Quantifying subglacial erosion rates and exploring pro-glacial bedrock as climate archive by in-situ cosmogenic C-14 and Be-10 techniques

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A growing consensus believes that the number one environmental problem of our time is climate change and the evaluation of its consequences. Fundamental to predicting these effects is knowing whether the climate during the Holocene Epoch (the last 11,500 years), the period during which human civilization has developed, was perhaps even warmer than today. Glaciers are highly sensitive to climate changes and fluctuate considerably in response to small temperature excursions, such as the Little Ice Age. This project investigates the climate history of selected mountain glaciers that retreated substantally during recent years : Rhone Glacier, Switzerland, Nigardsbreen, Norway, and Franz-Josef-Glacier, New Zealand. Analysis of in-situ cosmogenic Be-10 and C-14 from bedrock surfaces in proximity to these glaciers will address whether, and for how long, these glaciers were smaller than today during the Holocene. The project will also yield quantitative data for glacier-bedrock interactions that can be directly fed into glacier-geomorphic landscape models. Human civilation has developed during the extraordinarily stable Holocene warm period, but climate variability has been large enough to impact rise and fall of ancient societies, illustrating the significance of climate change. However, the record of this change is poor. Glaciers are among the few elements of our environment sensitive enough to respond quickly to climate changes. The present episode of glacier retreat is exposing a large amount of bedrock, which can be used to determine the amount and timing of glacial recession . Cosmogenic isotopes from these bedrock surfaces provide information about when these surfaces were exposed by melting ice. The glacier fluctuation data will be coupled with ice-flow models to interpret them in view of realistic climatic scenarios. This project will add fundamental information to kowledge of subglacial erosion rates and Holocene warm periods, a key parameter in climate prediction models. Additionally, this study will assist in the evaluation of water availability in times of retreating glaciers and increasing population around the globe.