[permaculture] Global Carbon Budget and the "trees as lungs" metaphor

robscott at freeshell.org robscott at freeshell.org
Fri Oct 21 12:40:36 EDT 2005


> William Genest <genest at 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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