Journal Article

Past terrestrial hydroclimate sensitivity controlled by Earth system feedbacks

Otto-Bliesner, Bette L., Contoux, Camille, Lunt, Daniel J., Dowsett, Harry J., Lohmann, Gerrit, Brady, Esther C., Peltier, W. Richard, Chan, Wing-Le, Feng, Ran, Hunter, Stephen J., Stepanek, Christian, Haywood, Alan M., Bhattacharya, Tripti, Williams, Charles J. R., Abe-Ouchi, Ayako, Zhang, Qiong, Tindall, Julia C., Kageyama, Masa, Tan, Ning, Zhang, Zhongshi, Guo, Chuncheng, Li, Xiangyu, Han, Zixuan, Chandan, Deepak

2022

Overview

Despite tectonic conditions and atmospheric CO 2 levels ( pCO 2 ) 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 CO 2 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 pCO 2 . 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 CO 2 forcing. In contrast to future projections, paleoclimate records often find wetter subtropics in tandem with elevated CO 2 . Here, a compilation of proxies and simulations are used to reveal the climate dynamics and feedbacks responsible for generating wet subtropics during the mid-Pliocene.

• Publisher: Nature Publishing Group UK,Nature Publishing Group,Nature Portfolio
• Subject: 704/106/413 / 704/106/694 / Carbon dioxide / Climate change / Continental interfaces, environment / Earth science / Earth, Planet / El Nino / Equilibrium / Feedback / Humanities and Social Sciences / Hydroclimate / Hypotheses / Ice Cover / Ice sheets / Laboratories / Land cover / multidisciplinary / Ocean, Atmosphere / Paleoclimate / Paleoclimatology / Pliocene / Precipitation / Proxies / Radiative forcing / Science / Science (multidisciplinary) / Sciences of the Universe / Simulation / Surface temperature / Tectonics / Vegetation / Vegetation changes