Past terrestrial hydroclimate sensitivity controlled by Earth system feedbacks

• Published in: Nature Communications
• Main Authors: Feng, Ran, Bhattacharya, Tripti, Otto-Bliesner, Bette L., Brady, Esther C., Haywood, Alan M., Tindall, Julia C., Hunter, Stephen J., Abe-Ouchi, Ayako, Chan, Wing-Le, Kageyama, Masa, Contoux, Camille, Guo, Chuncheng, Li, Xiangyu, Lohmann, Gerrit, Stepanek, Christian, Tan, Ning, Zhang, Qiong, Zhang, Zhongshi, Han, Zixuan, Williams, Charles J. R., Lunt, Daniel J., Dowsett, Harry J., Chandan, Deepak, Peltier, W. Richard
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: 2022
• Subjects: Ice Sheet
• Online Access: https://epic.awi.de/id/eprint/55824/; https://doi.org/10.1038/s41467-022-28814-7; https://hdl.handle.net/10013/epic.37a3b13a-06b2-4818-b3d7-c78fc35a6eff

Despite tectonic conditions and atmospheric CO2 levels (pCO2) similar to those of present-day, geological reconstructions from the mid-Pliocene (3.3-3.0 Ma) document high lake levels in the Sahel and mesic conditions in subtropical Eurasia, suggesting drastic reorganizations of subtropical terrestrial hydroclimate during this interval. Here, using a compilation of proxy data and multi-model paleoclimate simulations, we show that the mid-Pliocene hydroclimate state is not driven by direct CO2 radiative forcing but by a loss of northern high-latitude ice sheets and continental greening. These ice sheet and vegetation changes are long-term Earth system feedbacks to elevated pCO2. Further, the moist conditions in the Sahel and subtropical Eurasia during the mid-Pliocene are a product of enhanced tropospheric humidity and a stationary wave response to the surface warming pattern, which varies strongly with land cover changes. These findings highlight the potential for amplified terrestrial hydroclimate responses over long timescales to a sustained CO2 forcing.