Habitable Zones & Global Climate

Moderately High Obliquity Promotes Biospheric Oxygenation

By Keith Cowing
[astro-ph.EP
May 8, 2022
Filed under
Moderately High Obliquity Promotes Biospheric Oxygenation
Depiction and definitions of parameters of interest varied in models in this paper. The white dash-dotted horizontal line in right-most panel indicates the depth of the remineralization length-scale (RLS) in the schematic.

Planetary obliquity is a first order control on planetary climate and seasonal contrast, which has a number of cascading consequences for life.

How moderately high obliquity (obliquities greater than Earth’s current obliquity up to 45∘) affects a planet’s surface physically has been studied previously, but we lack an understanding of how marine life will respond to these conditions. We couple the ROCKE-3D general circulation model to the cGENIE 3D biogeochemical model to simulate the ocean biosphere’s response to various planetary obliquities, bioessential nutrient inventories, and biospheric structure.

We find that the net rate of photosynthesis increased by 35% and sea-to-air flux of biogenic oxygen doubled between the 0∘ and 45∘ obliquity scenarios, which is an equivalent response to doubling bioessential nutrients. Our results suggest that moderately high-obliquity planets have higher potential for biospheric oxygenation than their low-obliquity counterparts and that life on moderately high-obliquity habitable planets may be easier to detect with next generation telescopes. These moderately high-obliquity habitable planets may also be more conducive to the evolution of complex life.

Megan N. Barnett, Stephanie L. Olson

Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2205.02874 [astro-ph.EP] (or arXiv:2205.02874v1 [astro-ph.EP] for this version)
Submission history
From: Megan Barnett
[v1] Thu, 5 May 2022 18:19:56 UTC (9,098 KB)
https://arxiv.org/abs/2205.02874
Astrobiology

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