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Climate Change Minister David Parker says the United States' surprise sign-up to negotiations for a future climate change pact would make "an enormous difference" to efforts to reduce emissions.
After an apparent deadlock in the Bali talks, a breakthrough came on Saturday night when the US unexpectedly dropped its opposition to a proposal by the main bloc of developed nations for rich nations to help developing nations to curb emissions.
New Zealand was one of about 190 nations meeting in Bali over the past fortnight to work out the principles for negotiating a new international climate change pact, which will succeed the Kyoto Protocol when its first commitment period ends in 2012.
The new agreement sets out a "roadmap" to underpin negotiations for the new pact, which will be decided in Copenhagen in late 2009, to come into force in 2013.
Mr Parker said the United States' participation in a future pact was critical, not only because it was the world's largest emitter, but because of technology it could offer.
"It is a technological powerhouse, and that will be directed to bringing forward low-carbon technology. With their enormous financial clout, as well as their technological leadership, that will make an enormous difference to everyone else."
He said the outcome of the meeting effectively resolved two fundamental issues for any post-2012 agreement.
All developed countries will have to make comparable efforts to reduce emissions, and developing countries had also acknowledged they had to take some action.
He said that while developing countries baulked at any binding commitments on them, they had agreed to help with assistance from the developed world.
New Zealand was one of 15 countries chosen for an all-night sitting in a last-ditch attempt to negotiate the "thorny" issues, but Mr Parker said "in the end these things are crunched out by the big players ... [such as] China, India, the United States and European Union."
The Bali talks will ensure the post-2012 pact will have a wider reach than the current Kyoto group by including the United States as well as developing nations such as China and India.
