Sen. Christopher Dodd, D-Conn., has proposed a corporate carbon tax, while Sen. John McCain, R-Ariz, has outlined a cap-and-trade system on greenhouse gases, The Christian Science Monitor reported Monday.

Former Sen. John Edwards, D-N.C., is calling for an 80 percent reduction in greenhouse gases by 2050. Similarly, Sen. Barack Obama, D-Ill., has proposed reducing greenhouse gases to 80 percent below 1990 levels by 2050 but he also wants industries to pay for their greenhouse gas emission quotas.

Sen. Joseph Biden, D-Del., said he would raise vehicle fuel efficiency standards to 40 miles per gallon by 2017, "which will save approximately the amount of oil we import from Saudi Arabia," the Monitor said.

However, Rep. Tom Tancredo, R-Colo., said he believes the threat of climate change has been exaggerated.