improving monitoring programmes for invasive species currently in place. However, as mosquito species are known to be able to adapt to new environmental conditions within the invasion range quickly, niche evolution of invasive mosquito species should be closely followed upon in future studies.
This thesis develops a conceptual framework for a better understanding of the impact of slow-onset climate and environmental changes on human migration in developing countries. Its regional focus is on the West African Sahel, where the majority of the population depends on agriculture and thus is highly vulnerable to environmental changes. Migration from fragile environments is predominantly considered one of several household strategies to adapt to and minimise the risk of environmental stress. Based on qualitative and quantitative data from two selected rural study areas, Bandiagara in Mali and Linguère in Senegal, this thesis analyses the drivers of migration from the two areas.
The findings illustrate that, even though people highly depend on the natural environment, migration motives are manifold and that migration often is not a household strategy to cope with environmental changes. Although environmental conditions shape migration in the region and the migrants’ support is crucial for most households, environmental stress plays a relatively small role as a driver of migration - at least in Mali, where it is considerably less important than in Senegal. On the contrary, migration is often driven by better opportunities elsewhere rather than by livelihood stressors in the home area. Particularly the migration of young people is often an individual rather than a household decision and influenced by individual aspirations, such as aspirations for consumer goods or a better future, rather than by environmental stress.
This thesis claims that research should consider people’s capabilities to migrate or to stay as well as their individual aspirations and preferences - in addition to the household’s needs and the opportunities elsewhere. This is important in order to explain why some people stay in and others migrate from an area affected by environmental stress, though living under similar conditions. Depending on people’s capabilities to choose freely between staying and migrating and their preferences and aspirations for one or the other activity, people can either be “voluntary migrants”, “voluntary non-migrants”, “forced migrants” or “trapped people”.
Moreover, it is important to consider social trends and transformation processes in the analysis of the linkages between environment change and migration. Higher education levels and aspirations to a “modern” lifestyle among young people, for instance, might decrease the impact of environmental factors on migration, despite worsening environmental conditions.
This study examines the urban heat island (UHI) of Brussels, for both current (2000–2009) and projected future (2060–2069) climate conditions, by employing very high resolution (250 m) modelling experiments, using the urban boundary layer climate model UrbClim. Meteorological parameters that are related to the intensity of the UHI are identified and it is investigated how these parameters and the magnitude of the UHI evolve for two plausible trajectories for future climate conditions. UHI intensity is found to be strongly correlated to the inversion strength in the lowest 100 m of the atmosphere. The results for the future scenarios indicate that the magnitude of the UHI is expected to decrease slightly due to global warming. This can be attributed to the increased incoming longwave radiation, caused by higher air temperature and humidity values. The presence of the UHI also has a significant impact on the frequency of extreme temperature events in the city area, both in present and future climates, and exacerbates the impact of climate change on the urban population as the amount of heat wave days in the city increases twice as fast as in the rural surroundings.
Background: Mitochondrial genes are among the most commonly used markers in studies of species’ phylogeography and to draw conclusions about taxonomy. The Hyles euphorbiae complex (HEC) comprises six distinct mitochondrial lineages in the Mediterranean region, of which one exhibits a cryptic disjunct distribution. The predominant mitochondrial lineage in most of Europe, euphorbiae, is also present on Malta; however, it is nowadays strangely absent from Southern Italy and Sicily, where it is replaced by 'italica'. A separate biological entity in Italy is further corroborated by larval colour patterns with a congruent, confined suture zone along the Northern Apennines. By means of historic DNA extracted from museum specimens, we aimed to investigate the evolution of the mitochondrial demographic structure of the HEC in Italy and Malta throughout the Twentieth Century.
Results: At the beginning of the Twentieth Century, the European mainland lineages were also present at a moderate frequency in Southern Italy and Sicily. The proportion of 'italica' then steadily increased in this area from below 60 percent to near fixation in about 120 years. Thus, geographical sorting of mitochondrial lineages in the HEC was not as complete then as the current demography suggests. The pattern of an integral 'italica' core region and a disjunct euphorbiae distribution evolved very recently. To explain these strong demographic changes, we propose genetic drift due to anthropogenic habitat loss and fragmentation in combination with an impact from recent climate warming that favoured the spreading of the potentially better adapted 'italica' populations.
Conclusions: The pattern of geographically separated mitochondrial lineages is commonly interpreted as representing long term separated entities. However, our results indicate that such a pattern can emerge surprisingly quickly, even in a widespread and rather common taxon. We thus caution against drawing hasty taxonomic conclusions from biogeographical patterns of mitochondrial markers derived from modern sampling alone.
Die Auswirkungen des globalen Klimawandels werden zunehmend sichtbar. In Deutschland haben sich die Jahresdurchschnittstemperatur im vergangenen Jahrhundert um 1 °C und die jährliche Niederschlagsmenge um + 9 % erhöht. Bezogen auf die Jahreszeiten ergeben sich jedoch deutliche Unterschiede, während die Sommermonate zunehmend niederschlagsärmer werden, erhöht sich die Niederschlagsmenge in den Wintermonaten überproportional (Schönwiese, 2002; Schönwiese & Janoschitz, 2005). Welche Folgen diese Veränderungen für die Waldökosysteme haben werden, wird in der Forstwirtschaft zu nehmend diskutiert. Allerdings gibt es bisher nur ökophysiologische, autökologische Ansätze. Synökologische Ansätze, die insbesondere auch die potenziellen Schadinsekten und damit die indirekten Auswirkungen des Klimawandels berücksichtigen, fehlen zumeist. Dies gilt auch für die Rotbuche deren waldbauliche Zukunft in jüngster Zeit diskutiert wurde (Rennenberg & al., 2004; Ammer & al., 2005; Kölling, & al., 2005).
Die Auswirkungen des ablaufenden Klimawandels werden zunehmend sichtbar. Pflanzenarten wandern nach Norden, beziehungsweise in höher gelegene Lagen. Die Reaktionen sind aber nicht an allen Artarealgrenzen gleich und die Rolle des Klimas muss auch nicht immer an allen Grenzen von gleich grosser Bedeutung sein. Anhand von Fallbeispielen werden ‘erwartete‘ und ‘unerwartete‘ Vegetationsveränderungen vorgestellt und im Hinblick auf die Rolle veränderter Klimabedingungen diskutie
Observed global and European spatiotemporal related fields of surface air temperature, mean-sea-level pressure and precipitation are analyzed statistically with respect to their response to external forcing factors such as anthropogenic greenhouse gases, anthropogenic sulfate aerosol, solar variations and explosive volcanism, and known internal climate mechanisms such as the El Niño-Southern Oscillation (ENSO) and the North Atlantic Oscillation (NAO). As a first step, a principal component analysis (PCA) is applied to the observed spatiotemporal related fields to obtain spatial patterns with linear independent temporal structure. In a second step, the time series of each of the spatial patterns is subject to a stepwise regression analysis in order to separate it into signals of the external forcing factors and internal climate mechanisms as listed above as well as the residuals. Finally a back-transformation leads to the spatiotemporally related patterns of all these signals being intercompared. Two kinds of significance tests are applied to the anthropogenic signals. First, it is tested whether the anthropogenic signal is significant compared with the complete residual variance including natural variability. This test answers the question whether a significant anthropogenic climate change is visible in the observed data. As a second test the anthropogenic signal is tested with respect to the climate noise component only. This test answers the question whether the anthropogenic signal is significant among others in the observed data. Using both tests, regions can be specified where the anthropogenic influence is visible (second test) and regions where the anthropogenic influence has already significantly changed climate (first test).