Would dramatically reducing CO2 emissions be expensive?

No, surprisingly enough.

The British Stern report projected a cost of 1% of GDP per year, and later Stern revised that to 2%. I think that's too high. Fortunately, we don't have to rely on some kind of authority to figure this out - at least for the US, I think we can do the calculations ourselves.

Most CO2 emissions in the US come from coal - a solution that eliminates coal and a large % of oil consumption will get us most of the way.

Well, replacing coal with wind in the US would only have a net cost of about $400 billion*. Light vehicle transportation accounts for 45% of US oil consumption - replacing it wouldn't cost anything at all, if you include all costs and savings over the vehicle lifecycle**.

$400B divided into a $14T economy is 3%. Over 20 years, that's only .15% per year. Not much, really.

*, ** I'll show the calculations for this on following days.