| MadSci Network: Botany |
Plants, algae and some bacteria all conduct photosynthesis, which produces the atmosphere's oxygen gas. So if only plants were wiped out, there would still be a lot of photosynthesis conducted by algae and bacteria in the oceans. Some estimates are that half or more of global photosynthesis occurs in the oceans. Even if all photosynthetic organisms were wiped out, the atmospheric oxygen content is so great that it would take a few centuries for it to be depleted significantly by the oxygen breathers alive today. The atmosphere is about 21% oxygen. The first website cited estimates that global photosynthesis produces 1/2000 of the total oxygen content per year. Before oxygen became limiting due to no photosynthesis, carbon dioxide would rise to toxic levels. The immediate problem of no photosynthesis would be the collapse of food chains and starvation of animals and other hetertrophic organisms such as decomposers (many fungi and bacteria). Virtually all heterotrophic organisms depend directly or indirectly on photosynthetic organisms for food. The decomposers would be the last to starve because they would have plenty of dead bodies to feed on. So don't worry about suffocating. You would starve to death first unless you stockpiled huge amounts of food. References The Oxygen Cycle Re: Has the quantity of pure Oxygen in the atmosphere been declining? Re: Does the ratio of gases in the air vary? Re: Why doesn't the earth's oxygen/carbon dioxide ever get out of balance? Re: How much oxygen do land plants and marine algae add to the atmosphere?
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