# On Science Fiction

**URL:** <https://boards.straightdope.com/t/on-science-fiction/721491>\
**Category:** Cafe Society\
**Created:** [June 2, 2015, 11:38pm UTC](https://boards.straightdope.com/t/on-science-fiction/721491 "2015-06-02T23:38:42Z")\
**Posts on this page:** 2\
**Page:** 7

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**Author:** ![eburacum45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eburacum45/32/8690_2.png) [@eburacum45](https://boards.straightdope.com/u/eburacum45)\
**Post date:** [June 12, 2015, 7:14am UTC](https://boards.straightdope.com/t/on-science-fiction/721491/121 "2015-06-12T07:14:43Z")

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Ah - I see what has happened. My source was quoting from the Wiki page on the Oxygen Cycle, where the figure for chemical weathering is given as 50 x 10[sup]10[/sup] kilograms; he wrote this as 50 x 10E10kg, which I converted to 5 x 10E11. It should be 5 x 1E11.  
For a minute there I thought he mean 5 x 1E12.

> **[Oxygen cycle](https://en.wikipedia.org/wiki/Oxygen_cycle)**
>
> Oxygen cycle refers to the movement of oxygen through the atmosphere (air), biosphere (plants and animals) and the lithosphere (the Earth’s crust). The oxygen cycle demonstrates how free oxygen is made available in each of these regions, as well as how it is used. The oxygen cycle is the biogeochemical cycle of oxygen atoms between different oxidation states in ions, oxides, and molecules through redox reactions within and between the spheres/reservoirs of the planet Earth. The word oxygen in Ox...

This figure for chemical weathering does seem a bit low. The mass of atmospheric oxygen is a bit more than 1 x 1e18kg (I checked that several times, and it should be correct) so it would take 2 million years or so to remove all the oxygen by chemical weathering alone. Even I thought it would be faster than that.

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**Author:** ![eburacum45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eburacum45/32/8690_2.png) [@eburacum45](https://boards.straightdope.com/u/eburacum45)\
**Post date:** [June 12, 2015, 8:16am UTC](https://boards.straightdope.com/t/on-science-fiction/721491/122 "2015-06-12T08:16:17Z")

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Really, it’s not the oxygen content of the atmosphere you have to worry about - its the carbon dioxide. Oxidising the biosphere would raise the CO2 content to unprecedented levels, which would melt the methane clathrates and cause the sort of extreme global warming that environmentalists are worried about. Without a biosphere the planet would, indeed, be uninhabitable, so Mr Dibble is correct- but not quite for the reasons he gave.

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