Prime Minister Jacinda Ardern defends climate activist Greta Thunberg

Prime Minister Jacinda Ardern says she has deep admiration for youth climate activist Greta Thunberg. Photo / Mark Mitchell

Prime Minister Jacinda Ardern has defended Swedish climate activist Greta Thunberg – and her own Government's record on climate change.

Sixteen-year-old Thunberg has been met with both praise and backlash since a headline-grabbing speech to the United Nations Climate Action Summit last week in which she chastised politicians and business leaders for inaction, captured with the phrase: "How dare you!"

Speaking to reporters in Wellington Monday, Ardern – who was at the summit – was asked about some of the criticism that had arisen after the fiery speech, and to the climate strikes, inspired by Thunberg, across New Zealand on Friday.

"I don't think that's fair. I do think we need climate advocates," Ardern said.

"It certainly couldn't be easy having been thrust onto the world stage in that way, but I have deep admiration for her."

Ardern said she and Thunberg only had time to exchange a quick greeting in passing in New York.

But the Prime minister was also left defending her own Government's record on climate change, with climate strikers – who organisers say numbered 170,000 across the country - on Friday demanding Parliament declare a climate emergency.

Swedish Environmental activist Greta Thunberg addresses the Climate Action Summit in the United Nations General Assembly. Photo / Jason DeCrow

Green MP Chloe Swarbrick this year tried to have a climate emergency declared in Parliament but the motion was objected to and failed.

Ardern on Monday said she was instead focused on action.

"I absolutely hear the sentiment around the symbolism around an emergency, but what people want is for us to make progress," Ardern said.

"What people want is action."

She pointed to a swathe of Government efforts over the past two years, including: policies subsidising low-emissions cars, the Zero Carbon Act and a ban on future offshore oil exploration, among others.

"I am not going to pretend for a moment that that in itself is enough, but we are making progress. It is progress we are proud of, but I am not stopping," she said.

"Not everything is within our powers in the make-up of Parliament that we currently have. We've never used that as an excuse, and we will keep going."

Ardern last week also faced criticism from Opposition leader Simon Bridges for not raising climate change directly with US President Donald Trump when they met in New York - despite telling the UN summit that no one was exempt from the issue.

"I did mention the Climate Action Summit," Ardern said on Monday.

"I am sure that [Trump] knows my view, as he knows the view of everyone who maintains a membership of the Paris Agreement [on climate change].

Trump tweeted fondly about the face-to-face last week, calling it a "wonderful meeting!"