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Transient reducing greenhouse warming on early Mars

Wordsworth, R. and Kalugina, Y. and Lokshtanov, S. and Vigasin, A. and Ehlmann, B. and Head, J. and Sanders, C. and Wang, H. (2017) Transient reducing greenhouse warming on early Mars. Geophysical Research Letters, 44 (2). pp. 665-671. ISSN 0094-8276. https://resolver.caltech.edu/CaltechAUTHORS:20170111-074342372

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Abstract

The evidence for abundant liquid water on early Mars despite the faint young Sun is a long-standing problem in planetary research. Here we present new ab initio spectroscopic and line-by-line climate calculations of the warming potential of reduced atmospheres on early Mars. We show that the strength of both CO_2–H_2 and CO_2–CH_4 collision-induced absorption (CIA) has previously been significantly underestimated. Contrary to previous expectations, methane could have acted as a powerful greenhouse gas on early Mars due to CO_2–CH_4 CIA in the critical 250–500 cm^(−1) spectral window region. In atmospheres of 0.5 bar CO_2 or more, percent levels of H_2 or CH_4 raise annual mean surface temperatures by tens of degrees, with temperatures reaching 273 K for pressures of 1.25–2 bars and 2–10% of H_2 and CH_4. Methane and hydrogen produced following aqueous alteration of Mars' crust could have combined with volcanically outgassed CO_2 to form transient atmospheres of this composition 4.5–3.5 Ga. Our results also suggest that inhabited exoplanets could retain surface liquid water at significant distances from their host stars.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1002/2016GL071766DOIArticle
http://onlinelibrary.wiley.com/doi/10.1002/2016GL071766/abstractPublisherArticle
ORCID:
AuthorORCID
Wordsworth, R.0000-0003-1127-8334
Kalugina, Y.0000-0001-7642-3518
Vigasin, A.0000-0002-4677-9692
Ehlmann, B.0000-0002-2745-3240
Head, J.0000-0003-2013-560X
Wang, H.0000-0001-5167-8119
Additional Information:© 2017 American Geophysical Union. Received 1 NOV 2016; Accepted 2 JAN 2017; Accepted article online 5 JAN 2017; Published online 21 JAN 2017. R.W. acknowledges financial support from the Kavli Foundation and discussions with T. Robinson and F. Ding on line-by-line radiative calculations and K. Zahnle on atmospheric chemistry. S.L., Y.K., and A.V. gratefully acknowledge partial support of this work from RFBR grants 15-03-03302 and 15-05-00736 and the Russian Academy of Sciences Program 9. B.L.E. thanks B. Sherwood-Lollar and G. Etiope for discussion of H2/CH4 observed in terrestrial serpentinizing systems. The ab initio calculations were performed using the HPC resources of the FAS Research Computing Cluster (Harvard University) and the “Lomonosov” (Moscow State University) supercomputer. The CIA data produced from our spectroscopic calculations and the line-by-line and temperature data produced from our climate model are available from the lead author on request (rwordsworth@seas.harvard.edu).
Group:Astronomy Department
Funders:
Funding AgencyGrant Number
Kavli FoundationUNSPECIFIED
Russian Foundation for Basic Research15-03-03302
Russian Foundation for Basic Research15-05-00736
Russian Academy of SciencesProgram 9
Subject Keywords:Mars; valley networks; astrobiology; methane; hydrogen; paleoclimate
Issue or Number:2
Record Number:CaltechAUTHORS:20170111-074342372
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20170111-074342372
Official Citation:Wordsworth, R., Y. Kalugina, S. Lokshtanov, A. Vigasin, B. Ehlmann, J. Head, C. Sanders, and H. Wang (2017), Transient reducing greenhouse warming on early Mars, Geophys. Res. Lett., 44, 665–671, doi:10.1002/2016GL071766
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:73406
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:20 Jan 2017 00:49
Last Modified:20 Apr 2020 08:47

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