| This dissertation examines how external forcings drive environmental responses in an alpine watershed in the tropical Andes. The principal goal is to improve understanding of the processes of change and their causality in a microcosmic case study carried out in the watershed of Sibinacocha, an alpine lake in the Cordillera Vilcanota at 14°S. The research is highly interdisciplinary, with major components in climatology, mountain geography and global environmental change. The research foci examined are climatological variability, glacial trends, and the landscape ecology of the Sibinacocha watershed. Emphasis is placed on improving understanding in regional climatology and climate history to establish proper context for study within the other disciplines. Recognition of the existence of 4-stage annual seasonality is critical to understanding interannual variability. Regional climatic modulation is driven principally by the El Nino-Southern Oscillation (ENSO) through its control over seasonal durations of convective cloud regimes. A multicentennial climatic history is developed from ice cores drilled in 1983 atop the Quelccaya Ice Cap (5,670 m). Subjective errors in the original analysis diminished the clarity of signals in the stratigraphy, so a reanalysis methodology is developed to improve consistency between the two cores that also provides absolute dating for several centuries by using paleoearthquakes markers. Partial reconstruction of interannual climatic variations is established for 500 years, as well as a means to identify annual ENSO signals in dated ice stratigraphy. Initial results reveal that centennial-scale modes characterize ENSO and central Andean regional variability, and suggest that current rapid warming might remain within the realm of natural variability. Regional glaciation responded to these climate modes through the neoglacial advance of the Little Ice Age and deglaciating trend that characterized the 20th century.; Due to the inherent climatic instability, landscape and ecosystem change are omnipresent characteristics of the Sibinacocha watershed, since the landscape components cannot equilibrate with the moving target presented by highly varying climatic conditions. The study reveals, however, that growing anthropogenic influences is eroding the traditional determinism of climate over environmental outcomes, as humans respond to improving climatic conditions and the encroachment of markets into the highest zones of the Andes. |
