Monsoons impact large areas of the Earth, and affect the livelihoods of hundreds of millions of people each year. The objective of this doctoral dissertation research project is to precisely document changes in monsoon activity over time and to understand the factors (solar radiation, ocean conditions, ice volume, Heinrich events, Bond cycles) that have caused these changes. Much of the present knowledge about past monsoon activity has come from ocean and ice cores, lake sediments, and loess-paleosol sequences. However, in recent years, cave stalagmites have provided precisely dated, new information. The project's principal aims are (1) to develop the first high-resolution, continuous, and accurately dated Holocene record of climate change for the Southeastern U.S.A., (2) to produce and compare late Pleistocene and Holocene records of climate in Southwestern China and the Southeastern U.S.A., and (3) to examine the external factors that have influenced monsoon activity. The doctoral student will do this by studying stalagmites from two caves in Southern China and one in Alabama, U.S.A. Detailed records of climate and monsoon variability will be obtained by looking at variations in luminescence, color, O and C stable isotopes, and carbonate petrography along the growth axes of stalagmites. The student hopes to compare Asian monsoon variability between glacial and interglacial intervals and to produce detailed records of Holocene climate change in Southern China and the Southeastern U.S.A. that will show how the persistence of the Laurentide Ice Sheet into the early Holocene affected monsoon activity originating in the Gulf of Mexico. A unique aspect of the research will be the use of an electrical drilling rig to obtain vertical cores from large stalagmites that previously were not accessible to scientific research. This approach minimizes damage to the stalagmite but allows access to its long record of environmental change.
By understanding how and why monsoons have changed in the past, researchers may be able to better predict future changes. The knowledge gained will benefit societal long-term planning. This project is a collaborative study with Chinese faculty and students and thus will foster international collegiality. In addition, if the new drilling program is successful, it will provide scientists with a way to study stalagmites without removing them from caves and damaging the cave environment. A long-term benefit of this will be the preservation of cave environments for later generations.
