It is ironic, in a way, that George W. Bush owns a ranch in Texas.

Go back far enough and that land would have been no one's property, part of the apparently boundless rangeland of the American west. An ocean of grass. Cattle heaven.

But we have long ago learned that to avoid what economists call the tragedy of the commons - such as the overgrazing of common land which lays waste the resource and leaves everyone impoverished - there comes a point where some form of rationing becomes necessary: boundaries, fences, registries, property rights and a market.

What divides the United States and its loyal sidekick, Australia, from the rest of the developed world is whether that time of rationing and regulation has come for the atmosphere.

Can we continue to burn fossil fuels untrammelled and heedless of the impact on the global climate? Or do we need a system akin to land ownership or fishing quotas that limits those rights and a market to ensure they flow to whoever values them most? The Kyoto Protocol is, of course, an attempt to set up such a system.

But the largest emitter of greenhouse gases will have none of it. And that is not about to change, the chief US climate negotiator, Harlan Watson, made clear on a visit to Wellington late last week.

At the Gleneagles summit this month, the leaders of the eight largest industrial power, plus China, India, Brazil, Mexico and South Africa, agreed on a "plan of action". It is a package of worthy but modest measures to foster the development and uptake of clean technologies.

Ongoing dialogue is scheduled among the G8 plus five group, which includes the leading representatives of devolving countries which collectively will soon exceed the developed countries in greenhouse gas emissions.

But we should not see that as a path forward to some sort of multilateral agreement on a regime to succeed Kyoto after 2012 (the end of the treaty's first commitment period).

The gaps are still too wide.

"Our European colleagues are still very much looking at a targets and timetable approach. We are looking more at a technology-based approach and the 'plus five' are certainly not ready to adopt a targets and timetables approach," Watson said. China, for instance had made it clear in a number of forums that economic development was its priority.

"So we think it is going to be an interesting forum to carry on discussions but it is too early to speculate on what will evolve."

But, even viewed from this distance, it is clear that the US is neither monolithic nor immobile on the issue of global warming.