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Im Landschaftszustand und in der Landschaftsentwicklung kommen funktionale Beziehungen zwischen dem naturbedingten Energie-, Wasser- und Stoffhaushalt einerseits und den Auswirkungen der Landnutzung andererseits zum Ausdruck. Gegenwärtig verändert der globale Anstieg der bodennahen Temperaturen vielerorts den landschaftlichen Energie-, Wasser- und Stoffhaushalt, wobei besonders in Trockengebieten zu erwarten ist, dass dieser Trend in Verbindung mit einer unangepassten Landnutzung das Regenerationsvermögen der Vegetation einschränkt und zur Zerstörung der Bodendecke führt. Für die Mongolei und für benachbarte Gebiete Asiens sind in Szenarien zur globalen Erwärmung hohe Werte des Temperaturanstiegs prognostiziert worden. Eine globale Einschätzung der anthropogen induzierten Bodendegradation hat diese Region als stark oder extrem stark betroffen eingestuft. Vor diesem Hintergrund wurde im Uvs-Nuur-Becken, das im Nordwesten der Mongolei und damit in einer der trockensten Regionen des Landes gelegen ist, untersucht, wie sich der globale Temperaturanstieg auf der lokalen und regionalen Ebene widerspiegelt und wie der Landschaftshaushalt dabei verändert wird. Die Auswirkungen des sommerlichen Witterungsverlaufes auf den Landschaftszustand sind 1997 bis 1999 an einem Transsekt erfasst worden, das sich zwischen dem Kharkhiraa-Gebirge am Westrand des Beckens und dem See Uvs Nuur im Beckeninneren von den Polsterfluren und Matten der alpinen Stufe über die Gebirgswaldsteppe, die Trockensteppe bis zur Halbwüste erstreckt. An neun Messpunkten wurden witterungsklimatische Daten in Verbindung mit Merkmalen der Vegetation, des Bodens und der Bodenfeuchte aufgenommen. Die im Sommer 1998 gewonnenen Messwerte wurden mit Hilfe einer Clusteranalyse gebündelt und verdichtet. Auf dieser Grundlage konnten landschaftliche Zustandsformen inhaltlich gekennzeichnet, zeitlich eingeordnet und durch Zeit-Verhaltens-Modelle (Stacks) abgebildet werden. Aus den Zeit-Verhaltens-Modellen wird ersichtlich, dass man Zustandsformen, in denen die Hitze und die Trockenheit des Sommers 1998 besonders stark zum Ausdruck kommen, an allen Messpunkten beobachten kann, nimmt man die Station auf dem fast 3.000 m hohen Gipfel des Khukh Uul sowie die grundwasserbeeinflusste Station in unmittelbarer Seenähe aus. In ihrer extremen Form sind Trockenperioden jedoch nur im Beckeninneren und am Fuß der Randgebirge, also in der Halbwüste, in der Trockensteppe und in der Wiesensteppe aufgetreten. Im Bergwald sowie im Bereich der alpinen Matten und Polsterfluren fehlen sie. Am stärksten sind die grundwasserfreien Bereiche der Halbwüste von der Hitze und Niederschlagsarmut des Sommers 1998 betroffen. An vier Fünfteln der Tage des Beobachtungszeitraumes herrscht an diesem Messpunkt extreme Trockenheit. Es fällt entweder gar kein Niederschlag oder nur so wenig, dass der seit dem Frühjahr erschöpfte Bodenwasservorrat nicht aufgefüllt wird. Das Verhältnis zwischen Niederschlag und potenzieller Verdunstung liegt hier bei 1:12. In der Halbwüste zeichnet sich eine fortschreitende Desertifikation ab, zumal hier eine nichtangepasste Weidenutzung dominiert, in der Ziegen eine immer größere Rolle spielen. Dies gilt insbesondere für Bereiche in Siedlungsnähe. Örtlich ist auch der Bestand der Trockensteppe gefährdet, die sich an die Halbwüste zum Beckenrand hin anschließt. Hier ist nicht nur die Viehdichte am höchsten, sondern hier werden auch die meisten unbefestigten Fahrwege wild angelegt und die Bodendecke damit zerstört. Dies kann im Endeffekt zu einem Übergreifen von Prozessen der Desertifikation führen. Aus methodischer Sicht zeigt sich, dass die Kennzeichnung landschaftlicher Zustandsformen durch Zeit-Verhaltens-Modelle die Ermittlung der Auswirkungen von Witterung und Klima auf den Landschaftszustand erleichtert, da sie deren Aussage konzentriert. Zur Interpretation der Ergebnisse ist jedoch ein Rückgriff auf die beschreibende Darstellung der Messwerte notwendig. Die im westlichen Uvs-Nuur-Becken und seinen Randgebirgen angewandte Verfahrensweise ermöglicht es, globale Aussagen zur globalen Erwärmung der Kontinente regional oder lokal zu überprüfen und zu untersetzen."
Wie Klimaschutz finanzieren?
(2012)
Zur Finanzierung von Klimaschutz müssen öffentliche Mittel gezielt
eingesetzt werden. Dies beinhaltet auch die Rahmenbedingungen für
private Finanzströme signifikant zu verbessern. Anhand einer Problemanalyse
bestimmen die Autoren Eckdaten für diese Hebelwirkung.
Öffentliche Anschubfinanzierung kann somit die Grundlage für private
Investitionen sein. Dies wird exemplarisch an der Internationalen
Klimaschutzinitiative des Bundesumweltministeriums diskutiert.
The role of feedback between erosional unloading and tectonics controlling the development of the Himalaya is a matter of current debate. The distribution of precipitation is thought to control surface erosion, which in turn results in tectonic exhumation as an isostatic compensation process. Alternatively, subsurface structures can have significant influence in the evolution of this actively growing orogen. Along the southern Himalayan front new 40Ar/39Ar white mica and apatite fission track (AFT) thermochronologic data provide the opportunity to determine the history of rock-uplift and exhumation paths along an approximately 120-km-wide NE-SW transect spanning the greater Sutlej region of the northwest Himalaya, India. 40Ar/39Ar data indicate, consistent with earlier studies that first the High Himalayan Crystalline, and subsequently the Lesser Himalayan Crystalline nappes were exhumed rapidly during Miocene time, while the deformation front propagated to the south. In contrast, new AFT data delineate synchronous exhumation of an elliptically shaped, NE-SW-oriented ~80 x 40 km region spanning both crystalline nappes during Pliocene-Quaternary time. The AFT ages correlate with elevation, but show within the resolution of the method no spatial relationship to preexisting major tectonic structures, such as the Main Central Thrust or the Southern Tibetan Fault System. Assuming constant exhumation rates and geothermal gradient, the rocks of two age vs. elevation transects were exhumed at ~1.4 ±0.2 and ~1.1 ±0.4 mm/a with an average cooling rate of ~50-60 °C/Ma during Pliocene-Quaternary time. The locus of pronounced exhumation defined by the AFT data coincides with a region of enhanced precipitation, high discharge, and sediment flux rates under present conditions. We therefore hypothesize that the distribution of AFT cooling ages might reflect the efficiency of surface processes and fluvial erosion, and thus demonstrate the influence of erosion in localizing rock-uplift and exhumation along southern Himalayan front, rather than encompassing the entire orogen.Despite a possible feedback between erosion and exhumation along the southern Himalayan front, we observe tectonically driven, crustal exhumation within the arid region behind the orographic barrier of the High Himalaya, which might be related to and driven by internal plateau forces. Several metamorphic-igneous gneiss dome complexes have been exhumed between the High Himalaya to the south and Indus-Tsangpo suture zone to the north since the onset of Indian-Eurasian collision ~50 Ma ago. Although the overall tectonic setting is characterized by convergence the exhumation of these domes is accommodated by extensional fault systems.Along the Indian-Tibetan border the poorly described Leo Pargil metamorphic-igneous gneiss dome (31-34°N/77-78°E) is located within the Tethyan Himalaya. New field mapping, structural, and geochronologic data document that the western flank of the Leo Pargil dome was formed by extension along temporally linked normal fault systems. Motion on a major detachment system, referred to as the Leo Pargil detachment zone (LPDZ) has led to the juxtaposition of low-grade metamorphic, sedimentary rocks in the hanging wall and high-grade metamorphic gneisses in the footwall. However, the distribution of new 40Ar/39Ar white mica data indicate a regional cooling event during middle Miocene time. New apatite fission track (AFT) data demonstrate that subsequently more of the footwall was extruded along the LPDZ in a brittle stage between 10 and 2 Ma with a minimum displacement of ~9 km. Additionally, AFT-data indicate a regional accelerated cooling and exhumation episode starting at ~4 Ma. Thus, tectonic processes can affect the entire orogenic system, while potential feedbacks between erosion and tectonics appear to be limited to the windward sides of an orogenic systems.
This dissertation investigates the impact of the economic and fiscal crisis starting in 2008 on EU climate policy-making. While the overall number of adopted greenhouse gas emission reduction policies declined in the crisis aftermath, EU lawmakers decided to introduce new or tighten existing regulations in some important policy domains. Existing knowledge about the crisis impact on EU legislative decision-making cannot explain these inconsistencies. In response, this study develops an actor-centred conceptual framework based on rational choice institutionalism that provides a micro-level link to explain how economic crises translate into altered policy-making patterns. The core theoretical argument draws on redistributive conflicts, arguing that tensions between ‘beneficiaries’ and ‘losers’ of a regulatory initiative intensify during economic crises and spill over to the policy domain. To test this hypothesis and using social network analysis, this study analyses policy processes in three case studies: The introduction of carbon dioxide emission limits for passenger cars, the expansion of the EU Emissions Trading System to aviation, and the introduction of a regulatory framework for biofuels. The key finding is that an economic shock causes EU policy domains to polarise politically, resulting in intensified conflict and more difficult decision-making. The results also show that this process of political polarisation roots in the industry that is the subject of the regulation, and that intergovernmental bargaining among member states becomes more important, but also more difficult in times of crisis.
Over the last decades, the Arctic regions of the earth have warmed at a rate 2–3 times faster than the global average– a phenomenon called Arctic Amplification. A complex, non-linear interplay of physical processes and unique pecularities in the Arctic climate system is responsible for this, but the relative role of individual processes remains to be debated. This thesis focuses on the climate change and related processes on Svalbard, an archipelago in the North Atlantic sector of the Arctic, which is shown to be a "hotspot" for the amplified recent warming during winter. In this highly dynamical region, both oceanic and atmospheric large-scale transports of heat and moisture interfere with spatially inhomogenous surface conditions, and the corresponding energy exchange strongly shapes the atmospheric boundary layer. In the first part, Pan-Svalbard gradients in the surface air temperature (SAT) and sea ice extent (SIE) in the fjords are quantified and characterized. This analysis is based on observational data from meteorological stations, operational sea ice charts, and hydrographic observations from the adjacent ocean, which cover the 1980–2016 period. It is revealed that typical estimates of SIE during late winter range from 40–50% (80–90%) in the western (eastern) parts of Svalbard. However, strong SAT warming during winter of the order of 2–3K per decade dictates excessive ice loss, leaving fjords in the western parts essentially ice-free in recent winters. It is further demostrated that warm water currents on the west coast of Svalbard, as well as meridional winds contribute to regional differences in the SIE evolution. In particular, the proximity to warm water masses of the West Spitsbergen Current can explain 20–37% of SIE variability in fjords on west Svalbard, while meridional winds and associated ice drift may regionally explain 20–50% of SIE variability in the north and northeast. Strong SAT warming has overruled these impacts in recent years, though.
In the next part of the analysis, the contribution of large-scale atmospheric circulation changes to the Svalbard temperature development over the last 20 years is investigated. A study employing kinematic air-back trajectories for Ny-Ålesund reveals a shift in the source regions of lower-troposheric air over time for both the winter and the summer season. In winter, air in the recent decade is more often of lower-latitude Atlantic origin, and less frequent of Arctic origin. This affects heat- and moisture advection towards Svalbard, potentially manipulating clouds and longwave downward radiation in that region. A closer investigation indicates that this shift during winter is associated with a strengthened Ural blocking high and Icelandic low, and contributes about 25% to the observed winter warming on Svalbard over the last 20 years. Conversely, circulation changes during summer include a strengthened Greenland blocking high which leads to more frequent cold air advection from the central Arctic towards Svalbard, and less frequent air mass origins in the lower latitudes of the North Atlantic. Hence, circulation changes during winter are shown to have an amplifying effect on the recent warming on Svalbard, while summer circulation changes tend to mask warming.
An observational case study using upper air soundings from the AWIPEV research station in Ny-Ålesund during May–June 2017 underlines that such circulation changes during summer are associated with tropospheric anomalies in temperature, humidity and boundary layer height.
In the last part of the analysis, the regional representativeness of the above described changes around Svalbard for the broader Arctic is investigated. Therefore, the terms in the diagnostic temperature equation in the Arctic-wide lower troposphere are examined for the Era-Interim atmospheric reanalysis product. Significant positive trends in diabatic heating rates, consistent with latent heat transfer to the atmosphere over regions of increasing ice melt, are found for all seasons over the Barents/Kara Seas, and in individual months in the vicinity of Svalbard. The above introduced warm (cold) advection trends during winter (summer) on Svalbard are successfully reproduced. Regarding winter, they are regionally confined to the Barents Sea and Fram Strait, between 70°–80°N, resembling a unique feature in the whole Arctic. Summer cold advection trends are confined to the area between eastern Greenland and Franz Josef Land, enclosing Svalbard.
Interactions and feedbacks between tectonics, climate, and upper plate architecture control basin geometry, relief, and depositional systems. The Andes is part of a longlived continental margin characterized by multiple tectonic cycles which have strongly modified the Andean upper plate architecture. In the Andean retroarc, spatiotemporal variations in the structure of the upper plate and tectonic regimes have resulted in marked along-strike variations in basin geometry, stratigraphy, deformational style, and mountain belt morphology. These along-strike variations include high-elevation plateaus (Altiplano and Puna) associated with a thin-skin fold-and-thrust-belt and thick-skin deformation in broken foreland basins such as the Santa Barbara system and the Sierras Pampeanas. At the confluence of the Puna Plateau, the Santa Barbara system and the Sierras Pampeanas, major along-strike changes in upper plate architecture, mountain belt morphology, basement exhumation, and deformation style can be recognized. I have used a source to sink approach to unravel the spatiotemporal tectonic evolution of the Andean retroarc between 26 and 28°S. I obtained a large low-temperature thermochronology data set from basement units which includes apatite fission track, apatite U-Th-Sm/He, and zircon U-Th/He (ZHe) cooling ages. Stratigraphic descriptions of Miocene units were temporally constrained by U-Pb LA-ICP-MS zircon ages from interbedded pyroclastic material.
Modeled ZHe ages suggest that the basement of the study area was exhumed during the Famatinian orogeny (550-450 Ma), followed by a period of relative tectonic quiescence during the Paleozoic and the Triassic. The basement experienced horst exhumation during the Cretaceous development of the Salta rift. After initial exhumation, deposition of thick Cretaceous syn-rift strata caused reheating of several basement blocks within the Santa Barbara system. During the Eocene-Oligocene, the Andean compressional setting was responsible for the exhumation of several disconnected basement blocks. These exhumed blocks were separated by areas of low relief, in which humid climate and low erosion rates facilitated the development of etchplains on the crystalline basement. The exhumed basement blocks formed an Eocene to Oligocene broken foreland basin in the back-bulge depozone of the Andean foreland. During the Early Miocene, foreland basin strata filled up the preexisting Paleogene topography. The basement blocks in lower relief positions were reheated; associated geothermal gradients were higher than 25°C/km. Miocene volcanism was responsible for lateral variations on the amount of reheating along the Campo-Arenal basin. Around 12 Ma, a new deformational phase modified the drainage network and fragmented the lacustrine system. As deformation and rock uplift continued, the easily eroded sedimentary cover was efficiently removed and reworked by an ephemeral fluvial system, preventing the development of significant relief. After ~6 Ma, the low erodibility of the basement blocks which began to be exposed caused relief increase, leading to the development of stable fluvial systems. Progressive relief development modified atmospheric circulation, creating a rainfall gradient. After 3 Ma, orographic rainfall and high relief lead to the development of proximal fluvial-gravitational depositional systems in the surrounding basins.
Paleomagnetic dating of climatic events in Late Quaternary sediments of Lake Baikal (Siberia)
(2004)
Lake Baikal provides an excellent climatic archive for Central Eurasia as global climatic variations are continuously depicted in its sediments. We performed continuous rock magnetic and paleomagnetic analyses on hemipelagic sequences retrieved from 4 underwater highs reaching back 300 ka. The rock magnetic study combined with TEM, XRD, XRF and geochemical analyses evidenced that a magnetite of detrital origin dominates the magnetic signal in glacial sediments whereas interglacial sediments are affected by early diagenesis. HIRM roughly quantifies the hematite and goethite contributions and remains the best proxy for estimating the detrital input in Lake Baikal. Relative paleointensity records of the earth′s magnetic field show a reproducible pattern, which allows for correlation with well-dated reference curves and thus provides an alternative age model for Lake Baikal sediments. Using the paleomagnetic age model we observed that cooling in the Lake Baikal region and cooling of the sea surface water in the North Atlantic, as recorded in planktonic foraminifera δ18 O, are coeval. On the other hand, benthic δ18 O curves record mainly the global ice volume change, which occurs later than the sea surface temperature change. This proves that a dating bias results from an age model based on the correlation of Lake Baikal sedimentary records with benthic δ18 O curves. The compilation of paleomagnetic curves provides a new relative paleointensity curve, “Baikal 200”. With a laser-assisted grain size analysis of the detrital input, three facies types, reflecting different sedimentary dynamics can be distinguished. (1) Glacial periods are characterised by a high clay content mostly due to wind activity and by occurrence of a coarse fraction (sand) transported over the ice by local winds. This fraction gives evidence for aridity in the hinterland. (2) At glacial/interglacial transitions, the quantity of silt increases as the moisture increases, reflecting increased sedimentary dynamics. Wind transport and snow trapping are the dominant process bringing silt to a hemipelagic site (3) During the climatic optimum of the Eemian, the silt size and quantity are minimal due to blanketing of the detrital sources by the vegetal cover.
This study investigated the slope carbonates of two Miocene carbonate systems: the Maltese Islands (in the Central Mediterranean) and the Marion Plateau (Northeastern Australia, drilled during ODP Leg 194). The aim of the study was to trace the impact of the Miocene cooling steps (events Mi1-Mi6) in these carbonate systems, especially the Mi3 event, which took place around 13.6 Ma and deeply impacted the marine oxygen isotope record. This event also profoundly impacted oceanographic and climatic patterns, eventually leading to the establishment of the modern ice-house world. In particular, East Antarctica became ice covered at that period. The rational behind the present study was to investigate the impact that this event had on shallow water systems in order to complement the deep-sea record and hence acquire a more global perspective on Miocene climate change. The Maltese Islands were investigated for trends in bulk-rock carbon and oxygen isotopes, as well as bulk-rock mineralogy, clay minerals analysis and organic geochemisty. Results showed that the mid Miocene cooling event deeply impacted sedimentation at that location by changing sedimentation from carbonate to clay-rich sediments. Moreover, it was discovered that each phase of Antarctic glaciation, not just the major mid Miocene event, resulted in higher terrigenous input on Malta. Mass accumulation rates revealed that this was linked to increased runoff during periods when Antarctica was glaciated, and thus that the carbonate sediments were “diluted” by clay-rich sediments. The model subsequently developed to explain this implies feedback from Antarctic glaciations creating cold, dense air masses that push the ITCZ Northward, thus increasing precipitation on the North African subcontinent. Increased precipitation (or stronger African monsoon) accelerated continental weathering and runoff, thus bringing more terrigenous sediment to the paleo-location of the slope sediments of Malta. Spectral analysis of carbonate content and organic matter geochemical analysis furthermore suggest that the clay-rich intervals are similar to sapropelic deposits. On the Marion Plateau, trends in oxygen and carbon isotopes were obtained by measuring Cibicidoides spp foraminifers. Moreover, carbonate content was reconstructed using a chemical method (coulometer). Results show that the mid Miocene cooling step profoundly affected this system: a major drop in accumulation rates of carbonates occurs precisely at 13.8 Ma, around the time of the East Antarctic ice sheet formation. Moreover, sedimentation changes occurred at that time, carbonate fragments coming from neritic environments becoming less abundant, planktonic foraminifer content increasing and quartz and reworked glauconite being deposited. Conversely, a surprising result is that the major N12-N14 sea-level fall occurring around 11.5 Ma did not impact the accumulation of carbonates on the slope. This was unexpected since carbonate platform are very sensitive to sea-level changes. The model developed to explain that mass accumulation rates of carbonates diminished around 13.6 Ma (Mi3 Event) instead of 11.5 Ma (N12-N14 event), suggests that oceanic currents were controlling slope carbonate deposition on the Marion Plateau prior to the mid-Miocene, and that the mid Miocene event considerably increase their strength, hence reducing the amount of carbonate being deposited on slope sites. Moreover, by combining results from deep-sea oxygen isotopes with sea-level estimates based on coastal onlaps made during Leg 194, we constrain the amplitude of the N12-N14 sea-level fall to 90 meters. When integrating isotopic results from this study, this amplitude is lowered to 70 meters. A general conclusion of this work is that the mid Miocene climatic shift did impact carbonate systems, at least at the two locations studied. However, the nature of this response was highly dependant on the regional settings, in particular the presence of land mass (Malta) and the absence of a barrier to shelter from the effects of open ocean (Marion Plateau).
The India-Eurasia continental collision zone provides a spectacular example of active mountain building and climatic forcing. In order to quantify the critically important process of mass removal, I analyzed spatial and temporal precipitation patterns of the oscillating monsoon system and their geomorphic imprints. I processed passive microwave satellite data to derive high-resolution rainfall estimates for the last decade and identified an abnormal monsoon year in 2002. During this year, precipitation migrated far into the Sutlej Valley in the northwestern part of the Himalaya and reached regions behind orographic barriers that are normally arid. There, sediment flux, mean basin denudation rates, and channel-forming processes such as erosion by debris-flows increased significantly. Similarly, during the late Pleistocene and early Holocene, solar forcing increased the strength of the Indian summer monsoon for several millennia and presumably lead to analogous precipitation distribution as were observed during 2002. However, the persistent humid conditions in the steep, high-elevation parts of the Sutlej River resulted in deep-seated landsliding. Landslides were exceptionally large, mainly due to two processes that I infer for this time: At the onset of the intensified monsoon at 9.7 ka BP heavy rainfall and high river discharge removed material stored along the river, and lowered the baselevel. Second, enhanced discharge, sediment flux, and increased pore-water pressures along the hillslopes eventually lead to exceptionally large landslides that have not been observed in other periods. The excess sediments that were removed from the upstream parts of the Sutlej Valley were rapidly deposited in the low-gradient sectors of the lower Sutlej River. Timing of downcutting correlates with centennial-long weaker monsoon periods that were characterized by lower rainfall. I explain this relationship by taking sediment flux and rainfall dynamics into account: High sediment flux derived from the upstream parts of the Sutlej River during strong monsoon phases prevents fluvial incision due to oversaturation the fluvial sediment-transport capacity. In contrast, weaker monsoons result in a lower sediment flux that allows incision in the low-elevation parts of the Sutlej River.
Der Autor diskutiert die Chancen und Risiken bei der Einbindung
des Südens in die internationale Klimapolitik. Lange Zeit hatten die
Entwicklungsländer am wenigsten zum Klimawandel beigetragen,
wären aber am stärksten von ihm betroffen. Mittlerweile jedoch tragen
diese Länder in erheblichem Maße selbst zum Klimawandel bei. Allerdings
setzen deren Regierungen auf Zeit. Sie erwarten Ressourcentransfers.
Dies verstärkt auch alte Probleme des ‚Rent-Seeking‘.
In diesem einleitenden Beitrag des Themenschwerpunktes wird der
Hintergrund der internationalen Klimaverhandlungen erläutert und
die Ergebnisse des Kopenhagen-Akkords vorgestellt. Angesichts des
Scheiterns der Kopenhagener Konferenz muss die zeitnahe Schließung
eines rechtlich bindenden, globalen Klimaabkommens als unwahrscheinlich
gelten. Die Klimapolitik wird zukünftig verstärkt auf nationalstaatlicher
und transnationaler Ebene erfolgen.
Klimapolitik International
(2012)
Der Klimawandel birgt globale Risiken. Dies ist weithin anerkannt. Umstritten ist die Frage, wie diesen Gefahren zu begegnen ist. 14 Jahre nach Kyoto ist klar: Klimapolitik ist Interessenpolitik. Das zeigte zuletzt die UN-Klimakonferenz 2011 in Durban mit ihren unverbindlichen Ergebnissen. In diesem Sammelband analysieren Experten Ursachen für das Scheitern der vergangenen Klima-Konferenzen und Konsequenzen für die künftige Klimapolitik. Insbesondere geht es um die Politik der Akteure China und Indien, um die Rolle der NGOs und die Klimafrage in der Entwicklungspolitik. Zugleich wird die deutsche Klimapolitik diskutiert und die Politik Brandenburgs von der verantwortlichen Ministerin vorgestellt.
Klimapolitik am Ende?
(2012)
The lakes of the East African Rift System (EARS) have been intensively studied to better understand the influence of climate change on hydrological systems. The exceptional sensitivity of these rift lakes, however, is both a challenge and an opportunity when trying to reconstruct past climate changes from changes in the hydrological budget of lake basins on timescales 100 to 104 years. On one hand, differences in basin geometrics (shape, area, volume, depth), catchment rainfall distributions and varying erosion-deposition rates complicate regional interpretation of paleoclimate information from lacustrine sediment proxies. On the other hand, the sensitivity of rift lakes often provides paleoclimate records of excellent quality characterized by a high signal-to-noise ratio. This study aims at better understanding of the climate-proxy generating process in rift lakes by parameterizing the geomorphological and hydroclimatic conditions of a particular site providing a step towards the establishment of regional calibrations of transfer functions for climate reconstructions. The knowledge of the sensitivity of a lake basin to climate change furthermore is crucial for a better assessment of the probability of catastrophic changes in the future, which bear risks for landscapes, ecosystems, and organisms of all sorts, including humans. Part 1 of this thesis explores the effect of the morphology and the effective moisture of a lake catchment. The availability of digital elevation models (DEM) and gridded climate data sets facilitates the comparison of the morphological and hydroclimatic conditions of rift lakes. I used the hypsometric integral (HI) calculated from Shuttle Radar Topography Mission (SRTM) data to describe the morphology of ten lake basins in Kenya and Ethiopia. The aridity index (AI) describing the difference in the precipitation/evaporation balance within a catchment was used to compare the hydroclimatic of these basins. Correlating HI and AI with published Holocene lake-level variations revealed that lakes responding sensitively to relatively moderate climate change are typically graben shaped and characterized by a HI between 0.23-0.30, and relatively humid conditions with AI >1. These amplifier lakes, a term first introduced but not fully parameterized by Alayne Street-Perrott in the early 80s, are unexceptionally located in the crest of the Kenyan and Ethiopian domes. The non-amplifier lakes in the EARS either have lower HI 0.13-0.22 and higher AI (>1) or higher HI (0.31-0.37) and low AI (<1), reflecting pan-shaped morphologies with more arid hydroclimatic conditions. Part 2 of this work addresses the third important factor to be considered when using lake-level and proxy records to unravel past climate changes in the EARS: interbasin connectivity and groundwater flow through faulted and porous subsurface lithologies in a rift setting. First, I have compiled the available hydrogeological data including lithology, resistivity and water-well data for the adjacent Naivasha and Elmenteita-Nakuru basins in the Central Kenya Rift. Using this subsurface information and established records of lake-level decline at the last wet-dry climate transitions, i.e., the termination of the African Humid Period (AHP, 15 to 5 kyr BP), I used a linear decay model to estimate typical groundwater flow between the two basins. The results suggest a delayed response of the groundwater levels of ca. 5 kyrs if no recharge of groundwater occurs during the wet-dry transition, whereas the lag is 2-2.7 kyrs only using the modern recharge of ca. 0.52 m/yr. The estimated total groundwater flow from higher Lake Naivasha (1,880 m a.s.l. during the AHP) to Nakuru-Elmenteita (1,770 m) was 40 cubic kilometers. The unexpectedly large volume, more than half of the volume of the paleo-Lake Naivasha during the Early Holocene, emphasizes the importance of groundwater in hydrological modeling of paleo-lakes in rifts. Moreover, the subsurface connectivity of rift lakes also causes a significant lag time to the system introducing a nonlinear component to the system that has to be considered while interpreting paleo-lake records. Part 3 of this thesis investigated the modern intraseasonal precipitation variability within eleven lake basins discussed in the first section of the study excluding Lake Victoria and including Lake Tana. Remotely sensed rainfall estimates (RFE) from FEWS NET for 1996-2010, are used for the, March April May (MAM) July August September (JAS), October November (ON) and December January February (DJF). The seasonal precipitation are averaged and correlated with the prevailing regional and local climatic mechanisms. Results show high variability with Biennial to Triennial precipitation patterns. The spatial distribution of precipitation in JAS are linked to the onset and strength of the Congo Air Boundary (CAB) and Indian Summer Monsoon (ISM) dynamics. while in ON they are related to the strength of Positive ENSO and IOD phases This study describes the influence of graben morphologies, extreme climate constrasts within catchments and basins connectivity through faults and porous lithologies on rift lakes. Hence, it shows the importance of a careful characterization of a rift lake by these parameters prior to concluding from lake-level and proxy records to climate changes. Furthermore, this study highlights the exceptional sensitivity of rift lakes to relatively moderate climate change and its consequences for water availability to the biosphere including humans.
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?
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.
Einleitung
(2012)
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.
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.
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.
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.
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.
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.