A late Pleistocene‐Holocene record of tropical monsoon climate from groundwater noble gases and isotopes in the Leizhou Peninsula, Southern China

Abstract

Abstract

Groundwater from the Leizhou Peninsula in tropical South China provides one of the first noble‐gas based paleoclimate reconstructions from the East Asian monsoon region. Radiocarbon dating establishes a robust chronology spanning the Late Pleistocene to the Holocene. Noble gas temperatures reveal a minimum glacial‐to‐Holocene warming of ∼5°C–6°C, consistent with global low‐latitude groundwater records. Stable isotopes (δ 18 O) covary with excess air, indicating that they primarily reflect monsoon‐driven precipitation changes rather than temperature. These records point to suppressed recharge during the Last Glacial Maximum, a short‐lived weakening of the summer monsoon during the Younger Dryas, and intensified precipitation in the early Holocene. By jointly resolving temperature and precipitation signals, fossil groundwater offers a dual constraint on tropical paleoclimate that complements existing continental records and provides benchmarks for testing climate model sensitivity in East Asia.

Plain Language Summary

Reconstructing past climate in tropical East Asia is essential for understanding glacial‐interglacial transitions in low‐latitude regions. Here we use ancient groundwater from the Leizhou Peninsula in South China as a natural archive. When rainwater infiltrates the ground, it traps noble gases and isotopes that preserve the temperature and rainfall conditions at the time of recharge. Our results indicate that temperatures at the time of groundwater recharge during the last ice age were at least ∼5°C–6°C colder than today. The isotope record further reveals suppressed recharge during the peak of the Last Glacial Maximum, a short‐lived weakening of the summer monsoon during the Younger Dryas, and intensified precipitation in the early Holocene. Together, these findings demonstrate that ancient groundwater provides a powerful and underutilized archive of tropical paleoclimate change. Key Points Noble gas temperatures from Leizhou groundwater indicate a minimum ∼5°C–6°C glacial‐to‐Holocene warming in tropical East Asia Covariation of δ 18 O with excess air shows that isotopes primarily record monsoon precipitation and recharge dynamics, not temperature The groundwater record documents Last Glacial Maximum aridity, a short Younger Dryas weakening, and an early Holocene monsoon maximum, consistent with the regional lake and speleothem archives.

© 2026 American Geophysical Union. Open Access CC BY-NC 4.0.