Quote:
Originally Posted by engineerdude
...photosynthesis...removes CO2 from the air -- the rest of the life forms on our planet do the very opposite.
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This is a common, complicated misunderstanding.
Your focus on plants (over biomass) is understandable since we're talking about CO2 and we all know that plants take up CO2.
Biomass is more important because, to create biomass, CO2 must be converted into living creatures.
To oversimplify it [...and not counting the chemophiles.]--
CO2 + light = sugar
sugar + plants = plant biomass
plant biomass + animals = more animals + (less exhaled CO2 than was in the original plant biomass).
Animals (and microbes)
are sequestered CO2.
This is true in the same way that trees, plants, and algae
are sequestered CO2.
A food chain is just a subjective way of viewing a carbon sequestration chain.
Similar to the way that top predators accumulate toxins, top predators
are accumulated (sequestered) CO2.
Whether it's 100 pounds of meat, or 100 pounds of bacteria, or 100 pounds of tree; they each take about 100 pounds of CO2 to produce. Meat is sequestered carbon. Life propagates sequestered carbon.
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...put another way....
Ultimately all biomass comes from CO2 (or CH4, methane).
Photosynthesis "fixes" carbon, it doesn't create biomass.
Y'know, plants breath oxygen to grow and build tissue (biomass) just like animals and microbes do.
Photosynthesis is just a "food" (energy) accumulation mechanism. Plants, like animals and microbes, create more biomass by metabolising "food" using oxygen--burning the food and exhaling CO2.
Don't make the mistake of thinking photosynthesis creates biomass; it only creates food--so that life can burn that food (using oxygen) to create more biomass. The point is that some of the "fixed" CO2 becomes biomass--tissues, cell membranes/walls, and inter/intracellular matrices or fluids--not all of the CO2 is exhaled.
Shifting the balance between photosynthesis and respiration will have some effect on that "100 billion tons of carbon dioxide exchanged" each year, but it is the net increase or decrease in that 1,500 billion tons of biomass that will, "through sheer volume," most strongly affect our atmosphere.
...and of course, our emissions become a problem
if there is not an offsetting increase in
biomass--to sequester the emissions--say by
increasing desertification, deforestation, and denitrification.
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...to summarize.
It is that trillion-(plus) tons of biomass--the soil, which can rapidly be changed--that (as you say) continues "through sheer volume, to say what happens in our air."
