Abrupt Climate Change and Transient Climates during the Paleogene: A Marine Perspective
- 1 March 1993
- journal article
- Published by University of Chicago Press in The Journal of Geology
- Vol. 101 (2), 191-213
- https://doi.org/10.1086/648216
Abstract
Detailed investigations of high latitude sequences recently collected by the Ocean Drilling Program (ODP) indicate that periods of rapid climate change often culminated in brief transient climates, with more extreme conditions than subsequent long term climates. Two examples of such events have been identified in the Paleogene; the first in latest Paleocene time in the middle of a warming trend that began several million years earlier: the second in earliest Oligocene time near the end of a Middle Eocene to Late Oligocene global cooling trend. Superimposed on the earlier event was a sudden and extreme warming of both high latitude sea surface and deep ocean waters. Imbedded in the latter transition was an abrupt decline in high latitude temperatures and the brief appearance of a full size continental ice-sheet on Antarctica. In both cases the climate extremes were not stable, lasting for less than a few hundred thousand years, indicating a temporary or transient climate state. Geochemical and sedimentological evidence suggest that both Paleogene climate events were accompanied by reorganizations in ocean circulation, and major perturbations in marine productivity and the global carbon cycle. The Paleocene-Eocene thermal maximum was marked by reduced oceanic turnover and decreases in global delta 13C and in marine productivity, while the Early Oligocene glacial maximum was accompanied by intensification of deep ocean circulation and elevated delta 13C and productivity. It has been suggested that sudden changes in climate and/or ocean circulation might occur as a result of gradual forcing as certain physical thresholds are exceeded. We investigate the possibility that sudden reorganizations in ocean and/or atmosphere circulation during these abrupt transitions generated short-term positive feedbacks that briefly sustained these transient climatic states.Keywords
This publication has 53 references indexed in Scilit:
- Fractionation of carbon isotopes by phytoplankton and estimates of ancient CO2 levelsGlobal Biogeochemical Cycles, 1992
- Benthic foraminiferal δ18O in the ocean's temperature‐salinity‐density field: Constraints on Ice Age thermohaline circulationPaleoceanography and Paleoclimatology, 1991
- Planktonic foraminifera: Differential dissolution and the Quaternary stable isotope Record in the west equatorial PacificPaleoceanography and Paleoclimatology, 1989
- A GCM study of Antarctic glaciationClimate Dynamics, 1989
- Abyssal circulation and benthic foraminiferal changes near the Paleocene/Eocene boundaryPaleoceanography and Paleoclimatology, 1987
- Atlantic Eocene planktonic foraminiferal paleohydrographic indicators and stable isotope paleoceanographyPaleoceanography and Paleoclimatology, 1987
- The Small Ice Cap Instability in Diffusive Climate ModelsJournal of the Atmospheric Sciences, 1984
- Continental distribution as a forcing factor for global-scale temperatureNature, 1984
- Oxygen isotope ranking of late Eocene and Oligocene planktonic foraminifers: Implications for Oligocene sea-surface temperatures and global ice-volumeMarine Micropaleontology, 1984
- Biochronology and paleoclimatic implications of Middle Eocene to Oligocene planktic foraminiferal faunasMarine Micropaleontology, 1983