Temperature signals of ice core and speleothem isotopic records from Asian monsoon region as indicated by precipitation δ18O

Ice cores and speleothem delta O-18 records from Asia have been widely used as a proxy to reconstruct paleoclimate changes. However, whether those delta O-18 records are a proxy of temperature or monsoon intensity has remained a great controversy. Generally, ice core delta O-18 records from non-monsoon and transition regions indicate temperature, but ice core and speleothem delta O-18 records from monsoon regions have been regarded as proxies for monsoon intensity or precipitation. Here, we address the controversy by showing three 20-yr long daily precipitation delta O-18 (delta O-18(p)) series and 120 monthly sisop series based on 17461 precipitation samples throughout Asia. We find that the delta O-18 p signals preserved in precipitation are consistent with those in ice cores, both in the non-monsoon and monsoon regions. The results confirm previous research that ice core delta O-18 records in the non-monsoon region provide reliable histories of surface temperature. However, ice core delta O-18 records can still directly indicate surface temperature in the monsoon domain if winter/spring precipitation is heavy. When winter/spring precipitation is sparse, inverted ice core records show good agreement with surface temperature records. This may be due to the effect of cloud-top temperatures (which differ from surface temperatures) on summer delta O-18(p) values. Similarly, inverted speleothem delta O-18 records in the monsoon regions are similar to Greenland/Antarctic ice core delta O-18/delta D time series and other paleotemperature records. Our findings provide a reinterpretation of Asian ice core and speleothem delta O-18 records, and demonstrate that temperature signals have been preserved in those archives from the Asian monsoon region. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

The study found that the delta O-18 signals in precipitation samples from both non-monsoon and monsoon regions in Asia are consistent with ice core records. This confirms the reliability of ice core records in non-monsoon regions for surface temperature histories and indicates their potential to directly indicate surface temperature in monsoon regions.