Secretary of State Hillary Rodham Clinton today announced that Todd Stern will serve as her special envoy for climate change, signaling that the issue will be a key one for her department.

In this role, Stern will be the country’s lead climate negotiator at the United Nations and other international summits.

“President Obama and Secretary Clinton have left no doubt that a new day is dawning in the U.S. approach to climate change and clean energy. The time for denial, delay and dispute is over,” said Stern at a press conference today announcing his appointment.

“Containing climate change will require nothing less than transforming the global economy from a high-carbon to a low-carbon energy base,” he said. “But done right, this can free us from our dependence on foreign oil and become a driver for economic growth in the 21st century.”

Stern, who served as an adviser to the Obama transition team on environmental issues, was an assistant and staff secretary to Bill Clinton from 1993 to 1998. He was the senior White House negotiator for the Kyoto negotiations and coordinated the administration’s Initiative on Global Climate Change from 1997 to 1999. From 1999 to 2001, he worked at the Department of Treasury as an adviser to the secretary. He was an adjunct lecturer at Harvard’s Kennedy School of Government and a fellow at the German Marshall Fund after leaving government.

Stern now works as a senior fellow at the Center for American Progress, where he focuses on climate change and environmental issues. He drafted a proposal for creating a National Energy Council, an idea published in CAP’s Change for America: A Progressive Blueprint for the 44th President. He is also a partner at the law firm of Wilmer Cutler Pickering Hale and Dorr, where he is the vice chair of the firm’s Public Policy and Strategy practice.

Stern’s background on both the climate issue and the inner workings of the White House signal that he’s likely to play a big role in international negotiations for the State Department, and that it will be a key issue under the new Secretary of State.

Clinton echoed as much in her remarks today: “With the appointment today of a special envoy, we are sending an unequivocal message that the United States will be energetic, focused, strategic and serious about addressing global climate change and the corollary issue of clean energy.”

It’s an open question, however, how Stern will coordinate his actions with Carol Browner, the White House’s top adviser for climate and energy issues.