@techreport{ŠedovaČizmaziovaCook2021,
  type      = {Working Paper},
  author    = {Šedov{\´a}, Barbora and Čizmaziov{\´a}, Lucia and Cook, Athene},
  title     = {A meta-analysis of climate migration literature},
  series = {CEPA Discussion Papers},
  journal   = {CEPA Discussion Papers},
  number    = {29},
  issn      = {2628-653X},
  doi       = {10.25932/publishup-49982},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-499827},
  pages     = {83},
  year      = {2021},
  abstract  = {The large literature that aims to find evidence of climate migration delivers mixed findings. This meta-regression analysis i) summarizes direct links between adverse climatic events and migration, ii) maps patterns of climate migration, and iii) explains the variation in outcomes. Using a set of limited dependent variable models, we meta-analyze thus-far the most comprehensive sample of 3,625 estimates from 116 original studies and produce novel insights on climate migration. We find that extremely high temperatures and drying conditions increase migration. We do not find a significant effect of sudden-onset events. Climate migration is most likely to emerge due to contemporaneous events, to originate in rural areas and to take place in middle-income countries, internally, to cities. The likelihood to become trapped in affected areas is higher for women and in low-income countries, particularly in Africa. We uniquely quantify how pitfalls typical for the broader empirical climate impact literature affect climate migration findings. We also find evidence of different publication biases.},
  language  = {en}
}
@phdthesis{Schmidt2024,
  author    = {Schmidt, Lena Katharina},
  title     = {Altered hydrological and sediment dynamics in high-alpine areas - Exploring the potential of machine-learning for estimating past and future changes},
  doi       = {10.25932/publishup-62330},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-623302},
  school      = {Universit{\"a}t Potsdam},
  pages     = {xxi, 129},
  year      = {2024},
  abstract  = {Climate change fundamentally transforms glaciated high-alpine regions, with well-known cryospheric and hydrological implications, such as accelerating glacier retreat, transiently increased runoff, longer snow-free periods and more frequent and intense summer rainstorms. These changes affect the availability and transport of sediments in high alpine areas by altering the interaction and intensity of different erosion processes and catchment properties. Gaining insight into the future alterations in suspended sediment transport by high alpine streams is crucial, given its wide-ranging implications, e.g. for flood damage potential, flood hazard in downstream river reaches, hydropower production, riverine ecology and water quality. However, the current understanding of how climate change will impact suspended sediment dynamics in these high alpine regions is limited. For one, this is due to the scarcity of measurement time series that are long enough to e.g. infer trends. On the other hand, it is difficult - if not impossible - to develop process-based models, due to the complexity and multitude of processes involved in high alpine sediment dynamics. Therefore, knowledge has so far been confined to conceptual models (which do not facilitate deriving concrete timings or magnitudes for individual catchments) or qualitative estimates ('higher export in warmer years') that may not be able to capture decreases in sediment export. Recently, machine-learning approaches have gained in popularity for modeling sediment dynamics, since their black box nature tailors them to the problem at hand, i.e. relatively well-understood input and output data, linked by very complex processes. Therefore, the overarching aim of this thesis is to estimate sediment export from the high alpine {\"O}tztal valley in Tyrol, Austria, over decadal timescales in the past and future - i.e. timescales relevant to anthropogenic climate change. This is achieved by informing, extending, evaluating and applying a quantile regression forest (QRF) approach, i.e. a nonparametric, multivariate machine-learning technique based on random forest. The first study included in this thesis aimed to understand present sediment dynamics, i.e. in the period with available measurements (up to 15 years). To inform the modeling setup for the two subsequent studies, this study identified the most important predictors, areas within the catchments and time periods. To that end, water and sediment yields from three nested gauges in the upper {\"O}tztal, Vent, S{\"o}lden and Tumpen (98 to almost 800 km² catchment area, 930 to 3772 m a.s.l.) were analyzed for their distribution in space, their seasonality and spatial differences therein, and the relative importance of short-term events. The findings suggest that the areas situated above 2500 m a.s.l., containing glacier tongues and recently deglaciated areas, play a pivotal role in sediment generation across all sub-catchments. In contrast, precipitation events were relatively unimportant (on average, 21 \% of annual sediment yield was associated to precipitation events). Thus, the second and third study focused on the Vent catchment and its sub-catchment above gauge Vernagt (11.4 and 98 km², 1891 to 3772 m a.s.l.), due to their higher share of areas above 2500 m. Additionally, they included discharge, precipitation and air temperature (as well as their antecedent conditions) as predictors. The second study aimed to estimate sediment export since the 1960s/70s at gauges Vent and Vernagt. This was facilitated by the availability of long records of the predictors, discharge, precipitation and air temperature, and shorter records (four and 15 years) of turbidity-derived sediment concentrations at the two gauges. The third study aimed to estimate future sediment export until 2100, by applying the QRF models developed in the second study to pre-existing precipitation and temperature projections (EURO-CORDEX) and discharge projections (physically-based hydroclimatological and snow model AMUNDSEN) for the three representative concentration pathways RCP2.6, RCP4.5 and RCP8.5. The combined results of the second and third study show overall increasing sediment export in the past and decreasing export in the future. This suggests that peak sediment is underway or has already passed - unless precipitation changes unfold differently than represented in the projections or changes in the catchment erodibility prevail and override these trends. Despite the overall future decrease, very high sediment export is possible in response to precipitation events. This two-fold development has important implications for managing sediment, flood hazard and riverine ecology. This thesis shows that QRF can be a very useful tool to model sediment export in high-alpine areas. Several validations in the second study showed good performance of QRF and its superiority to traditional sediment rating curves - especially in periods that contained high sediment export events, which points to its ability to deal with threshold effects. A technical limitation of QRF is the inability to extrapolate beyond the range of values represented in the training data. We assessed the number and severity of such out-of-observation-range (OOOR) days in both studies, which showed that there were few OOOR days in the second study and that uncertainties associated with OOOR days were small before 2070 in the third study. As the pre-processed data and model code have been made publically available, future studies can easily test further approaches or apply QRF to further catchments.},
  language  = {en}
}
@phdthesis{Popp2007,
  author    = {Popp, Alexander},
  title     = {An integrated modelling approach for sustainable management of semi-arid and arid rangelands},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-15103},
  school      = {Universit{\"a}t Potsdam},
  year      = {2007},
  abstract  = {The need to develop sustainable resource management strategies for semi-arid and arid rangelands is acute as non-adapted grazing strategies lead to irreversible environmental problems such as desertification and associated loss of economic support to society. In such vulnerable ecosystems, successful implementation of sustainable management strategies depends on well-founded under-standing of processes at different scales that underlay the complex system dynamic. There is ample evidence that, in contrast to traditional sectoral approaches, only interdisciplinary research does work for resolving problems in conservation and natural resource management. In this thesis I combined a range of modeling approaches that integrate different disciplines and spatial scales in order to contribute to basic guidelines for sustainable management of semi-arid and arid range-lands. Since water availability and livestock management are seen as most potent determinants for the dynamics of semi-arid and arid ecosystems I focused on (i) the interaction of ecological and hydro-logical processes and (ii) the effect of farming strategies. First, I developed a grid-based and small-scaled model simulating vegetation dynamics and inter-linked hydrological processes. The simulation results suggest that ecohydrological interactions gain importance in rangelands with ascending slope where vegetation cover serves to obstruct run-off and decreases evaporation from the soil. Disturbances like overgrazing influence these positive feedback mechanisms by affecting vegetation cover and composition. In the second part, I present a modeling approach that has the power to transfer and integrate ecological information from the small scale vegetation model to the landscape scale, most relevant for the conservation of biodiversity and sustainable management of natural resources. I combined techniques of stochastic modeling with remotely sensed data and GIS to investigate to which ex-tent spatial interactions, like the movement of surface water by run-off in water limited environments, affect ecosystem functioning at the landscape scale. My simulation experiments show that overgrazing decreases the number of vegetation patches that act as hydrological sinks and run-off increases. The results of both simulation models implicate that different vegetation types should not only be regarded as provider of forage production but also as regulator of ecosystem functioning. Vegetation patches with good cover of perennial vegetation are capable to catch and conserve surface run-off from degraded surrounding areas. Therefore, downstream out of the simulated system is prevented and efficient use of water resources is guaranteed at all times. This consequence also applies to commercial rotational grazing strategies for semi-arid and arid rangelands with ascending slope where non-degraded paddocks act as hydrological sinks. Finally, by the help of an integrated ecological-economic modeling approach, I analyzed the relevance of farmers' ecological knowledge for longterm functioning of semi-arid and arid grazing systems under current and future climatic conditions. The modeling approach consists of an ecological and an economic module and combines relevant processes on either level. Again, vegetation dynamics and forage productivity is derived by the small-scaled vegetation model. I showed that sustainable management of semi-arid and arid rangelands relies strongly on the farmers' knowledge on how the ecosystem works. Furthermore, my simulation results indicate that the projected lower annual rainfall due to climate change in combination with non-adapted grazing strategies adds an additional layer of risk to these ecosystems that are already prone to land degradation. All simulation models focus on the most essential factors and ignore specific details. Therefore, even though all simulation models are parameterized for a specific dwarf shrub savanna in arid southern Namibia, the conclusions drawn are applicable for semi-arid and arid rangelands in general.},
  language  = {en}
}
@misc{SmithBookhagen2020,
  author    = {Smith, Taylor and Bookhagen, Bodo},
  title     = {Assessing Multi-Temporal Snow-Volume Trends in High Mountain Asia From 1987 to 2016 Using High-Resolution Passive Microwave Data},
  series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  number    = {1020},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-48417},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-484176},
  pages     = {15},
  year      = {2020},
  abstract  = {High Mountain Asia (HMA) is dependent upon both the amount and timing of snow and glacier meltwater. Previous model studies and coarse resolution (0.25° × 0.25°, ∼25 km × 25 km) passive microwave assessments of trends in the volume and timing of snowfall, snowmelt, and glacier melt in HMA have identified key spatial and seasonal heterogeneities in the response of snow to changes in regional climate. Here we use recently developed, continuous, internally consistent, and high-resolution passive microwave data (3.125 km × 3.125 km, 1987-2016) from the special sensor microwave imager instrument family to refine and extend previous estimates of changes in the snow regime of HMA. We find an overall decline in snow volume across HMA; however, there exist spatially contiguous regions of increasing snow volume—particularly during the winter season in the Pamir, Karakoram, Hindu Kush, and Kunlun Shan. Detailed analysis of changes in snow-volume trends through time reveal a large step change from negative trends during the period 1987-1997, to much more positive trends across large regions of HMA during the periods 1997-2007 and 2007-2016. We also find that changes in high percentile monthly snow-water volume exhibit steeper trends than changes in low percentile snow-water volume, which suggests a reduction in the frequency of high snow-water volumes in much of HMA. Regions with positive snow-water storage trends generally correspond to regions of positive glacier mass balances.},
  language  = {en}
}
@phdthesis{Courtin2023,
  author    = {Courtin, J{\´e}r{\´e}my},
  title     = {Biodiversity changes in Siberia between quaternary glacial and interglacial stages},
  doi       = {10.25932/publishup-59584},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-595847},
  school      = {Universit{\"a}t Potsdam},
  pages     = {vi, 199},
  year      = {2023},
  abstract  = {Der vom Menschen verursachte Klimawandel wirkt sich auf die biologische Vielfalt der Erde und damit auf die {\"O}kosysteme und ihre Leistungen aus. Die {\"O}kosysteme in den hohen Breitengraden sind aufgrund der verst{\"a}rkten Erw{\"a}rmung an den Polen noch st{\"a}rker betroffen als der Rest der n{\"o}rdlichen Hemisph{\"a}re. Dennoch ist es schwierig, die Dynamik von {\"O}kosystemen in den hohen Breitengraden vorherzusagen, da die Wechselwirkungen zwischen abiotischen und biotischen Komponenten sehr komplex sind. Da die Vergangenheit der Schl{\"u}ssel zur Zukunft ist, ist die Interpretation vergangener {\"o}kologischer Ver{\"a}nderungen m{\"o}glich, um laufende Prozesse besser zu verstehen. Im Quart{\"a}r durchlief das Pleistoz{\"a}n mehrere glaziale und interglaziale Phasen, welche die {\"O}kosysteme der Vergangenheit beeinflussten. W{\"a}hrend des letzten Glazials bedeckte die pleistoz{\"a}ne Steppentundra den gr{\"o}ßten Teil der unvergletscherten n{\"o}rdlichen Hemisph{\"a}re und verschwand parallel zum Aussterben der Megafauna am {\"U}bergang zum Holoz{\"a}n (vor etwa 11 700 Jahren). Der Ursprung des R{\"u}ckgangs der Steppentundra ist nicht gut erforscht, und die Kenntnis {\"u}ber die Mechanismen, die zu den Ver{\"a}nderungen in den vergangenen Lebensgemeinschaften und {\"O}kosystemen gef{\"u}hrt haben, ist von hoher Priorit{\"a}t, da sie wahrscheinlich mit denen vergleichbar sind, die sich auf moderne {\"O}kosysteme auswirken. Durch die Entnahme von See- oder Permafrostkernsedimenten kann die vergangene Artenvielfalt an den {\"U}berg{\"a}ngen zwischen Eis- und Zwischeneiszeiten untersucht werden. Sibirien und Beringia waren der Ursprung der Ausbreitung der Steppentundra, weshalb die Untersuchung dieses Gebiets hohe Priorit{\"a}t hat. Bis vor kurzem waren Makrofossilien und Pollen die g{\"a}ngigsten Methoden. Sie dienen der Rekonstruktion vergangener Ver{\"a}nderungen in der Zusammensetzung der Bev{\"o}lkerung, haben aber ihre Grenzen und Schw{\"a}chen. Seit Ende des 20. Jahrhunderts kann auch sediment{\"a}re alte DNA (sedaDNA) untersucht werden. Mein Hauptziel war es, durch den Einsatz von sedaDNA-Ans{\"a}tzen wissenschaftliche Beweise f{\"u}r Ver{\"a}nderungen in der Zusammensetzung und Vielfalt der {\"O}kosysteme der n{\"o}rdlichen Hemisph{\"a}re am {\"U}bergang zwischen den quart{\"a}ren Eiszeiten und Zwischeneiszeiten zu liefern. In dieser Arbeit liefere ich Momentaufnahmen ganzer alter {\"O}kosysteme und beschreibe die Ver{\"a}nderungen in der Zusammensetzung zwischen Quart{\"a}rglazialen und Interglazialen und best{\"a}tige die Vegetationszusammensetzung sowie die r{\"a}umlichen und zeitlichen Grenzen der pleistoz{\"a}nen Steppentundra. Ich stelle einen allgemeinen Verlust der Pflanzenvielfalt fest, wobei das Aussterben der Pflanzen parallel zum Aussterben der Megafauna verlief. Ich zeige auf, wie der Verlust der biotischen Widerstandsf{\"a}higkeit zum Zusammenbruch eines zuvor gut etablierten Systems f{\"u}hrte, und diskutiere meine Ergebnisse im Hinblick auf den laufenden Klimawandel. Mit weiteren Arbeiten zur Eingrenzung von Verzerrungen und Grenzen kann sedaDNA parallel zu den etablierteren Makrofossilien- und Pollenans{\"a}tzen verwendet werden oder diese sogar ersetzen, da meine Ergebnisse die Robustheit und das Potenzial von sedaDNA zur Beantwortung neuer pal{\"a}o{\"o}kologischer Fragen wie Ver{\"a}nderungen der Pflanzenvielfalt und -verluste belegen und Momentaufnahmen ganzer alter Biota liefern.},
  language  = {en}
}
@phdthesis{Gudipudi2017,
  author    = {Gudipudi, Venkata Ramana},
  title     = {Cities and global sustainability},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-407113},
  school      = {Universit{\"a}t Potsdam},
  pages     = {xxii, 101},
  year      = {2017},
  abstract  = {In the wake of 21st century, humanity witnessed a phenomenal raise of urban agglomerations as powerhouses for innovation and socioeconomic growth. Driving much of national (and in few instances even global) economy, such a gargantuan raise of cities is also accompanied by subsequent increase in energy, resource consumption and waste generation. Much of anthropogenic transformation of Earth's environment in terms of environmental pollution at local level to planetary scale in the form of climate change is currently taking place in cities. Projected to be crucibles for entire humanity by the end of this century, the ultimate fate of humanity predominantly lies in the hands of technological innovation, urbanites' attitudes towards energy/resource consumption and development pathways undertaken by current and future cities. Considering the unparalleled energy, resource consumption and emissions currently attributed to global cities, this thesis addresses these issues from an efficiency point of view. More specifically, this thesis addresses the influence of population size, density, economic geography and technology in improving urban greenhouse gas (GHG) emission efficiency and identifies the factors leading to improved eco-efficiency in cities. In order to investigate the in uence of these factors in improving emission and resource efficiency in cities, a multitude of freely available datasets were coupled with some novel methodologies and analytical approaches in this thesis. Merging the well-established Kaya Identity to the recently developed urban scaling laws, an Urban Kaya Relation is developed to identify whether large cities are more emission efficient and the intrinsic factors leading to such (in)efficiency. Applying Urban Kaya Relation to a global dataset of 61 cities in 12 countries, this thesis identifed that large cities in developed regions of the world will bring emission efficiency gains because of the better technologies implemented in these cities to produce and utilize energy consumption while the opposite is the case for cities in developing regions. Large cities in developing countries are less efficient mainly because of their affluence and lack of efficient technologies. Apart from the in uence of population size on emission efficiency, this thesis identified the crucial role played by population density in improving building and on-road transport sector related emission efficiency in cities. This is achieved by applying the City Clustering Algorithm (CCA) on two different gridded land use datasets and a standard emission inventory to attribute these sectoral emissions to all inhabited settlements in the USA. Results show that doubling the population density would entail a reduction in the total CO2 emissions in buildings and on-road sectors typically by at least 42 \%. Irrespective of their population size and density, cities are often blamed for their intensive resource consumption that threatens not only local but also global sustainability. This thesis merged the concept of urban metabolism with benchmarking and identified cities which are eco-efficient. These cities enable better socioeconomic conditions while being less burden to the environment. Three environmental burden indicators (annual average NO2 concentration, per capita waste generation and water consumption) and two socioeconomic indicators (GDP per capita and employment ratio) for 88 most populous European cities are considered in this study. Using two different non-parametric ranking methods namely regression residual ranking and Data Envelopment Analysis (DEA), eco-efficient cities and their determining factors are identified. This in-depth analysis revealed that mature cities with well-established economic structures such as Munich, Stockholm and Oslo are eco-efficient. Further, correlations between objective eco-efficiency ranking with each of the indicator rankings and the ranking of urbanites' subjective perception about quality of life are analyzed. This analysis revealed that urbanites' perception about quality of life is not merely confined to the socioeconomic well-being but rather to their combination with lower environmental burden. In summary, the findings of this dissertation has three general conclusions for improving emission and ecological efficiency in cities. Firstly, large cities in emerging nations face a huge challenge with respect to improving their emission efficiency. The task in front of these cities is threefold: (1) deploying efficient technologies for the generation of electricity and improvement of public transportation to unlock their leap frogging potential, (2) addressing the issue of energy poverty and (3) ensuring that these cities do not develop similar energy consumption patterns with infrastructure lock-in behavior similar to those of cities in developed regions. Secondly, the on-going urban sprawl as a global phenomenon will decrease the emission efficiency within the building and transportation sector. Therefore, local policy makers should identify adequate fiscal and land use policies to curb urban sprawl. Lastly, since mature cities with well-established economic structures are more eco-efficient and urbanites' perception re ects its combination with decreasing environmental burden; there is a need to adopt and implement strategies which enable socioeconomic growth in cities whilst decreasing their environment burden.},
  language  = {en}
}
@misc{BansardPattbergWiderberg2017,
  author    = {Bansard, Jennifer S. and Pattberg, Philipp H. and Widerberg, Oscar},
  title     = {Cities to the rescue?},
  series = {Postprints der Universit{\"a}t Potsdam Wirtschafts- und Sozialwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam Wirtschafts- und Sozialwissenschaftliche Reihe},
  number    = {105},
  issn      = {1867-5808},
  doi       = {10.25932/publishup-42980},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-429806},
  pages     = {229 -- 246},
  year      = {2017},
  abstract  = {Despite the proliferation and promise of subnational climate initiatives, the institutional architecture of transnational municipal networks (TMNs) is not well understood. With a view to close this research gap, the article empirically assesses the assumption that TMNs are a viable substitute for ambitious international action under the United Nations Framework Convention on Climate Change (UNFCCC). It addresses the aggregate phenomenon in terms of geographical distribution, central players, mitigation ambition and monitoring provisions. Examining thirteen networks, it finds that membership in TMNs is skewed toward Europe and North America while countries from the Global South are underrepresented; that only a minority of networks commit to quantified emission reductions and that these are not more ambitious than Parties to the UNFCCC; and finally that the monitoring provisions are fairly limited. In sum, the article shows that transnational municipal networks are not (yet) the representative, ambitious and transparent player they are thought to be.},
  language  = {en}
}
@phdthesis{Mtilatila2023,
  author    = {Mtilatila, Lucy Mphatso Ng'ombe},
  title     = {Climate change effects on drought, freshwater availability and hydro-power generation in an African environment},
  doi       = {10.25932/publishup-59929},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-599298},
  school      = {Universit{\"a}t Potsdam},
  pages     = {xv, 167},
  year      = {2023},
  abstract  = {The work is designed to investigate the impacts and sensitivity of climate change on water resources, droughts and hydropower production in Malawi, the South-Eastern region which is highly vulnerable to climate change. It is observed that rainfall is decreasing and temperature is increasing which calls for the understanding of what these changes may impact the water resources, drought occurrences and hydropower generation in the region. The study is conducted in the Greater Lake Malawi Basin (Lake Malawi and Shire River Basins) and is divided into three projects. The first study is assessing the variability and trends of both meteorological and hydrological droughts from 1970-2013 in Lake Malawi and Shire River basins using the standardized precipitation index (SPI) and standardized precipitation and evaporation Index (SPEI) for meteorological droughts and the lake level change index (LLCI) for hydrological droughts. And later the relationship of the meteorological and hydrological droughts is established. While the second study extends the drought analysis into the future by examining the potential future meteorological water balance and associated drought characteristics such as the drought intensity (DI), drought months (DM), and drought events (DE) in the Greater Lake Malawi Basin. The sensitivity of drought to changes of rainfall and temperature is also assessed using the scenario-neutral approach. The climate change projections from 20 Coordinated Regional Climate Downscaling Experiment (CORDEX) models for Africa based on two scenarios (RCP4.5 and RCP8.5) for the periods 2021-2050 and 2071-2100 are used. The study also investigates the effect of bias-correction (i.e., empirical quantile mapping) on the ability of the climate model ensemble in reproducing observed drought characteristics as compared to raw climate projections. The sensitivity of key hydrologic variables and hydropower generation to climate change in Lake Malawi and Shire River basins is assessed in third study. The study adapts the mesoscale Hydrological Model (mHM) which is applied separately in the Upper Lake Malawi and Shire River basins. A particular Lake Malawi model, which focuses on reservoir routing and lake water balance, has been developed and is interlinked between the two basins. Similar to second study, the scenario-neutral approach is also applied to determine the sensitivity of climate change on water resources more particularly Lake Malawi level and Shire River flow which later helps to estimate the hydropower production susceptibility. Results suggest that meteorological droughts are increasing due to a decrease in precipitation which is exacerbated by an increase in temperature (potential evapotranspiration). The hydrological system of Lake Malawi seems to have a >24-month memory towards meteorological conditions since the 36-months SPEI can predict hydrological droughts ten-months in advance. The study has found the critical lake level that would trigger hydrological drought to be 474.1 m.a.s.l. Despite the differences in the internal structures and uncertainties that exist among the climate models, they all agree on an increase of meteorological droughts in the future in terms of higher DI and longer events (DM). DI is projected to increase between +25\% and +50\% during 2021-2050 and between +131\% and +388\% during 2071-2100. This translates into +3 to +5, and +7 to +8 more drought months per year during both periods, respectively. With longer lasting drought events, DE is decreasing. Projected droughts based on RCP8.5 are 1.7 times more severe than droughts based on RCP4.5. It is also found that an annual temperature increase of 1°C decreases mean lake level and outflow by 0.3 m and 17\%, respectively, signifying the importance of intensified evaporation for Lake Malawi's water budget. Meanwhile, a +5\% (-5\%) deviation in annual rainfall changes mean lake level by +0.7 m (-0.6 m). The combined effects of temperature increase and rainfall decrease result in significantly lower flows on Shire River. The hydrological river regime may change from perennial to seasonal with the combination of annual temperature increase and precipitation decrease beyond 1.5°C (3.5°C) and -20\% (-15\%). The study further projects a reduction in annual hydropower production between 1\% (RCP8.5) and 2.5\% (RCP4.5) during 2021-2050 and between 5\% (RCP4.5) and 24\% (RCP8.5) during 2071-2100. The findings are later linked to global policies more particularly the United Nations Framework Convention on Climate Change (UNFCCC)'s Paris Agreement and the United Nations (UN)'s Sustainable Development Goals (SDGs), and how the failure to adhere the restriction of temperature increase below the global limit of 1.5°C will affect drought and the water resources in Malawi consequently impact the hydropower production. As a result, the achievement of most of the SDGs will be compromised. The results show that it is of great importance that a further development of hydro energy on the Shire River should take into account the effects of climate change. The information generation is important for decision making more especially supporting the climate action required to fight against climate change. The frequency of extreme climate events due to climate change has reached the climate emergency as saving lives and livelihoods require urgent action.},
  language  = {en}
}
@misc{AyzelIzhitskiy2019,
  author    = {Ayzel, Georgy and Izhitskiy, Alexander},
  title     = {Climate change impact assessment on freshwater inflow into the Small Aral Sea},
  series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  number    = {1071},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-47279},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-472794},
  pages     = {21},
  year      = {2019},
  abstract  = {During the last few decades, the rapid separation of the Small Aral Sea from the isolated basin has changed its hydrological and ecological conditions tremendously. In the present study, we developed and validated the hybrid model for the Syr Darya River basin based on a combination of state-of-the-art hydrological and machine learning models. Climate change impact on freshwater inflow into the Small Aral Sea for the projection period 2007-2099 has been quantified based on the developed hybrid model and bias corrected and downscaled meteorological projections simulated by four General Circulation Models (GCM) for each of three Representative Concentration Pathway scenarios (RCP). The developed hybrid model reliably simulates freshwater inflow for the historical period with a Nash-Sutcliffe efficiency of 0.72 and a Kling-Gupta efficiency of 0.77. Results of the climate change impact assessment showed that the freshwater inflow projections produced by different GCMs are misleading by providing contradictory results for the projection period. However, we identified that the relative runoff changes are expected to be more pronounced in the case of more aggressive RCP scenarios. The simulated projections of freshwater inflow provide a basis for further assessment of climate change impacts on hydrological and ecological conditions of the Small Aral Sea in the 21st Century.},
  language  = {en}
}
@phdthesis{Waha2012,
  author    = {Waha, Katharina},
  title     = {Climate change impacts on agricultural vegetation in sub-Saharan Africa},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-64717},
  school      = {Universit{\"a}t Potsdam},
  year      = {2012},
  abstract  = {Agriculture is one of the most important human activities providing food and more agricultural goods for seven billion people around the world and is of special importance in sub-Saharan Africa. The majority of people depends on the agricultural sector for their livelihoods and will suffer from negative climate change impacts on agriculture until the middle and end of the 21st century, even more if weak governments, economic crises or violent conflicts endanger the countries' food security. The impact of temperature increases and changing precipitation patterns on agricultural vegetation motivated this thesis in the first place. Analyzing the potentials of reducing negative climate change impacts by adapting crop management to changing climate is a second objective of the thesis. As a precondition for simulating climate change impacts on agricultural crops with a global crop model first the timing of sowing in the tropics was improved and validated as this is an important factor determining the length and timing of the crops´ development phases, the occurrence of water stress and final crop yield. Crop yields are projected to decline in most regions which is evident from the results of this thesis, but the uncertainties that exist in climate projections and in the efficiency of adaptation options because of political, economical or institutional obstacles have to be considered. The effect of temperature increases and changing precipitation patterns on crop yields can be analyzed separately and varies in space across the continent. Southern Africa is clearly the region most susceptible to climate change, especially to precipitation changes. The Sahel north of 13° N and parts of Eastern Africa with short growing seasons below 120 days and limited wet season precipitation of less than 500 mm are also vulnerable to precipitation changes while in most other part of East and Central Africa, in contrast, the effect of temperature increase on crops overbalances the precipitation effect and is most pronounced in a band stretching from Angola to Ethiopia in the 2060s. The results of this thesis confirm the findings from previous studies on the magnitude of climate change impact on crops in sub-Saharan Africa but beyond that helps to understand the drivers of these changes and the potential of certain management strategies for adaptation in more detail. Crop yield changes depend on the initial growing conditions, on the magnitude of climate change, and on the crop, cropping system and adaptive capacity of African farmers which is only now evident from this comprehensive study for sub-Saharan Africa. Furthermore this study improves the representation of tropical cropping systems in a global crop model and considers the major food crops cultivated in sub-Saharan Africa and climate change impacts throughout the continent.},
  language  = {en}
}
@phdthesis{Olonscheck2016,
  author    = {Olonscheck, Mady},
  title     = {Climate change impacts on electricity and residential energy demand},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-98378},
  school      = {Universit{\"a}t Potsdam},
  pages     = {XXIV, 127},
  year      = {2016},
  abstract  = {The energy sector is both affected by climate change and a key sector for climate protection measures. Energy security is the backbone of our modern society and guarantees the functioning of most critical infrastructure. Thus, decision makers and energy suppliers of different countries should be familiar with the factors that increase or decrease the susceptibility of their electricity sector to climate change. Susceptibility means socioeconomic and structural characteristics of the electricity sector that affect the demand for and supply of electricity under climate change. Moreover, the relevant stakeholders are supposed to know whether the given national energy and climate targets are feasible and what needs to be done in order to meet these targets. In this regard, a focus should be on the residential building sector as it is one of the largest energy consumers and therefore emitters of anthropogenic CO 2 worldwide. This dissertation addresses the first aspect, namely the susceptibility of the electricity sector, by developing a ranked index which allows for quantitative comparison of the electricity sector susceptibility of 21 European countries based on 14 influencing factors. Such a ranking has not been completed to date. We applied a sensitivity analysis to test the relative effect of each influencing factor on the susceptibility index ranking. We also discuss reasons for the ranking position and thus the susceptibility of selected countries. The second objective, namely the impact of climate change on the energy demand of buildings, is tackled by means of a new model with which the heating and cooling energy demand of residential buildings can be estimated. We exemplarily applied the model to Germany and the Netherlands. It considers projections of future changes in population, climate and the insulation standards of buildings, whereas most of the existing studies only take into account fewer than three different factors that influence the future energy demand of buildings. Furthermore, we developed a comprehensive retrofitting algorithm with which the total residential building stock can be modeled for the first time for each year in the past and future. The study confirms that there is no correlation between the geographical location of a country and its position in the electricity sector susceptibility ranking. Moreover, we found no pronounced pattern of susceptibility influencing factors between countries that ranked higher or lower in the index. We illustrate that Luxembourg, Greece, Slovakia and Italy are the countries with the highest electricity sector susceptibility. The electricity sectors of Norway, the Czech Republic, Portugal and Denmark were found to be least susceptible to climate change. Knowledge about the most important factors for the poor and good ranking positions of these countries is crucial for finding adequate adaptation measures to reduce the susceptibility of the electricity sector. Therefore, these factors are described within this study. We show that the heating energy demand of residential buildings will strongly decrease in both Germany and the Netherlands in the future. The analysis for the Netherlands focused on the regional level and a finer temporal resolution which revealed strong variations in the future heating energy demand changes by province and by month. In the German study, we additionally investigated the future cooling energy demand and could demonstrate that it will only slightly increase up to the middle of this century. Thus, increases in the cooling energy demand are not expected to offset reductions in heating energy demand. The main factor for substantial heating energy demand reductions is the retrofitting of buildings. We are the first to show that the given German and Dutch energy and climate targets in the building sector can only be met if the annual retrofitting rates are substantially increased. The current rate of only about 1 \% of the total building stock per year is insufficient for reaching a nearly zero-energy demand of all residential buildings by the middle of this century. To reach this target, it would need to be at least tripled. To sum up, this thesis emphasizes that country-specific characteristics are decisive for the electricity sector susceptibility of European countries. It also shows for different scenarios how much energy is needed in the future to heat and cool residential buildings. With this information, existing climate mitigation and adaptation measures can be justified or new actions encouraged.},
  language  = {en}
}
@phdthesis{Holsten2013,
  author    = {Holsten, Anne},
  title     = {Climate change vulnerability assessments in the regional context},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-66836},
  school      = {Universit{\"a}t Potsdam},
  year      = {2013},
  abstract  = {Adapting sectors to new conditions under climate change requires an understanding of regional vulnerabilities. Conceptually, vulnerability is defined as a function of sensitivity and exposure, which determine climate impacts, and adaptive capacity of a system. Vulnerability assessments for quantifying these components have become a key tool within the climate change field. However, there is a disagreement on how to make the concept operational in studies from a scientific perspective. This conflict leads to many still unsolved challenges, especially regarding the quantification and aggregation of the components and their suitable level of complexity. This thesis therefore aims at advancing the scientific foundation of such studies by translating the concept of vulnerability into a systematic assessment structure. This includes all components and implies that for each considered impact (e.g. flash floods) a clear sensitive entity is defined (e.g. settlements) and related to a direction of change for a specific climatic stimulus (e.g. increasing impact due to increasing days with heavy precipitation). Regarding the challenging aggregation procedure, two alternative methods allowing a cross-sectoral overview are introduced and their advantages and disadvantages discussed. This assessment structure is subsequently exemplified for municipalities of the German state North Rhine-Westphalia via an indicator-based deductive approach using information from literature. It can be transferred also to other regions. As for many relevant sectors, suitable indicators to express the vulnerability components are lacking, new quantification methods are developed and applied in this thesis, for example for the forestry and health sector. A lack of empirical data on relevant thresholds is evident, for example which climatic changes would cause significant impacts. Consequently, the multi-sectoral study could only provide relative measures for each municipality, in relation to the region. To fill this gap, an exemplary sectoral study was carried out on windthrow impacts in forests to provide an absolute quantification of the present and future impact. This is achieved by formulating an empirical relation between the forest characteristics and damage based on data from a past storm event. The resulting measure indicating the sensitivity is then combined with wind conditions. Multi-sectoral vulnerability assessments require considerable resources, which often hinders the implementation. Thus, in a next step, the potential for reducing the complexity is explored. To predict forest fire occurrence, numerous meteorological indices are available, spanning over a range of complexity. Comparing their performance, the single variable relative humidity outperforms complex indicators for most German states in explaining the monthly fire pattern. This is the case albeit it is itself an input factor in most indices. Thus, this meteorological factor alone is well suited to evaluate forest fire danger in many Germany regions and allows a resource-efficient assessment. Similarly, the complexity of methods is assessed regarding the application of the ecohydrological model SWIM to the German region of Brandenburg. The inter-annual soil moisture levels simulated by this model can only poorly be represented by simpler statistical approach using the same input data. However, on a decadal time horizon, the statistical approach shows a good performance and a strong dominance of the soil characteristic field capacity. This points to a possibility to reduce the input factors for predicting long-term averages, but the results are restricted by a lack of empirical data on soil water for validation. The presented assessments of vulnerability and its components have shown that they are still a challenging scientific undertaking. Following the applied terminology, many problems arise when implementing it for regional studies. Advances in addressing shortcomings of previous studies have been made by constructing a new systematic structure for characterizing and aggregating vulnerability components. For this, multiple approaches were presented, but they have specific advantages and disadvantages, which should also be carefully considered in future studies. There is a potential to simplify some methods, but more systematic assessments on this are needed. Overall, this thesis strengthened the use of vulnerability assessments as a tool to support adaptation by enhancing their scientific basis.},
  language  = {en}
}
@phdthesis{Schwager2005,
  author    = {Schwager, Monika},
  title     = {Climate change, variable colony sizes and temporal autocorrelation : consequences of living in changing environments},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-5744},
  school      = {Universit{\"a}t Potsdam},
  year      = {2005},
  abstract  = {Natural and human induced environmental changes affect populations at different time scales. If they occur in a spatial heterogeneous way, they cause spatial variation in abundance. In this thesis I addressed three topics, all related to the question, how environmental changes influence population dynamics. In the first part, I analysed the effect of positive temporal autocorrelation in environmental noise on the extinction risk of a population, using a simple population model. The effect of autocorrelation depended on the magnitude of the effect of single catastrophic events of bad environmental conditions on a population. If a population was threatened by extinction only, when bad conditions occurred repeatedly, positive autocorrelation increased extinction risk. If a population could become extinct, even if bad conditions occurred only once, positive autocorrelation decreased extinction risk. These opposing effects could be explained by two features of an autocorrelated time series. On the one hand, positive autocorrelation increased the probability of series of bad environmental conditions, implying a negative effect on populations. On the other hand, aggregation of bad years also implied longer periods with relatively good conditions. Therefore, for a given time period, the overall probability of occurrence of at least one extremely bad year was reduced in autocorrelated noise. This can imply a positive effect on populations. The results could solve a contradiction in the literature, where opposing effects of autocorrelated noise were found in very similar population models. In the second part, I compared two approaches, which are commonly used for predicting effects of climate change on future abundance and distribution of species: a "space for time approach", where predictions are based on the geographic pattern of current abundance in relation to climate, and a "population modelling approach" which is based on correlations between demographic parameters and the inter-annual variation of climate. In this case study, I compared the two approaches for predicting the effect of a shift in mean precipitation on a population of the sociable weaver Philetairus socius, a common colonially living passerine bird of semiarid savannahs of southern Africa. In the space for time approach, I compared abundance and population structure of the sociable weaver in two areas with highly different mean annual precipitation. The analysis showed no difference between the two populations. This result, as well as the wide distribution range of the species, would lead to the prediction of no sensitive response of the species to a slight shift in mean precipitation. In contrast, the population modelling approach, based on a correlation between reproductive success and rainfall, predicted a sensitive response in most model types. The inconsistency of predictions was confirmed in a cross-validation between the two approaches. I concluded that the inconsistency was caused, because the two approaches reflect different time scales. On a short time scale, the population may respond sensitively to rainfall. However, on a long time scale, or in a regional comparison, the response may be compensated or buffered by a variety of mechanisms. These may include behavioural or life history adaptations, shifts in the interactions with other species, or differences in the physical environment. The study implies that understanding, how such mechanisms work, and at what time scale they would follow climate change, is a crucial precondition for predicting ecological consequences of climate change. In the third part of the thesis, I tested why colony sizes of the sociable weaver are highly variable. The high variation of colony sizes is surprising, as in studies on coloniality it is often assumed that an optimal colony size exists, in which individual bird fitness is maximized. Following this assumption, the pattern of bird dispersal should keep colony sizes near an optimum. However, I showed by analysing data on reproductive success and survival that for the sociable weaver fitness in relation to colony size did not follow an optimum curve. Instead, positive and negative effects of living in large colonies overlaid each other in a way that fitness was generally close to one, and density dependence was low. I showed in a population model, which included an evolutionary optimisation process of dispersal that this specific shape of the fitness function could lead to a dispersal strategy, where the variation of colony sizes was maintained.},
  subject      = {Populationsbiologie},
  language  = {en}
}
@phdthesis{Huber2010,
  author    = {Huber, Veronika Emilie Charlotte},
  title     = {Climate impact on phytoplankton blooms in shallow lakes},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-42346},
  school      = {Universit{\"a}t Potsdam},
  year      = {2010},
  abstract  = {Lake ecosystems across the globe have responded to climate warming of recent decades. However, correctly attributing observed changes to altered climatic conditions is complicated by multiple anthropogenic influences on lakes. This thesis contributes to a better understanding of climate impacts on freshwater phytoplankton, which forms the basis of the food chain and decisively influences water quality. The analyses were, for the most part, based on a long-term data set of physical, chemical and biological variables of a shallow, polymictic lake in north-eastern Germany (M{\"u}ggelsee), which was subject to a simultaneous change in climate and trophic state during the past three decades. Data analysis included constructing a dynamic simulation model, implementing a genetic algorithm to parameterize models, and applying statistical techniques of classification tree and time-series analysis. Model results indicated that climatic factors and trophic state interactively determine the timing of the phytoplankton spring bloom (phenology) in shallow lakes. Under equally mild spring conditions, the phytoplankton spring bloom collapsed earlier under high than under low nutrient availability, due to a switch from a bottom-up driven to a top-down driven collapse. A novel approach to model phenology proved useful to assess the timings of population peaks in an artificially forced zooplankton-phytoplankton system. Mimicking climate warming by lengthening the growing period advanced algal blooms and consequently also peaks in zooplankton abundance. Investigating the reasons for the contrasting development of cyanobacteria during two recent summer heat wave events revealed that anomalously hot weather did not always, as often hypothesized, promote cyanobacteria in the nutrient-rich lake studied. The seasonal timing and duration of heat waves determined whether critical thresholds of thermal stratification, decisive for cyanobacterial bloom formation, were crossed. In addition, the temporal patterns of heat wave events influenced the summer abundance of some zooplankton species, which as predators may serve as a buffer by suppressing phytoplankton bloom formation. This thesis adds to the growing body of evidence that lake ecosystems have strongly responded to climatic changes of recent decades. It reaches beyond many previous studies of climate impacts on lakes by focusing on underlying mechanisms and explicitly considering multiple environmental changes. Key findings show that climate impacts are more severe in nutrient-rich than in nutrient-poor lakes. Hence, to develop lake management plans for the future, limnologists need to seek a comprehensive, mechanistic understanding of overlapping effects of the multi-faceted human footprint on aquatic ecosystems.},
  language  = {en}
}
@misc{AlterMeyerPostetal.2015,
  author    = {Alter, S. Elizabeth and Meyer, Matthias and Post, Klaas and Czechowski, Paul and Gravlund, Peter and Gaines, Cork and Rosenbaum, Howard C. and Kaschner, Kristin and Turvey, Samuel T. and van der Plicht, Johannes and Shapiro, Beth and Hofreiter, Michael},
  title     = {Climate impacts on transocean dispersal and habitat in gray whales from the Pleistocene to 2100},
  series = {Postprints der Universit{\"a}t Potsdam : Mathematisch Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam : Mathematisch Naturwissenschaftliche Reihe},
  number    = {965},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-43892},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-438920},
  pages     = {1510 -- 1522},
  year      = {2015},
  abstract  = {Arctic animals face dramatic habitat alteration due to ongoing climate change. Understanding how such species have responded to past glacial cycles can help us forecast their response to today's changing climate. Gray whales are among those marine species likely to be strongly affected by Arctic climate change, but a thorough analysis of past climate impacts on this species has been complicated by lack of information about an extinct population in the Atlantic. While little is known about the history of Atlantic gray whales or their relationship to the extant Pacific population, the extirpation of the Atlantic population during historical times has been attributed to whaling. We used a combination of ancient and modern DNA, radiocarbon dating and predictive habitat modelling to better understand the distribution of gray whales during the Pleistocene and Holocene. Our results reveal that dispersal between the Pacific and Atlantic was climate dependent and occurred both during the Pleistocene prior to the last glacial period and the early Holocene immediately following the opening of the Bering Strait. Genetic diversity in the Atlantic declined over an extended interval that predates the period of intensive commercial whaling, indicating this decline may have been precipitated by Holocene climate or other ecological causes. These first genetic data for Atlantic gray whales, particularly when combined with predictive habitat models for the year 2100, suggest that two recent sightings of gray whales in the Atlantic may represent the beginning of the expansion of this species' habitat beyond its currently realized range.},
  language  = {en}
}
@phdthesis{Leins2023,
  author    = {Leins, Johannes A.},
  title     = {Combining model detail with large scales},
  doi       = {10.25932/publishup-58283},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-582837},
  school      = {Universit{\"a}t Potsdam},
  pages     = {xv, 168},
  year      = {2023},
  abstract  = {The global climate crisis is significantly contributing to changing ecosystems, loss of biodiversity and is putting numerous species on the verge of extinction. In principle, many species are able to adapt to changing conditions or shift their habitats to more suitable regions. However, change is progressing faster than some species can adjust, or potential adaptation is blocked and disrupted by direct and indirect human action. Unsustainable anthropogenic land use in particular is one of the driving factors, besides global heating, for these ecologically critical developments. Precisely because land use is anthropogenic, it is also a factor that could be quickly and immediately corrected by human action. In this thesis, I therefore assess the impact of three climate change scenarios of increasing intensity in combination with differently scheduled mowing regimes on the long-term development and dispersal success of insects in Northwest German grasslands. The large marsh grasshopper (LMG, Stethophyma grossum, Linn{\´e} 1758) is used as a species of reference for the analyses. It inhabits wet meadows and marshes and has a limited, yet fairly good ability to disperse. Mowing and climate conditions affect the development and mortality of the LMG differently depending on its life stage. The specifically developed simulation model HiLEG (High-resolution Large Environmental Gradient) serves as a tool for investigating and projecting viability and dispersal success under different climate conditions and land use scenarios. It is a spatially explicit, stage- and cohort-based model that can be individually configured to represent the life cycle and characteristics of terrestrial insect species, as well as high-resolution environmental data and the occurrence of external disturbances. HiLEG is a freely available and adjustable software that can be used to support conservation planning in cultivated grasslands. In the three case studies of this thesis, I explore various aspects related to the structure of simulation models per se, their importance in conservation planning in general, and insights regarding the LMG in particular. It became apparent that the detailed resolution of model processes and components is crucial to project the long-term effect of spatially and temporally confined events. Taking into account conservation measures at the regional level has further proven relevant, especially in light of the climate crisis. I found that the LMG is benefiting from global warming in principle, but continues to be constrained by harmful mowing regimes. Land use measures could, however, be adapted in such a way that they allow the expansion and establishment of the LMG without overly affecting agricultural yields. Overall, simulation models like HiLEG can make an important contribution and add value to conservation planning and policy-making. Properly used, simulation results shed light on aspects that might be overlooked by subjective judgment and the experience of individual stakeholders. Even though it is in the nature of models that they are subject to limitations and only represent fragments of reality, this should not keep stakeholders from using them, as long as these limitations are clearly communicated. Similar to HiLEG, models could further be designed in such a way that not only the parameterization can be adjusted as required, but also the implementation itself can be improved and changed as desired. This openness and flexibility should become more widespread in the development of simulation models.},
  language  = {en}
}
@phdthesis{Smith2018,
  author    = {Smith, Taylor},
  title     = {Decadal changes in the snow regime of High Mountain Asia, 1987-2016},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-407120},
  school      = {Universit{\"a}t Potsdam},
  pages     = {xiii, 142},
  year      = {2018},
  abstract  = {More than a billion people rely on water from rivers sourced in High Mountain Asia (HMA), a significant portion of which is derived from snow and glacier melt. Rural communities are heavily dependent on the consistency of runoff, and are highly vulnerable to shifts in their local environment brought on by climate change. Despite this dependence, the impacts of climate change in HMA remain poorly constrained due to poor process understanding, complex terrain, and insufficiently dense in-situ measurements. HMA's glaciers contain more frozen water than any region outside of the poles. Their extensive retreat is a highly visible and much studied marker of regional and global climate change. However, in many catchments, snow and snowmelt represent a much larger fraction of the yearly water budget than glacial meltwaters. Despite their importance, climate-related changes in HMA's snow resources have not been well studied. Changes in the volume and distribution of snowpack have complex and extensive impacts on both local and global climates. Eurasian snow cover has been shown to impact the strength and direction of the Indian Summer Monsoon -- which is responsible for much of the precipitation over the Indian Subcontinent -- by modulating earth-surface heating. Shifts in the timing of snowmelt have been shown to limit the productivity of major rangelands, reduce streamflow, modify sediment transport, and impact the spread of vector-borne diseases. However, a large-scale regional study of climate impacts on snow resources had yet to be undertaken. Passive Microwave (PM) remote sensing is a well-established empirical method of studying snow resources over large areas. Since 1987, there have been consistent daily global PM measurements which can be used to derive an estimate of snow depth, and hence snow-water equivalent (SWE) -- the amount of water stored in snowpack. The SWE estimation algorithms were originally developed for flat and even terrain -- such as the Russian and Canadian Arctic -- and have rarely been used in complex terrain such as HMA. This dissertation first examines factors present in HMA that could impact the reliability of SWE estimates. Forest cover, absolute snow depth, long-term average wind speeds, and hillslope angle were found to be the strongest controls on SWE measurement reliability. While forest density and snow depth are factors accounted for in modern SWE retrieval algorithms, wind speed and hillslope angle are not. Despite uncertainty in absolute SWE measurements and differences in the magnitude of SWE retrievals between sensors, single-instrument SWE time series were found to be internally consistent and suitable for trend analysis. Building on this finding, this dissertation tracks changes in SWE across HMA using a statistical decomposition technique. An aggregate decrease in SWE was found (10.6 mm/yr), despite large spatial and seasonal heterogeneities. Winter SWE increased in almost half of HMA, despite general negative trends throughout the rest of the year. The elevation distribution of these negative trends indicates that while changes in SWE have likely impacted glaciers in the region, climate change impacts on these two pieces of the cryosphere are somewhat distinct. Following the discussion of relative changes in SWE, this dissertation explores changes in the timing of the snowmelt season in HMA using a newly developed algorithm. The algorithm is shown to accurately track the onset and end of the snowmelt season (70\% within 5 days of a control dataset, 89\% within 10). Using a 29-year time series, changes in the onset, end, and duration of snowmelt are examined. While nearly the entirety of HMA has experienced an earlier end to the snowmelt season, large regions of HMA have seen a later start to the snowmelt season. Snowmelt periods have also decreased in almost all of HMA, indicating that the snowmelt season is generally shortening and ending earlier across HMA. By examining shifts in both the spatio-temporal distribution of SWE and the timing of the snowmelt season across HMA, we provide a detailed accounting of changes in HMA's snow resources. The overall trend in HMA is towards less SWE storage and a shorter snowmelt season. However, long-term and regional trends conceal distinct seasonal, temporal, and spatial heterogeneity, indicating that changes in snow resources are strongly controlled by local climate and topography, and that inter-annual variability plays a significant role in HMA's snow regime.},
  language  = {en}
}
@phdthesis{Heybl2016,
  author    = {Heybl, Christine},
  title     = {Der Klimawandel},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-102442},
  school      = {Universit{\"a}t Potsdam},
  pages     = {293},
  year      = {2016},
  abstract  = {Was ist Gerechtigkeit? Wie k{\"o}nnten gerechte Regelungen aussehen f{\"u}r die Katastrophen und Leiden, die der Klimawandel ausl{\"o}st bzw. ausl{\"o}sen wird? Diese sind h{\"a}ufig ungerecht, weil sie oft deutlich st{\"a}rker diejenigen treffen, die am wenigsten zur Klimaver{\"a}nderung beigetragen haben. Doch was genau verstehen wir unter dem Schlagwort: ‚Klimawandel'? Und kann dieser wirklich den Menschen direkt treffen? Ein kurzer naturwissenschaftlicher Abriss kl{\"a}rt hier die wichtigsten Fragen. Da es sich hierbei um eine philosophische Arbeit handelt, muss zun{\"a}chst gekl{\"a}rt werden, ob der Mensch {\"u}berhaupt die Ursache von so etwas sein kann wie z.B. der Klimaerw{\"a}rmung. Robert Spaemanns These dazu ist, dass der Mensch durch seinen freien Willen mit seinen Einzelhandlungen das Weltgeschehen ver{\"a}ndern kann. Hans Jonas f{\"u}gt dem hinzu, dass wir durch diese F{\"a}higkeit, verantwortlich sind f{\"u}r die gewollten und ungewollten Folgen unserer Handlungen. Damit w{\"a}re aus naturwissenschaftlicher Sicht (1. Teil der Arbeit) und aus philosophischer Sicht (Anfang 2. Teil) gekl{\"a}rt, dass der Mensch mit gr{\"o}ßter Wahrscheinlichkeit die Ursache des Klimawandels ist und diese Verursachung moralische Konsequenzen f{\"u}r ihn hat. Ein philosophischer Gerechtigkeitsbegriff wird aus der Kantischen Rechts- und Moralphilosophie entwickelt, weil diese die einzige ist, die dem Menschen {\"u}berhaupt ein Recht auf Rechte zusprechen kann. Diese entspringt der transzendentalen Freiheitsf{\"a}higkeit des Menschen, weshalb jedem das Recht auf Rechte absolut und immer zukommt. Gleichzeitig m{\"u}ndet Kants Philosophie wiederum in dem Freiheitsgedanken, indem Gerechtigkeit nur existiert, wenn alle Menschen gleichermaßen frei sein k{\"o}nnen. Was heißt das konkret? Wie k{\"o}nnte Gerechtigkeit in der Realit{\"a}t wirklich umgesetzt werden? Die Realisierung schl{\"a}gt zwei Grundrichtungen ein. John Rawls und Stefan Gosepath besch{\"a}ftigen sich u.a. eingehend mit der prozeduralen Gerechtigkeit, was bedeutet, dass gerechte Verfahren gefunden werden, die das gesellschaftliche Zusammenleben regeln. Das leitende Prinzip hierf{\"u}r ist vor allem: ein Mitbestimmungsrecht aller, so dass sich im Prinzip alle B{\"u}rger ihre Gesetze selbst geben und damit frei handeln. In Bezug auf den Klimawandel steht die zweite Ausrichtung im Vordergrund - die distributive oder auch Verteilungs-Gerechtigkeit. Materielle G{\"u}ter m{\"u}ssen so aufgeteilt werden, dass auch trotz empirischer Unterschiede alle Menschen als moralische Subjekte anerkannt werden und frei sein k{\"o}nnen. Doch sind diese philosophischen Schlussfolgerungen nicht viel zu abstrakt, um auf ein ebenso schwer fassbares und globales Problem wie den Klimawandel angewendet zu werden? Was k{\"o}nnte daher eine Klimagerechtigkeit sein? Es gibt viele Gerechtigkeitsprinzipien, die vorgeben, eine gerechte Grundlage f{\"u}r die Klimaprobleme zu bieten wie z.B. das Verursacherprinzip, das F{\"a}higkeitsprinzip oder das Grandfathering-Prinzip, bei dem die Hauptverursacher nach wie vor am meisten emittieren d{\"u}rfen (dieses Prinzip leitete die bisherigen internationalen Verhandlungen). Das Ziel dieser Arbeit ist, herauszufinden, wie die Klimaprobleme gel{\"o}st werden k{\"o}nnen, so dass f{\"u}r alle Menschen unter allen Umst{\"a}nden die universellen Menschenrechte her- und sichergestellt werden und diese frei und moralisch handeln k{\"o}nnen. Die Schlussfolgerung dieser Arbeit ist, dass Kants Gerechtigkeitsbegriff durch eine Kombination des Subsistenzemissions-Rechts, des Greenhouse-Development-Rights-Principles (GDR-Prinzip) und einer internationalen Staatlichkeit durchgesetzt werden k{\"o}nnte. Durch das Subsistenzemissions-Recht hat jeder Mensch das Recht, so viel Energie zu verbrauchen und damit zusammenh{\"a}ngende Emissionen zu produzieren, dass er ein menschenw{\"u}rdiges Leben f{\"u}hren kann. Das GDR-Prinzip errechnet den Anteil an der weltweiten Gesamtverantwortung zum Klimaschutz eines jeden Landes oder sogar eines jeden Weltb{\"u}rgers, indem es die historischen Emissionen (Klimaschuld) zu der jetzigen finanziellen Kapazit{\"a}t des Landes/ des Individuums (Verantwortungsf{\"a}higkeit) hinzuaddiert. Die Implementierung von internationalen Gremien wird verteidigt, weil es ein globales, grenz{\"u}berschreitendes Problem ist, dessen Effekte und dessen Verantwortung globale Ausmaße haben. Ein schlagendes Argument f{\"u}r fast alle Klimaschutzmaßnahmen ist, dass sie Synergien aufweisen zu anderen gesellschaftlichen Bereichen aufweisen wie z.B. Gesundheit und Armutsbek{\"a}mpfung, in denen auch noch um die Durchsetzung unserer Menschenrechte gerungen wird. Ist dieser L{\"o}sungsansatz nicht v{\"o}llig utopisch? Dieser Vorschlag stellt f{\"u}r die internationale Gemeinschaft eine große Herausforderung dar, w{\"a}re jedoch die einzig gerechte L{\"o}sung unserer Klimaprobleme. Des Weiteren wird an dem Kantischen Handlungsgrundsatz festgehalten, dass das ewige Streben auf ideale Ziele hin, die beste Verwirklichung dieser durch menschliche, fehlbare Wesen ist.},
  language  = {de}
}
@phdthesis{Jaiser2013,
  author    = {Jaiser, Ralf},
  title     = {Dreidimensionale Diagnostik der großskaligen Zirkulation der Tropo- und Stratosph{\"a}re},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-69064},
  school      = {Universit{\"a}t Potsdam},
  year      = {2013},
  abstract  = {In dieser Arbeit werden Konzepte f{\"u}r die Diagnostik der großskaligen Zirkulation in der Troposph{\"a}re und Stratosph{\"a}re entwickelt. Der Fokus liegt dabei auf dem Energiehaushalt, auf der Wellenausbreitung und auf der Interaktion der atmosph{\"a}rischen Wellen mit dem Grundstrom. Die Konzepte werden hergeleitet, wobei eine neue Form des lokalen Eliassen-Palm-Flusses unter Einbeziehung der Feuchte eingef{\"u}hrt wird. Angewendet wird die Diagnostik dann auf den Reanalysedatensatz ERA-Interim und einen durch beobachtete Meerestemperatur- und Eisdaten angetriebenen Lauf des ECHAM6 Atmosph{\"a}renmodells. Die diagnostischen Werkzeuge zur Analyse der großskaligen Zirkulation sind einerseits n{\"u}tzlich, um das Verst{\"a}ndnis der Dynamik des Klimasystems weiter zu f{\"o}rdern. Andererseits kann das gewonnene Verst{\"a}ndnis des Zusammenhangs von Energiequellen und -senken sowie deren Verkn{\"u}pfung mit synoptischen und planetaren Wellensystemen und dem resultierenden Antrieb des Grundstroms auch verwendet werden, um Klimamodelle auf die korrekte Wiedergabe dieser Beobachtungen zu pr{\"u}fen. Hier zeigt sich, dass die Abweichungen im untersuchten ECHAM6-Modelllauf bez{\"u}glich des Energiehaushalts klein sind, jedoch teils starke Abweichungen bez{\"u}glich der Ausbreitung von atmosph{\"a}rischen Wellen existieren. Planetare Wellen zeigen allgemein zu große Intensit{\"a}ten in den Eliassen-Palm-Fl{\"u}ssen, w{\"a}hrend innerhalb der Strahlstr{\"o}me der oberen Troposph{\"a}re der Antrieb des Grundstroms durch synoptische Wellen verf{\"a}lscht ist, da deren vertikale Ausbreitung gegen{\"u}ber den Beobachtungen verschoben ist. Untersucht wird auch der Einfluss von arktischen Meereis{\"a}nderungen ausgehend vom Bedeckungsminimum im August/September bis in den Winter. Es werden starke positive Temperaturanomalien festgestellt, welche an der Oberfl{\"a}che am gr{\"o}ßten sind. Diese f{\"u}hren vor allem im Herbst zur Intensivierung von synoptischen Systemen in den arktischen Breiten, da die Stabilit{\"a}t der troposph{\"a}rischen Schichtung verringert ist. Im darauffolgenden Winter stellen sich barotrope bis in die Stratosph{\"a}re reichende {\"A}nderungen der großskaligen Zirkulation ein, welche auf Meereis{\"a}nderungen zur{\"u}ckzuf{\"u}hren sind. Der meridionale Druckgradient sinkt und f{\"u}hrt so zu einem Muster {\"a}hnlich einer negativen Phase der arktischen Oszillation in der Troposph{\"a}re und einem geschw{\"a}chten Polarwirbel in der Stratosph{\"a}re. Diese Zusammenh{\"a}nge werden ebenfalls in einem ECHAM6-Modelllauf untersucht, wobei vor allem der Erw{\"a}rmungstrend in der Arktis zu gering ist. Die großskaligen Ver{\"a}nderungen im Winter k{\"o}nnen zum Teil auch im Modelllauf festgestellt werden, jedoch zeigen sich insbesondere in der Stratosph{\"a}re Abweichungen f{\"u}r die Periode mit der geringsten Eisausdehnung. Die vertikale Ausbreitung planetarer Wellen von der Troposph{\"a}re in die Stratosph{\"a}re ist in ECHAM6 mit sehr großen Abweichungen wiedergegeben. Somit stellt die Wellenausbreitung insgesamt den gr{\"o}ßten in dieser Arbeit festgestellten Mangel in ECHAM6 dar.},
  language  = {de}
}
@misc{OguntundeAbiodunLischeidetal.2020,
  author    = {Oguntunde, Philip G. and Abiodun, Babatunde Joseph and Lischeid, Gunnar and Abatan, Abayomi A.},
  title     = {Droughts projection over the Niger and Volta River basins of West Africa at specific global warming levels},
  series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  number    = {13},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-52594},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-525943},
  pages     = {14},
  year      = {2020},
  abstract  = {This study investigates possible impacts of four global warming levels (GWLs: GWL1.5, GWL2.0, GWL2.5, and GWL3.0) on drought characteristics over Niger River basin (NRB) and Volta River basin (VRB). Two drought indices-Standardized Precipitation Index (SPI) and Standardized Precipitation-Evapotranspiration Index (SPEI)-were employed in characterizing droughts in 20 multi-model simulation outputs from the Coordinated Regional Climate Downscaling Experiment (CORDEX). The performance of the simulation in reproducing basic hydro-climatological features and severe drought characteristics (i.e., magnitude and frequency) in the basins were evaluated. The projected changes in the future drought frequency were quantified and compared under the four GWLs for two climate forcing scenarios (RCP8.5 and RCP4.5). The regional climate model (RCM) ensemble gives a realistic simulation of historical hydro-climatological variables needed to calculate the drought indices. With SPEI, the simulation ensemble projects an increase in the magnitude and frequency of severe droughts over both basins (NRB and VRB) at all GWLs, but the increase, which grows with the GWLs, is higher over NRB than over VRB. More than 75\% of the simulations agree on the projected increase at GWL1.5 and all simulations agree on the increase at higher GWLs. With SPI, the projected changes in severe drought is weaker and the magnitude remains the same at all GWLs, suggesting that SPI projection may underestimate impacts of the GWLs on the intensity and severity of future drought. The results of this study have application in mitigating impact of global warming on future drought risk over the regional water systems.},
  language  = {en}
}