Red Baron Farms
Philosopher
Some of your critical thinking on it is pretty good! Thanks for that. The section I cut out above though is demonstrably off. If the absorption is 123PgC/yr which yields a net of ~ 3.5-4 (about 1/2 the 7 human activities emit) It does not necessarily follow that it would take double the absorption (246PgC/yr) to yield a net of ~7. And in fact in this case, it absolutely doesn't. If you green desertified land, yes that will increase the total absorption somewhat. To what degree is unknown but certainly far less than double. The exact amount is trivial though compared to what is happening. It is not the total absorption that changes as much as it is the rate of sequestration. In other words, what % of the carbon is removed from the short term carbon cycle and sequestered into the soil in a long term carbon cycle. If that rate stays the same, yes you would have to double the total vegetation of the planet (pretty difficult). But if you change the rate of sequestration enough you wouldn't necessarily need to increase the total vegetation at all.No one seems to have addressed these "critical thinking skills" that you used so here goes, Red Baron Farms
Oceans and plants also absorb carbon from other sources that is released into atmosphere. The estimated total absorption by vegetation alone of all of the carbon in the atmosphere (human and other sources) is ~ 123 PgC/yr.
The point is that it is the 7 billion metric tons of carbon that human activities release into the atmosphere each year that is driving global warming. So we have to double the absorption by plants (and maybe oceans) to that value to stop global warming.
HM and most other related "carbon farming" techniques do increase the total vegetation, but more importantly when discussing their potential as mitigation tools, they change the rate that vegetation sequesters carbon in the soil. In other words they change the % of that 123PgC/yr absorbed carbon that ends up as humus.
In highly simplified approximate form what we have now is:
123PgC/yr x .28 = 3.5PgC/yr
Which is less than the 7PgC/yr we humans emit.
And what we would be shooting for is:
(123PgC/yr + XPg/yr) x (.28 + Y) = ZPgC/yr
Where X is increased vegetative absorption due to more vegetative growth, Y is increased vegetative sequestration due to an increased % of absorbed C being turned to humus, and Z total is greater than the carbon we humans emit.
The main reason HM works is because it increases humus in the soil which allows more vegetative growth. Increased vegetative growth increases humus, which also allow more vegetative growth...etc... It is a positive feedback curve. So HM affects both variables not just one. The proposal is to turn the negative feedback curve we have now called desertification, into a positive feedback curve which is called regenerative agriculture. HMPG is not the only regenerative agriculture, but it is a big one potentially. Obviously it becomes much easier if emissions are also reduced. Then our target value for Z is smaller and requires less changes in the X and Y variables HM affects.
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