Republican leaders don't even believe that global warming is real, Rep. Ed MarkeyEd MarkeyBiden's FDA nominee advances through key Senate committee Overnight Energy & Environment — Manchin raises hopes on climate spending Warren, Democrats ask federal government to resume tracking breakthrough cases MORE (D-Mass.), one of the principal authors of the climate change bill before the House said Monday.

Markey maligned a GOP alternative to his bill with Rep. Henry WaxmanHenry Arnold WaxmanThe Hill's Top Lobbyists 2021 Former lawmakers sign brief countering Trump's claims of executive privilege in Jan. 6 investigation Democrats call for oil company executives to testify on disinformation campaign MORE (D-Calif.) as only doubling down on harmful environmental practices.

"The Republicans are now on the attack. It begins with their leaders not believing that global warming is real," Markey said during a conference call sponsored by the global warming group 1Sky.

Markey mocked the GOP alternative, as well, likening it to a smoker who increases their consumption of cigarettes in light of harmful health effects.

"They have an alternative plan!" he said. "It's almost as though they're saying not only is there no problem -- we're going from one pack a day to two packs a day."

Waxman, the chairman of the House Energy and Commerce Committee, said that the House should seize the opportunity to pass climate change legislation, which he said only really comes once every 15 years or so.

"If I could go back to the first years of Jimmy Carter -- if I could go back to the first two years of Bill Clinton, I would do things differently," Waxman said, lamenting missed opportunities where Democratic Congresses and White Houses did not pass climate change regulations.

For his part, Markey also blamed the Bush administration's work on global warming for spurring the current legislation, too.

"For the preceding 8 years, we had an administration that only had aspirational goals in dealing with this issue," he said. "Unfortunately, we had an administration...they still had done nothing on the day they walked out of the White House."