H2O2 Greenhouse Warming On Oxidized Early Mars

Absorption cross sections of three oxidized gases, CO2 (magenta), H2O (cyan), and H2O2 (green) at 250 K and 1 bar, as functions of wavenumber. These cross sections are produced using the line profile calculation code EXOCROSS (Yurchenko et al. 2018). The absorption data and the assumed line profiles are described in Sec. 2.

The existence of liquid water within an oxidized environment on early Mars has been inferred by the Mn-rich rocks found during recent explorations on Mars. The oxidized atmosphere implied by the Mn-rich rocks would basically be comprised of CO2 and H2O without any reduced greenhouse gases such as H2 and CH4.

So far, however, it has been thought that early Mars could not have been warm enough to sustain water in liquid form without the presence of reduced greenhouse gases. Here, we propose that H2O2 could have been the gas responsible for warming the surface of the oxidized early Mars. Our one-dimensional atmospheric model shows that only 1 ppm of H2O2 is enough to warm the planetary surface because of its strong absorption at far-infrared wavelengths, in which the surface temperature could have reached over 273~K for a CO2 atmosphere with a pressure of 3~bar.

A wet and oxidized atmosphere is expected to maintain sufficient quantities of H2O2 gas in its upper atmosphere due to its rapid photochemical production in slow condensation conditions. Our results demonstrate that a warm and wet environment could have been maintained on an oxidized early Mars, thereby suggesting that there may be connections between its ancient atmospheric redox state and possible aqueous environment.

Yuichi Ito, George L. Hashimoto, Yoshiyuki O, Takahashi, Masaki Ishiwatari, Kiyoshi Kuramoto

Comments: 8 pages, 7 figures, published in ApJ
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Atmospheric and Oceanic Physics (physics.ao-ph)
DOI: 10.3847/1538-4357/ab7db4
Cite as: arXiv:2012.10616 [astro-ph.EP] (or arXiv:2012.10616v1 [astro-ph.EP] for this version)
Submission history
From: Yuichi Ito
[v1] Sat, 19 Dec 2020 07:30:46 UTC (1,348 KB)

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