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 (similar to 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 similar to 34 Ma. Superimposed dust fertilization and biological pump action amplified this CO2 removal before similar to 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.

Automated summary

Stimulation of the biological pump by iron-bearing dust in the eastern equatorial Pacific Ocean plays an important role in long-term carbon sequestration, but the impact of past dust fertilization on CO2 perturbations over major climate transitions is still debated.