672 / 2024-09-18 22:47:22

Holocene changes in the relationship of the Asian monsoon and the Pacific Decadal Oscillation

Speleothem δ18O,Asian monsoon,Pacific Decadal Oscillation,Paleoclimate reconstruction,Holocene

Session 65 - Oceanic-atmospheric processes over the Indian and western Pacific Oceans

The relationship of the Asian monsoon (AM) and Pacific Decadal Oscillation (PDO) is crucial for understanding the role of ocean-atmosphere coupling in affecting climate changes in monsoon regions and predicting future changes in the monsoon. Earlier studies have demonstrated that this relationship is temporally unstable during the instrumental era due to the influence of anthropogenic climate warming. However, long-term changes in the relationship and forcing mechanisms remain unclear because of chronological uncertainty of different proxy records. This study utilizes Holocene reconstructions of AM and PDO derived from a large‐scale compilation of speleothem isotope records from Chinese monsoon region, in which speleothem records are generally accepted as good indicators of large-scale circulation, to unveil Holocene evolution of AM-PDO relationships across different time scales. We show that the relationship varies during different periods of the Holocene, characterized by a strongly negative correlation in the mid-Holocene (4-8 ka BP) and more positive correlations in the early and late Holocene. During the last millennium, the AM-PDO relationship exhibits a significant trend towards an intensified negative correlation. We identified that the relationship has significant multi-centennial and millennial periodicities with a cyclical shift occurring around 4ka BP, attributed to the concurrent changes in the Atlantic sea surface temperature variability. Our findings provide vital evidence regarding multi-scale relationships of the monsoon and PDO under the same chronological framework, which will facilitate to constrain their relationships in the climate models.