It was a question posed by conservative Liberal senator Alex Antic at senate estimates on Monday, which left bureaucrats and senators giggling at the charge.

The South Australian senator, who is known for his conservative views and is a climate change sceptic, used his allotted question time to ask Home Affairs Department secretary Mike Pezzullo whether his department had been "captured by leftist ideology".

A series of questions had set this wheel in motion.

Why did the department consider climate change a national security risk when counter-terrorism, espionage and cyber security were front of mind? He asked.

And did that mean Home Affairs public servants actually worked on the assumption that human-induced climate change was a factual reality?

"Is that comedy? Parody? Or is that serious?" Senator Antic said.

"I genuinely don't know how to respond to a rather oddly put question," Mr Pezzullo said in a response.

"You're asking me whether it's comedy? It's my job."

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Most of the room was dumbfounded, Mr Pezzullo included, but Senator Antic pressed further.

"I find it extraordinary that the Department of Home Affairs is spending time away from cyber security, counter-terrorism," he said.

"I know the left in this building think that everything relates to their issues, that's not the case. The average Australians don't think that - they're worried about real issues."

Mr Pezzullo, incredulous, responded in fluent bureaucratise.

"On the presumption it wasn't a rhetorical question ... we are captured by nothing other than the public interest, we serve the public interest under the Public Service Act, we serve the government of the day, and we faithfully execute, impartially and apolitically, its policies," he said.

While the "war on climate change" is over, Senator Antic's antics, along with that of his party colleague Senator Gerard Rennick and crossbench mate One Nation senator Malcolm Roberts, are a reminder of the discourse most assumed was left behind.

In just four years, Australia has experienced an increased battering from bushfires and flooding, as foreseen by climate scientists, making climate scepticism a tough sell.

Top officials appear less fearful of discussing climate change in public forums and linking it directly to the work of governments.

The real comedy in all this was Senator Antic's questions.

But if its sole purpose was to garner attention, he certainly got it.

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