Substantial Extension of the Lifetime of the Terrestrial Biosphere
Approximately one billion years (Gyr) in the future, as the Sun brightens, Earth’s carbonate-silicate cycle is expected to drive CO2 below the minimum level required by vascular land plants, eliminating most macroscopic land life.
Here, we couple global-mean models of temperature- and CO2-dependent plant productivity for C3 and C4 plants, silicate weathering, and climate to re-examine the time remaining for terrestrial plants.
If weathering is weakly temperature-dependent (as recent data suggest) and/or strongly CO2-dependent, we find that the interplay between climate, productivity, and weathering causes the future luminosity-driven CO2 decrease to slow and temporarily reverse, averting plant CO2 starvation.
This dramatically lengthens plant survival from 1 Gyr up to ∼1.6-1.86 Gyr, until extreme temperatures halt photosynthesis, suggesting a revised kill mechanism for land plants and potential doubling of the future lifespan of Earth’s land macrobiota. An increased future lifespan for the complex biosphere may imply that Earth life had to achieve a smaller number of “hard steps” (unlikely evolutionary transitions) to produce intelligent life than previously estimated.
These results also suggest that complex photosynthetic land life on Earth and exoplanets may be able to persist until the onset of the moist greenhouse transition.
R.J. Graham, Itay Halevy, Dorian Abbot
Comments: 19 pages, 6 figures. Accepted for publication in Planetary Science Journal
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Populations and Evolution (q-bio.PE)
Cite as: arXiv:2409.10714 [astro-ph.EP] (or arXiv:2409.10714v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2409.10714
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Submission history
From: R.J. Graham
[v1] Mon, 16 Sep 2024 20:38:12 UTC (1,410 KB)
https://arxiv.org/abs/2409.10714
Astrobiology, Gaia,
