BOULDER, Colo. | EPA chief Gina McCarthy said Wednesday that the Obama administration is finished waiting for Congress to act on climate change and plans to bypass the legislative branch in developing a federal response.

Ms. McCarthy, who was confirmed last month as Environmental Protection Agency administrator, cited President Obama’s June 25 speech at Georgetown University, in which he unveiled his Climate Action Plan and vowed to make combatting climate change a priority of his second term.

Mr. Obama gave “what I really think is a most remarkable speech by a president of the United States,” said Ms. McCarthy in remarks at the University of Colorado Boulder.

“Essentially, he said that it is time to act,” she said. “And he said he wasn’t going to wait for Congress, but that he had administrative authorities and that it was time to start utilizing those more effectively and in a more concerted way.”

She insisted that reducing greenhouse-gas emissions could be accomplished without harming economic growth, calling the tension between the two priorities a “false choice.”

“We’re going to do this this year, next year, the following year, until people understand these are not scary things to do, these are actions we can all do, they’re actions that benefit everybody, that will grow the economy, and they’re actions that will protect the health and safety of individuals,” Ms. McCarthy said.