[extropy-chat] Global warming news
mstriz at gmail.com
Sat Mar 25 16:43:54 UTC 2006
On 3/25/06, spike <spike66 at comcast.net> wrote:
> > -----Original Message-----
> > From: extropy-chat-bounces at lists.extropy.org [mailto:extropy-chat-
> > bounces at lists.extropy.org] On Behalf Of Martin Striz
> > While it's obviously beneficial to preserve the rain forest, the
> > amount of biomass that is being cleared away has an insignificant
> > effect on CO2 levels compared to the stuff we're pumping out...
> Hold that thought. Recall that when a tree is cut, the log rots over
> perhaps a century or more, releasing all that carbon over a long period.
> > Consider that the amount of biomass that disappears during the winter
> > in the northern hemisphere is orders of magnitude more than what has
> > been cleared from the Amazon rain forest...
> This isn't clear to me. The biomass disappears? Are you referring to the
> leaves on deciduous trees? I agree there isn't much mass there, but I don't
> see how this compares to clearing forests.
> , yet produces miniscule
> > fluctuations in CO2 throughout the year. According to
> > http://en.wikipedia.org/wiki/Carbon_dioxide#Atmosphere the
> > fluctuations are 5 microliters per liter of CO2, or 0.0005% (the total
> > CO2 fluctuations are larger for other reasons).
> > Since the current CO2 levels are rising by 3 ppm on top of 380 ppm, or
> > about 1%, we'd need a biomass 2,000 times that of the deciduous parts
> > of the northern hemisphere to keep up. Maybe if the trees were a mile
> > tall.
> > Martin
> Martin, I do not follow your reasoning here. The fluctuation level you are
> describing here has nothing to do with my notion of drawing down carbon
> dioxide by establishing hardwood forests.
Sure it does. When leaves grow on trees, that also fixes carbon from
the atmosphere, so the effect of yearly cycling of leaves tells you
how much of an effect on CO2 that much biomass has, and it takes into
account both plant metabolism and fixed mass. Now granted, the
fraction of mass that leaves make up is, let's say as a conservative
estimate, 1/10 that of the entire tree. But as I pointed out, you
need 2000 times that mass to keep up with current CO2 increases, which
is still 200 times the mass of whole trees (of the entire northern
hemisphere deciduous zone). You couldn't plant it on the surface of
the earth (taking into account arid and cold zones).
> Recall that the entire atmosphere
> has a mass of about 10 meters of water over the entire globe, so the 380 ppm
> of carbon dioxide equates to a layer of water 4 millimeters depth.
You don't want to fix all the carbon dioxide or you'd suffocate plant
life. Also, I don't know where you're getting this 4 mm figure from.
> the globe is 70% covered in water, the mass of carbon dioxide equates to a
> layer of wood on all the land about a couple centimeters thick. My notion
> is that we can create forests on a fraction of the land that would equate to
> a layer of wood a couple centimeters thick over all the dry land.
> But don't take my word for it, get out the spreadsheet and do the calcs.
> Estimate the mass of a tree and multiply it out. Forests take up a lot of
> carbon dioxide. Those rainforests that were cut in Brazil will be releasing
> CO2 for the next century. But we can plant and support new forests.
> I will get you started with these BOTECs (BOTECs are rocket-scientist-speak
> for Back Of The Envelope Calculations). The atmosphere is about 6E18kg, so
> the carbon dioxide is about 380 ppm or 2E15kg, and CO2 is 30% carbon, so the
> carbon is about 6e14kg, in all the carbon dioxide.
A tree isn't just made of elemental carbon. It's not a diamondoid
structure. The oxygen from CO2 also gets incorporated into the mass,
as does all of CHNOPS and other elements, and just like animals, a
tree is mostly water. So the total carbon of a tree is a fraction of
its mass, although the CO2 that is fixed is equal (molarity wise) to
> A hardwood tree that is
> like those at Mt. Rainier is about a couple meters at the base and about 50
> meters tall, so the mass is about 50 cubic meters or about 4e4kg of carbon
> per tree. So all the CO2 would be taken down by a mere 15 billion such
> trees. I estimate trees that size could grow on about 40 meter centers, so
> you need a square grid about 5000 km on a side, which could *easily* fit in
> Siberia, almost could fit inside the North American continent, never mind
> the vast stretches of nothing in Alaska that can be pressed into service.
I think your model is far too simplistic. The biomass that you
describe is probably LESS than the total leaf-cycling biomass of the
northern hemisphere, yet that leaf mass accounts for CO2 fluctuations
of only 0.0005%.
We all know the simple model that animals produce CO2 which plants
use, and plants produce O2 which animals use, so they maintain a
cycle. I used to wonder how it was possible that the animal-to-plant
ratio could be maintained so that one or the other doesn't suffocate.
In reality, plants and animals have such an insignificant effect on
CO2 fluctuations (there's such a huge reserve of O2 and CO2 in the
atmosphere) that even if you wiped out one entire kingdom, O2 and CO2
levels would change so slowly that the other kingdom could evolve fast
enough to compensante (like fish in the 36% salinity ocean).
I don't think you can have a measurable impact on CO2 levels by
playing with biomass. You need to replace fossil fuel burning. We
have been able to proliferate great technology and power huge cities
because our energy is so cheap, but that energy is cheap because we
use a short cut to produce it: burning fossil fuels. That short cut
produces incredible waste (particularly CO2) and isn't sustainable.
If anything, we should be amortizing the possible future economic
costs of CO2 emissions into our coal, oil and natural gas purchases.
That would put a more realistic price on fossil fuel burning.
I hope for $5/ga gasoline, because when it went up to $3/ga I heard
people for the first time talk seriously about alternative energy
sources. And just wait until 2 billion Indians and Chinese start
driving. My Indian friends tell me that buying a car is all the rage
in India. Every young man wants to impress the ladies with a Western
automobile. So the problem is just going to get way way worse.
Nanotech solar panels with 90% efficiency would be great. E85 (85%
ethanol) fuel would be great.
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