[astro-ph.EP] Over 4 billion years, Earth’s atmosphere has been transformed from a composition devoid of molecular oxygen (O2) to one where O2 is now 21% of our modern atmosphere by volume.
With high quantities of O2, an ozone (O3) layer can form and partially shield the surface from biologically harmful ultraviolet radiation (UV).
The evolution of the O3 layer has previously been simulated under the modern Sun by independent groups with separate models. Here, we present simulations of Earth’s atmosphere from four open-source one-dimensional (1D) photochemical models and a 3D chemistry-climate model, focussing on O3.
We find that the O3 layer thickness exhibits a clear deviation between the 1D models and the 3D model due to several factors, including treatments of O2 photolysis, chemical networks, H2O microphysics and 3D transport. We find that 1D models introduce a bias for unobserved climate states and show how these biases may propagate to calculations of biological UV damage and surface habitability.
We show that when applied to specific exoplanet atmospheres, these discrepancies can become more pronounced, propagating through to observational predictions for the next generation of telescopes, such as HWO and LIFE, that will search for habitable and inhabited exoplanets.
Akhil Kumar, Gregory J. Cooke
Comments: 66 pages, 18 figures, resubmitted after first revision to Royal Society Open Science
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Atmospheric and Oceanic Physics (physics.ao-ph)
Cite as: arXiv:2610.18864 [astro-ph.EP] (or arXiv:2610.18864v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2610.18864
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Submission history
From: Akhil Anil Kumar Mr
[v1] Tue, 13 Oct 2026 17:59:34 UTC (6,239 KB)
https://arxiv.org/abs/2610.18864
Astrobiology,
