Under the direction of President Obama's White House, the Environmental Protection Agency has announced new guidelines to cut down on the pollution caused by fossil fuels. Today, EPA administrator Gina McCarthy said that the agency is setting strict limits on how much carbon coal- and gas-powered plants will be able to emit. In a press conference, McCarthy said that the rules were necessary for preventing a wide range of environmental problems, from global warming to smog to polluted water. "We must meet our moral obligation for the next generation and be stewards of our valuable natural resources," she says.

As Reuters reports, the guidelines are an update to rules made in 2012. Under the rules, any new coal plant will have to be built with technology to capture carbon emissions, and new coal- and natural gas-fired plants will both need to meet nationwide pollution standards. Coal-fired plants can emit no more than 1,100 pounds of CO2 per MWh, while large national gas plants can emit no more than 1,000 pounds per MWh. Smaller gas plants, which are less efficient, can emit up to 1,100 pounds. If coal plants are willing to meet a slightly tighter standard, though, they can average their emissions over seven years — starting at higher levels and reducing emissions over time.

Existing power plants aren't affected by the new guidelines

A present-day coal plant, by contrast, might emit 1,800 pounds per MWh. And that, for now, isn't changing. McCarthy emphasized that the new guidelines wouldn't affect anyone who has already built a plant, and that reducing emissions from existing infrastructure was a complicated problem. The EPA plans to examine the issue over the coming years, putting out a proposal for reducing pollution by old plants in June of 2014. The guidelines announced today are also still open to public comment, just as last year's were.

Any action by the EPA is highly controversial, both because of the importance of coal and other fossil fuels in local economies and because of a charged political debate about the threat (or even existence) of climate change; critics have accused Obama of fighting a "war on coal." In response to critical questions, McCarthy insisted that she was not "effectively banning coal" with new carbon capture requirements, though the technology has seen only limited tests and usage so far. She compared carbon limits to existing emission rules for cars, which have been successfully implemented without disaster. And none of the hurdles of reducing pollution, she said, reduced the responsibility Americans bore towards future generations. "It's about our obligation to leave our children a world that is as healthy and as safe as the one we inherited."

Update: As expected, Republican lawmakers have criticized the EPA guidelines. Representatives Fred Upton (R-MI) and Ed Whitfield (R-KY) of the House Energy and Commerce Committee have said that the committee will soon hold a hearing on the possible negative impacts of the plan. "This impractical rule restricts access to one of our most abundant, affordable, and dependable energy sources. The consequences will be more job losses and a weaker economy," says Upton. He and Whitfield also criticize the carbon capture system upon which the plan is based, saying the standards would "require the use of expensive new technologies that are not commercially viable." Secretary of Energy Ernest Moniz, however, says that the Department of Energy is committed to implementing the changes, granting $8 billion in loan guarantees for projects that could put more options to reduce pollution on the table.