Increased abyssal ocean density stratification across the Middle Pleistocene Transition

Thomas, Nicola C.; Ford, Heather L.; Greaves, Mervyn; Hodell, David A.

doi:10.5194/cp-22-1559-2026

Articles | Volume 22, issue 8

https://doi.org/10.5194/cp-22-1559-2026

© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/cp-22-1559-2026

© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 22, issue 8

Research article

|

19 Aug 2026

Research article |

| 19 Aug 2026

Increased abyssal ocean density stratification across the Middle Pleistocene Transition

Nicola C. Thomas, Heather L. Ford, Mervyn Greaves, and David A. Hodell

Supplement

https://doi.org/10.5194/cp-22-1559-2026-supplement

Data sets

IODP Site U1385 paired benthic δ¹⁸Ο and Mg/Ca ratios for the past 1.5 Myr, and compiled North Atlantic, Pacific and Mean Deep Ocean stacks of reconstructed deep-water temperature and δ¹⁸Oseawater N. C. Thomas et al. https://doi.org/10.1594/PANGAEA.980075

Benthic and planktonic oxygen and carbon isotopes and XRF data at IODP Site U1385 and core MD01-2444 from 0 to 1.5 Ma D. A. Hodell et al. https://doi.org/10.1594/PANGAEA.951401

Short summary

We reconstruct interbasinal temperature and salinity gradients using stacked Mg/Ca and benthic δ¹⁸O records for the past 1.5 Myr. Across the Middle Pleistocene Transition, the deep Atlantic cooled and the Pacific became more saline, increasing deep ocean density stratification. The glacial ocean became a more effective carbon trap, which lowered atmospheric pCO₂, and led to the growth of larger ice sheets. Results support a physical role for abyssal ocean stratification in explaining the MPT.