It’s sort of like the stock market. But instead of buying and selling stocks, local governments and corporations trade credits for reducing greenhouse gas emissions. The Board of Supervisors Tuesday voted to join the program.

Supervisor Roger Dickinson supports it. He says the county’s initial commitment would be to reduce greenhouse gas emissions 6% by 2010. 

"If we exceed that standard, should we join the exchange, then we actually would accumulate credits which have a monetary value which we could sell or hold. If we don’t meet that goal then we would have to buy some credits on the exchange."

Sacramento County is the first county in the state and only the second county in the US to join the Chicago Climate Exchange.