Orbital Asian summer monsoon dynamics revealed using an isotope-enabled global climate model.

Caley, Thibaut; Roche, Didier M; Renssen, Hans · Nat Commun · 2014

basic_science · Level V

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Abstract

The Asian summer monsoon dynamics at the orbital scale are a subject of considerable debate. The validity of Asian speleothem δ(18)O records as a proxy for summer monsoon intensity is questioned together with the ultimate forcing and timing of the monsoon. Here, using the results of a 150,000-year transient simulation including water isotopes, we demonstrate that Asian speleothem δ(18)O records are not a valid proxy for summer monsoon intensity only at the orbital timescale. Rather, our results show that these records reflect annual variations in hydrologic processes and circulation regime over a large part of the Indo-Asian region. Our results support the role of internal forcing, such as sea surface temperature in the equatorial Pacific, to modulate the timing of monsoon precipitation recorded in paleo-proxies inside the Asian region.