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A completely revised and enhanced version of the water balance model MODBIL of the regional water balance dynamics of Cyprus was developed for this study. The model is based on a physical, process-oriented, spatially distributed concept and is applied for the calculation of all important water balance components of the island for the time period of 1961-2004. The calibrated results are statistically analysed and visualised for the whole island area, and evaluated with respect to the renewability of natural water resources. Climate variability and changes of the past decades are analysed with regard to their influence on water balances. A further part of the study focusses on the simulation of impacts of potential climate change. The water balances are simulated under changing climatic conditions on the base of theoretical precipitation, temperature and relative humidity changes and the revealed impacts on the water balances and renewable resources are discussed. Furthermore, a first principal water balance scenario is developed for the assessment of the regional hydrological changes expected for Cyprus by the end of the 21st century. The scenarios are based on recently calculated climate change assessments for this part of the Mediterranean, under an assumed further increase of greenhouse gasses in the atmosphere.
Climate change assessment in Southeast Asia and implications for agricultural production in Vietnam
(2011)
For many years, the study of climatic changes and variations has become the main objective of climatic research, as has been appreciated in the IPCC's reports and several publications regarding climatic evolution on different space-time scales. Since the 80's, many research groups have generated the extensive database from which the analysis of temperature, precipitation and other climatic parameters has been performed on a global scale (Jones et al., 1986; Hansen and Lebedeff, 1987, 1988; Vinnikov et al., 1987, 1990). The most important result of these research projects is the evidence of global warming during the 20th century, especially in the last two decades. However, numerous challenges still exist about the structure and dimension of the climatic change on a considerable scale. Therefore, it is necessary to carry out studies on a local and regional scale that allow for a more precise evaluation of the global warming phenomenon. A statistical analysis approach was developed to identify systematic differences between large-scale climatic variable from the General Circulation Models (GCM), NCEP, CRU re-analysis data set and climatic parameters (temperature and precipitation data). Models are able to satisfactorily reproduce the spatial patterns of the regional temperature and precipitation field. The response of the climate system to various emission scenario simulated by the GCM was used to analyze and predict the local climate change. The main objective of this study is to analysis the time evolution of the annual and seasonal temperature and precipitation during the 21st century and in order to contribute to our knowledge of temperature and precipitation trends over the century on a regional scale, not only in Southeast Asia but also in Vietnam; the study focuses to develop a dynamical – statistical model describing the relationship between the major climate variation and agricultural production in Vietnam. This study will be an important contribution to the present-day assessment of climate change impacts in the low latitudes. Regional scenarios of climate change, including both rainfall and mean temperature were then used to assess the impact of climate change on crop production in the region in order to evaluate the vulnerability of the system to global warming. Climate change has adverse impacts on the socio - economic development of all nations. But the degree of the impact will vary across nations. It is expected that changes in the earth's climate will impact on developing countries like Vietnam, in particular, hardest because their economies are strongly dependent on crude forms of natural resources and their economic structure is less flexible to adjust to such drastic changes. In Chapter 1: Introduction and background I describe in general terms climate, climate change, climate change model with benefits and problems. Chapter 2: methodology discusses the methods including interpolation, validation, clustering, correlation and regression which were applied in the study. Chapter 3 and chapter 4 describe the database and study area. The most important is chapter 5 Results. The last is chapter 6 Conclusion and outlook followed by the reference list and an appendix.
Mit der vorliegenden Arbeit werden konventionelle thermische Kraftwerke an deutschen Flüssen identifiziert, bei denen aufgrund hoher Flusswassertemperaturen im Zusammenhang mit wasserrechtlichen Grenzwerten Leistungseinschränkungen auftraten. Weiterhin wird aufgezeigt, wie sich die Wassertemperaturen der Flüsse in der Vergangenheit (rezent) entwickelt haben und wie sie sich zukünftig im Kontext des Klimawandels entwickeln könnten.
Mittels Literaturrecherche, Medienanalyse und schriftlicher Befragung wurden konventionelle thermische Kraftwerke identifiziert, welche wassertemperaturbedingte Leistungseinschränkungen verzeichneten. Die meisten dieser Leistungseinschränkungen zwischen 1976 und 2007 zeigen sich bei großen Kraftwerken mit einer elektrischen Bruttoleistung über 300 Megawatt, bei Steinkohle- und Kernkraftwerken, bei Kraftwerken mit Durchlaufkühlung und bei solchen, die zwischen 1960 und 1990 in Betrieb gingen.
Trendanalysen interpolierter und homogenisierter, rezenter Wassertemperaturzeitreihen deutscher Flüsse ergeben positive Trends v. a. im Frühjahr und Sommer. Die Zählstatistik zeigt in den Jahren 1994, 2003 und 2006 die meisten Tage mit sehr hohen und extrem hohen Wassertemperaturen in den Sommermonaten. In diesen Jahren traten gleichzeitig 63 % aller identifizierter wassertemperaturbedingter Leistungseinschränkungen bei Kraftwerken, meist zwischen Juni und August, auf.
Für die Trendanalysen und den Mittelwertvergleich simulierter zukünftiger Wassertemperaturzeitreihen wurden drei Szenarien – B1, A1B und A2 sowie drei Zukunftsperioden 2011-2040, 2011/2041-2070, 2011/2071-2100 betrachtet. Es ergeben sich für die Zukunftsperiode 2011-2040 des A1B- oder A2-Szenarios in mindestens einem der Sommermonate eine Erwärmung und für das B1-Szenario negative oder keine Trends. Die mittleren Wassertemperaturen der Zukunftsperiode 2011-2040 zeigen in allen drei Szenarien gegenüber denen der Klimanormalperiode 1961-1990 positive Unterschiede in mindestens einem der Sommermonate. Für die beiden späteren Zukunftsperioden bis 2070 bzw. bis 2100 liegen in allen Wassertemperaturzeitreihen der drei Szenarien im Sommer positive Trends bzw. Differenzen gegenüber den mittleren Wassertemperaturen der Klimanormalperiode vor.
Durch die Synthese der drei Analysen ist erkennbar, dass Isar, Rhein, Neckar, Saar, Elbe und Weser die meisten Kraftwerksstandorte mit wassertemperaturbedingten Leistungseinschränkungen verzeichnen. Es zeigen sich hier positive Trends sowohl in den rezenten als auch zukünftigen Wassertemperaturen für die Zukunftsperiode 2011-2040 des A1B- und A2-Szenarios in jeweils mindestens einem der Sommermonate. Gegenüber den mittleren Wassertemperaturen der Klimanormalperiode liegen für alle drei Szenarien positive Unterschiede der Wassertemperaturen vor.
Bei einer Kraftwerkslaufzeit von 40-50 Jahren und einem Kernenergieausstieg 2022 bzw. 2034, werden 48-64 % bzw. 67-91 % der Kraftwerke mit wassertemperaturbedingten Leistungseinschränkungen bis 2022 bzw. 2034 außer Betrieb gehen. Bei einer Laufzeitverlängerung würden nach 2022 fünf der elf betroffenen Kernkraftwerke weiter am Netz bleiben. Somit kann es wieder zu wassertemperaturbedingten Leistungseinschränkungen kommen. In Deutschland sind nach wie vor große Kraftwerke an Flüssen geplant. Deren Kühlsysteme müssen entsprechend ausgewählt und konstruiert werden, um der zu erwartenden Erhöhung der Flusstemperaturen Rechnung zu tragen.
Der Klimawandel und insbesondere die globale Erwärmung gehören aktuell zu den größten Herausforderungen an Politik und Wissenschaft. Steigende CO2-Emissionen sind hierbei maßgeblich für die Klimaerwärmung verantwortlich. Ein regulierender Faktor beim CO2-Austausch mit der Atmosphäre ist die Vegetation, welche als CO2-Senke aber auch als CO2-Quelle fungieren kann. Diese Funktionen können durch Analysen der Landbedeckungsänderung in Kombination mit Modellierungen der Kohlenstoffbilanz quantifiziert werden, was insbesondere von aktuellen und zukünftigen politischen Instrumenten wie CDM (Clean Development Mechanism) oder REDD (Reducing Emissions from Deforestation and Degradation) gefordert wird. Vor allem in Regionen mit starker Landbedeckungsänderung und hoher Bevölkerungsdichte sowie bei geringem Wissen über die Produktivität und CO2-Speicherpotentiale der Vegetation, bedarf es einer Erforschung und Quantifizierung der terrestrischen Kohlenstoffspeicher. Eine Region, für die dies in besonderem Maße zutrifft, ist Westafrika. Jüngste Studien haben gezeigt, dass sich einerseits die Folgen des Klimawandels und Umweltveränderungen sehr stark in Westafrika auswirken werden und andererseits Bevölkerungswachstum eine starke Änderung der Landbedeckung für die Nutzung als agrarische Fläche bewirkt hat. Folglich sind in dieser Region die terrestrischen Kohlenstoffspeicher durch Ausdehnung der Landwirtschaft und Waldrodung besonders gefährdet. Große Flächen agieren anstelle ihrer ursprünglichen Funktion als CO2-Senke bereits als CO2-Quelle. [...]
Surveys by the Universities of Wuerzburg and Berlin, starting in the 1970´s have revealed the existence of palaeolakes in remote areas in Niger. Initial research has shown that the sediments found are suitable for reconstructing its late quaternary palaeoenvironment. Although a high number of investigations focused on the succession of climatological conditions in the Central Sahara, some uncertainties still exist as the results show discontinuities and mostly are of low temporal and spatial
resolution.
Two expeditions in 2005 and 2006 headed to the northeastern parts of Niger to investigate the known remains of palaeolakes and search some new and undetected ones. Samples were taken at several study sites in order to receive a complete picture of the Late Quaternary environmental settings and to produce high-resolution proxies for palaeoclimate modelling.
The most valuable and best-investigated study site is the sebkha of Seggedim, where a core of 15 meters length could be extracted which revealed a composition of high-resolution sections. Stratigraphical, structural and geochemical investigations as well as the analysis of thin sections allow the characterization of different environmental conditions from Early to Mid Holocene. Driven by climate and hydrogeological influence, the water body developed from a water pond of several metres depth within a stable, grass and shrub vegetated landscape, to an alternating freshwater lake in a more dynamic environmental setting. Radiocarbon dates set the beginning of the stage at about 10.6 ka cal BP, with an exceptionally stable regime to 6.6 ka cal BP (at 12.6 metres’ depth), when a major change in the sedimentation regime of the basin is recorded in the core. Increased erosion, likely due to decreased vegetation cover within the basin, led to the siltation/filling of the lake within a few hundred years and the subsequent development of a sebkha/salt pan due to massive evaporation. Due to the lack of dateable material in the upper core section, the termination of the lake stage and the onset of the subsequent sebkha stage cannot be determined precisely but can be narrowed to a period around 6 ka BP.
The results obtained from the core are compared with those from terrestrial and lacustrine sediments from outside the depression, situated a few hundred kilometres further to the north. These supplementary study sites are required to validate the information obtained from the coring. Within the plateau landscape of Djado, Mangueni and Tchigai, two depressions and a valley containing lacustrine deposits, were investigated for palaeoenvironmental reconstruction. Depending on modifying local factors, these sediment archives were of shorter existence than IX the lake, but reveal additional information about the landscape dynamics from Early to Mid Holocene.
A damming situation within a small tributary at Enneri Achelouma led to lacustrine sedimentation conditions at Early Holocene in the upper reaches of the valley. The remnants of the lacustrine accumulations show distinct changes in the environmental conditions within the small catchment, as the archive immediately responded to local climate-induced changes of precipitation. Radiocarbon dating of the deposited sediments revealed ages from 8780 ± 260 cal a BP to 9480 ± 80 cal a BP.
The sites of Yoo Ango and Fabérgé show a completely different sedimentation milieu as they consist of basins within the foothills of the Tchigai. The study sites show increased catchment sizes, probably extending towards the Tchigai massif and are most likely influenced by groundwater charge. The widespread occurrence of wind shaped relicts and the limited amount of lacustrine remnants indicate a generally high aeolian activity in both areas. Only in wind sheltered spots, parts of the lacustrine sequences were preserved, that show ages spanning from Early to Mid Holocene (9440 ± 140 cal a BP – 6810 ±140 cal a BP) and give additional evidence of fires from pre-LGM periods. Although intensively weathered, all profiles indicate distinct changes in the sedimentation conditions by alternating geochemical values and the mineralogical composition.
The information obtained from the records investigated in this work confirms the heterogeneity of reconstructed environmental succession in the Central Sahara. The Mid Holocene rapid (within decades) and uniform development from more humid to extremely arid environmental conditions cannot be confirmed for the Central Sahara. In addition, a division of Early and Mid Holocene wet periods cannot be confirmed, either. Actually, the evidences obtained from the palaeoenvironmental reconstructions revealed major variations in the timing and extend of lacustrine and aeolian periods. Evidently, a transitional time has existed between 7 to 5 ka BP where alternating influences prevailed. This is indicated by the varying sedimentation conditions in the Seggedim depression as well as the evidence of soil properties on a fossil dune, with a time of deposition dated to 6200 ± 400 cal a BP and the removal of lacustrine Sediments at the Seeterrassental at Mid Holocene. In respect to provide a complete picture of landscape succession and to avoid misinterpretation, the investigation of several dissimilar spots within a designated study area is prerequisite for further investigations.
Glacier outlines during the ‘Little Ice Age’ maximum in Jotunheimen were mapped by using remote sensing techniques (vertical aerial photos and satellite imagery), glacier outlines from the 1980s and 2003, a digital terrain model (DTM), geomorphological maps of individual glaciers, and field-GPS measurements. The related inventory data (surface area, minimum and maximum altitude) and several other variables (e.g. slope, range) were calculated automatically by using a geographical information system. The length of the glacier flowline was mapped manually based on the glacier outlines at the maximum of the ‘Little Ice Age’ and the DTM. The glacier data during the maximum of the ‘Little Ice Age’ were compared with the Norwegian glacier inventory of 2003. Based on the glacier inventories during the maximum of the ‘Little Ice Age’, the 1980s and 2003, a simple parameterization after HAEBERLI & HOELZLE (1995) was performed to estimate unmeasured glacier variables, as e.g. surface velocity or mean net mass balance. Input data were composed of surface glacier area, minimum and maximum elevation, and glacier length. The results of the parameterization were compared with the results of previous parameterizations in the European Alps and the Southern Alps of New Zealand (HAEBERLI & HOELZLE 1995; HOELZLE et al. 2007). A relationship between these results of the inventories and of the parameterization and climate and climate changes was made.