The California Air Resources Board had a meeting with four automakers in order to see whether the parties can agree on nationwide standards for carbon dioxide emissions. The Aspen Institute confirmed Thursday that it had brought together a group of carmakers, California emissions officials and environmental groups for a private “candid exchange” on the regulation of greenhouse-gas emissions from cars and trucks.

The group of stakeholders included: Ford Motor Co., General Motors Corp., Honda Motor Co., Toyota Motor Corp., the California Air Resources Board, the Sierra Club, the Union of Concerned Scientists and the Natural Resources Defense Council. According to a statement on the institute’s Web site, the parties “explored ways to achieve national and state goals for reduction of greenhouse gas emissions and fuel economy improvements.”

As you likely already know, the amount of CO2 that is emitted from your vehicle's tailpipe is directly proportionate to how much fuel you are burning, so cars that get better gas mileage emit less carbon dioxide.

It is highly probable that the rules that the air regulators have to develop going forward, namely, apportioning out the right to emit greenhouse gases among various industries, and then slowly lowering the emissions ceiling on all industries, will have to be justified not just within the air agency, but to outside economists who may or may not know about the technical details of controlling air pollution.

Automakers fear that the EPA will authorize California and 13 other states to regulate emissions of carbon dioxide, which contribute to global warming. The California Air Resources Board wants to cut greenhouse gas emissions from vehicles in that state by 30 percent from 2009 through 2016.