Rainfall and Vegetation of Indonesia during the Late Pleistocene and Holocene Wicaksono, Satrio Adi creator 2016 xix, 219 p. born digital Thesis (Ph.D. -- Brown University (2016) Russell, James Director Clemens, Steven Reader Huang, Yongsong Reader Mustard, John Reader King, John Reader Brown University. Geological Sciences sponsor theses The atmosphere over the tropical Indonesian archipelago is highly convective and has high annual precipitation, giving rise to its widespread lowland evergreen rainforests. The region is a key driver of the global energy cycle and atmospheric circulation, yet the histories of Indonesian rainfall and vegetation remain unclear due to a limited number of proxy records and significant disagreement in their climatic and ecological interpretations. This highlights the need to rigorously assess Indonesia’s rainfall and vegetation in the past to obtain a more complete understanding of global climate variability. This dissertation aims to understand how the rainfall and vegetation of central and eastern Indonesia varied during the late Pleistocene and Holocene and the forcings driving those variations. The late Pleistocene includes the Last Glacial Maximum (LGM, ca. 26-19 kyr BP), a period when the Earth had very different boundary conditions than today, and the last deglaciation (19-11 kyr BP), one of the most recent dramatic periods of climatic change. Leaf wax carbon isotope records (δ13Cwax) from central Indonesian lacustrine and marine sediments indicate strong glacial-interglacial climate changes, with extensive drying and increased grasses in the lowlands during the LGM, although the highlands remained highly forested. Analyses of leaf wax hydrogen isotope records (δDwax) suggest that the dry LGM is associated with a southward Intertropical Convergence Zone (ITCZ) shift and an intensified Austral-Asian monsoon circulation, likely due to strong southern hemisphere summer insolation and the presence of large northern hemisphere ice sheets. Central Indonesia δ13Cwax was anti-correlated with δDwax during the LGM and the last deglaciation, but was positively correlated during the Holocene, indicating time-varying controls on rainfall isotopes. In contrast, δ13Cwax and δDwax data measured on southeastern Indonesia sediment cores are strongly coupled, indicating that the amount of rainfall has been the chief mechanism controlling eastern Indonesia vegetation and precipitation isotopes since the last deglaciation. A significant rainfall reduction and grassland expansion between 12 and 6 kyr BP indicate that eastern Indonesia precipitation is primarily controlled on the orbital scale by southern hemisphere summer insolation and ITCZ movement, which differs from central Indonesia. Precipitation Vegetation Biomarker Maritime Continent Precipitation (Meteorology)PlantsBiochemical markersCarbonHydrogenIsotopesIndonesia RPB 20160629 engEnglish10.7301/Z0QV3JZHIn CopyrightCollection is open for research.dissertations