What drives glacial climate cycles? This fundamental question lies at the heart of understanding global changes of recent ice ages. The PI and others have suggested that abrupt reorganizations of the ocean-atmosphere system are the key events linking orbital perturbations to global ice-age climate changes. This hypothesis has fundamental implication about understanding past climate changes as well as anticipating changes in the earth's present climate. It is suggested that major ocean and atmospheric changes begin abruptly and synchronously on a global scale during major climate transitions. To test such a prediction the PI proposes to compare detailed paleoclimatic records of glacier margins and equilibrium-line altitudes (which are sensitive indicators of atmospheric temperature changes) at mid latitudes in both polar hemispheres through the last glacial-interglacial transition. For this test, he seeks a precise Southern Hemisphere alpine glacier record. This is a grant to support obtaining the necessary glacial record while avoiding the inherent and time-consuming gamble of mapping a moraine sequence and coming up empty for radiocarbon age control. Most projects on alpine glaciation have not been particularly helpful because of lack of radiocarbon dates. After examining Southern Hemisphere alpine areas in New Zealand and South America, the PI proposes reconnaissance field work in southern Chile in the area covered by a former alpine glacier system that extended form the crest of the Andes westward to Chile Island. This field work will involve reconnaissance mapping multiple moraines and outwash bodies of Llanquihue (late Wisconsin/marine isotope stage 2) age on Chiloe Island and the adjacent mainland. Existing radiocarbon sites will be tied into this map and abundant new stratigraphic sites with organic material will be examined and dated to determine if they can yield additional chronologic control. Pollen and spore stratigraphy will be examined for intertill peats. Finally, the PI will determine if minimum ages for ice recession deep into the mountains can be obtained from basal dates in lakes and bogs. The resulting preliminary chronology will clarify whether this region of the Southern Andes is capable of producing a paleoclimatic record with the detailed age control necessary to test the hypothesis of abrupt ocean-atmosphere reorganizations. Hence, the feasibility of a long-term study in the southern Andes will emerge from this preliminary chronology. This work is supported by a Small Grant for Exploratory Research and is important because it seeks to understand climate changes on time scales relevant to human activities.
