kutulu

I don't know if individuals actually can purchase carbon credits. One thing to remember is that there is a difference between offsets and credits. Offsets are things like planting trees, energy reduction, etc. There is little regulation (if any).

Carbon credits (like the ones my company deals with) are real emissions reductions that satisfy the requirements of Kyoto. Kyoto is basically a cap and trade program. Nations are assigned CO2 emissions caps. The nation may then assign caps on emitters. If a company makes a change that reduces emissions below their cap (assuming the change meets certain requirements of course), the business recieves credits that they can either hold onto for later or sell on the market. Emitters that cannot stay under their cap, either because it costs too much to install the necessary equipment or because they want to expand, purchase credits.

The whole idea of cap and trade isn't unique to Kyoto. We do it here in the US for volatile organic compounds (VOCs) and sulfur dioxide (SO2) (maybe even CO and NOx as well) in regions that are classified as non-attainment areas. There is also a voluntary carbon trading market called the Chicago Climate Exchange.