John McCain, Barack Obama and Joseph Lieberman plan to introduce a bill today that they say will reduce annual global-warming gases by two-thirds by midcentury, the San Diego Union Tribune reports. It will cut GHG emissions by two percent a year.

Sens. McCain, R-Ariz., Obama, D-Ill., and Lieberman, the Connecticut independent, are calling for mandatory caps on greenhouse emissions for power plants, industry and oil refineries. Their plan would require releases of heat-trapping gases to return to 2004 levels by 2012 and to 1990 levels by 2020.

Under the proposed legislation, greenhouse gas emissions would be cut from 6,100 metric tons of carbon equivalent in 2004 to about 2,100 metric tons in 2050.

McCain and Lieberman offered a climate bill two years ago that was defeated in the Senate.