Steffen Vogt

A Review of 2000 Years of Paleoclimatic Evidence in the Mediterranean

The integration of climate information from instrumental data and documentary and natural archives; evidence of past human activity derived from historical, paleoecological, and archaeological records; and new climate modeling techniques promises major breakthroughs for our understanding of climate sensitivity, ecological processes, environmental response, and human impact. In this chapter, we review the availability and potential of instrumental data, less well-known written records, and terrestrial and marine natural proxy archives for climate in the Mediterranean region over the last 2000 years. We highlight the need to integrate these different proxy archives and the importance for multiproxy studies of disentangling complex relationships among climate, sea-level changes, fire, vegetation, and forests, as well as land use and other human impacts. Focusing on dating uncertainties, we address seasonality effects and other uncertainties in the different proxy records. We describe known and anticipated challenges posed by integrating multiple diverse proxies in high-resolution climate-variation reconstructions, including proxy limitations to robust reconstruction of the natural range of climate variability and problems specific to temporal scales from interannual to multicentennial. Finally, we highlight the potential of paleo models to contribute to climate reconstructions in the Mediterranean, by narrowing the range of climate-sensitivity estimates and by assimilating multiple proxies.

Spatial Distribution of, and Risk Factors for, Opisthorchis viverrini Infection in Southern Lao PDR

Background Opisthorchis viverrini is a food-borne trematode species that might give rise to biliary diseases and the fatal cholangiocarcinoma. In Lao PDR, an estimated 2.5 million individuals are infected with O. viverrini, but epidemiological studies are scarce and the spatial distribution of infection remains to be determined. Our aim was to map the distribution of O. viverrini in southern Lao PDR, identify underlying risk factors, and predict the prevalence of O. viverrini at non-surveyed locations. Methodology A cross-sectional parasitological and questionnaire survey was carried out in 51 villages in Champasack province in the first half of 2007. Data on demography, socioeconomic status, water supply, sanitation, and behavior were combined with remotely sensed environmental data and fed into a geographical information system. Bayesian geostatistical models were employed to identify risk factors and to investigate the spatial pattern of O. viverrini infection. Bayesian kriging was utilized to predict infection risk at non-surveyed locations. Principal Findings The prevalence of O. viverrini among 3,371 study participants with complete data records was 61.1%. Geostatistical models identified age, Lao Loum ethnic group, educational attainment, occupation (i.e., rice farmer, fisherman, and animal breeder), and unsafe drinking water source as risk factors for infection. History of praziquantel treatment, access to sanitation, and distance to freshwater bodies were found to be protective factors. Spatial patterns of O. viverrini were mainly governed by environmental factors with predictive modeling identifying two different risk profiles: low risk of O. viverrini in the mountains and high risk in the Mekong corridor. Conclusions/Significance We present the first risk map of O. viverrini infection in Champasack province, which is important for spatial targeting of control efforts. Infection with O. viverrini appears to be strongly associated with exposure to the second intermediate host fish, human behavior and culture, whereas high transmission is sustained by the lack of sanitation.

An improved topographic database for King George Island: compilation, application and outlook

A new topographic database for King George Island, one of the most visited areas in Antarctica, is presented. Data from differential GPS surveys, gained during the summers 1997/98 and 1999/2000, were combined with up to date coastlines from a SPOT satellite image mosaic, and topographic information from maps as well as from the Antarctic Digital Database. A digital terrain model (DTM) was generated using ARC/INFO GIS. From contour lines derived from the DTM and the satellite image mosaic a satellite image map was assembled. Extensive information on data accuracy, the database as well as on the criteria applied to select place names is given in the multilingual map. A lack of accurate topographic information in the eastern part of the island was identified. It was concluded that additional topographic surveying or radar interferometry should be conducted to improve the data quality in this area. In three case studies, the potential applications of the improved topographic database are demonstrated. The first two examples comprise the verification of glacier velocities and the study of glacier retreat from the various input data-sets as well as the use of the DTM for climatological modelling. The last case study focuses on the use of the new digital database as a basic GIS (Geographic Information System) layer for environmental monitoring and management on King George Island.

Variations of glacier frontal positions on the northern Antarctic Peninsula

Abstract Changes in the ice fronts on the Antarctic Peninsula north of 70˚ S are currently being investigated through a comprehensive analysis of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and Landsat Thematic Mapper (TM) data as part of the international research initiative ‘Global land Ice Measurements from Space’ (GLIMS). Regional case studies are presented that cover a variety of glacial systems distributed over the northern Antarctic Peninsula and provide data on glacier front variations during the period 1986–2002. The results confirm a general trend of regional glacier front recession, but a range of different glacier variations are observed throughout the study area. Areas of predominant retreat are located in the northeastern and southwestern sectors, while stationary ice fronts characterize glacial behaviour on the northwestern coast of the peninsula. In addition, a significant increase in glacier recession is identified on James Ross Island, where retreat rates doubled during the period 1988–2001 compared to the previous investigation period, 1975–88. These observations are interpreted as being direct consequences of the rapidly changing climate in the region, which differentially affects the local accumulation and ablation patterns of the glacial systems.

A time series of SAR data for monitoring changes in boundaries of glacier zones on the Antarctic Peninsula

Abstract Drastic changes have been detected in glacial systems of the Antarctic Peninsula in the last few decades and are well documented in numerous scientific publications. However, the spatial and temporal distribution of glacier changes on the Antarctic Peninsula remains largely restricted to ice fronts. To expand the current monitoring of a few glaciers, unevenly distributed along the peninsula, to a representative set, we developed a method to simplify the detection of boundaries between glacier zones using satellite SAR data. The evolution of glacier zones is greatly influenced by local and regional climatic and meteorological settings. Their variations in response to changes in energy or mass balance are considered as good indicators of climatic changes. In this paper, we describe the results of knowledge-based image analysis algorithms on test areas located at Trinity Peninsula and near Marguerite Bay. In general, the two analyzed areas show different patterns of glacier zone development. The bare-ice zone occurs mainly on glaciers located on the eastern side of Trinity Peninsula. Its upper boundary shows a good correlation with the mean summer air temperature. Finally, the position of the dry-snow line shows different spatial patterns of change in both study areas.

THE COMPILATION OF A DTM AND A NEW SATELLITE IMAGE MAP FOR KING GEORGE ISLAND, ANTARCTICA

An improved topographic database for King George Island, one of the most frequently visited regions in Antarctica, is presented. A first step consisted in combining data from differential GPS surveys gained during the austral summers 1997–1998 and 1999–2000, with the current coastline from a SPOT satellite image mosaic, topographic information from existing maps and from the Antarctic Digital Database. From this data sets, a digital terrain model (DTM) was generated using Arc/Info GIS. In a second step, a satellite image map at the scale 1:100 000 was assembled from contour lines derived from the DTM and the satellite mosaic. A lack of accurate topographic information in the eastern part of the island was identified. Additional topographic surveying or SAR interferometry should be used to improve the data quality in that area. The GIS integrated database will be indispensable for glaciological and climatological studies and administrative and scientific purposes. In future, the application of GIS techniques will be mandatory for environmental impact studies and environmental monitoring as well as for management plans on King George Island.

KGI-XGIS supporting decision making with knowledge-based techniques

The concept of the King George Island Expert GIS (KGI-XGIS) is introduced. KGI-XGIS is a combination of a rule-based expert system and a GIS meant to form an intelligent spatial decision support system. The system provides the spatial knowledge necessary for the environmental impact assessment process as dictated by the ‘Madrid Protocol’ for King George Island (South Shetland Islands, Antarctica). It also serves as information system to the scientific user community. Topographic maps, remote sensing data, thematic maps based on field surveys and other digital data form the input data to the GIS. Given the sparseness of the available data these must be combined and used in the most efficient way. Therefore expert knowledge of different domains will be coded into a rule-based expert system which is coupled to the GIS. To handle the expert knowledge and the spatial data of different types and different quality the KGI-XGIS incorporates knowledge-based techniques and fuzzy reasoning. The selection of a camp site on the ice free area of Fildes Peninsula and data quality management are used as two examples to demonstrate the capabilities of the system.