Question

If the Earth’s crust contained twice as much iron as it does, would atmospheric oxygen buildup have been slowed down or sped up during the past 2.5 billion years?

What would the consequence of this have been for the evolution of aerobic respiration, the ozone layer, green plants, and animals?

Answer 1

Had the earth's crust contained twice as much as iron as it does, a lot more oxygen would have been consumed by iron leading to the formation of rust, thereby leaving most of the soil not suitable for cultivation of a large number crops.

Oxygen buildup would definitely have slowed down, plus the plants which we see today might not have evolved due to huge quantities of iron oxide in the soil. Aerobic respiration would have evolved slower than it has, leading to an increase in the number of organisms breathing anaerobically. Plus decreased oxygen would slow down the evolution of oxygen consuming organism which on earth are currently a majority.

The ozone layer would have formed slower, that is the replenishment of oxygen in the oxygen-ozone cycle would have diminished, since there would lesser number of O atoms available for the synthesis of ozone, thus exposing life on earth to the harmful UV rays.

Please upvote if my answer helped you. Have a nice day.