[logancg]

Sounds interesting. The two big barriers to this system are:

1. Political buy-in to set a cost of carbon emission 2. Economic viability of removal (often referred to as carbon capture and storage, or CCS)

1 is non-trivial, but happening. Canada has a provincial carbon tax measure which requires setting a price. A price is also defined in the European cap-and-trade system.

2 is also non-trivial, as the economics are pretty bad right now. However, CCS costs are projected to decrease rapidly. [0]

Right now, integrating CCS is on average more expensive than purchasing carbon credits. Carbon offsetting companies are, to your point, an example of private enterprise filling a gap.

[0] http://www.ccsassociation.org/why-ccs/affordability/