OT Hydrogen economy, not? - Page 20

 On Wed, 23 Jul 2008 19:30:13 GMT, James Arthur



Of course plants are inefficient solar collectors. They're starving
for CO2.

John

 
  How much has their growth rate increased in the past century, when
atmospheric CO2 concentration increased about 35-36%?

 - Don Klipstein (don@misty.com)

 On Thu, 24 Jul 2008 00:53:13 +0000 (UTC), don@manx.misty.com (Don
Klipstein) wrote:


Dunno. I'd imagine that high-yield plant breeding has tracked ambient
CO2 levels. People who grow stuff in (real) greenhouses often add
extra CO2.

http://www.advancegreenhouses.com/greenhouse_co2_generators_from_a.htm

If you look at estimated CO2 levels over the last zillion years

http://upload.wikimedia.org/wikipedia/commons/7/76/Phanerozoic_Carbon_Dioxide.png

http://www.aps.org/units/fps/newsletters/200807/monckton.cfm   fig 7

it looks like CO2 levels have dropped almost linearly, from a peak of
about 2500 PPM, over about the last 120 million years, and not exactly
linearly from 7000 PPM in the last semi-gigayear. One could
extrapolate the curves to zero in another 25 million or so.

Plants wouldn't like that. Perhaps the planet is cooling off, with
fewer massive volcanic events, and plants continue (greedy green
buggers) to strain CO2 out of the air and sequester it.

Certainly plants could evolve to use sunlight better, much better, but
at current CO2 levels, it's probably not worth the effort.


John

 Don Klipstein wrote:

About 6.2% in the last 20 years according to this article:
   http://www.financialpost.com/story.html?idV9586

Hey, that outpaces CO2 ppm increases, doesn't it?

Cheers,
James Arthur

 
  OK, to the extent this is allowed to cause biomass to increase we have a
negative feedback mechanism.
  Some of this was not due to increased CO2 but due to increase in
sufficiently warm land area.  Some of this is also from breeding of
faster-growing plants, irrigation and other developments for agriculture.


  Latest 20 year period in the Mauna Loa data is 1984 to 2004.  CO2
increase was 9.6% for that stretch.

 - Don Klipstein (don@misty.com)