What happens after Copenhagen?

There were high hopes for Copenhagen but on Dec. 18 it's time to come home, with or without a treaty. It's doubtful anything binding will result, so it's up to Congress to follow through on President Barack Obama's goals for slashing emissions.

The House passed a bill in June. The Senate's version of the cap-and-trade part of the legislation passed through committee in November, but all the Republicans on the committee abstained from the vote. Global warming legislation in the Senate is now on the back burner as senators debate the health care bill.

If the cap-and-trade bill does make it to the Senate floor and gets passed, a conference committee would have to sort out the differences between the House and Senate versions of the bill before sending it back to both chambers for a final vote.

Even if the bill in Congress does pass, adjustments will likely be needed along the way. It would be the first time carbon emissions are regulated in the U.S., so no one knows for sure if everything will work the way it's designed.

Some are worried already about how the carbon market under a cap-and-trade scheme will be regulated to make sure it doesn't become volatile. Environmentalists are concerned about polls showing public interest in global warming may be slipping. If that turns out to be the case, there could be public resistance to the changes.

If Congress fails to act, several regions of the country have vowed to move forward with regional global warming policy. In the Midwest, an advisory group appointed by the Midwestern Governors Association has developed recommendations for such a policy, although Minnesota Gov. Tim Pawlenty and others haven't yet signed on.