On Jul 25, 9:32*am, "J. Clarke" wrote:
On 7/25/2010 7:59 AM, wrote:



On Jul 25, 2:47 am, "Ed *wrote:

This is different carbon?

Yeah, this is VERY different carbon. When you sequester vast amounts of it
underground, for millions of years, and then release large quantities of
that carbon over a couple of hundred years, you wind up increasing the CO2
content of the atmosphere.

When you sequester carbon via photosynthesis (the source of all of our
food), and re-release it in a cycle of a few years, at most -- unless you
eat trees -- you don't have any significant effect. The effect is
steady-state, in which you have small amounts of carbon tied up over a short
period of time and then re-release it.

You have an engineering background, Don. Don't play dumb. d8-)

--
Ed Huntress

Don is not playing stupid. *He is just pointing out that a molecule of
CO2 does not know if it was released in a cycle of a few years or
hundreds of years. *So it makes no difference in how the CO2 was
released into the atmosphere. *It is faulty logic. *I too have an
engineering background. *The effect of releasing a lb. of CO2 into the
atmosphere is the same regardless of where it came from.

However the long term effect of releasing a pound that was sequestered
by a corn plant over the last several months and will be resequestered
by the corn plant you are planting in the same location next spring is
different from the long term effect of releasing a pound that has been
buried in a hole in the ground for the past million years.

If there is a difficulty with CO2 (and I'm not taking that as proven)
the difficulty comes from releasing 150 or so million years worth of
sequestered carbon in a century or so, with no in-place process for
resorbing it.

So, yes, the source does matter.

Ah, but the lb of CO2 that was sequestered by the corn plant is not
going to be the same lb of CO2 that will be sequestered by the corn
plant in the same location. The lb of CO2 sequestered by the corn
plant next spring could be a lb of CO2 that has been buried in the
ground for the last million years. The source only matters to those
that want it to matter.

It is pretty silly that the US is considering taxes to limit CO2
release from cars and light trucks when it would be a lot cheaper to
put out the coal fires in China that release more CO2 than the cars
and light trucks in the US. But to some the source matters. So CO2
from underground fires in coal mines does not count, but CO2 from cars
counts. And of course CO2 from humans does not count in their minds
because there is not much that can be done about it. In fact it is
all fungible. A lb of CO2 is a lb of CO2.

Dan