A national environmental group says coal-dependent Indiana ranks fourth in the nation for carbon dioxide emissions from power plants that contribute to global warming.

The report released Tuesday by Washington-based Environment America ranks Indiana behind Texas, Ohio and Florida. Pennsylvania is fifth.

The study says 73 percent of the carbon dioxide emissions in the U.S. came from plants built before 1980.

The study is based on U.S. Environmental Protection Agency data for 2007.

The report also says Duke Energy's Gibson Power Station near Princeton is the fourth dirtiest power plant in the United States.