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Title: Revisiting the Early Late Cretaceous Equable Climate Problem Through a Model‐Data Perspective
Abstract Early Late Cretaceous (∼90–100 Ma) Sea surface temperatures (SST) records suggest extremely warm Southern Hemisphere high latitudes and a meridional gradient as low as 5°C, attributed to elevated atmospheric CO2. Climate models have been unable to reproduce such extreme warmth, questioning model performance and/or the validity of SSTs reconstructions. Indeed, the latter partly rely on the measurement of oxygen isotopic composition of marine organisms (δ18Oc), a proxy that requires knowledge of the δ18O of past seawater (δ18Osw). Here we use the water isotope‐enabled Community Earth System Model (iCESM1.2) to investigate how paleogeography and pCO2affect δ18Oswdistribution and our understanding of Cenomanian‐Turonian SSTs. Our simulations suggest that the semi‐isolation of southern South Atlantic‐Indian Ocean resulted in locally very negative δ18Oswexplaining low δ18Ocmeasured on planktonic foraminifera. Accounting for this δ18Oswspatio‐temporal variability increases the estimated meridional temperature gradient by 5°C and narrows the gap between model and proxy‐based reconstructions.  more » « less
Award ID(s):
2309580
PAR ID:
10642285
Author(s) / Creator(s):
 ;  ;  
Publisher / Repository:
AGU Publications
Date Published:
Journal Name:
Paleoceanography and Paleoclimatology
Volume:
40
Issue:
4
ISSN:
2572-4517
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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