(Table S) Planktonic foraminifera I/Ca during the PETM

As yet no evidence has been presented for pervasive deoxygenation in the upper water column through expansion of Oxygen Minimum Zones (OMZs) during the PETM. We apply a novel proxy for paleo-redox conditions, the iodine to calcium ratio (I/Ca) in bulk coarse fraction sediment and planktonic foraminiferal tests from pelagic sites in different oceans, and compared our reconstruction with modeled oxygen levels. The reconstructed iodate gradients indicate that deoxygenation occurred in the upper water column in the Atlantic, Indian Oceans, and possibly the Pacific Ocean as well during the PETM, due to vertical and potentially lateral expansion of OMZs.