Orbital modulation of an intensified hydrological cycle during the Paleocene-Eocene Thermal Maximum

The Paleocene-Eocene Thermal Maximum (PETM, ∼56 Ma) was an abrupt global warming event linked to massive carbon release into the ocean-atmosphere system. As such, it is considered a potentially useful analogue for present and future climate change. Consequently, deciphering its impact on the hydroclimate is important for predicting future changes under high pCO2 and temperature conditions, especially in East Asia where more than a quarter of the world's population lives. Here, we use magnetic and geochemical data obtained through a thick lacustrine record of the PETM from China to demonstrate a large-scale increase in weathering and precipitation coeval with the PETM. Moreover, we show that precipitation variations through the PETM were strongly controlled by eccentricity, precession and half-precession climate cycles. Our results show that orbital forcing of low-latitude insolation played a key role in driving hydroclimate fluctuations and multi-phase changes in precipitation during the PETM, emphasizing the sensitivity of East Asian hydroclimate to subtle changes in insolation under conditions of high temperature and pCO2, perhaps similar to those expected in the future.