KEY POINTS:
The word is "convergence" - the distance between the two major parties on climate change has shortened. The policy issue is no longer whether to act but how and when. Climate change has got big.
Prime Minister Helen Clark wants us to be the first "sustainable" nation, the first carbon-neutral country (which leaves out methane). "Seize the brand," she urged a business audience in Wellington last month.
Opposition leader John Key has signed National up to an active climate change policy with a tough emissions reduction target - basing his position on the science of climate change, the risks to the economy from international consumer choice, business practice and government regulation and the market opportunities in a climate-conscious world.
Both say there's money to be made and, without action, lost.
The Greens are chuffed. Their agenda now has a high billing and they are travelling nicely in the polls. Of course, they want earlier and deeper action - for example, they want their comprehensive carbon-pricing scheme implemented until trading is ready, saying it would help set the cap for the trading scheme.
And the Greens would regulate polluters harder and offer more and faster incentives for energy conservation and efficiency, for which co-leader Jeanette Fitzsimons is government spokeswoman.
United Future has declared Climate Change Minister David Parker's emissions trading plan "exactly in line" with its position. New Zealand First has fallen in step. The Maori party wants action but with particular attention to Maori property rights, including the treatment of forest sinks, where it has lined up with the forest owners against the Government.
Act, while sceptical of apocalyptic climate change scenarios that invigorate and scare the Greens, favours tradable property rights as the basis for environmental initiatives.
Compared with only a year ago, this degree of convergence is remarkable.
This is not because Parliament has suddenly become cuddly - it is the result of international developments and greater domestic public awareness.
Consumer habits in rich countries are changing, bringing campaigns on "food miles" and "travel miles" and possibly, down the track, carbon profiling of goods and services as business practices adapt to consumer sensitivities - and to rapidly changing government policies.
Around half the states of the US have taken some climate change or energy steps, pre-eminently California, which has a target of reducing emissions by 80 per cent from 1990 levels by 2050. Britain has a 60 per cent 2050 reduction target and Norway, picking up Clark's rhetoric, a target of carbon neutrality by 2050. The European Union is in its second year of compulsory carbon cap-and-trading for large emitters.
That sea-change offshore - coupled with a big public opinion shift here - has moved business opinion in this country. As a senior National MP says, "Politicians are struggling to stay up. Business is pushing past them."
Business has to manage risk (so do governments but most aren't much good at it). Climate change is now a recognised risk - just ask reinsurance and investment companies.
A large part of business' risk is government policy. Businesses need numbers and black-letter law, then they can decide whether to pack up and go or, if staying, how to factor the policy into business plans.
It is at that point that convergence reverses into divergence. When Parker gets to the detail, there will be space for dispute and disagreement, both among parties and among lobby groups. Forest owners and farmers are very wary.
One dimension is the balance between markets, financial incentives and regulation (and penalties).
Government parties and the Greens are instinctively more comfortable with regulation than with markets, which some on the left and in the Maori party equate with "privatising" what is traded. Hence their reluctance to develop a system of fully tradable water rights to ration water.
So the Government plumped initially for a tax. Only when that sank, holed by too many exemptions, did it turn to emissions trading, grateful for the Stock Exchange's initiative.
Having dawdled for seven years, in part because of strong adverse public opinion, the Government is now racing to make up time. Officials who have been frustrated by conflicting signals from the Beehive - wanting bold, imaginative policies but subordinating them repeatedly to number-crunching with minor parties - are now under the whip.
Policy is to be on the basis of "all sectors in, all gases in, no exemptions", though with different reduction "stringencies" to allow for the fact that there is no known method yet of reducing the methane in ruminant animals' breath and to take account of "leakage", or moving an emitting industrial plant to a less climate-change-conscious country. The "all-in" approach now has general backing from peak business organisations.
The timeline is ambitious: design completed by September, legislation in Parliament in October and passed by next May, with detail filled in while the bill is in the parliamentary mill. The Stock Exchange's trading platform is, in theory, to be trading Kyoto credits by the middle of next year.
Some long-time students of trading systems and climate change reckon that is too big an ask. Clark insists the timeline will be met. The Treasury is now playing a more active part.
Some big questions have to be resolved.
* How will allowances be allocated: on the basis of historical emissions, which would disadvantage cleaner operators, by bureaucrats, or by auction, as market theorists advocate?
* At what level, and when, will the cap, or caps, be set? What trajectory will they follow?
* Will targets and times to meet the targets be set, and when?
* How will international links to other markets work?
* When will the standards be set on what constitutes a credit? How will trading be monitored?
At least officials here have the European example of profligate over-allocation of emissions allowances as a warning of what not to do.
And the stories proliferating in the international media of cheating by traders (emissions reductions sold that are not carried out or sold twice) are another warning.
This leaves wide scope, and need, for engagement by business, including agribusiness, with policymakers. And wide scope for some serious disagreements.
Despite the general acceptance of "all sectors in", there are wide variations among the business lobbies, such as the Business Roundtable, Business New Zealand, the Business Council for Sustainable Development, the Chambers of Commerce, the Forest Owners Association and Federated Farmers.
The big players, Fonterra, New Zealand Steel, Rio Tinto, Fletcher Building, Solid Energy and the big electricity generators, all have different angles.
Still, "all sectors in" has helped National join the bus. It had already accepted global warming and the Kyoto protocol in the Blue Greens' discussion paper issued last October. Now it is hunting urban liberals and believes climate change is a key to their votes.
The Blue Greens are one strand of National thinking. They accept the British Treasury report by Sir Nicholas Stern as making a "compelling case about the catastrophic effects of climate change" and Stern's economic calculation that "the long-term cost of inaction is likely to far outweigh the short-term cost of action".
They have set a target of 50 per cent emissions reduction by 2050 - ambitious, given that methane accounts for half current emissions. Last month Key bought their target and heaped scorn on Clark's caution about targets.
Clark has cause: Targets are routinely missed, so better to get the policies right first. That was also National's deputy leader Bill English's position - and is that of a large proportion of its conservative members.
Both National strands, and Act and United Future, clearly prefer markets and financial mechanisms and only limited resort to regulation - though to get efficient markets for energy and allow for distributed generation, for example, legislation will be needed. The same goes for reducing energy demand, improving transport efficiency and waste.
Still, there is heavy and light regulation.
National, Act and United Future will argue for light regulation and lightening existing regulation, most notably the Resource Management Act. The urgent Greens believe stronger medicine is needed. Labour (and Jim Anderton) and New Zealand First steer a middle course, though more green than blue.
For Key, climate change politics is the chance to leapfrog Clark in next year's election. For Clark it represents her best chance to project vision.
The risk for both is that the public opinion wind in their sails dies away.
Most environmental issues are "yes, unless" issues, supported until the pocket-book, property rights or a holiday is interfered with. The new mood has yet to be tested.
And it might subside into complacency on this country's good news: that climate change will affect us less than others - and likely benignly in the early stages; and that we have abundant clean and cleanable energy available, even, eventually, for transport.
So what's the fuss? It's the brand, says Clark. It's the opportunity, says Key.
