Former prime minister Helen Clark is refusing to be drawn into a domestic argument over climate change but says there is growing momentum behind the issue in the United States.
The Government is facing criticism after announcing it will not sign New Zealand up for fresh commitments for reducing greenhouse gas emissions under the Kyoto Protocol, an international agreement under which countries agreed to set targets.
Greenpeace has labelled the move embarrassing.
Clark, United Nations Development Programme Administrator, said she had no comment on the Government's position.
But she said Hurricane Sandy, which caused widespread damage in the US, had focused huge attention on the issue there.
"One thing that has changed is the prominence now being given to climate change in the United States; Hurricane Sandy was such a horrific event [and] it comes hard on the heels of Hurricane Irene ... which also had New York on standby and did quite a lot of damage where it hit."
New York Mayor Michael Bloomberg's endorsement of US President Obama because of his policies on climate change during the recent presidential election campaign had also upped the ante.
"In this second term there has to be a prospect that the president will see tackling climate change as part of his legacy," Clark said.
"The politics of this have been very, very difficult in the United States but you're now seeing opinion poll evidence suggesting that a very large majority of Americans feel that human induced global warming is a significant problem and that leads to wanting their government to do something about it.
"It will still be a very hard fought issue ... but this is now the changed dynamic which could make it possible to reach a global agreement in 2015."
Clark was in Wellington to deliver a lecture on global governance to a packed theatre at Victoria University.
Her visit coincides with fresh speculation swirling around the Labour leadership but Clark, who is now based in New York, refused to comment. The leadership of the party was for a "new generation" of Labour members to debate, she said.
Is Andrew Little a good choice to lead Labour?