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Abschied von KyotoPlus?
(2012)
Die Ergebnisse des Klimagipfels von Kopenhagen sind eine bittere
Enttäuschung für die EU. Ihr ist es nicht gelungen, ihren Führungsambitionen
beim globalen Klimaschutz gerecht zu werden und die
Konferenz zur Weichenstellung für ein rechtsverbindliches Klimaabkommen
nach 2012 zu nutzen. Damit steht die Union vor grundlegenden
strategischen Fragen zum Kurs ihrer Klimapolitik.
Dentro de la cuenca intermontana de Quito-Guay llabamba de Ecuador, se han identificado y analizado en este estudio, cinco depósitos coluviales inusualmente grandes de antiguos deslizamientos. El gran deslizamiento rotacional MM-5 Guayllabamba es el más extenso, con un volumen de 1183 millones de m3. Las mega avalanchas de escombros MM-1 Conocoto, MM-3 Oyacoto, y MM-4 San Francisco fueron desencadenadas originalmente por una ruptura inicial que estuvo asociada a un deslizamiento rotacional, los depósitos correspondientes tienen volúmenes entre 399 a 317 millones de m3. Finalmente, el depósito de menor volumen, el deslizamiento rotacional y caída de detritos MM-2 Batán, tiene un volumen de 8,7 millones de m3. En esta tesis, se realizó un estudio detallado de estos grandes movimientos en masa utilizando métodos neotectónicos y lito-tefrostratigráficos para comprender las condiciones geológicas y geomorfológicas de contorno que podrían ser relevantes para desencadenar estos movimientos en masa. La parte neotectónica del estudio se basó en el análisis geomorfológico cualitativo y cuantitativo de estos grandes depósitos de movimientos en masa, a través de la caracterización estructural de anticlinales ubicados al este de la subcuenca de Quito y sus flancos colapsados que constituyen las áreas de ruptura. Esta parte del análisis fue además apoyada por la aplicación de diferentes índices morfométricos para revelar procesos de evolución del paisaje forzados tectónicamente que pueden haber contribuido a la generación de movimientos en masa. La parte lito-tefrostratigráfica del estudio se basó en el análisis de las características petrográficas, geoquímicas y geocronológicas de los horizontes del suelo y de las cenizas volcánicas intercaladas, con el objetivo de restringir la cronología de los eventos individuales de movimientos en masa y su posible de correlación. Los resultados se integraron en esquemas cronoestratigráficos utilizando superficies de ruptura, relaciones transversales y de superposición de depósitos de deslizamiento y estratos posteriores para comprender los movimientos en masa en el contexto tectónico y temporal del entorno de la cuenca intermontana, así como para identificar los mecanismos desencadenantes de cada evento. El movimiento en masa MM-5 Guayllabamba es el resultado del colapso de la ladera suroeste del volcán Mojanda y fue desencadenado por la interacción de condiciones geológicas y morfológicas hace aproximadamente 0,81 Ma. El primer episodio de avalancha de escombros de los movimientos en masa MM-3 Oyacoto y MM-4 San Francisco podría estar relacionado con condiciones tanto geológicas como morfológicas, dadas las rocas altamente fracturadas y el levantamiento del anticlinal Bellavista-Catequilla que posteriormente fue inciso al pie de la ladera por la erosión fluvial. Este primer episodio de colapso probablemente ocurrió alrededor de los 0,8 Ma. El movimiento en masa MM-2 Batán posiblemente también fue desencadenado por una combinación de condiciones geológicas y morfológicas, asociadas a una reducción de los esfuerzos litostáticos que afectaron a las formaciones Chiche y Machángara y a un aumento de los esfuerzos de cizalla durante procesos de socavación fluvial lateral en los flancos de las áreas de origen. Esto apunta a un proceso vinculado entre la erosión fluvial y los procesos de levantamiento asociados a la evolución del anticlinal El Batán-La Bota que podría haber ocurrido entre 0,5 y 0,25 Ma. La voluminosa avalancha de escombros MM-1 Conocoto, así como el segundo episodio de avalancha de escombros que generó los movimientos en masa MM-3 Oyacoto y MM-4 San Francisco, fueron provocados por el colapso gravitacional de las formaciones Mojanda y Cangahua que se caracterizan por la intercalación de cenizas volcánicas. La falla del flanco oriental de los anticlinales probablemente estuvo asociada al incremento de la humedad disponible relacionada con las variaciones climáticas regionales del Holoceno. Los resultados de la cronología de los paleosuelos combinados con los datos cronoestratigráficos y paleoclimáticos regionales sugieren que estas avalanchas de escombros se desencadenaron entre 5 y 4 ka.
La tectónica activa ha modelado los rasgos morfológicos de la cuenca intermontana Quito-Guayllabamba. El desencadenamiento de movimientos en masa en este ambiente está asociado a rupturas en litologías del Pleistoceno (sedimentos lacustres, depósitos aluviales y volcánicos) sometidas a procesos de deformación, actividad sísmica y episodios superpuestos de variabilidad climática. El Distrito Metropolitano de Quito es parte integral de este complejo entorno y de las condiciones geológicas, climáticas y topográficas que continúan influyendo en el espacio geográfico urbano dentro de esta cuenca intermontana. La ciudad de Quito comprende el área de mayor consolidación urbana incluyendo las subcuencas de Quito y San Antonio, con una población de 2,872 millones de habitantes, lo que refleja la importancia del estudio de las amenazas geológicas y climáticas inherentes a esta región.
The Tibetan Plateau is the largest elevated landmass in the world and profoundly influences atmospheric circulation patterns such as the Asian monsoon system. Therefore this area has been increasingly in focus of palaeoenvironmental studies. This thesis evaluates the applicability of organic biomarkers for palaeolimnological purposes on the Tibetan Plateau with a focus on aquatic macrophyte-derived biomarkers. Submerged aquatic macrophytes have to be considered to significantly influence the sediment organic matter due to their high abundance in many Tibetan lakes. They can show highly 13C-enriched biomass because of their carbon metabolism and it is therefore crucial for the interpretation of δ13C values in sediment cores to understand to which extent aquatic macrophytes contribute to the isotopic signal of the sediments in Tibetan lakes and in which way variations can be explained in a palaeolimnological context. Additionally, the high abundance of macrophytes makes them interesting as potential recorders of lake water δD. Hydrogen isotope analysis of biomarkers is a rapidly evolving field to reconstruct past hydrological conditions and therefore of special relevance on the Tibetan Plateau due to the direct linkage between variations of monsoon intensity and changes in regional precipitation / evaporation balances. A set of surface sediment and aquatic macrophyte samples from the central and eastern Tibetan Plateau was analysed for composition as well as carbon and hydrogen isotopes of n-alkanes. It was shown how variable δ13C values of bulk organic matter and leaf lipids can be in submerged macrophytes even of a single species and how strongly these parameters are affected by them in corresponding sediments. The estimated contribution of the macrophytes by means of a binary isotopic model was calculated to be up to 60% (mean: 40%) to total organic carbon and up to 100% (mean: 66%) to mid-chain n-alkanes. Hydrogen isotopes of n-alkanes turned out to record δD of meteoric water of the summer precipitation. The apparent enrichment factor between water and n-alkanes was in range of previously reported ones (≈-130‰) at the most humid sites, but smaller (average: -86‰) at sites with a negative moisture budget. This indicates an influence of evaporation and evapotranspiration on δD of source water for aquatic and terrestrial plants. The offset between δD of mid- and long-chain n-alkanes was close to zero in most of the samples, suggesting that lake water as well as soil and leaf water are affected to a similar extent by those effects. To apply biomarkers in a palaeolimnological context, the aliphatic biomarker fraction of a sediment core from Lake Koucha (34.0° N; 97.2° E; eastern Tibetan Plateau) was analysed for concentrations, δ13C and δD values of compounds. Before ca. 8 cal ka BP, the lake was dominated by aquatic macrophyte-derived mid-chain n-alkanes, while after 6 cal ka BP high concentrations of a C20 highly branched isoprenoid compound indicate a predominance of phytoplankton. Those two principally different states of the lake were linked by a transition period with high abundances of microbial biomarkers. δ13C values were relatively constant for long-chain n-alkanes, while mid-chain n-alkanes showed variations between -23.5 to -12.6‰. Highest values were observed for the assumed period of maximum macrophyte growth during the late glacial and for the phytoplankton maximum during the middle and late Holocene. Therefore, the enriched values were interpreted to be caused by carbon limitation which in turn was induced by high macrophyte and primary productivity, respectively. Hydrogen isotope signatures of mid-chain n-alkanes have been shown to be able to track a previously deduced episode of reduced moisture availability between ca. 10 and 7 cal ka BP, indicated by a 20‰ shift towards higher δD values. Indications for cooler episodes at 6.0, 3.1 and 1.8 cal ka BP were gained from drops of biomarker concentrations, especially microbial-derived hopanoids, and from coincidental shifts towards lower δ13C values. Those episodes correspond well with cool events reported from other locations on the Tibetan Plateau as well as in the Northern Hemisphere. To conclude, the study of recent sediments and plants improved the understanding of factors affecting the composition and isotopic signatures of aliphatic biomarkers in sediments. Concentrations and isotopic signatures of the biomarkers in Lake Koucha could be interpreted in a palaeolimnological context and contribute to the knowledge about the history of the lake. Aquatic macrophyte-derived mid-chain n-alkanes were especially useful, due to their high abundance in many Tibetan Lakes and their ability to record major changes of lake productivity and palaeo-hydrological conditions. Therefore, they have the potential to contribute to a fuller understanding of past climate variability in this key region for atmospheric circulation systems.
Atmospheric circulation and the surface mass balance in a regional climate model of Antarctica
(2007)
Understanding the Earth's climate system and particularly climate variability presents one of the most difficult and urgent challenges in science. The Antarctic plays a crucial role in the global climate system, since it is the principal region of radiative energy deficit and atmospheric cooling. An assessment of regional climate model HIRHAM is presented. The simulations are generated with the HIRHAM model, which is modified for Antarctic applications. With a horizontal resolution of 55km, the model has been run for the period 1958-1998 creating long-term simulations from initial and boundary conditions provided by the European Centre for Medium-Range Weather Forecasts (ECMWF) ERA40 re-analysis. The model output is compared with observations from observation stations, upper air data, global atmospheric analyses and satellite data. In comparison with the observations, the evaluation shows that the simulations with the HIRHAM model capture both the large and regional scale circulation features with generally small bias in the modeled variables. On the annual time scale the largest errors in the model simulations are the overestimation total cloud cover and the colder near-surface temperature over the interior of the Antarctic plateau. The low-level temperature inversion as well as low-level wind jet is well captured by the model. The decadal scale processes were studied based on trend calculations. The long-term run was divided into two 20 years parts. The 2m temperature, 500 hPa temperature, MSLP, precipitation and net mass balance trends were calculated for both periods and over 1958 - 1998. During the last two decades the strong surface cooling was observed over the Eastern Antarctica, this result is in good agreement with the result of Chapman and Walsh (2005) who calculated the temperature trend based on the observational data. The MSLP trend reveals a big disparity between the first and second parts of the 40 year run. The overall trend shows the strengthening of the circumpolar vortex and continental anticyclone. The net mass balance as well as precipitation show a positive trend over the Antarctic Peninsula region, along Wilkes Land and in Dronning Maud Land. The Antarctic ice sheet grows over the Eastern part of Antarctica with small exceptions in Dronning Maud Land and Wilkes Land and sinks in the Antarctic Peninsula; this result is in good agreement with the satellite-measured altitude presented in Davis (2005) . To better understand the horizontal structure of MSLP, temperature and net mass balance trends the influence of the Southern Annual Mode (SAM) on the Antarctic climate was investigated. The main meteorological parameters during the positive and negative Antarctic Oscillation (AAO) phases were compared to each other. A positive/negative AAO index means strengthening/weakening of the circumpolar vortex, poleward/northward storm tracks and prevailing/weakening westerly winds. For detailed investigation of global teleconnection, two positive and one negative periods of AAO phase were chosen. The differences in MSLP and 2m temperature between positive and negative AAO years during the winter months partly explain the surface cooling during the last decades.
China und Indien
(2012)
Der Artikel analysiert die neue Rolle aufsteigender Schwellenländer
in den internationalen Klimaverhandlungen am Beispiel Chinas und
Indiens. Die Ablehnung verbindlicher Reduktionsziele für Treibhausgase
wurde in Kopenhagen als Blockadepolitik beider Länder gewertet.
China und Indien können sich in ihrer Position behaupten, da ihr
gestiegenes Gewicht in der multipolaren Weltordnung und die Untätigkeit
führender Industrieländer ihre Verhandlungsposition stärkt. Die
Autorin diskutiert Kooperationsmöglichkeiten auf subnationaler Ebene,
die die Blockadeposition nationaler Regierungen umgehen können.
Die Zivilgesellschaft hat dazu beigetragen, dass die Klimakonferenz in
Kopenhagen zu einem Medienereignis wurde. Fernab großer Demonstrationen
haben Nichtregierungsorganisationen (NRO) seit Jahren
einen guten Zugang zu den internationalen Klimaverhandlungen. Am
Beispiel von Chile wird gezeigt, wie Nichtregierungsorganisationen
durch professionellen Lobbyismus ihre Positionen in politische Prozesse
einspeisen. Sie befinden sich in einem Spannungsfeld von Kooperation
und Instrumentalisierung durch politische Entscheidungsträger.
Einleitung
(2012)
Understanding how organisms adapt to their local environment is a major focus of evolutionary biology. Local adaptation occurs when the forces of divergent natural selection are strong enough compared to the action of other evolutionary forces. An improved understanding of the genetic basis of local adaptation can inform about the evolutionary processes in populations and is of major importance because of its relevance to altered selection pressures due to climate change. So far, most insights have been gained by studying model organisms, but our understanding about the genetic basis of local adaptation in wild populations of species with little genomic resources is still limited.
With the work presented in this thesis I therefore set out to provide insights into the genetic basis of local adaptation in populations of two voles species: the common vole (Microtus arvalis) and the bank vole (Myodes glareolus). Both voles species are small mammals, they have a high evolutionary potential compared to their dispersal capabilities and are thus likely to show genetic responses to local conditions, moreover, they have a wide distribution in which they experience a broad range of different environmental conditions, this makes them an ideal species to study local adaptation.
The first study focused on producing a novel mitochondrial genome to facilitate further research in M. arvalis. To this end, I generated the first mitochondrial genome of M. arvalis using shotgun sequencing and an iterative mapping approach. This was subsequently used in a phylogenetic analysis that produced novel insights into the phylogenetic relationships of the Arvicolinae.
The following two studies then focused on the genetic basis of local adaptation using ddRAD-sequencing data and genome scan methods. The first of these involved sequencing the genomic DNA of individuals from three low-altitude and three high-altitude M. arvalis study sites in the Swiss Alps. High-altitude environments with their low temperatures and low levels of oxygen (hypoxia) pose considerable challenges for small mammals. With their small body size and proportional large body surface they have to sustain high rates of aerobic metabolism to support thermogenesis and locomotion, which can be restricted with only limited levels of oxygen available. To generate insights into high-altitude adaptation I identified a large number of single nucleotide polymorphisms (SNPs). These data were first used to identify high levels of differentiation between study sites and a clear pattern of population structure, in line with a signal of isolation by distance. Using genome scan methods, I then identified signals of selection associated with differences in altitude in genes with functions related to oxygen transport into tissue and genes related to aerobic metabolic pathways. This indicates that hypoxia is an important selection pressure driving local adaptation at high altitude in M. arvalis. A number of these genes were linked with high-altitude adaptation in other species before, which lead to the suggestion that high-altitude populations of several species have evolved in a similar manner as a response to the unique conditions at high altitude
The next study also involved the genetic basis of local adaptation, here I provided insights into climate-related adaptation in M. glareolus across its European distribution. Climate is an important environmental factor affecting the physiology of all organisms. In this study I identified a large number of SNPs in individuals from twelve M. glareolus populations distributed across Europe. I used these, to first establish that populations are highly differentiated and found a strong pattern of population structure with signal of isolation by distance. I then employed genome scan methods to identify candidate loci showing signals of selection associated with climate, with a particular emphasis on polygenic loci. A multivariate analysis was used to determine that temperature was the most important climate variable responsible for adaptive genetic variation among all variables tested. By using novel methods and genome annotation of related species I identified the function of genes of candidate loci. This showed that genes under selection have functions related to energy homeostasis and immune processes. Suggesting that M. glareolus populations have evolved in response to local temperature and specific local pathogenic selection pressures.
The studies presented in this thesis provide evidence for the genetic basis of local adaptation in two vole species across different environmental gradients, suggesting that the identified genes are involved in local adaptation. This demonstrates that with the help of novel methods the study of wild populations, which often have little genomic resources available, can provide unique insights into evolutionary processes.
Gescheiterte Klimapolitik?
(2012)
Der Kopenhagener Klimagipfel 2009 ist mit Spannung erwartet worden.
Erreicht wurde lediglich ein Minimalkonsens. Der Autor liefert eine
akteurszentrierte Deutung des Kopenhagener Abkommens und stellt die
Frage nach dem Präzedenzcharakter der Verhandlungen: Handelte es sich
um ein einmaliges Versagen multilateraler Diplomatie oder um einen
Vorgeschmack auf die weltpolitische Routine des 21. Jahrhunderts?