Unknown
Chalk, Thomas B
;
Hain, Mathis P
;
Foster, Gavin L
;
[et al.]
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
PANGAEA
In:
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
Publication Date:
2024-04-13
Description:
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.
Type:
Dataset
Format:
application/zip, 6 datasets
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