United Nations Development Programme administrator Helen Clark is optimistic an international meeting on climate change in Doha later this month could reach an agreement.
Miss Clark said in Wellington there was growing acceptance in the United States about the impact of human-induced climate change.
She says the US might not be in a position to ratify any agreement but if it signs one, that will get other countries involved.
Ms Clark says that having won a second term, United States President Barack Obama may want to make action on climate change one of his legacy policies.
