Equatorial Pacific dust fertilization and source weathering influences on Eocene to Miocene global CO₂ decline

Stimulation of the biological pump by iron-bearing dust in the eastern equatorial Pacific Ocean plays an important role in long-term carbon sequestration, yet past dust fertilization and its impact on CO₂ perturbations over major climate transitions remain debated. Here, we integrate proxies of dust input, source-region weathering, and biological pump activity from late Eocene to early Miocene sediments of Integrated Ocean Discovery Program Hole U1333, which includes the Eocene-Oligocene Transition (~34 million years ago) when a major ice sheet was first established on Antarctica. We find that intensified chemical weathering in the large central Asian dust source region enhanced atmospheric CO₂ removal at ~34 Ma. Superimposed dust fertilization and biological pump action amplified this CO₂ removal before ~34 Ma, while weakening of this amplification process helped to moderate the CO₂ decline after that time. The observed inter-linked, counteracting processes with different timescales illustrate the complexity of carbon cycle feedbacks associated with major climate changes.

Dunfan Wang, Andrew P. Roberts, Eelco J. Rohling, Weiqi Yao, Yi Zhong, Zhengquan Yao, Yang Lu, Qingsong Liu