You're either terribly set in your ways or very uninformed. Either way, you
just aren't getting it. When you put carbon into the air faster than the
earth can remove it, the levels rise. The carbon won't dissipate from the
atmosphere any faster just because you are burning biofuels. Growing more
plants for biofuel won't scrub the atmosphere any faster either. All the
cropland is already covered with vegetation.

Actually much cropland is not covered in vegetation.

If it's cropland, it's growing crops. That takes some amount of
carbon out of the air. It is yet to be shown that converting
cropland (or non-crop greenspace) to fuel-corn increases
the amount of carbon sucked out of the air by exactly the amount
of carbon pumped INTO the air by burning the fuel-part, and
that's what you have to show for it to be "carbon-nuetral"
by one definition. (by another definition, you'd have to
show only that burning the corn-oil releases the same amont
of carbon that the plant concentrated in the first place.
Obviously this can be true only if you use the entire plant
for fuel. Which we don't, and probably won't)
By neither definition is there any particular reason to
believe that bio-fuel is actually carbon nuetral.

But carbon nuetrality isn't what we care about, anyway.
A simplified model is that we burn a certain amount
of carbon-fuel, adding that much carbon to the atmosphere (F)
If that fuel comed from corn-oil (or whatever) then
we have a certain amount of land growing corn, which will
suck a certain amount or carbon OUT of the air. Call that (C).
If, on the other hand, we get our fuel from dead dinosaurs,
then the land that WOULD be growing corn will instead grow
something else, and that something else will suck
a different amount of carbon out of the air. Call that (D)

The question that MATTERS is whether C D.

My suspicion is that we'dd end up with less carbon in
the air if we go ahead and keep burning dead dinosaurs,
and use the cropland to produce things that permanantly
remove carbon, like CAF panels, construction-lumber, and
pencil-leads.


Also, modern hybrids have shorter stalks, and thus lay down less carbon
per acre than heritage varieties.

I'm not sure that that matters. The ratio of the useful part of
the plant to the non-useful part goes up. Which part has
more carbon in it? probably the part that makes good fuel.
It's quite possible (even likely) that the new varieties actually
INCREASE the carbon-per-acre.

Some crops grow more Biomas per acre than others, compare strawberries
and Sugarcane...