Significance of Photosynthesis

Photosynthesis performs several jobs that go far beyond simply feeding the plant that carries it out. First, photosynthetic organisms are the food source, directly or indirectly, for essentially every other living organism on Earth - they are the primary producers that every food chain ultimately traces back to. Second, photosynthesis is the only large-scale natural process that liberates oxygen into the atmosphere, and so is what keeps the atmosphere's oxygen level from falling as respiration (in every organism, all the time) steadily consumes it. Third, and closely related, photosynthesis balances the atmosphere's oxygen and carbon cycles together, since it consumes the CO2 that respiration continuously adds and releases the O2 that respiration continuously consumes - the two processes run in opposite chemical directions and roughly balance each other globally. Fourth, today's fossil fuels - coal, petroleum and natural gas - are the geologically preserved remains of ancient photosynthetic organisms, so essentially all of the world's fuel economy is stored, ancient photosynthetic output. Fifth, because photosynthetic organisms are the primary producers, literally every consumer in every ecosystem - herbivores, carnivores and decomposers alike - ultimately depends on photosynthesis for its energy supply. Sixth, on a more everyday economic level, photosynthesis is also what makes fodder, fibre, firewood, timber and countless medicinal plant products possible, since all of these are, in the end, products of a plant's photosynthetic productivity. Photosynthesis is also an enormous energy transaction at planetary scale: it produces roughly 1700 mi …