In Cali, A Grand Experiment to Rein In Climate Change

http://www.nytimes.com/2012/10/14/science/earth/in-california-a-grand-experiment-to-rein-in-climate-change.html?hpw

Such audits will be crucial as California embarks on its grand experiment in reining in climate change. On Jan. 1, it will become the first state in the nation to charge industries across the economy for the greenhouse gases they emit. Under the system, known as “cap and trade,” the state will set an overall ceiling on those emissions and assign allowable emission amounts for individual polluters. A portion of these so-called allowances will be allocated to utilities, manufacturers and others; the remainder will be auctioned off. 

Over time, the number of allowances issued by the state will be reduced, which should force a reduction in emissions. 

To obtain the allowances needed to account for their emissions, companies can buy them at auction or on the carbon market. They can secure offset credits, as they are known, either by buying leftover allowances from emitters that have met their targets or by purchasing them from projects that remove carbon dioxide or other greenhouse gases from the atmosphere, like the woods where Mr. Hrubes was working.