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dc.contributor.authorHenry, M
dc.contributor.authorVallis, GK
dc.date.accessioned2022-09-14T09:16:10Z
dc.date.issued2022-08-15
dc.date.updated2022-09-14T08:25:02Z
dc.description.abstractThe climate of the early Eocene was characterized by much higher temperatures and a smaller equator-to-pole surface temperature gradient than today. Comprehensive climate models have been reasonably successful in simulating that climate in the annual average. However, good simulations of the seasonal variations, and in particular much warmer Arctic winters over land, have proven more difficult. Further, while increased greenhouse gases seems necessary to achieve an Eocene climate, it is unclear whether there is a unique combination of factors that leads to agreement with all available proxies. Here we use a very flexible General Circulation Model to examine the sensitivity of the modeled climate to differences in CO2 concentration, land surface properties, ocean heat transport, and cloud extent and thickness. Even in the absence of ice or changes in cloudiness, increasing the CO2 concentration leads to a polar-amplified surface temperature change because of increased water vapor levels combined with the lack of convection at high latitudes, with the nonlinear dependence of longwave radiation on temperature amplifying the increase in winter over land. Additional low clouds over Arctic land generally decrease summer temperatures and further increase winter temperatures (except at very high CO2 levels). An increase in the land surface heat capacity, plausible given large changes in vegetation, also decreases the Arctic land seasonality. Thus, different combinations of factors—high CO2 levels, changes in low-level clouds, and an increase in land surface heat capacity—can lead to a simulation within the proxy uncertainty range of the majority of proxy data.en_GB
dc.description.sponsorshipNatural Environment Research Councilen_GB
dc.description.sponsorshipNational Science Foundationen_GB
dc.identifier.citationVol. 37, No. 8, article e2021PA004375en_GB
dc.identifier.doihttps://doi.org/10.1029/2021pa004375
dc.identifier.grantnumberNE/T00942X/1en_GB
dc.identifier.urihttp://hdl.handle.net/10871/130827
dc.identifierORCID: 0000-0003-4498-6476 (Henry, Matthew)
dc.identifierORCID: 0000-0002-5971-8995 (Vallis, Geoffrey K)
dc.language.isoenen_GB
dc.publisherWiley / American Geophysical Union (AGU)en_GB
dc.relation.sourceData Availability Statement: The data is available at Henry and Vallis (2021a) and the code to reproduce the figures is available at Henry (2022). The proxy values for ocean surface temperature in Figures 2, 4, 5, and 10 are taken from Zhu et al. (2019). The proxy values for land surface temperature in Figures 2, 3, 4, 5, and 10 are taken from Huber and Caballero (2011)en_GB
dc.rights© 2022. The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.en_GB
dc.subjectEoceneen_GB
dc.subjectidealized climate modelingen_GB
dc.subjectArctic climateen_GB
dc.titleVariations on a pathway to an early Eocene climateen_GB
dc.typeArticleen_GB
dc.date.available2022-09-14T09:16:10Z
dc.identifier.issn2572-4517
exeter.article-numberARTN e2021PA004375
dc.descriptionThis is the final version. Available from Wiley via the DOI in this record. en_GB
dc.identifier.eissn2572-4525
dc.identifier.journalPaleoceanography and Paleoclimatologyen_GB
dc.relation.ispartofPaleoceanography and Paleoclimatology, 37(8)
dc.rights.urihttp://creativecommons.org/licenses/by/4.0/en_GB
dcterms.dateAccepted2022-07-26
rioxxterms.versionVoRen_GB
rioxxterms.licenseref.startdate2022-08-15
rioxxterms.typeJournal Article/Reviewen_GB
refterms.dateFCD2022-09-14T09:13:30Z
refterms.versionFCDVoR
refterms.dateFOA2022-09-14T09:16:23Z
refterms.panelBen_GB
refterms.dateFirstOnline2022-08-15


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© 2022. The Authors.

This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Except where otherwise noted, this item's licence is described as © 2022. The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.