Polar front shift and atmospheric CO2 during the glacial maximum of the Early Paleozoic Icehouse

Vandenbroucke, T.R.A.; Armstrong, H.A.; Williams, M.; Paris, F.; Zalasiewicz, Jan A.; Sabbe, K.; Nõlvak, J.A.; Challands, T.J.; Verniers, J.; Servais, T.

doi:10.1073/pnas.1003220107

Polar front shift and atmospheric CO2 during the glacial maximum of the Early Paleozoic Icehouse

Vandenbroucke, T.R.A.; Armstrong, H.A.; Williams, M.; Paris, F.; Zalasiewicz, Jan A.; Sabbe, K.; Nõlvak, J.A.; Challands, T.J.; Verniers, J.; Servais, T.

Authors

T.R.A. Vandenbroucke

H.A. Armstrong

M. Williams

F. Paris

Jan A. Zalasiewicz

K. Sabbe

J.A. Nõlvak

T.J. Challands

J. Verniers

T. Servais

Abstract

Our new data address the paradox of Late Ordovician glaciation under supposedly high pCO2 (8 to 22× PAL: preindustrial atmospheric level). The paleobiogeographical distribution of chitinozoan (“mixed layer”) marine zooplankton biotopes for the Hirnantian glacial maximum (440 Ma) are reconstructed and compared to those from the Sandbian (460 Ma): They demonstrate a steeper latitudinal temperature gradient and an equatorwards shift of the Polar Front through time from 55°–70° S to ∼40° S. These changes are comparable to those during Pleistocene interglacial-glacial cycles. In comparison with the Pleistocene, we hypothesize a significant decline in mean global temperature from the Sandbian to Hirnantian, proportional with a fall in pCO2 from a modeled Sandbian level of ∼8× PAL to ∼5× PAL during the Hirnantian. Our data suggest that a compression of midlatitudinal biotopes and ecospace in response to the developing glaciation was a likely cause of the end-Ordovician mass extinction.

Citation

Vandenbroucke, T., Armstrong, H., Williams, M., Paris, F., Zalasiewicz, J. A., Sabbe, K., …Servais, T. (2010). Polar front shift and atmospheric CO2 during the glacial maximum of the Early Paleozoic Icehouse. Proceedings of the National Academy of Sciences, 107(34), 14983-14986. https://doi.org/10.1073/pnas.1003220107

Journal Article Type	Article
Publication Date	Aug 1, 2010
Deposit Date	Nov 5, 2010
Publicly Available Date	Oct 28, 2011
Journal	Proceedings of the National Academy of Sciences
Print ISSN	0027-8424
Publisher	National Academy of Sciences
Peer Reviewed	Peer Reviewed
Volume	107
Issue	34
Pages	14983-14986
DOI	https://doi.org/10.1073/pnas.1003220107
Keywords	Chitinozoans, Ordovician, Zooplankton biotopes, Hirnantian glaciations, Climate belts.