Just read an interesting article on SF about the Indigo Ag "TerraTon" initiative. CEO David Perry says:
“Prior to land being cultivated for crops, over 3.6 billion acres, soils on average contained 3% carbon. Now, that average is 1%,” says Perry. “If we took every cultivated acre on Earth and increased the carbon (content) from 1% to 3%, that also is 1 trillion tons of carbon dioxide. The size of the potential solution is equivalent to the size of the problem.”
So what he's saying is that burning oil and gas and coal have nothing to do with the CO2 in the atmosphere - it's all from cultivation of the earth's farmland and the lost organic matter (carbon) stored there! If we get back to 3% organic matter we will be back to pre-industrial levels of CO2 in the atmosphere!
Of course, his math is wrong. He makes the mistake of conflating hydrocarbons with CO2, and neglecting the ongoing carbon cycle. When you burn a hydrocarbon, you get CO2, but the "O2" part was already in the atmosphere. So if atmospheric CO2 increases by a "terraton", you only need to burn about 27% of that amount of carbon. (carbon weighs 12 and each oxygen weighs 16).
Next is the carbon cycle, where animals "burn" carbon in their cells to make energy and exhale CO2, while plants absorb energy from the sun and combine CO2 and H2O and other trace elements to make carbohydrates and cellulose, and seeds. When a plant dies, the above ground part usually decays back to CO2 and H2O, but, if undisturbed, the roots become part of the soil organic matter. When large quantities of plant matter get buried deeply over eons, they can become hydrocarbon deposits, which man has learned to extract to utilize the stored solar energy therein.
So there is a grand balance - carbon going between plants and animals, getting sequestered, and coming out of sequestration. More unsequestered carbon means more life, and maybe a different equilibrium point in the overall climate, but not dramatically different. Who is man to say that just before the start of the industrial revolution was the only "perfect" equilibrium point in the entire history of the planet?
