Former Secretary of State John Kerry and Defense Secretary Chuck Hagel offered a scathing rebuke of President Donald Trump’s climate change policies to lawmakers on the House Oversight and Reform Committee.

But while they were there Tuesday, both men also had to tussle with the panel’s conservative firebrands who said fears of climate change were “alarmist notions” and repeatedly challenged Kerry and Hagel on whether they were qualified to talk about the subject.

Ranking Republican Jim Jordan of Ohio, harkened back to Obama administration scandals like one regarding now-bankrupt solar panel company Solyndra, calling the loan guarantee program that spurred it the “first Green New Deal.”

[Some climate change panel members are literally invested in the issue]

North Carolina Republican Mark Meadows challenged Kerry’s assertion that climate-related issues may be exacerbating political unrest in Syria, suggesting the former secretary was saying that “droughts only started once the combustion engine” was invented. Louisiana GOP Rep. Clay Higgins at one point remarked, “I don’t believe mankind is responsible for climate change on Mars.”

Watch: Climate debate heats up Oversight Committee

And Rep. Thomas Massie questioned whether Kerry, who helped negotiate the 2015 Paris climate accords, was qualified to talk about climate science because he did not have a degree in the subject. It was “somewhat appropriate that somebody with a pseudoscience degree is here pushing pseudoscience in front of our committee today,” the Kentucky Republican said.

“Are you serious? I mean this is really, a serious, happening here?” Kerry replied, to laughter in the audience.

[On the campaign trail, climate change can no longer be ignored]

During another spirited debate with Massie later in the hearing, Kerry remarked, “Mr. Chairman, this is just not a serious conversation.”

Unlike some Republicans who have warmed to debating climate legislation, GOP lawmakers on the panel seemed locked into their denial of what scientists and federal agencies warn is a coming catastrophe of rising temperatures and sea levels and related natural disasters and crop failures.

When they did not contest the scientific consensus on mankind’s impacts on climate change, they pivoted to demonizing the Democrats’ Green New Deal resolution, a nonbinding measure that endorses climate change mitigation through a sweeping economic overhaul.

Neither man shared their thoughts on the legislation; Hagel said he hadn’t read the resolution. But Kerry, a former Democratic presidential nominee, used the proposal’s ambitions to throw a jab at the president.

[Creation of a panel disputing climate change causes White House infighting]

“In proposing what she has proposed … Congresswoman [Alexandria Ocasio-Cortez] has in fact offered more leadership in one day or in one week than President Trump has in his lifetime on [climate change],” he said.

Kerry and Hagel made their points known over the fiery and sometimes confusing back-and-forths with Republicans.

They said sea level rise and increased natural disasters were already damaging U.S. military bases and housing for military families and increasing disease factors and migration patterns. Both criticized Trump for pulling out of the Paris climate accord and reportedly proposing a National Security Council panel to re-examine scientific consensus on whether the climate is changing and whether mankind is contributing to the problem.

The U.S. was ceding global leadership to China, which is “investing heavily in carbon emission technology,” Kerry said. He added that “they are trying to fill the vacuum that the United States is leaving behind in this area.”

“We better pay attention to what our scientists, our intelligence people, [and] our military leaders are saying, how serious this is and the impact it’s going to have, and is having, on our readiness and our capabilities and our national security,” Hagel said.

Also Watch: Matt Gaetz unveils ‘Green Real Deal’