Back in February, presidential hopeful Sen. Chris Dodd, D-Conn., quietly made a bold move. He co-sponsored the “gold standard” of global warming bills, Sanders-Boxer, cutting greenhouse gas emissions 80 percent from 1990 levels by 2050.

This week, three other presidential candidates joined the Sanders-Boxer bandwagon, Sens. Joe Biden, D-Del., Hillary Clinton, D-N.Y. and Barack Obama, D-Illinois.