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  • From: "robscott@freeshell.org" <robscott@freeshell.org>
  • To: permaculture@lists.ibiblio.org
  • Subject: Re: [permaculture] Global Carbon Budget and the "trees as lungs" metaphor
  • Date: Fri, 21 Oct 2005 16:40:36 +0000 (UTC)


William Genest <genest@pivot.net> wrote:

Great info thanks.
What did you mean by this ?

The Ocean may "breathe" more O2 than trees,
but it is within the tree "breathing" that we have reason to
suspect an imbalence.

What imbalance do you refer to ?

Hello Genest. I am the data Robot Scott. In the case with the global carbon budget I posted (again below), there is an annual flux of 0.9 x10^15g/C into the atmosphere from "destruction of vegetation". That's 900 billion kilograms released mainly because of deforestation. If you want to make a case for "trees breathing oxygen" and the disruption of those "lungs of the earth" etc. then you could make a case that the O flux is out of balence, either sequestering more than is released, or releasing more than is sequestered. I thought that's what you were getting at or maybe I didn't understand your original comment. Point is: I've never seen data that shows a global Oxygen disequilibrium. The "lungs of the earth" are breathing out extra CO2 but not extra O2.
At least, not that I know of.

A quick websearch found the fluxes that follow (in x10^15 mols O2 /year)
sequestration by plants +4.6
respired by plants -4.6

into oceans +140
out of oceans -140

That's basically my response in numbers. The ocean "breathes" more O than forests, but maybe there's a disequilibrium in the forests since humans are harvesting forests. The above is only O2 and doesn't count O in H2O and aluminosilicate clays. It's also on a mol scale not gram weight. If you multiply by 16 (atomic mass for O) you get it in 10^15 grams.

The above numbers are in a drawing at:
http://www.ess.uci.edu/~reeburgh/fig2.html

Rob Scott
Urbana, IL

I wrote:

GLOBAL CARBON BUDGET
These numbers are multiplied by 10^15 grams for the total Carbon on Earth.
That is, you multiply the numbers below times 1,000,000,000,000,000 to get
the number of grams of carbon on earth in each sink and annual flux rates.

major carbon "sinks"
oceans 38,000
soils 1,500
atmosphere 750
terrestrial plants 560

carbon "fluxes" (per year)
sequestration by plants +120
respired by plants -60
respired by soils -60

into oceans +92
out of oceans -90

increase in atmosphere +3.2
fossil fuel emissions -6
destruction of vegetation -0.9

Fossil fuel emissions, destruction of vegetation add 6.9 every year.
The ocean and the atmosphere take back 5.2.
The remaining 1.7 is unaccounted for, in what has been termed "the missing
Carbon sink".

Genest, I don't have a global O budget in front of me but I'm pretty sure
most of the Oxygen on the planet is in water (H20) and soil (SiO). Do with
that what you will. You can say the trees "exhale" O2 and so do the oceans
and the soils. They also sequester it. The crucial distinction is whether
the two balance each other. The Ocean may "breathe" more O2 than trees,
but it is within the tree "breathing" that we have reason to suspect an
imbalence.

Source: "Biogeochemistry: An Analysis of Global Change" 2nd Ed. by W.H.
Schlesinger, 1997. (a classic text on the science of global biogeochemical
cycles)

Rob Scott
Urbana, IL





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