Chalk, Thomas B; Hain, Mathis P; Foster, Gavin L; Rohling, Eelco J; Sexton, Philip F; Badger, Marcus P S; Cherry, Soraya G; Hasenfratz, Adam P; Haug, Gerald H; Jaccard, Samuel H; Martínez‐García, Alfredo; Pälike, Heiko; Pancost, Richard D; Wilson, Paul A (2017): Mid-Pleistocene Transition d11B based carbon dioxide levels from ODP Site 165-999. PANGAEA, https://doi.pangaea.de/10.1594/PANGAEA.882551 (DOI registration in progress), Supplement to: Chalk, Thomas B; Hain, Mathis P; Foster, Gavin L; Rohling, Eelco J; Sexton, Philip F; Badger, Marcus P S; Cherry, Soraya G; Hasenfratz, Adam P; Haug, Gerald H; Jaccard, Samuel L; Martínez‐García, Alfredo; Pälike, Heiko; Pancost, Richard D; Wilson, Paul A (2017): Causes of ice age intensification across the Mid-Pleistocene Transition. Proceedings of the National Academy of Sciences, 114(50), 13114-13119, https://doi.org/10.1073/pnas.1702143114
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During the Mid-Pleistocene Transition (MPT; 1,200-800 kya), Earth's orbitally paced ice age cycles intensified, lengthened from ~40,000 (~40 ky) to ~100 ky, and became distinctly asymmetrical. Testing hypotheses that implicate changing atmospheric CO2 levels as a driver of the MPT has proven difficult with available observations. Here, we use orbitally resolved, boron isotope CO2 data to show that the glacial to interglacial CO2 difference increased from ~43 to ~75 µatm across the MPT, mainly because of lower glacial CO2 levels. Through carbon cycle modeling, we attribute this decline primarily to the initiation of substantive dust-borne iron fertilization of the Southern Ocean during peak glacial stages. We also observe a twofold steepening of the relationship between sea level and CO2-related climate forcing that is suggestive of a change in the dynamics that govern ice sheet stability, such as that expected from the removal of subglacial regolith or interhemispheric ice sheet phase-locking. We argue that neither ice sheet dynamics nor CO2 change in isolation can explain the MPT. Instead, we infer that the MPT was initiated by a change in ice sheet dynamics and that longer and deeper post-MPT ice ages were sustained by carbon cycle feedbacks related to dust fertilization of the Southern Ocean as a consequence of larger ice sheets.
Henehan, Michael J; Rae, James W B; Foster, Gavin L; Erez, Jonathan; Prentice, Katherine C; Kucera, Michal; Bostock, Helen C; Martínez-Botí, Miquel Àngel; Milton, J Andy; Wilson, Paul A; Marshall, Brittney J; Elliott, Tim (2013): Calibration of the boron isotope proxy in the planktonic foraminifera Globigerinoides ruber for use in palaeo-CO2 reconstruction. Earth and Planetary Science Letters, 364, 111-122, https://doi.org/10.1016/j.epsl.2012.12.029
Zeebe, Richard E; Wolf-Gladrow, Dieter A (2001): CO2 in Seawater: Equilibrium, Kinetics, Isotopes. Imprint: Elsevier Science, 65, 360
Median Latitude: 12.743767 * Median Longitude: -78.739633 * South-bound Latitude: 12.743650 * West-bound Longitude: -78.739800 * North-bound Latitude: 12.744000 * East-bound Longitude: -78.739300
Date/Time Start: 1995-01-10T00:00:00 * Date/Time End: 1996-01-29T00:00:00
Datasets listed in this publication series
- Chalk, TB; Hain, MP; Foster, GL et al. (2017): Early Mid-Pleistocene Transition (MPT) carbon dioxide from ODP Site 165-999. https://doi.org/10.1594/PANGAEA.882545
- Chalk, TB; Hain, MP; Foster, GL et al. (2017): Late Pleistocene carbon dioxide from ODP Site 165-999. https://doi.org/10.1594/PANGAEA.882546
- Chalk, TB; Hain, MP; Foster, GL et al. (2017): Late Pleistocene isotopes analysis from ODP Site 165-999. https://doi.org/10.1594/PANGAEA.882547
- Chalk, TB; Hain, MP; Foster, GL et al. (2017): Mid Pleistocene isotopes analysis from ODP Site 165-999. https://doi.org/10.1594/PANGAEA.882548
- Chalk, TB; Hain, MP; Foster, GL et al. (2017): Stable isotope record of Cibicidoides wuellerstorfi and Globigerinoides ruber of ODP Hole 165-999A. https://doi.org/10.1594/PANGAEA.882550
- Chalk, TB; Hain, MP; Foster, GL et al. (2017): Stable isotope record of Cibicidoides wuellerstorfi of ODP Hole 165-999A. https://doi.org/10.1594/PANGAEA.882549