The agency's plan would target the sources of 70% of U.S. emissions. It sends a timely message to foreign allies in the fight against climate change -- and to lawmakers in Congress.

    Reporting from Washington - The Environmental Protection Agency unveiled a detailed proposal Wednesday for using the government's regulatory powers to curb greenhouse gas emissions -- reassuring foreign allies of the U.S. commitment to fight climate change and warning Congress that the administration will act on its own if lawmakers fail to address the issue.

    The proposed regulations would apply to large-scale industrial sources of heat-trapping gases, including power plants, factories and refineries, but not to smaller sources such as new schools, as some critics of EPA action had feared.

    The rules would force new or substantially modified industrial plants emitting at least 25,000 tons of greenhouse gases a year to employ "best available control technologies and energy-efficiency measures" to minimize emissions. That would cover the sources responsible for 70% of greenhouse gas emissions in the U.S., the EPA said -- primarily carbon dioxide created by burning fossil fuels.

    To read more about the EPA's newest plan to regulate greenhouse gas emissions, click here.