Global commitments to greenhouse gas reductions ahead of a world summit in Paris are not enough to tackle climate change - and developed countries, including New Zealand, need "to do more", United Nations Development Programme administrator Helen Clark says.

The former Prime Minister was in New Zealand this week giving a lecture on the challenges the world faces in 2015, including climate change.

In it she said the commitments made ahead of the United Nations Conference on Climate Change in Paris in November would not add up to what's really needed to tackle the problem.

Speaking on TV3's The Nation this morning, Ms Clark repeated that sentiment, saying those commitments "are not enough".


"They're not enough to stop that tip-over point of global warming going above 2C above the pre-industrial levels," she said.

"The EU is calling for more action, the UN's calling for more action. We need Paris to be a success. Whether things will add up to enough by Paris is obviously a moot point. If they don't, we just have to keep at it until it does add up."

Every country "needs to do more", she said, but there was a "special responsibility" on developed countries, which have historically contributed more to carbon in the atmosphere.

"But we need every economy to act. We need the emerging economies to act as well," she said.

Pushed on whether New Zealand was included in that, she said: "Well, we need New Zealand to act. We need everyone to act. We need China to act, we need India to act. Everybody has to act."

There needed to be "a lift in ambition" among countries around the world in setting and hitting targets to combat climate change, Ms Clark said.

"Otherwise, the world's poorest people are going to suffer the most from this.

"But we all suffer. Look at the erratic climate in New Zealand now - much less predictable. You hear the same thing from the Kiwi farmers you hear from the smallholder in Africa - don't know whether the rain's going to come, how long they'll be, whether there'll be a cloudburst, whether it will be consistent rain, when do you plant, does your crop get ruined? It's very, very difficult for agriculture."

Ms Clark also spoke about multi-national companies evading tax, the refugee crisis in Europe and humanitarian relief efforts in the Middle East.

Asked if New Zealand should accept more refugees, she said "everybody could do more", but the "basic problem" was the ongoing conflict in Syria.

"In the last decade humanitarian relief spending has tripled, and it's still not enough," she said.

"It's also draining money from day-to-day development in the stable but poor countries. So we have a problem. And I hope that perhaps there'll be a reflection about investing longer term in what makes for more peaceful, more inclusive, stable societies. This is the long-term answer.

"In the short to medium term, peace in Syria would help enormously. But that's not about to happen. So what the international community can do is support the efforts to build the resilience of the countries in the neighbourhood to host the large numbers of people, the services."