Thursday's confirmation hearing for President Obama’s nominee to lead the Environmental Protection Agency became the latest forum for an ongoing argument over global warming, jobs, the future of the U.S. coal industry, and the role of the federal government.                  

This will continue over the course of Obama’s second term, as the EPA looks set to become the President’s biggest weapon in his efforts to take on climate change.  

In his February State of the Union speech, Obama said that if Congress won’t pass climate-change legislation—a virtual certainty given partisan gridlock on Capitol Hill—then his administration will do as much as it can using its existing authority. One likely course of action will be to have EPA mandate cuts in air pollution from coal-fired power plants and oil refineries.

That will put Gina McCarthy, the woman he’s tapped to run the agency, at the heart of a fight over a priority that Obama views as a cornerstone of his legacy – and that the fossil-fuel industry views as a threat to its very existence.

Appearing Thursday before the Senate Environment and Public Works Committee, McCarthy said,  “As the President made clear, we must take steps to combat climate change. This is one of the greatest challenges of our generation and our great obligation to future generations. I am convinced that those steps can and must be pursued with common sense.”

McCarthy, who has worked as an environmental regulator at the state and federal level for over 20 years, is currently the EPA’s top clean air official. Over the course of Obama’s first term, she was the chief architect of a series of controversial regulations restricting toxic air pollution from coal-fired power plants – rules which were attacked in Obama’s re-election campaign as a “war on coal.” During Obama’s second term, it’s expected that she will oversee far more sweeping climate change regulations, which would restrict greenhouse gas emissions from new and existing coal-fired power plants – the nation’s top contributor to global warming pollution. Depending on how they’re structured, the rules could effectively freeze construction of new coal plants and lead to closures of existing coal plants.

That’s made McCarthy a top target for Senate Environment and Public Works Committee member John Barrasso of Wyoming – the nation’s biggest producer of coal.  

“I’m not sure the nominee is aware of how many people have lost their jobs due to the EPA,” Barrasso said to McCarthy. He cited stories of Wyoming miners who have struggled and lost their jobs as a direct result of EPA coal regulations.  

“The EPA is making it impossible for coal miners to feed their families.”

Alabama Republican Jeff Sessions cited concerns about the scope of the environmental agency’s reach, tapping into conservative ire about the size and scope of government.“I don’t think there’s any agency in government  +today that has such reach, touching all the way down to people’s lives,” he said. “EPA has extraordinary powers. It’s a massive reach in the pure sense of federal power, in areas never before contemplated and never legislated by the U.S. Congress.”

 As Republicans piled up attacks, Sen. Bernard Sanders, I-Vt., shot back, “This is not a debate about Gina McCarthy…it is a debate about global warming and whether we are going to listen to the leading scientists of this country who are telling us that global warming is the most serious planetary crisis we face.”

McCarthy, who’s known for her pragmatic, no-nonsense style and her ability to work well even with the heads of polluting industries she regulates, defused some of the heat from her attackers.  

To Barrasso and Sessions she responded, “The Clean Air act requires us to regulate and it is appropriate to regulate given the law and the science,” but she added,  “I believe coal has been and will continue to play a role in the U.S. energy mix…we’re going to have to be sensitive of the impact of every rule. We don’t want to have unintended consequences on small businesses.”

While Republicans continued a steady barrage of attacks, none threatened to block her confirmation. Even Sen. Jim Inhofe of Oklahoma, who describes global warming as a “hoax,” told McCarthy, “If you are confirmed I want to develop same relationship with you  I had with (previous administrator) Lisa Jackson. While I didn’t agree with her on policy, we got along well.”

The top Republican on the Environment Committee,  David Vitter of Lousiana, also launched a barrage of criticism at the EPA – but he barely mentioned the issue of climate change.  

 Vitter’s home state is one of the biggest oil producers in the U.S. – although it’s also one of the states most vulnerable to economic destruction from rising sea levels and extreme hurricanes, which climate scientists link to global warming.   

Vitter focused his questioning on the issue of transparency, accusing the EPA of concealing information  as it prepares controversial regulations that could have profound impacts on the economy.

“I am concerned that the central functions of the Agency have been obfuscated by ideology, frustrated by a severe lack of transparency, undermined by science the Agency keeps hidden, and implemented without regard for economic consequences,” Vitter said. “The EPA eschews at all costs economic modeling that would verify the true impacts of the regulatory agenda that now provides this country with the lowest workforce participation rate since the Carter Administration.  Cost/benefit analyses as required under various executive orders and as required by the Clean Air Act…yet EPA remains intransigent in its opposition to having a transparent economic analysis process.”

Vitter has sent letters to the EPA asking for details about emails sent by the EPA’s previous administrator, Lisa Jackson, from a private account with the name “Richard Windsor.”

“There’s been a pattern of abuse of using personal emails at EPA,” he said. “it’s clear that this practice was used to hide information from the public,”

Senate Environment Chairwoman Barbara Boxer told Vitter that due to the high volume of emails received by the EPA administrator, it has become common practice for the agency head to create private email accounts – the practice was also followed by George W. Bush EPA chiefs Christine Todd Whitman and her deputies. Previous EPA chief email usernames  have included “Tofu” and “ToWhit,” she said.

Of usernames most appropriate for an EPA chief, Vitter said, “Richard Windsor sounds pretty monarchist. I thinks that’s appropriate. But my vote is for Tofu.”

McCarthy told Vitter, “I share your concern for transparency and accountability – I do not conduct business with personal email. There are times when I’ve gone home to Boston and I’ve used my personal email to send documents from EPA home for printing – but those have never left the government email systems. Those would comply with [Freedom of Information Act] requests.”

Vitter also pressed McCarthy on the use of instant messaging, as another way agency officials could communicate without leaving a traceable record.  

McCarthy responded, “One good thing about being 58 is that I don’t know how to use that. I’ve never used that and I don’t know how.”