Rep. Henry Waxman's retirement will create a vacuum for House leadership on climate change, though allies say the California Democrat has helped cultivated a young crop of like-minded lawmakers to fill the void.

Waxman announced Thursday that he will not seek re-election this year. The top Democrat on the House Energy and Commerce Committee, he is the lower chamber's most visible and outspoken lawmaker on climate change issues.

"After 40 years in Congress, it’s time for someone else to have the chance to make his or her mark, ideally someone who is young enough to make the long-term commitment that’s required for real legislative success," Waxman said.

Supporters say there's plenty of ambitious lawmakers who speak loudly and often about climate change, and they say Waxman's advocacy laid the groundwork. Still, they say few are immediately ready to step into the role he has occupied in the House.

"The combination of his passion for the issue and his knowledge of it and his incredible legislative savvy is a powerful combination, and one that we will miss a great deal," said Tiernan Sittenfeld, senior vice president of government affairs with the League of Conservation Voters.

Some of the more active, experienced House lawmakers on climate change issues include Democratic Reps. Frank Pallone and Rush Holt of New Jersey, Peter Welch of Vermont, and Earl Blumenauer of Oregon. Lawmakers also credited Waxman with helping to usher in a new guard in the Democratic caucus when it comes to climate.

Sen. Ed Markey, D-Mass., who co-authored cap-and-trade legislation with Waxman in 2009 when both served in the House, said Waxman's enthusiasm has shifted the discourse on climate change. He said that has made it easier for newer lawmakers to promote the issue.

"I can't tell you how many incredibly talented members there are who care about it, and I don't want to single out anyone for fear that I'm going to leave out the others," Markey told reporters in the Capitol. "There are so many members. It's a caucus-wide phenomenon. And we saw that when Waxman-Markey passed, and it still exists there."

Waxman-Markey, as the cap-and-trade bill was known, passed the House in 2009. The contentious bill eventually failed in the Senate as the economy took a downturn and lawmakers questioned whether such a scheme was prudent.

Climate talk was largely taken off the table in Congress following the flop of Waxman-Markey, which was officially The American Clean Energy and Security Act of 2009. But the topic has come back in full force since October 2012, when Hurricane Sandy ravaged the East Coast in a storm that scientists say was intensified by warmer waters and higher sea levels associated with climate change.

Waxman, along with Markey, Sen. Sheldon Whitehouse, D-R.I., and Sen. Barbara Boxer, D-Calif., among others, quickly took the lead on climate issues following the storm. They have worked on a number of bicameral efforts to raise the issue since then.

Sen. Martin Heinrich, D-N.M., a favorite of green groups who joined the upper chamber last year after serving two terms in the House, said that Democrats are energized on climate, but that it could take time for a leader to emerge.

"We'll just have to wait and see who is willing to pick up that mantle. There's a lot of new blood in the House. At the State of the Union the other night, when I went over — I haven't been gone for too long — there were a lot of new faces," Heinrich told the Washington Examiner in the Capitol.

For now, the prospects of advancing legislation through the GOP-controlled House look slim. Many Republicans there deny or are skeptical of the scientific consensus that humans are driving climate change, mostly from burning fossil fuels that pump greenhouse gases into the atmosphere.

Whoever assumes Waxman's spot on Energy and Commerce will be tasked with that challenge. Who that will be has not been decided, though Rep. John Dingell, D-Mich., whom Waxman ousted from the chairman slot in 2009, released a statement Thursday saying that he would "take a deep breath and look at everything."

Dingell, however, hasn't necessarily been a climate change stalwart. He has criticized the Obama administration's use of the Clean Air Act to regulate greenhouse gas emissions from power plants — the cornerstone of President Obama's climate agenda — while those in Waxman's camp support the effort.

Waxman touched on that issue in a statement announcing his retirement.

“Even if Congress won’t act on climate, President Obama can," he said. "Whether Congress acts or not, the Clean Air Act gives President Obama – and future presidents – ample authority to achieve these emission reductions."