Ansatz einer umfassenden, vergleichenden Bewertung von Climate Engineering Massnahmen: Metriken, Indikatoren und Unsicherheiten

Climate Engineering (CE) as an option to prevent dangerous climate change has reached the political debate. For a well informed decision on CE research and deployment in the future, work towards a comprehensive, comparative assessment is needed. In the first part of this thesis, climate impacts and side effects of an artificial Arctic ocean albedo modification scheme are studied. The second part of this thesis presents a parameter sensitivity study on the uncertainty in the response of transpiration to CO2 and implications for climate change. Is the application of indicators used for the historical time period valid for a comprehensive assessment of future climate change? In the third part of the thesis we introduce a methodological approach to systematically evaluate correlation matrices, identifying robust indicators from Earth system variables, to be used in a natural-science based assessment. In the fourth part of this thesis this method is applied to three exemplary CE scenarios: Large-scale afforestation, ocean alkalinity enhancement and solar radiation management. Changes in correlation patterns provide information on which variables might become more relevant under CE scenarios. To enable a comprehensive comparison of the three scenarios, the common correlation matrix is systematically evaluated to identify an indicator set. A preliminary evaluation of the three scenarios based on these indicators remains inconclusive. If the indicators are further aggregated into a metric to reduce the complexity, a ranking of the different scenarios becomes evident. Given all assumptions, we find that overall the RCP4.5 scenario performs ’best’ in staying close to todays climate state. Solar Radiation Management is identified as the ’best’ CE scenario, followed by Ocean Alkalinity Enhancement and Large-scale Afforestation. These analyses advance the natural-science based assessment of CE, which is essential prior to a decision making process.Auf politischer Ebene hat man begonnen über Climate Engineering (CE) als mögliche Option gegen den mensch-gemachten Klimawandel zu sprechen. Um gut informierte Entscheidungen zum Thema zukünftiger Forschung oder potentiellen Umsetzung von CE Massnahmen zu treffen, benötigt man eine umfassende und vergleichende Einschätzung der verschiedenen Methoden. Im ersten Teil der Arbeit werden Effekte und Nebenwirkungen der CE Methode Ozeanoberlächenaufhellung in der Arktis (AOAM) untersucht. Im zweiten Teil der Arbeit wird eine Parameter Studie zur CO2 Sensitivität von Vegetationstranspiration vorgestellt. Ist es ausreichend die Indikatoren für die historische Zeitspanne zu benutzen, um zukünftigen Klimawandel umfassend zu beschreiben? Im dritten Teil der Arbeit wird eine Methodik eingeführt, um systematisch Korrelationsmatrizen auszuwerten. Das ermöglicht die Identifizierung eines Indikatorensets für eine umfassende, naturwissenschaftliche Beurteilung der gegebenen Fragestellung. Im vierten Teil der Arbeit wird diese Methode auf drei CE Szenarien angewendet, wodurch Änderungen in den jeweiligen Korrelationsmustern gegenüber der zwei Klimawandel Szenarien identifiziert werden können. Eine erste Beurteilung der drei exemplarischen CE Methoden, basierend auf den ausgewählten Indikatoren, bleibt zunächst ergebnislos. Erst wenn die Indikatoren zu einer Metrik zusammen gefasst werden, gelangen wir zu einem klareren Ranking der Szenarien. Unter den gegebenen Annahmen, stellen wir fest, dass das RCP4.5 Szenario am nächsten an dem gewählten Referenzklimazustand bleibt. Das Strahlungsmanagement Szenario ist das ’beste’ CE Szenario, gefolgt von der Ozeankalkung und der gross-skaligen Aufforstung. Diese Analysen bringen das naturwissenschaftliche Verständnis von verschiedenen CE Methoden voran, welches massgeblich für eine spätere Entscheidungsfindung ist

The Role of Intervertebral Disc Cartilage Catabolites in Modic Type 1 Changes

The thesis investigates the pathobiology of Modic changes (MCs), specifically focusing on Modic type 1 changes (MC1), emphasizing the complexity of the disease. Although MCs manifest as vertebral bone marrow lesions, the inflammation and degeneration observed in the neighboring intervertebral disc and cartilage endplate (CEP) are also closely linked to MCs. However, the underlying mechanisms and how the tissues crosstalk to induce MC development are unclear to this point. Yet, comprehending these pathobiological mechanisms is crucial for the development of targeted therapies, which are currently nonexistent. The thesis explores various aspects of MC1 addressing pathologic processes seen within the MC1 bone marrow, the CEP and the disc. Finally, the project's findings suggest a new disease mechanism for MC1 development initiated through MC1 specific disc degeneration. Chapter three investigated the impact of bone marrow stromal cells (BMSC) from MC1 on neurite outgrowth, using an in-vitro co-culture system. Multiple studies have reported an elevated presence of nerve fibers in the MC1 bone marrow and endplate, a definitive connection to the underlying cause has not been established. For the first time, the dysregulated MC1 BMSCs were directly linked to increased neurite outgrowth. With this knowledge, an important treatment target has been identified, paving the way for further studies to explore how to mitigate this effect. The fourth chapter explores the concept of a disc microbiome, particularly focusing on the MC1 and MC2 microbiomes, using metagenomic analysis. The disc microbiome challenges the conventional notion of disc sterility, necessitating clear methodological definitions for further investigation. Although our analysis confirmed the presence of a disc microbiome, the findings deviated from those of previous studies on degenerated MC discs, even after aligning the parameters of bioinformatic analysis to the previous studies. This study underscores the importance of not only standardizing bioinformatic analysis approaches but also further investigating factors that influence the bacterial composition of the disc microbiome. Differences could stem from sample preparation techniques or variations in the geographical and ethnic backgrounds of patients. Once clarified, the exploration of the disc microbiome will unlock numerous opportunities for diagnostic and treatment applications. The fifth chapter of the thesis highlights the to this point overlooked biological role of CEP cells. The experiments were able to confirm the presence of Toll-like receptors (TLRs) on CEP cells and particularly emphasized the presence of TLR2 as it was the only TLR that was upregulated through direct stimulation. The discovery of TLRs on CEP cells is noteworthy due to their high density compared to the cells in the adjacent disc and their ability to induce inflammation and promote the production of catabolic enzymes, potentially leading to endplate degeneration. This not only enhances our understanding of CEP cells but also reveals novel treatment targets. The sixth chapter presents the main project of the thesis, which focuses on understanding MC1 pathobiology and proposes a new mechanism for MC1 development beginning with MC1-specific disc degeneration. It is grounded in the fact that although disc degeneration is often observed in the disc adjacent to MC1, not all degenerated discs progress to MC1. The proposed MC1-specific disc degeneration is hypothesized to generate more fragments, triggering inflammation in the adjacent endplate, causing endplate destruction. This ultimately breaches the CEP barrier between the disc and bone marrow, allowing pro-inflammatory fragments (damage associated molecular patterns (DAMPs)) and inflammatory cytokines to spill over into the bone marrow, inducing MC1. Although the study is ongoing, significant discoveries have been made. MC1 discs were found to have a higher abundance of extracellular matrix derived fragments as well a greater abundance of the protease high temperature requirement serine protease 1 (HTRA1) than degenerated nonMC discs. In a subsequent phase, the abundant cartilage intermediate layer protein 1 (CILP1) fragments were successfully replicated by exposure to HTRA1 and were demonstrated to possess pro-inflammatory properties via TLR4 signaling activation, thereby classifying them as DAMPs. A CEP explant model was used to show that TLR activation can induce CEP tissue destruction, connecting the DAMP abundance in the disc to CEP damage. However, further experiments are necessary to address the gaps within the proposed mechanism. MC1 is a pathology associated with distinct inflammatory and pain-related processes, suggesting it could and should be treated specifically. This thesis demonstrates this and thus marks an important step towards targeted therapy for MC1

Korrelationen zwischen Änderungen des Windstresses, des Meeresspiegels und der Dichteschichtung im atlantischen Sektor des Südlichen Ozeans im Bezug auf den Jahresgang und auf zwischenjährliche Zeitskalen

Due to the increasing data coverage of the Southern Ocean by programs like the Argo Float Program, an analysis for this area concerning seasonal timescales is possible (Sallee). During the last three decades observations show an increase of the Southern Hemisphere westerlies (Visbeck (2007)). In most of the climate projections this trend tends to continue (Böning et. al. (2008)). By now the reactions of the Antarctic Circumpolar Current (Antarctic Circumpolar Current) concerning these changes in wind stress are not sufficiently clarified as well as in what timescales theses reactions might occur. In this bachelor thesis it is examined whether correlations can be found between changes in wind stress, in the steepness of the sea surface and stratification using CERSAT- scatterometer, AVISO - altimeter and Argo float data. These studies concern seasonal and interannual timescales. Therefore the chronological sequence of the mean wind stress from 40◦S to 55◦S, as well as the variation in time of the height differences of the sea surface and depth differences of the sigma27.2 density surface between 40◦S and 55◦S are observed. As a conclusion the development of the density surface on seasonal timescales arises to 61% from the influence of the wind stress. There is a time lag of two months between the wind stress and the reaction in the isopycnal tilt. The strength of the influence of the sea surface steepness is still uncertain. It is not possible to state clear positions concerning correlations on interannual timescales, as the time series of the float-data is too short (five years) for exact calculations