Bloomberg proposes greenhouse gas tax (AP)

New York Mayor Michael Bloomberg, left, smiles as he walks past Alexander Calder's 'Eagle' while touring the Seattle Art Museum sculpture park with director Mimi Gates, Friday, Nov. 2, 2007, in Seattle. Bloomberg, a potential independent presidential candidate, proposed a national 'pollution pricing' plan Friday that envisions taxing companies directly for the greenhouse gases they release. (AP Photo/Elaine Thompson)AP - New York City Mayor Michael Bloomberg proposed a national "pollution pricing" plan Friday that would tax companies directly for the greenhouse gases they release.