TY - GEN A1 - Pearce, Warren A1 - Özkula, Suay M. A1 - Greene, Amanda K. A1 - Teeling, Lauren A1 - Bansard, Jennifer S. A1 - Omena, Janna Joceli A1 - Rabello, Elaine Teixeira T1 - Visual cross-platform analysis BT - Digital methods to research social media images T2 - Zweitveröffentlichungen der Universität Potsdam : Wirtschafts- und Sozialwissenschaftliche Reihe N2 - Analysis of social media using digital methods is a flourishing approach. However, the relatively easy availability of data collected via platform application programming interfaces has arguably led to the predominance of single-platform research of social media. Such research has also privileged the role of text in social media analysis, as a form of data that is more readily gathered and searchable than images. In this paper, we challenge both of these prevailing forms of social media research by outlining a methodology for visual cross-platform analysis (VCPA), defined as the study of still and moving images across two or more social media platforms. Our argument contains three steps. First, we argue that cross-platform analysis addresses a gap in research methods in that it acknowledges the interplay between a social phenomenon under investigation and the medium within which it is being researched, thus illuminating the different affordances and cultures of web platforms. Second, we build on the literature on multimodal communication and platform vernacular to provide a rationale for incorporating the visual into cross-platform analysis. Third, we reflect on an experimental cross-platform analysis of images within social media posts (n = 471,033) used to communicate climate change to advance different modes of macro- and meso-levels of analysis that are natively visual: image-text networks, image plots and composite images. We conclude by assessing the research pathways opened up by VCPA, delineating potential contributions to empirical research and theory and the potential impact on practitioners of social media communication. T3 - Zweitveröffentlichungen der Universität Potsdam : Wirtschafts- und Sozialwissenschaftliche Reihe - 199 KW - research methodology KW - visual analysis KW - social media KW - climate change Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-515539 SN - 1867-5808 IS - 2 ER - TY - JOUR A1 - Pearce, Warren A1 - Özkula, Suay M. A1 - Greene, Amanda K. A1 - Teeling, Lauren A1 - Bansard, Jennifer S. A1 - Omena, Janna Joceli A1 - Rabello, Elaine Teixeira T1 - Visual cross-platform analysis JF - Information, Communication and Society: digital methods to research social media images N2 - Analysis of social media using digital methods is a flourishing approach. However, the relatively easy availability of data collected via platform application programming interfaces has arguably led to the predominance of single-platform research of social media. Such research has also privileged the role of text in social media analysis, as a form of data that is more readily gathered and searchable than images. In this paper, we challenge both of these prevailing forms of social media research by outlining a methodology for visual cross-platform analysis (VCPA), defined as the study of still and moving images across two or more social media platforms. Our argument contains three steps. First, we argue that cross-platform analysis addresses a gap in research methods in that it acknowledges the interplay between a social phenomenon under investigation and the medium within which it is being researched, thus illuminating the different affordances and cultures of web platforms. Second, we build on the literature on multimodal communication and platform vernacular to provide a rationale for incorporating the visual into cross-platform analysis. Third, we reflect on an experimental cross-platform analysis of images within social media posts (n = 471,033) used to communicate climate change to advance different modes of macro- and meso-levels of analysis that are natively visual: image-text networks, image plots and composite images. We conclude by assessing the research pathways opened up by VCPA, delineating potential contributions to empirical research and theory and the potential impact on practitioners of social media communication. KW - research methodology KW - visual analysis KW - social media KW - climate change Y1 - 2018 U6 - https://doi.org/10.1080/1369118X.2018.1486871 SN - 1468-4462 SN - 1369-118X VL - 23 IS - 2 SP - 161 EP - 180 PB - Routledge CY - London ER - TY - JOUR A1 - Perring, Michael P. A1 - Bernhardt-Roemermann, Markus A1 - Baeten, Lander A1 - Midolo, Gabriele A1 - Blondeel, Haben A1 - Depauw, Leen A1 - Landuyt, Dries A1 - Maes, Sybryn L. A1 - De Lombaerde, Emiel A1 - Caron, Maria Mercedes A1 - Vellend, Mark A1 - Brunet, Joerg A1 - Chudomelova, Marketa A1 - Decocq, Guillaume A1 - Diekmann, Martin A1 - Dirnboeck, Thomas A1 - Doerfler, Inken A1 - Durak, Tomasz A1 - De Frenne, Pieter A1 - Gilliam, Frank S. A1 - Hedl, Radim A1 - Heinken, Thilo A1 - Hommel, Patrick A1 - Jaroszewicz, Bogdan A1 - Kirby, Keith J. A1 - Kopecky, Martin A1 - Lenoir, Jonathan A1 - Li, Daijiang A1 - Malis, Frantisek A1 - Mitchell, Fraser J. G. A1 - Naaf, Tobias A1 - Newman, Miles A1 - Petrik, Petr A1 - Reczynska, Kamila A1 - Schmidt, Wolfgang A1 - Standovar, Tibor A1 - Swierkosz, Krzysztof A1 - Van Calster, Hans A1 - Vild, Ondrej A1 - Wagner, Eva Rosa A1 - Wulf, Monika A1 - Verheyen, Kris T1 - Global environmental change effects on plant community composition trajectories depend upon management legacies JF - Global change biology N2 - The contemporary state of functional traits and species richness in plant communities depends on legacy effects of past disturbances. Whether temporal responses of community properties to current environmental changes are altered by such legacies is, however, unknown. We expect global environmental changes to interact with land-use legacies given different community trajectories initiated by prior management, and subsequent responses to altered resources and conditions. We tested this expectation for species richness and functional traits using 1814 survey-resurvey plot pairs of understorey communities from 40 European temperate forest datasets, syntheses of management transitions since the year 1800, and a trait database. We also examined how plant community indicators of resources and conditions changed in response to management legacies and environmental change. Community trajectories were clearly influenced by interactions between management legacies from over 200 years ago and environmental change. Importantly, higher rates of nitrogen deposition led to increased species richness and plant height in forests managed less intensively in 1800 (i.e., high forests), and to decreases in forests with a more intensive historical management in 1800 (i.e., coppiced forests). There was evidence that these declines in community variables in formerly coppiced forests were ameliorated by increased rates of temperature change between surveys. Responses were generally apparent regardless of sites’ contemporary management classifications, although sometimes the management transition itself, rather than historic or contemporary management types, better explained understorey responses. Main effects of environmental change were rare, although higher rates of precipitation change increased plant height, accompanied by increases in fertility indicator values. Analysis of indicator values suggested the importance of directly characterising resources and conditions to better understand legacy and environmental change effects. Accounting for legacies of past disturbance can reconcile contradictory literature results and appears crucial to anticipating future responses to global environmental change. KW - biodiversity change KW - climate change KW - disturbance regime KW - forestREplot KW - herbaceous layer KW - management intensity KW - nitrogen deposition KW - plant functional traits KW - time lag KW - vegetation resurvey Y1 - 2017 U6 - https://doi.org/10.1111/gcb.14030 SN - 1354-1013 SN - 1365-2486 VL - 24 IS - 4 SP - 1722 EP - 1740 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Huang, Xiaozhong A1 - Peng, Wei A1 - Rudaya, Natalia A1 - Grimm, Eric C. A1 - Chen, Xuemei A1 - Cao, Xianyong A1 - Zhang, Jun A1 - Pan, Xiaoduo A1 - Liu, Sisi A1 - Chen, Chunzhu A1 - Chen, Fahu T1 - Holocene vegetation and climate dynamics in the Altai Mountains and Surrounding Areas JF - Geophysical research letters N2 - A comprehensive understanding of the regional vegetation responses to long-term climate change will help to forecast Earth system dynamics. Based on a new well-dated pollen data set from Kanas Lake and a review on the published pollen records in and around the Altai Mountains, the regional vegetation dynamics and forcing mechanisms are discussed. In the Altai Mountains, the forest optimum occurred during 10-7ka for the upper forest zone and the tree line decline and/or ecological shifts were caused by climatic cooling from around 7ka. In the lower forest zone, the forest reached an optimum in the middle Holocene, and then increased openness of the forest, possibly caused by both climate cooling and human activities, took place in the late Holocene. In the lower basins or plains around the Altai Mountains, the development of protograssland or forest benefited from increasing humidity in the middle to late Holocene. Plain Language Summary In the Altai Mountains and surrounding area of central Asia, the previous studies of the Holocene paleovegetation and paleoclimate studies did not discuss the different ecological limiting factors for the vegetation in high mountains and low-elevation areas due to limited data. With accumulating fossil pollen data and surface pollen data, it is possible to understand better the geomorphological effect on the vegetation and discrepancies of vegetation/forest responses to large-scale climate forcing, and it is also possible to get reliable quantitative reconstructions of climate. Here our new pollen data and review on the published fossil pollen data will help us to look into the past climate change and vertical evolution of vegetation in this important area of the Northern Hemisphere. Based on our study, it can be concluded that the growth of taiga forest in the wetter areas may be promoted under a future warmer climate, while the forest in the relatively dry areas is liable to decline, and the different vegetation dynamics will contribute to future high-resolution coupled vegetation-climate model for Earth system modelling. KW - climate change KW - Kanas Lake KW - Altai Mountains KW - vegetation dynamics KW - taiga forest Y1 - 2018 U6 - https://doi.org/10.1029/2018GL078028 SN - 0094-8276 SN - 1944-8007 VL - 45 IS - 13 SP - 6628 EP - 6636 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Grimm-Seyfarth, Annegret A1 - Mihoub, Jean-Baptiste A1 - Gruber, Bernd A1 - Henle, Klaus T1 - Some like it hot BT - from individual to population responses of an arboreal arid-zone gecko to local and distant climate JF - Ecological monographs N2 - Accumulating evidence has demonstrated considerable impact of climate change on biodiversity, with terrestrial ectotherms being particularly vulnerable. While climate-induced range shifts are often addressed in the literature, little is known about the underlying ecological responses at individual and population levels. Using a 30-yr monitoring study of the long-living nocturnal gecko Gehyra variegata in arid Australia, we determined the relative contribution of climatic factors acting locally (temperature, rainfall) or distantly (La Nina induced flooding) on ecological processes ranging from traits at the individual level (body condition, body growth) to the demography at population level (survival, sexual maturity, population sizes). We also investigated whether thermoregulatory activity during both active (night) and resting (daytime) periods of the day can explain these responses. Gehyra variegata responded to local and distant climatic effects. Both high temperatures and high water availability enhanced individual and demographic parameters. Moreover, the impact of water availability was scale independent as local rainfall and La Nina induced flooding compensated each other. When water availability was low, however, extremely high temperatures delayed body growth and sexual maturity while survival of individuals and population sizes remained stable. This suggests a trade-off with traits at the individual level that may potentially buffer the consequences of adverse climatic conditions at the population level. Moreover, hot temperatures did not impact nocturnal nor diurnal behavior. Instead, only cool temperatures induced diurnal thermoregulatory behavior with individuals moving to exposed hollow branches and even outside tree hollows for sun-basking during the day. Since diurnal behavioral thermoregulation likely induced costs on fitness, this could decrease performance at both individual and population level under cool temperatures. Our findings show that water availability rather than high temperature is the limiting factor in our focal population of G.variegata. In contrast to previous studies, we stress that drier rather than warmer conditions are expected to be detrimental for nocturnal desert reptiles. Identifying the actual limiting climatic factors at different scales and their functional interactions at different ecological levels is critical to be able to predict reliably future population dynamics and support conservation planning in arid ecosystems. KW - behavioral adaptation KW - body condition KW - body growth rate KW - climate change KW - El Nino Southern Oscillation (ENSO) KW - Gehyra variegata KW - population dynamics KW - population size KW - survival KW - thermoregulation Y1 - 2018 U6 - https://doi.org/10.1002/ecm.1301 SN - 0012-9615 SN - 1557-7015 VL - 88 IS - 3 SP - 336 EP - 352 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - van Kleunen, Mark A1 - Essl, Franz A1 - Pergl, Jan A1 - Brundu, Giuseppe A1 - Carboni, Marta A1 - Dullinger, Stefan A1 - Early, Regan A1 - Gonzalez-Moreno, Pablo A1 - Groom, Quentin J. M. A1 - Hulme, Philip E. A1 - Kueffer, Christoph A1 - Kühn, Ingolf A1 - Maguas, Cristina A1 - Maurel, Noelie A1 - Novoa, Ana A1 - Parepa, Madalin A1 - Pysek, Petr A1 - Seebens, Hanno A1 - Tanner, Rob A1 - Touza, Julia A1 - Verbrugge, Laura A1 - Weber, Ewald A1 - Dawson, Wayne A1 - Kreft, Holger A1 - Weigelt, Patrick A1 - Winter, Marten A1 - Klonner, Guenther A1 - Talluto, Matthew V. A1 - Dehnen-Schmutz, Katharina T1 - The changing role of ornamental horticulture in alien plant invasions JF - Biological reviews N2 - The number of alien plants escaping from cultivation into native ecosystems is increasing steadily. We provide an overview of the historical, contemporary and potential future roles of ornamental horticulture in plant invasions. We show that currently at least 75% and 93% of the global naturalised alien flora is grown in domestic and botanical gardens, respectively. Species grown in gardens also have a larger naturalised range than those that are not. After the Middle Ages, particularly in the 18th and 19th centuries, a global trade network in plants emerged. Since then, cultivated alien species also started to appear in the wild more frequently than non-cultivated aliens globally, particularly during the 19th century. Horticulture still plays a prominent role in current plant introduction, and the monetary value of live-plant imports in different parts of the world is steadily increasing. Historically, botanical gardens - an important component of horticulture - played a major role in displaying, cultivating and distributing new plant discoveries. While the role of botanical gardens in the horticultural supply chain has declined, they are still a significant link, with one-third of institutions involved in retail-plant sales and horticultural research. However, botanical gardens have also become more dependent on commercial nurseries as plant sources, particularly in North America. Plants selected for ornamental purposes are not a random selection of the global flora, and some of the plant characteristics promoted through horticulture, such as fast growth, also promote invasion. Efforts to breed non-invasive plant cultivars are still rare. Socio-economical, technological, and environmental changes will lead to novel patterns of plant introductions and invasion opportunities for the species that are already cultivated. We describe the role that horticulture could play in mediating these changes. We identify current research challenges, and call for more research efforts on the past and current role of horticulture in plant invasions. This is required to develop science-based regulatory frameworks to prevent further plant invasions. KW - botanical gardens KW - climate change KW - horticulture KW - naturalised plants KW - ornamental plants KW - pathways KW - plant invasions KW - plant nurseries KW - trade KW - weeds Y1 - 2018 U6 - https://doi.org/10.1111/brv.12402 SN - 1464-7931 SN - 1469-185X VL - 93 IS - 3 SP - 1421 EP - 1437 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Steffen, Will A1 - Röckstrom, Johan A1 - Richardson, Katherine A1 - Lenton, Timothy M. A1 - Folke, Carl A1 - Liverman, Diana A1 - Summerhayes, Colin P. A1 - Barnosky, Anthony D. A1 - Cornell, Sarah E. A1 - Crucifix, Michel A1 - Donges, Jonathan Friedemann A1 - Fetzer, Ingo A1 - Lade, Steven J. A1 - Scheffer, Marten A1 - Winkelmann, Ricarda A1 - Schellnhuber, Hans Joachim T1 - Trajectories of the Earth System in the Anthropocene JF - Proceedings of the National Academy of Sciences of the United States of America N2 - We explore the risk that self-reinforcing feedbacks could push the Earth System toward a planetary threshold that, if crossed, could prevent stabilization of the climate at intermediate temperature rises and cause continued warming on a "Hothouse Earth" pathway even as human emissions are reduced. Crossing the threshold would lead to a much higher global average temperature than any interglacial in the past 1.2 million years and to sea levels significantly higher than at any time in the Holocene. We examine the evidence that such a threshold might exist and where it might be. If the threshold is crossed, the resulting trajectory would likely cause serious disruptions to ecosystems, society, and economies. Collective human action is required to steer the Earth System away from a potential threshold and stabilize it in a habitable interglacial-like state. Such action entails stewardship of the entire Earth System-biosphere, climate, and societies-and could include decarbonization of the global economy, enhancement of biosphere carbon sinks, behavioral changes, technological innovations, new governance arrangements, and transformed social values. KW - Earth System trajectories KW - climate change KW - Anthropocene KW - biosphere feedbacks KW - tipping elements Y1 - 2018 U6 - https://doi.org/10.1073/pnas.1810141115 SN - 0027-8424 VL - 115 IS - 33 SP - 8252 EP - 8259 PB - National Acad. of Sciences CY - Washington ER - TY - JOUR A1 - Tape, Ken D. A1 - Jones, Benjamin M. A1 - Arp, Christopher D. A1 - Nitze, Ingmar A1 - Grosse, Guido T1 - Tundra be dammed BT - beaver colonization of the arctic JF - Global change biology N2 - Increasing air temperatures are changing the arctic tundra biome. Permafrost is thawing, snow duration is decreasing, shrub vegetation is proliferating, and boreal wildlife is encroaching. Here we present evidence of the recent range expansion of North American beaver (Castor canadensis) into the Arctic, and consider how this ecosystem engineer might reshape the landscape, biodiversity, and ecosystem processes. We developed a remote sensing approach that maps formation and disappearance of ponds associated with beaver activity. Since 1999, 56 new beaver pond complexes were identified, indicating that beavers are colonizing a predominantly tundra region (18,293km(2)) of northwest Alaska. It is unclear how improved tundra stream habitat, population rebound following overtrapping for furs, or other factors are contributing to beaver range expansion. We discuss rates and likely routes of tundra beaver colonization, as well as effects on permafrost, stream ice regimes, and freshwater and riparian habitat. Beaver ponds and associated hydrologic changes are thawing permafrost. Pond formation increases winter water temperatures in the pond and downstream, likely creating new and more varied aquatic habitat, but specific biological implications are unknown. Beavers create dynamic wetlands and are agents of disturbance that may enhance ecosystem responses to warming in the Arctic. KW - arctic tundra KW - beaver KW - climate change KW - permafrost KW - population recovery KW - salmon KW - shrub expansion KW - stream Y1 - 2018 U6 - https://doi.org/10.1111/gcb.14332 SN - 1354-1013 SN - 1365-2486 VL - 24 IS - 10 SP - 4478 EP - 4488 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Coch, Caroline A1 - Lamoureux, Scott F. A1 - Knoblauch, Christian A1 - Eischeid, Isabell A1 - Fritz, Michael A1 - Obu, Jaroslav A1 - Lantuit, Hugues T1 - Summer rainfall dissolved organic carbon, solute, and sediment fluxes in a small Arctic coastal catchment on Herschel Island (Yukon Territory, Canada) JF - Artic science N2 - Coastal ecosystems in the Arctic are affected by climate change. As summer rainfall frequency and intensity are projected to increase in the future, more organic matter, nutrients and sediment could bemobilized and transported into the coastal nearshore zones. However, knowledge of current processes and future changes is limited. We investigated streamflow dynamics and the impacts of summer rainfall on lateral fluxes in a small coastal catchment on Herschel Island in the western Canadian Arctic. For the summer monitoring periods of 2014-2016, mean dissolved organic matter flux over 17 days amounted to 82.7 +/- 30.7 kg km(-2) and mean total dissolved solids flux to 5252 +/- 1224 kg km(-2). Flux of suspended sediment was 7245 kg km(-2) in 2015, and 369 kg km(-2) in 2016. We found that 2.0% of suspended sediment was composed of particulate organic carbon. Data and hysteresis analysis suggest a limited supply of sediments; their interannual variability is most likely caused by short-lived localized disturbances. In contrast, our results imply that dissolved organic carbon is widely available throughout the catchment and exhibits positive linear relationship with runoff. We hypothesize that increased projected rainfall in the future will result in a similar increase of dissolved organic carbon fluxes. KW - permafrost KW - hydrology KW - lateral fluxes KW - hysteresis KW - climate change Y1 - 2018 U6 - https://doi.org/10.1139/as-2018-0010 SN - 2368-7460 VL - 4 IS - 4 SP - 750 EP - 780 PB - Canadian science publishing CY - Ottawa ER - TY - JOUR A1 - Maes, Sybryn L. A1 - Perring, Michael P. A1 - Vanhellemont, Margot A1 - Depauw, Leen A1 - Van den Bulcke, Jan A1 - Brumelis, Guntis A1 - Brunet, Jorg A1 - Decocq, Guillaume A1 - den Ouden, Jan A1 - Härdtle, Werner A1 - Hedl, Radim A1 - Heinken, Thilo A1 - Heinrichs, Steffi A1 - Jaroszewicz, Bogdan A1 - Kopecký, Martin A1 - Malis, Frantisek A1 - Wulf, Monika A1 - Verheyen, Kris T1 - Environmental drivers interactively affect individual tree growth across temperate European forests JF - Global change biology N2 - Forecasting the growth of tree species to future environmental changes requires abetter understanding of its determinants. Tree growth is known to respond to global‐change drivers such as climate change or atmospheric deposition, as well as to localland‐use drivers such as forest management. Yet, large geographical scale studiesexamining interactive growth responses to multiple global‐change drivers are relativelyscarce and rarely consider management effects. Here, we assessed the interactiveeffects of three global‐change drivers (temperature, precipitation and nitrogen deposi-tion) on individual tree growth of three study species (Quercus robur/petraea, Fagus syl-vatica and Fraxinus excelsior). We sampled trees along spatial environmental gradientsacross Europe and accounted for the effects of management for Quercus. We collectedincrement cores from 267 trees distributed over 151 plots in 19 forest regions andcharacterized their neighbouring environment to take into account potentially confounding factors such as tree size, competition, soil conditions and elevation. Wedemonstrate that growth responds interactively to global‐change drivers, with species ‐specific sensitivities to the combined factors. Simultaneously high levels of precipita-tion and deposition benefited Fraxinus, but negatively affected Quercus’ growth, high-lighting species‐specific interactive tree growth responses to combined drivers. ForFagus, a stronger growth response to higher temperatures was found when precipita-tion was also higher, illustrating the potential negative effects of drought stress underwarming for this species. Furthermore, we show that past forest management canmodulate the effects of changing temperatures on Quercus’ growth; individuals in plotswith a coppicing history showed stronger growth responses to higher temperatures.Overall, our findings highlight how tree growth can be interactively determined by glo-bal‐change drivers, and how these growth responses might be modulated by past for-est management. By showing future growth changes for scenarios of environmentalchange, we stress the importance of considering multiple drivers, including past man-agement and their interactions, when predicting tree growth. KW - basal area increment KW - climate change KW - Fagus KW - Fraxinus KW - historical ecology KW - nitrogen deposition KW - Quercus KW - tree-ring analysis Y1 - 2018 U6 - https://doi.org/10.1111/gcb.14493 SN - 1354-1013 SN - 1365-2486 VL - 25 IS - 1 SP - 201 EP - 217 PB - Wiley CY - Hoboken ER - TY - THES A1 - Steiglechner, Peter T1 - Estimating global warming from anthropogenic heat emissions T1 - Abschätzung der globalen Erwärmung durch anthropogene Abwärme BT - conceptual and numerical modelling approaches BT - konzeptionelle und numerische Modellierungsansätze N2 - The forcing from the anthropogenic heat flux (AHF), i.e. the dissipation of primary energy consumed by the human civilisation, produces a direct climate warming. Today, the globally averaged AHF is negligibly small compared to the indirect forcing from greenhouse gas emissions. Locally or regionally, though, it has a significant impact. Historical observations show a constant exponential growth of worldwide energy production. A continuation of this trend might be fueled or even amplified by the exploration of new carbon-free energy sources like fusion power. In such a scenario, the impacts of the AHF become a relevant factor for anthropogenic post-greenhouse gas climate change on the global scale, as well. This master thesis aims at estimating the climate impacts of such a growing AHF forcing. In the first part of this work, the AHF is built into simple and conceptual, zero- and one-dimensional Energy Balance Models (EBMs), providing quick order of magnitude estimations of the temperature impact. In the one-dimensional EBM, the ice-albedo feedback from enhanced ice melting due to the AHF increases the temperature impact significantly compared to the zero-dimensional EBM. Additionally, the forcing is built into a climate model of intermediate complexity, CLIMBER-3α. This allows for the investigation of the effect of localised AHF and gives further insights into the impact of the AHF on processes like the ocean heat uptake, sea ice and snow pattern changes and the ocean circulation. The global mean temperature response from the AHF today is of the order of 0.010 − 0.016 K in all reasonable model configurations tested. A transient tenfold increase of this forcing heats up the Earth System additionally by roughly 0.1 − 0.2 K in the presented models. Further growth can also affect the tipping probability of certain climate elements. Most renewable energy sources do not or only partially contribute to the AHF forcing as the energy from these sources dissipates anyway. Hence, the transition to a (carbon-free) renewable energy mix, which, in particular, does not rely on nuclear power, eliminates the local and global climate impacts from the increasing AHF forcing, independent of the growth of energy production. N2 - Das Forcing durch die Emission von anthropogener Abwärme (AHF), d.h. die Dissipation von konsumierter Primärenergie, stellt einen Beitrag zu einer direkten Klimaerwärmung dar. Der global gemittelte AHF ist heutzutage vernachlässigbar klein im Vergleich zu dem indirekten Forcing durch Treibhausgasemissionen. Auf lokaler oder regionaler Ebene hat das Forcing jedoch einen signifikanten Einfluss. Die Energieproduktion hat in der Vergangenheit ein konstant exponentielles Wachstum aufgezeigt. Dieser Trend kann durch die Erschließung neuer CO2-neutraler Energiequellen, wie zum Beispiel Fusionsenergie, weiter bestärkt und angetrieben werden. In solch einem Szenario führt das AHF Forcing zu einem auch global relevanten Beitrag zum menschengemachten Klimawandel abseits der Treibhausgasemissionen. In dieser Arbeit sollen die Auswirkungen eines wachsenden AHF auf das Klima abgeschätzt werden. Im ersten Teil wird das zusätzliche Forcing in einfache und konzeptionelle, null- und eindimensionale Energiebilanzmodelle (EBM) eingebaut. Diese bieten schnelle Größenordnungsabschätzungen des Temperaturanstiegs. Im eindimensionalen EBM erhöht die Eis-Albedo-Rückkopplung die Temperatur signifikant im Verlgeich zum nulldimensionalen Fall aufgrund von verstärkter Eisschmelze. Zusätzlich, wird das AHF Forcing in das Erdsystemmodell mittlerer Komplexität CLIMBER-3α eingebaut. Dieses erlaubt eine Analyse des Effekts eines heterogenen AHF Forcings und gibt weitere Einblicke in die Einflüsse auf Prozessse wie den Wärmefluss in den Ozean, Veränderungen in Meereis und Schneebedeckung und die Ozeanzirkulation. Der global gemittelte Temperaturanstieg für das heutige AHF Forcing beträgt 0.010 − 0.016 K in allen realistischen, getesteten Modellkonfigurationen. Ein transienter Anstieg des Forcings auf den zehnfachen Wert erwärmt die Erde um weitere 0.1 − 0.2 K in den vorgestellten Modellen. Weiteres Wachstum kann zusätzlich auch das Kippen von bestimmten Klimaelementen beeinflussen. Die meisten erneuerbaren Energiequellen tragen nicht oder nur kaum zu der anthropogenen Abwärme bei, da deren Energie sowieso dissipiert. Daher beseitigt ein Wechsel auf einen CO2-neutralen, erneuerbaren Energiemix, der explizit nicht auf nuklearen Brennstoffen basiert, unabhängig von dem Wachstum der Energieproduktion die lokalen wie auch globalen Auswirkungen des AHF Effekts. KW - climate change KW - waste heat KW - heat island KW - energy balance model KW - climate model of intermediate complexity KW - Klimawandel KW - Abwärme KW - Wärmeinsel KW - Energiebilanzmodell KW - Klimamodell mittlerer Komplexität Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-498866 ER - TY - GEN A1 - Metin, Ayse Duha A1 - Dung, Nguyen Viet A1 - Schröter, Kai A1 - Guse, Björn A1 - Apel, Heiko A1 - Kreibich, Heidi A1 - Vorogushyn, Sergiy A1 - Merz, Bruno T1 - How do changes along the risk chain affect flood risk? T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - Flood risk is impacted by a range of physical and socio-economic processes. Hence, the quantification of flood risk ideally considers the complete flood risk chain, from atmospheric processes through catchment and river system processes to damage mechanisms in the affected areas. Although it is generally accepted that a multitude of changes along the risk chain can occur and impact flood risk, there is a lack of knowledge of how and to what extent changes in influencing factors propagate through the chain and finally affect flood risk. To fill this gap, we present a comprehensive sensitivity analysis which considers changes in all risk components, i.e. changes in climate, catchment, river system, land use, assets, and vulnerability. The application of this framework to the mesoscale Mulde catchment in Germany shows that flood risk can vary dramatically as a consequence of plausible change scenarios. It further reveals that components that have not received much attention, such as changes in dike systems or in vulnerability, may outweigh changes in often investigated components, such as climate. Although the specific results are conditional on the case study area and the selected assumptions, they emphasize the need for a broader consideration of potential drivers of change in a comprehensive way. Hence, our approach contributes to a better understanding of how the different risk components influence the overall flood risk. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1067 KW - global sensitivity analysis KW - climate change KW - river floods KW - frequency KW - Europe KW - model KW - vulnerability KW - adaptation KW - strategies KW - catchment Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-468790 SN - 1866-8372 IS - 1067 ER - TY - GEN A1 - Epp, Laura Saskia A1 - Kruse, Stefan A1 - Kath, Nadja J. A1 - Stoof-Leichsenring, Kathleen Rosemarie A1 - Tiedemann, Ralph A1 - Pestryakova, Luidmila Agafyevna A1 - Herzschuh, Ulrike T1 - Temporal and spatial patterns of mitochondrial haplotype and species distributions in Siberian larches inferred from ancient environmental DNA and modeling T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - Changes in species' distributions are classically projected based on their climate envelopes. For Siberian forests, which have a tremendous significance for vegetation-climate feedbacks, this implies future shifts of each of the forest-forming larch (Larix) species to the north-east. However, in addition to abiotic factors, reliable projections must assess the role of historical biogeography and biotic interactions. Here, we use sedimentary ancient DNA and individual-based modelling to investigate the distribution of larch species and mitochondrial haplotypes through space and time across the treeline ecotone on the southern Taymyr peninsula, which at the same time presents a boundary area of two larch species. We find spatial and temporal patterns, which suggest that forest density is the most influential driver determining the precise distribution of species and mitochondrial haplotypes. This suggests a strong influence of competition on the species' range shifts. These findings imply possible climate change outcomes that are directly opposed to projections based purely on climate envelopes. Investigations of such fine-scale processes of biodiversity change through time are possible using paleoenvironmental DNA, which is available much more readily than visible fossils and can provide information at a level of resolution that is not reached in classical palaeoecology. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1052 KW - ecological genetics KW - ecological modelling KW - palaeoecology KW - plant ecology KW - climate change KW - introgression KW - temperature KW - treeline KW - vegetation KW - mitochondrial haplotypes KW - Siberian larch KW - larch species KW - range shifts KW - vegetation-climate feedbacks KW - ecosystems KW - impacts KW - dynamics Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-468352 SN - 1866-8372 IS - 1052 ER - TY - GEN A1 - Jongejans, Loeka L. A1 - Strauss, Jens A1 - Lenz, Josefine A1 - Peterse, Francien A1 - Mangelsdorf, Kai A1 - Fuchs, Matthias A1 - Grosse, Guido T1 - Organic matter characteristics in yedoma and thermokarst deposits on Baldwin Peninsula, west Alaska T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - As Arctic warming continues and permafrost thaws, more soil and sedimentary organic matter (OM) will be decomposed in northern high latitudes. Still, uncertainties remain in the quality of the OM and the size of the organic carbon (OC) pools stored in different deposit types of permafrost landscapes. This study presents OM data from deep permafrost and lake deposits on the Baldwin Peninsula which is located in the southern portion of the continuous permafrost zone in west Alaska. Sediment samples from yedoma and drained thermokarst lake basin (DTLB) deposits as well as thermokarst lake sediments were analyzed for cryostratigraphical and biogeochemical parameters and their lipid biomarker composition to identify the below-ground OC pool size and OM quality of ice-rich permafrost on the Baldwin Peninsula. We provide the first detailed characterization of yedoma deposits on Baldwin Peninsula. We show that three-quarters of soil OC in the frozen deposits of the study region (total of 68 Mt) is stored in DTLB deposits (52 Mt) and one-quarter in the frozen yedoma deposits (16 Mt). The lake sediments contain a relatively small OC pool (4 Mt), but have the highest volumetric OC content (93 kgm(-3)) compared to the DTLB (35 kgm(-3)) and yedoma deposits (8 kgm(-3)), largely due to differences in the ground ice content. The biomarker analysis indicates that the OM in both yedoma and DTLB deposits is mainly of terrestrial origin. Nevertheless, the relatively high carbon preference index of plant leaf waxes in combination with a lack of a degradation trend with depth in the yedoma deposits indi-cates that OM stored in yedoma is less degraded than that stored in DTLB deposits. This suggests that OM in yedoma has a higher potential for decomposition upon thaw, despite the relatively small size of this pool. These findings show that the use of lipid biomarker analysis is valuable in the assessment of the potential future greenhouse gas emissions from thawing permafrost, especially because this area, close to the discontinuous permafrost boundary, is projected to thaw substantially within the 21st century. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 985 KW - northern seward peninsula KW - deep permafrost carbon KW - Laptev Sea region KW - Arctic Siberia KW - climate change KW - gas production KW - Lena delta KW - soils KW - release KW - tundra Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-446250 SN - 1866-8372 IS - 20 SP - 6033 EP - 6048 ER - TY - GEN A1 - Triet, Nguyen Van Khanh A1 - Dung, Nguyen Viet A1 - Merz, Bruno A1 - Apel, Heiko T1 - Towards risk-based flood management in highly productive paddy rice cultivation BT - concept development and application to the Mekong Delta T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - Flooding is an imminent natural hazard threatening most river deltas, e.g. the Mekong Delta. An appropriate flood management is thus required for a sustainable development of the often densely populated regions. Recently, the traditional event-based hazard control shifted towards a risk management approach in many regions, driven by intensive research leading to new legal regulation on flood management. However, a large-scale flood risk assessment does not exist for the Mekong Delta. Particularly, flood risk to paddy rice cultivation, the most important economic activity in the delta, has not been performed yet. Therefore, the present study was developed to provide the very first insight into delta-scale flood damages and risks to rice cultivation. The flood hazard was quantified by probabilistic flood hazard maps of the whole delta using a bivariate extreme value statistics, synthetic flood hydrographs, and a large-scale hydraulic model. The flood risk to paddy rice was then quantified considering cropping calendars, rice phenology, and harvest times based on a time series of enhanced vegetation index (EVI) derived from MODIS satellite data, and a published rice flood damage function. The proposed concept provided flood risk maps to paddy rice for the Mekong Delta in terms of expected annual damage. The presented concept can be used as a blueprint for regions facing similar problems due to its generic approach. Furthermore, the changes in flood risk to paddy rice caused by changes in land use currently under discussion in the Mekong Delta were estimated. Two land-use scenarios either intensifying or reducing rice cropping were considered, and the changes in risk were presented in spatially explicit flood risk maps. The basic risk maps could serve as guidance for the authorities to develop spatially explicit flood management and mitigation plans for the delta. The land-use change risk maps could further be used for adaptive risk management plans and as a basis for a cost-benefit of the discussed land-use change scenarios. Additionally, the damage and risks maps may support the recently initiated agricultural insurance programme in Vietnam. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 931 KW - climate change KW - hazard analysis KW - sea level KW - Tho city KW - Vietnam KW - damage KW - uncertainty KW - models KW - floodplains KW - hydrology Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-446032 SN - 1866-8372 IS - 931 SP - 2859 EP - 2876 ER - TY - JOUR A1 - Drewes, Julia A1 - Moreiras, Stella A1 - Korup, Oliver T1 - Permafrost activity and atmospheric warming in the Argentinian Andes JF - Geomorphology : an international journal on pure and applied geomorphology N2 - Rock glaciers are permafrost or glacial landforms of debris and ice that deform under the influence of gravity. Recent estimates hold that, in the semiarid Chilean Andes for example, active rock glaciers store more water than glaciers. However, little is known about how many rock glaciers might decay because of global warming and how much this decay might contribute to water and sediment release. We investigated an inventory of >6500 rock glaciers in the Argentinian Andes, spanning the climatic gradient from the Desert Andes to cold-temperate Tierra del Fuego. We used active rock glaciers as a diagnostic of permafrost, assuming that the toes mark the 0 degrees C isotherm in climate scenarios for the twenty-first century and their impact on freezing conditions near the rock glacier toes. We find that, under future worst case warming, up to 95% of rock glaciers in the southern Desert Andes and in the Central Andes will rest in areas above 0 degrees C and that this freezing level might move up more than twice as much (similar to 500 m) as during the entire Holocene (similar to 200 m). Many active rock glaciers are already well below the current freezing level and exemplify how local controls may confound regional prognoses. A Bayesian Multifactor Analysis of Variance further shows that only in the Central Andes are the toes of active rock glaciers credibly higher than those of inactive ones. Elsewhere in the Andes, active and inactive rock glaciers occupy indistinguishable elevation bands, regardless of aspect, the formation mechanism, or shape of rock glaciers. The state of rock glacier activity predicts differences in elevations of toes to 140 m at best so that regional inference of the distribution of discontinuous permafrost from rock-glacier toes cannot be more accurate than this in the Argentinian Andes. We conclude that the Central Andes-where rock glaciers are largest, cover the most area, and have a greater density than glaciers-is likely to experience the most widespread disturbance to the thermal regime of the twenty-first century. (C) 2018 Elsevier B.V. All rights reserved. KW - rock glacier KW - Argentina KW - permafrost KW - climate change Y1 - 2018 U6 - https://doi.org/10.1016/j.geomorph.2018.09.005 SN - 0169-555X SN - 1872-695X VL - 323 SP - 13 EP - 24 PB - Elsevier CY - Amsterdam ER - TY - GEN A1 - Unterberger, Christian A1 - Hudson, Paul A1 - Botzen, W. J. Wouter A1 - Schroeer, Katharina A1 - Steininger, Karl W. T1 - Future public sector flood risk and risk sharing arrangements BT - an assessment for Austria T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - Climate change, along with socio-economic development, will increase the economic impacts of floods. While the factors that influence flood risk to private property have been extensively studied, the risk that natural disasters pose to public infrastructure and the resulting implications on public sector budgets, have received less attention. We address this gap by developing a two-staged model framework, which first assesses the flood risk to public infrastructure in Austria. Combining exposure and vulnerability information at the building level with inundation maps, we project an increase in riverine flood damage, which progressively burdens public budgets. Second, the risk estimates are integrated into an insurance model, which analyzes three different compensation arrangements in terms of the monetary burden they place on future governments' budgets and the respective volatility of payments. Formalized insurance compensation arrangements offer incentives for risk reduction measures, which lower the burden on public budgets by reducing the vulnerability of buildings that are exposed to flooding. They also significantly reduce the volatility of payments and thereby improve the predictability of flood damage expenditures. These features indicate that more formalized insurance arrangements are an improvement over the purely public compensation arrangement currently in place in Austria. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 634 KW - climate change KW - adaptation KW - flood risk KW - insurance KW - public sector KW - risk reduction Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-424629 SN - 1866-8372 IS - 634 ER - TY - THES A1 - Willner, Sven N. T1 - Global economic response to flood damages under climate change T1 - Global-ökonomische Reaktion auf klimabedingte Überschwemmungsschäden N2 - Climate change affects societies across the globe in various ways. In addition to gradual changes in temperature and other climatic variables, global warming is likely to increase intensity and frequency of extreme weather events. Beyond biophysical impacts, these also directly affect societal and economic activity. Additionally, indirect effects can occur; spatially, economic losses can spread along global supply-chains; temporally, climate impacts can change the economic development trajectory of countries. This thesis first examines how climate change alters river flood risk and its local socio-economic implications. Then, it studies the global economic response to river floods in particular, and to climate change in general. Changes in high-end river flood risk are calculated for the next three decades on a global scale with high spatial resolution. In order to account for uncertainties, this assessment makes use of an ensemble of climate and hydrological models as well as a river routing model, that is found to perform well regarding peak river discharge. The results show an increase in high-end flood risk in many parts of the world, which require profound adaptation efforts. This pressure to adapt is measured as the enhancement in protection level necessary to stay at historical high-end risk. In developing countries as well as in industrialized regions, a high pressure to adapt is observed - the former to increase low protection levels, the latter to maintain the low risk levels perceived in the past. Further in this thesis, the global agent-based dynamic supply-chain model acclimate is developed. It models the cascading of indirect losses in the global supply network. As an anomaly model its agents - firms and consumers - maximize their profit locally to respond optimally to local perturbations. Incorporating quantities as well as prices on a daily basis, it is suitable to dynamically resolve the impacts of unanticipated climate extremes. The model is further complemented by a static measure, which captures the inter-dependencies between sectors across regions that are only connected indirectly. These higher-order dependencies are shown to be important for a comprehensive assessment of loss-propagation and overall costs of local disasters. In order to study the economic response to river floods, the acclimate model is driven by flood simulations. Within the next two decades, the increase in direct losses can only partially be compensated by market adjustments, and total losses are projected to increase by 17% without further adaptation efforts. The US and the EU are both shown to receive indirect losses from China, which is strongly affected directly. However, recent trends in the trade relations leave the EU in a better position to compensate for these losses. Finally, this thesis takes a broader perspective when determining the investment response to the climate change damages employing the integrated assessment model DICE. On an optimal economic development path, the increase in damages is anticipated as emissions and consequently temperatures increase. This leads to a significant devaluation of investment returns and the income losses from climate damages almost double. Overall, the results highlight the need to adapt to extreme weather events - local physical adaptation measures have to be combined with regional and global policy measures to prepare the global supply-chain network to climate change. N2 - Der Klimawandel betrifft Gesellschaften weltweit auf verschiedenste Weise. Neben graduellen Veränderungen der Temperatur und anderer klimatischer Variablen werden wahrscheinlich auch die Intensität und die Häufigkeit von Extremwetterereignissen zunehmen. Diese beeinflussen neben ihren bio-physikalischen Auswirkungen auch unmittelbar die gesellschaftliche und wirtschaftliche Aktivität. Zusätzlich können indirekte Effekte auftreten: Die räumliche Dimension umfasst die Ausbreitung wirtschaftlicher Schäden entlang globaler Versorgungsketten, zeitlich betrachtet können Klimaauswirkungen die wirtschaftlichen Entwicklungspfade von Ländern prägen. Die vorliegende Dissertation widmet sich zunächst der Frage, wie sich (Fluss-)Hochwasserrisiken und ihre gesellschaftlichen sowie wirtschaftlichen Implikationen durch den Klimawandel verändern. Weiterhin wird die Reaktionsdynamik des globalen ökonomischen Systems auf Klimawandel im Allgemeinen und auf Überschwemmungsereignisse an Flüssen im Speziellen untersucht. So werden die Risiken von schweren Fluss-Überschwemmungen für die nächsten drei Jahrzehnte global mit hoher räumlicher Auflösung berechnet. Zur Berücksichtigung von Unsicherheiten wird dabei auf ein Ensemble von Klima- und hydrologischen Modellen zurückgegriffen. Dabei werden die hydrologischen Modelle mit einem Flussverteilungsmodel, das die verbesserte Abbildung von Extrempegelständen an Flüssen ermöglicht, kombiniert. Die Berechnungen zeigen einen Anstieg des Überschwemmungsrisikos für weite Teile der Erde. Der damit einhergehende Anpassungsdruck wird in dieser Studie als Anpassung des Schutzniveaus berechnet, die notwendig ist, um das bestehende Überschwemmungsrisiko beizubehalten. Ein hoher Anpassungsdruck besteht dabei sowohl in Entwicklungs- als auch in Industriestaaten. Während in Ersteren oft erst adäquate Hochwasserschutzmaßnahmen ergriffen werden müssen, müssen Letztere oft ihr aktuelles Schutzniveau ausbauen. Weiterhin wird in der vorliegenden Arbeit das globale, agenten-basierte und dynamische Modell acclimate entwickelt, welches Kaskaden von indirekten ökonomischen Schäden im globalen Versorgungsnetzwerk modelliert. Acclimate ist als Anomalienmodell angelegt, dessen Agenten - Firmen und Konsumenten - durch Profitmaximierung versuchen, optimal auf lokale Störungen zu reagieren. Da das Modell sowohl Warenströme als auch die zugehörigen Preise nach Tagen aufgelöst abbildet, ist es besonders gut geeignet, die kurzfristigen ökonomischen Auswirkungen unvorhergesehener Klimaextreme zu beschreiben. Das dynamische Modell wird ergänzt durch ein neues statisches Maß, das die Abhängigkeiten zwischen regionalen Sektoren beschreibt. Dabei werden nicht nur die direkten Handelsverbindungen betrachtet, sondern auch solche höherer Ordnung. Es zeigt sich, dass diese für eine umfassende Abschätzung der Schadenskaskaden und damit der Gesamtkosten lokaler Extremereignisse nicht vernachlässigt werden dürfen. Zur Untersuchung der ökonomischen Reaktionsdynamik auf Hochwasserereignisse wird das acclimate-Modell für Simulationen von Flussüberschwemmungen angewandt. Bis zum Jahr 2035 wird dabei ein Anstieg des direkten Schadens prognostiziert. Dieser kann nur teilweise durch Marktmechanismen ausgeglichen werden, so dass die Gesamtschäden weltweit um 17% zunehmen - sofern keine zusätzlichen Anpassungsmaßnahmen getroffen werden. Für die USA und die EU zeigt sich, dass diese durch ihre Handelsverbindungen insbesondere zu China indirekt betroffen sind, da China starke direkte Flussüberflutungen zu erwarten hat. Die Entwicklungen der globalen Handelsbeziehungen in den letzten Jahren versetzen die EU jedoch in die Lage einen zunehmenden Teil dieser Verluste auszugleichen. In einem weiter gefassten Ansatz wird schlussendlich die Änderung des Investitionsverhaltens aufgrund der Schäden durch Klimawandel unter Zuhilfenahme des ökonomischen Wachstumsmodells DICE untersucht. Es lässt sich festhalten, dass auf einem optimalen ökonomischen Entwicklungspfad die Zunahme der Schäden bereits antizipiert wird, wenn Emissionen und dem darauf folgend die Temperatur ansteigen. Dies führt zu einer signifikanten Abwertung von Kapitalerträgen, was die direkten Verluste durch Klimaschäden nahezu verdoppelt. Insgesamt unterstreichen die Ergebnisse dieser Arbeit die Notwendigkeit der Anpassung an klimabedingte Extremwetterereignisse. Dazu müssen lokale, physikalische Anpassungsmaßnahmen durch regionale und globale Politikinstrumente ergänzt werden, um das globale Versorgungsnetzwerk adäquat auf den Klimawandel vorzubereiten. KW - climate change KW - river floods KW - higher-order effects KW - economic network KW - climate impacts KW - Klimawandel KW - Überschwemmungen KW - Wirtschaftsnetzwerk Y1 - 2018 ER - TY - THES A1 - Hesse, Cornelia T1 - Integrated water quality modelling in meso- to large-scale catchments of the Elbe river basin under climate and land use change T1 - Integrierte Gewässergütemodellierung in mittel- bis großskaligen Einzugsgebieten der Elbe unter dem Einfluss von Klima- und Landnutzungsänderungen N2 - In einer sich ändernden Umwelt sind Fließgewässerökosysteme vielfältigen direkten und indirekten anthropogenen Belastungen ausgesetzt, die die Gewässer sowohl in ihrer Menge als auch in ihrer Güte beeinträchtigen können. Ein übermäßiger Eintrag von Nährstoffen verursacht etwa Massenentwicklungen von Algen und Sauerstoffdefizite in den Gewässern, was zum Verfehlen der Ziele der Wasserrahmenrichtlinie (WRRL) führen kann. In vielen europäischen Einzugsgebieten und auch dem der Elbe sind solche Probleme zu beobachten. Während der letzten Jahrzehnte entstanden diverse computergestützte Modelle, die zum Schutz und Management von Wasserressourcen genutzt werden können. Sie helfen beim Verstehen der Nährstoffprozesse und Belastungspfade in Einzugsgebieten, bei der Abschätzung möglicher Folgen von Klima- und Landnutzungsänderungen für die Wasserkörper, sowie bei der Entwicklung eventueller Kompensationsmaßnahmen. Aufgrund der Vielzahl an sich gegenseitig beeinflussenden Prozessen ist die Modellierung der Wasserqualität komplexer und aufwändiger als eine reine hydrologische Modellierung. Ökohydrologische Modelle zur Simulation der Gewässergüte, einschließlich des Modells SWIM (Soil and Water Integrated Model), bedürfen auch häufig noch einer Weiterentwicklung und Verbesserung der Prozessbeschreibungen. Aus diesen Überlegungen entstand die vorliegende Dissertation, die sich zwei Hauptanliegen widmet: 1) einer Weiterentwicklung des Nährstoffmoduls des ökohydrologischen Modells SWIM für Stickstoff- und Phosphorprozesse, und 2) der Anwendung des Modells SWIM im Elbegebiet zur Unterstützung eines anpassungsfähigen Wassermanagements im Hinblick auf mögliche zukünftige Änderungen der Umweltbedingungen. Die kumulative Dissertation basiert auf fünf wissenschaftlichen Artikeln, die in internationalen Zeitschriften veröffentlicht wurden. Im Zuge der Arbeit wurden verschiedene Modellanpassungen in SWIM vorgenommen, wie etwa ein einfacher Ansatz zur Verbesserung der Simulation der Wasser- und Nährstoffverhältnisse in Feuchtgebieten, ein um Ammonium erweiterter Stickstoffkreislauf im Boden, sowie ein Flussprozessmodul, das Umwandlungsprozesse, Sauerstoffverhältnisse und Algenwachstum im Fließgewässer simuliert, hauptsächlich angetrieben von Temperatur und Licht. Auch wenn dieser neue Modellansatz ein sehr komplexes Modell mit einer Vielzahl an neuen Kalibrierungsparametern und steigender Unsicherheit erzeugte, konnten gute Ergebnisse in den Teileinzugsgebieten und dem gesamten Gebiet der Elbe erzielt werden, so dass das Modell zur Abschätzung möglicher Folgen von Klimavariabilitäten und veränderten anthropogenen Einflüssen für die Gewässergüte genutzt werden konnte. Das neue Fließgewässermodul ist ein wichtiger Beitrag zur Verbesserung der Nährstoffmodellierung in SWIM, vor allem für Stoffe, die hauptsächlich aus Punktquellen in die Gewässer gelangen (wie z.B. Phosphat). Der neue Modellansatz verbessert zudem die Anwendbarkeit von SWIM für Fragestellungen im Zusammenhang mit der WRRL, bei der biologische Qualitätskomponenten (wie etwa Phytoplankton) eine zentrale Rolle spielen. Die dargestellten Ergebnisse der Wirkungsstudien können bei Entscheidungsträgern und anderen Akteuren das Verständnis für zukünftige Herausforderungen im Gewässermanagement erhöhen und dazu beitragen, ein angepasstes Management für das Elbeeinzugsgebiet zu entwickeln. N2 - In a changing world facing several direct or indirect anthropogenic challenges the freshwater resources are endangered in quantity and quality. An excessive supply of nutrients, for example, can cause disproportional phytoplankton development and oxygen deficits in large rivers, leading to failure of the aims requested by the Water Framework Directive (WFD). Such problems can be observed in many European river catchments including the Elbe basin, and effective measures for improving water quality status are highly appreciated. In water resources management and protection, modelling tools can help to understand the dominant nutrient processes and to identify the main sources of nutrient pollution in a watershed. They can be effective instruments for impact assessments investigating the effects of changing climate or socio-economic conditions on the status of surface water bodies, and for testing the usefulness of possible protection measures. Due to the high number of interrelated processes, ecohydrological model approaches containing water quality components are more complex than the pure hydrological ones, and their setup and calibration require more efforts. Such models, including the Soil and Water Integrated Model (SWIM), still need some further development and improvement. Therefore, this cumulative dissertation focuses on two main objectives: 1) the approach-related objectives aiming in the SWIM model improvement and further development regarding nutrient (nitrogen and phosphorus) process description, and 2) the application-related objectives in meso- to large-scale Elbe river basins to support adaptive river basin management in view of possible future changes. The dissertation is based on five scientific papers published in international journals and dealing with these research questions. Several adaptations were implemented in the model code to improve the representation of nutrient processes including a simple wetland approach, an extended by ammonium nitrogen cycle in the soils, as well as a detailed in-stream module, simulating algal growth, nutrient transformation processes and oxygen conditions in the river reaches, mainly driven by water temperature and light. Although this new approaches created a highly complex ecohydrological model with a large number of additional calibration parameters and rising uncertainty, the calibration and validation of the SWIM model enhanced by the new approaches in selected subcatchment and the entire Elbe river basin delivered satisfactory to good model results in terms of criteria of fit. Thus, the calibrated and validated model provided a sound base for the assessment of possible future changes and impacts in climate, land use and management in the Elbe river (sub)basin(s). The new enhanced modelling approach improved the applicability of the SWIM model for the WFD related research questions, where the ability to consider biological water quality components (such as phytoplankton) is important. It additionally enhanced its ability to simulate the behaviour of nutrients coming mainly from point sources (e.g. phosphate phosphorus). Scenario results can be used by decision makers and stakeholders to find and understand future challenges and possible adaptation measures in the Elbe river basin. KW - Elbe KW - SWIM KW - Wassergütemodellierung KW - water quality modelling KW - Nährstoffe KW - nutrients KW - Nährstoffretention KW - nutrient retention KW - Flussprozesse KW - in-stream processes KW - climate change KW - land use change KW - Klimaänderung KW - Landnutzungsänderung Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-422957 ER - TY - THES A1 - Smith, Taylor T1 - Decadal changes in the snow regime of High Mountain Asia, 1987-2016 T1 - Veränderungen in der Schnee-Regen-Bilanz auf dekadischen Zeitskalen im zentralasiatischen Hochgebirge (1987-2016) N2 - 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. N2 - Mehr als eine Milliarde Menschen ist von Wasser aus Flüssen, welche im Hochgebirge Asiens (HA) entspringen, abhängig. Diese werden, im Wesentlichen durch Schmelzwasser von Schnee und Gletschern gespeist. Gemeinden auf dem Land sind im hohem Maße auf die Beständigkeit des Wasserabflusses angewiesen, und folglich stark anfällig für durch Klimawandel hervorgerufene Veränderungen der Umwelt auf regionaler Ebene. Der extensive Gletscherrückzug ist ein deutlich sichtbarer und weitgehend erforschter Marker für den Klimawandel auf regionaler und globaler Ebene. In vielen Einzugsgebieten machen jedoch Schnee und Schneeschmelzen einen sehr viel größeren Anteil des jährlichen Wasserbudgets aus also Gletscherschmelzwasser. Dennoch sind die klimaabhängigen Veränderungen auf Schneeressourcen im HA nicht ausreichend untersucht. Passive Mikrowellenradiometer (PM) basierte Fernerkundung ist eine etablierte empirische Methode zur Untersuchung von Schneeressourcen in weit ausgedehnten Gebieten. Seit 1987 wurden täglich konsistente PM Messungen auf globaler Ebene durchgeführt, die zur Abschätzung der Schneehöhe verwendet werden können, und folglich den Anteil des Wassers in der Schneemasse wiederspiegeln – das Schneewasser Äquivalent (SWE). In dieser Studie die lokalen Veränderungen des SWE über dem gesamten HA untersucht. Trotz großer räumlicher und saisonaler Heterogenität, wurde eine Gesamtverringerung des SWE (10,6 mm/yr) festgestellt. Im Winter jedoch hat das SWE in etwa 50% des HAs trotz der negativen Trends im restlichen Verlauf des Jahres zugenommen. Wie aus der Diskussion über die relativen Veränderungen im SWE hervorgeht, wird in dieser Studie mithilfe eines neuentwickelten Algorithmus die Untersuchung der Veränderungen des Zeitlichen einsetzen der Schneeschmelzperiode im HA. Während im nahezu gesamten Gebiet des HA das Ende Schneeschmelzsaison verfrüht einsetzt, so ist in der Hälfte des Gebietes der Begin dieser nach hinten verschoben. Die Schneeschmelzperioden haben im so gut wie gesamten Gebiet des HA abgenommen, was darauf hindeutet dass sich diese über dem gesamten HA generell verkürzt haben und frühzeitig beendet werden. Durch die Untersuchung der räumlich-zeitlichen Verteilung der Schneevolumens und des Schneeschmelzperioden im gesamten HA konnten wir eine lückenlose Bilanz der Veränderungen der Schneeressourcen im HA erstellen. Der allgemeine Trend zeigt eine geringere Speicherung des SWE und kürzere Schneeschmelzperioden im gesamten HA. Langfristige und regionale Trends überdecken jedoch verschiedene saisonale, temporäre und räumliche Heterogenität, was wiederum zeigt dass Veränderungen der Schneebedeckung stark von lokalem Klima und der Topographie abhängen, und dass jährliche Schwankungen zu einem erheblichen Anteil zum Schneeregime des HA beitragen. KW - climate change KW - snow KW - remote sensing KW - Schnee KW - Klimawandel KW - Fernerkundung Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-407120 ER -