Document Detail


Abrupt climate change and transient climates during the Paleogene: a marine perspective.
MedLine Citation:
PMID:  11537739     Owner:  NASA     Status:  MEDLINE    
Abstract/OtherAbstract:
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.
Authors:
J C Zachos; K C Lohmann; J C Walker; S W Wise
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The Journal of geology     Volume:  101     ISSN:  0022-1376     ISO Abbreviation:  J. Geol.     Publication Date:  1993 Mar 
Date Detail:
Created Date:  1995-09-20     Completed Date:  1995-09-20     Revised Date:  2009-11-19    
Medline Journal Info:
Nlm Unique ID:  100955718     Medline TA:  J Geol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  191-213     Citation Subset:  S    
Affiliation:
Dept. of Geological Sciences, University of Michigan, Ann Arbor 48109.
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MeSH Terms
Descriptor/Qualifier:
Animals
Atmosphere
Climate*
Earth (Planet)
Eukaryota
Fossils
Geological Phenomena
Geology*
Isotopes
Marine Biology
Oceans and Seas
Paleontology
Grant Support
ID/Acronym/Agency:
OCE-9012389/CE/NCIPC CDC HHS; OCE-9101861/CE/NCIPC CDC HHS
Chemical
Reg. No./Substance:
0/Isotopes
Investigator
Investigator/Affiliation:
J C Walker / U MI, Ann Arbor, Dept Geological Sciences

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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