Paula Bennett is lashing out at the Prime Minister over her openness to declaring a "climate emergency", describing the prospect as "ridiculous".

Bennett, the deputy leader of the National Party, said Prime Minister Jacinda Ardern is trying to "juggle the Greens and New Zealand First" and is "trying to keep everybody happy".

"It just seems like it's yet another case of this Government making a big statement with nothing behind it. It's rhetoric... and personally I think it's ridiculous," Bennett told Magic Talk.

Ardern was asked last week if she would consider declaring a climate emergency, after more than 50 of New Zealand's top scientists called on Parliament to take action.

She said there had been an attempt to move a motion in Parliament, and that it was declined in May, which she said was mainly due to process and procedure.

"We're not opposed to the idea of declaring an emergency in Parliament because certainly, I'd like to think our policies and our approach demonstrate that we do see it as an emergency."

New Zealand would join the UK, Canada, Ireland and France if the Government declared a "climate emergency". So far, only local authorities have done so in New Zealand, the most significant being Auckland Council.

Bennett said declarations of emergency should only be used for "very serious events" like the Christchurch earthquakes.