Precession-band variance missing from East Asian monsoon runoff
Abstract
Speleothem CaCO3 δ18O is a commonly employed paleomonsoon proxy. However, inferring local rainfall amount from speleothem δ18O can be complicated due to changing source water δ18O, temperature effects, and rainout over the moisture transport path. These complications are addressed using δ18O of planktonic foraminiferal CaCO3, offshore from the Yangtze River Valley (YRV). The advantage is that the effects of global seawater δ18O and local temperature changes can be quantitatively removed, yielding a record of local seawater δ18O, a proxy that responds primarily to dilution by local precipitation and runoff. Whereas YRV speleothem δ18O is dominated by precession-band (23 ky) cyclicity, local seawater δ18O is dominated by eccentricity (100 ky) and obliquity (41 ky) cycles, with almost no precession-scale variance. These results, consistent with records outside the YRV, suggest that East Asian monsoon rainfall is more sensitive to greenhouse gas and high-latitude ice sheet forcing than to direct insolation forcing.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Aug 22, 2018
- Source ID
- 10.1038/s41467-018-05814-0
Entities
People
- A. Holbourn
- Arin D. Nelson
- Baylor Fox-Kemper
- Genyu Chen
- K. E. Lee
- Steven Clemens
- Y. Kubota
- Zengqian Liu
Organizations
- Japan Society for the Promotion of Science
- National Science Foundation
- Office of Naval Research