Climate Change Negotiations Minister Tim Groser has been asked to lead a key strand of the climate talks which have just begun in Cancun, Mexico.
The talks he has been asked to facilitate at Cancun relate to the issue of measurement, reporting and verification (MRV).
Before going into politics, Groser was a diplomat and trade negotiator, eventually chairing the agriculture negotiations of the World Trade Organisation's Doha round.
"If a package is agreed at Cancun that takes us towards the holy grail of a final ratifiable agreement, the two crucial elements are long-term financing in exchange for clarity of commitments from the large developing country emitters," he said.
Last year's negotiations at Copenhagen envisaged a fund worth eventually US$100 billion ($134 billion) a year. But contributors need to know what they would be getting for their money.
"No one expects developing countries to reduce their emissions. That is impossible in terms of their development objectives," Groser said.
"The goal is to reduce the rate of growth of emissions in China, India, Indonesia and other big developing countries below business as usual."
So you need to know what was being assumed about a country's economic growth and the emissions intensity of that growth, he said.
"And you have got to be able to measure it, to report it and to verify it. People are not going to just give away money for nothing."
Groser said he is often called upon to defend the Government's climate change policies by questioners convinced New Zealand is doing more than anyone else.
To argue that we are not, he has to rely on what he knows of the European emissions scheme, what US states are doing, or Chinese initiatives.
"That's the best I can do. I need something much more systematic than that. I need an international MRV system that can say precisely what every major emitting country is doing and allow some comparability of the efforts of New Zealand and other countries," he said.
"[MRV] is rooted in the reality that you will not sustain political support for climate change policy if it is seen by your people that you are the only [Government] imposing costs on your country."