Professor Richard Lawrence Edwards, who was elected as a foreign member of the Chinese Academy of Sciences in 2015, was invited to attend the related conferences at the Chinese Academy of Sciences and the Great Hall of the People on May 29-30, 2016. After these conferences, he visited the Institute of Geology and Geophysics, Chinese Academy of Sciences (IGGCAS) on May 31 and gave a presentation entitled "A 600,000 year record of the Asian Monsoon from Chinese Caves".
In his talk, he introduced the formation of speleothems, the history of U-Th dating, and the correlations among the Chinese cave records, ice core, and marine records. The main conclusions of his work are as follows: 1. Well chosen cave calcite (low detrital-content, low porosity) can be dated precisely and accurately with U-Th techniques. 2. Insolation affects both millennial and orbital-scale variations in the monsoon, but through very different processes. 3. The Chinese cave records are correlated with ice cores (methane) and marine records (e.g., ice rafted debris-Heinrich events). 4. CO2 rise coincides with marine termination II and with boreal summer insolation rise. Finally, he described in detail the processes that ocurrs during the end of ice ages. Namely, that 1) increased atmospheric methane predisposes ice sheet to breakup; 2) slight rises in insolation triggers initial melting of ice sheet, ice rafting and fresh water discharge to North Atlantic; 3) suppression of North Atlantic deepwater formation and associated heat transport, cools the North Atlantic causing North Atlantic sea ice expansion, which shuts down the monsoon and shifts the ITCZ south; 4) bi-polar seesaw effects, heat the South Ocean, triggering a rise in atmospheric CO2 and accelerating ice sheet melting.
After the presentation, Professor Richard Lawrence Edwards visited the U-Series Dating Lab and discussed his work with IGGCAS researchers.
Richard Lawrence Edwards is a Regents Professor and the Gunn Professor of Earth Sciences at the University of Minnesota. He is renowned for his role in the development of modern uranium-thorium dating techniques and their application to the study of climate history. He champions cave deposits as recorders of historic and pre-historic climate. He and many outstanding Chinese collaborators have reconstructed over 600,000 years of Asian Monsoon history. This work helps us to understand the causes of abrupt climate change and the rapid melting of ice sheets at the end of glacial cycles.
Professor Richard Lawrence Edwards is giving a report.