[extropy-chat] Global warming news
spike66 at comcast.net
Sat Mar 25 06:33:58 UTC 2006
> -----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
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. 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. Since
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 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.
Get a globe, note the scale and cut a square of paper to represent the size
of that forest. Five thousand kilometers is about 45 degrees of arc. Cut
up that square any way you like and look around on the globe for places it
would fit, but keep in mind that we don't need all of that, since that much
area covered in big trees represents *all* of the CO2 currently in the
atmosphere. We do not want to draw it all down of course, for that would
slay the plants which must draw carbon dioxide from the atmosphere.
In all these number games, do occasionally look at life from the point of
view of plants and sea creatures. The plants must have been gasping for
lack of carbon dioxide for all these millennia. Now they are getting ever
more comfortable, and may get even more so as the planet provides more
carbon dioxide and more hospitable climates for most life forms. If we
humans must pull back a few tens of kilometers from our current coastlines
over the next few centuries, it is a minor enough inconvenience given the
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