As Mitt Romney ended his bid for the Republican nomination on February 7th, the overall debate on climate change shifted. Now all front-runners in the Presidential race concur that climate change is real and is a problem that needs to be addressed. Sens. McCain (R-AZ), Hillary Clinton (D-NY) and Barack Obama (D-IL) believe that mandatory limits on emissions of greenhouse gases (GHG) should be instituted. In fact, in the last two Congresses, Sen. McCain co-sponsored and actively advocated for climate change legislation with Sen. Joe Lieberman (I-CT), similar to the more current Lieberman-Warner bill under consideration in the Senate. Some economists and political observers now believe that the U.S will set a mandatory limit on GHG in the next three years.