Mountain glaciers outside the polar regions have proved to contain valuable archives recording regional climate fluctuations and atmospheric pollution history. Ice from such glaciers is well suited for the reconstruction of the concentration of species with a short residence time in the atmosphere. These species are not well recorded in polar ice sheets (Antarctica, Greenland), that are relatively far away from the source regions. From some geographic regions, however, such long term records are not yet available, although suitable glaciers principally exist there. This thesis presents results from three such glaciers: Two glaciers from South America where ice cores have been drilled and analyzed chemically for the first time, and one glacier from the European Alps.

The two glaciers in the sub-tropical Andes (33°S, Chile, and 32°S, Argentina) were investigated for their suitability as climate archives. They are located in an area of particular climatic interest as the region is strongly influenced by the El Niño climate phenomenon, which is not yet fully understood. A glacier from this region might provide a long-term archive of past variations. A reconnaissance study was conducted in 2003. Shallow firn cores were drilled and radar measurements were performed at both sites providing an estimation of the respective glacier thicknesses. After glacio-chemical analysis, the glacier in Chile was discovered to be strongly influenced by surface melting and water percolation although the drilling site was at an altitude of more than 5,300 m. Thus, this glacier was unsuitable for paleo (past) climate reconstructions.

In Argentina, a shallow firn core (13 m) was recovered from Glaciar La Ollada. Results of the analyses demonstrated the general suitability of the glacier and that melt water percolation was insignificant. The accumulation rate was 0.45 m water equivalent per year and the average δ¹⁸O was -21.4‰. Snow was accumulated in summer and in winter. Due to the limited time span covered by the core (1986–2002), the existing data did not allow for reconstructions prior to available instrumental records. This project is being continued on a new deep ice core (104 m) recovered in 2005.

The second part of the thesis is devoted to the glacio-chemical analysis of an ice core that was drilled in September 2003 on Colle Gnifetti, European Alps, Switzerland, at an altitude of 4450 m (45°56' N, 7°53' E). This glacier is one of the few, if not the only site in the Alps, where the archive extends far into the past. Previous studies estimated the age of the ice at bedrock to be at least 2,000 years old. Despite the long history of ice core drilling on Colle Gnifetti (the first core was drilled in 1976), some questions have remained unanswered. A stable isotope record (δ¹⁸O, δD), potentially recording summer temperature variations over the last millennia, has never been published in international scientific journals. Such a record would represent a new proxy for the reconstruction of European climate variability and it could also be used for comparison with other important reconstructions based on tree ring studies.

For this study, the younger part of the 2003 core was dated by a combination of several methods: Annual layer counting, nuclear dating (²¹⁰Pb) and the use of reference horizons (nuclear weapon testing, Saharan dust deposition). By the application of an ice flow model based on the radiocarbon dates and other reference horizons, a continuous chronology was obtained. The theoretical basis of such flow models is discussed.

For the old part of the core, a new dating method (developed by Theo Jenk), which is based on radiocarbon measurements in carbonaceous micro-particles, was applied on this core. This showed the presence of ice older than several millennia. The lowermost core section turned out to be more than 11,700 years old, suggesting the presence of ice from the last glacial period (Würm glaciation). To date, Colle Gnifetti is the glacier containing the oldest ice found in the Alps.

The accumulation rate on Colle Gnifetti was known to be comparatively low. For the ice core presented here, it was found to be between 0.36 and 0.40 m water equivalent. Borehole measurements showed temperatures ranging from -12 to -14°C.

Close to bedrock an intense yellow dust layer was observed. The layer was characterized chemically and mineralogically. Among components common for the region (e.g.\ quartz and feldspar) it also contained 7% of gypsum which is not found in this mountain range. This indicates that the dust is of aeolian (wind-blown) origin. It is speculated that it originates from the end of the last glacial.

Major ion records showed much higher concentration for nitrate, sulfate and ammonium during the industrial period when compared to the preindustrial period. This was attributable to increasing emissions of sulfur dioxide, nitrous oxides and ammonia. Other species such as chloride showed no trend.

A high-resolution record of stable isotopes (δ¹⁸O) for the time period 550–2003 A.D. is presented and its validity for temperature reconstructions is discussed. Eventual influences of shifts in the precipitation pattern on δ¹⁸O are evaluated. The highest values in the δ¹⁸O record were observed during the Medieval Warm Period around 1020 A.D. The 20^th century shows a strong increase in δ¹⁸O of 2.1±0.2‰.