Seminar

As one of the most significant climate events during the Cenozoic era, the Eocene to Oligocene transition (EOT) marks the Earth entering into an icehouse world. The climatic responses of Northern and Southern Hemispheres to the EOT are suggested to be asymmetric. Such a thermal asymmetry was related to heat transport change, which was likely driven by the strengthened Atlantic meridional overturning circulation (AMOC). However, whether the effect of enhanced AMOC transmitted to the Asia continent remains to be explored. Here we studied EOT changes at three localities, with two terrestrial records at Asian low (i.e., Maoming Basin) and mid-latitudes (i.e., Qaidam Basin) respectively, and an ocean record (i.e., IODP Site U1411) in the North Atlantic, to investigate how the AMOC imprint was distributed in the Northern Hemisphere. Our results indicate that 1) terrestrial aridification occurred at both Asian low and mid-latitudes during the EOT, and rapid hydrological changes followed the Southern high-latitude cooling; 2) the gradual cooling trend and enhanced ventilation in the North Atlantic during the EOT indicate strengthened AMOC; 3) the effect of strengthened AMOC did not transmit to the Asia continent, challenging modeling simulations of increased precipitation in the whole Northern Hemisphere during the EOT.

Additional information: Ms. WANG Cece, u3005314@connect.hku.hk