by Paul Baker

(No abstract available in database. This proposal may not have been fully imported from legacy systems.)

• The major focus of our proposed research is on tropical paleoclimatic (including glacial) reconstruction. This is the goal that we feel is most societally-relevant and most scientifically compelling, for which Lake Titicaca is optimally situated, and for which drilling is the ideal (and only), capable method. Secondary, but important, goals include recovery of a record of regional Andean volcanic activity and elucidating the tectonic origin of the lake basin. We present a list of questions (hypotheses) to be addressed by the drilling of Lake Titicaca. *What is the nature of climate change in tropical South America during the past 0.5 Myr? We know from seismic records that there have been large changes in effective moisture and lake level—when were these? Were they caused by variations in the South American summer monsoon? Were they forced by the known variations of insolation at orbital time scales (especially the precessional variations at 20 kyr time scales)? What is the phasing of Amazon moisture variability with respect to the global methane signature as observed in ice cores (e.g. Chappelaz et al.,
• 1993)? *Are there Pleistocene millennial-scale changes in precipitation and temperature such as we have already observed in the Holocene and late glacial record of the lake? What is the nature of their phasing with respect to Heinrich events and Dansgaard-Oeschger cycles of the high-latitude North Atlantic region? How does the amplitude of these events in the tropics differ between glacial and interglacial stages? *What are the linkages between tropical climate change and global change? How do atmosphericallyforced wet-dry cycles in tropical South America correlate with the global and regional patterns of seasurface temperature variability on a variety of resolvable time scales, but time scales that are much longer than modern instrumental records (answers to this question may need to await high resolution SST reconstructions on marine cores throughout the Atlantic, comparable to the coverage by CLIMAP (1981), but at many different time slices and with reliable temperatures).
• Today we describe regional patterns of SST variability or atmospheric variability using numerous indices (e.g.ENSO, NAO, PADO, PDO, AO, the tropical dipole, etc.) that serve to capture much of the variability of climate for the last few decades. Do the same “centers of action” or geographic patterns of variability hold on longer time scales? Do the centers of action or patterns of variability change with different global mean states (e.g. glacial-interglacial)? *What is the timing of tropical glaciation? Our piston cores from Lake Titicaca contain a clear record of tropical glacial advance and retreat for the last glacial maximum (LGM). We can think of no other sites worldwide that are as likely as Lake Titicaca to contain a continuous and easily decipherable record of tropical glaciers prior to the LGM. What was the timing of previous glacial advances and retreats? Were these always in phase with the high-latitude “global” glacial stages? Or, as seems more likely, were they forced by major climate change (increased wetness and perhaps lower temperatures) at precessional time scales? *To what extent was the climate of tropical South America affected by changing high-latitude boundary conditions (e.g. glaciation) and global surface temperature changes? Is there any evidence for a role of the natural variability of CO2 in forcing tropical climate, perhaps through a vegetation feedback (e.g. Kutzbach et al.,
• 1996). *What is the record of volcanic activity in the late Quaternary? Are there detectable changes in the frequency of eruptions from different volcanic centers? *What is the age and nature of seismically-identified basement underlying the late Quaternary sediments at our drill sites? We expect that basement rocks will help elucidate the tectonic origin and timing of the formation of the Lake Titicaca basin. *What is the heat flow at these sites and is there any evidence for deep fluid flow?

Andes, Bolivia, Climate Change, GLAD, GLAD800, Global Environment, ICDP-2000/12, Lake Drilling, Peru, South America, TITICACA

Latitude: -16.12053, Longitude: -69.12053