KEY POINTS:
Petrol and electricity would cost more and the dairy sector would face a bill of hundreds of millions of dollars under Green Party policies to make emitters face the cost of gases blamed for global warming.
Under present Government policies the cost of meeting obligations under the Kyoto climate change treaty falls entirely on taxpayers rather than emitters.
The Treasury's current estimate of that bill is just under $600 million for the period from 2008 to 2102. It would be about three times larger than that without the offsetting credits the country gets for carbon taken out of the atmosphere by Kyoto forests, planted since 1990 on land not previously forested.
The Greens' policy would require a flow of money from emitting sectors to the Government, sufficient to cover its liability to other Kyoto governments but with enough left over to "recycle" in various ways.
They include assistance with insulating older homes, public transport, some recompense for Kyoto forest owners and shelter for large industrial emitters whose international competitiveness would otherwise be put at risk.
Only large companies would have to get involved in the arcane world of international carbon trading.
Oil companies would need to acquire carbon credits - internationally traded rights to emit greenhouse gases - to cover the emissions from the fuel they import or produce in New Zealand.
Assuming that was passed on to consumers, at the carbon price the Treasury uses to estimate the Crown's liability that would add about 4c a litre to petrol and diesel. But international carbon prices move around and are subject to the vagaries of the exchange rate.
Power companies that burn coal or natural gas would have to acquire credits to cover their emissions, too.
That would push up power prices since it is the thermal generators that generally set the wholesale price. Any windfall profits made by the state-owned renewable generators, notably Meridian Energy, should be recycled into climate-friendly projects, the Greens say. Agriculture generates half the country's greenhouse gas emissions.
Greens co-leader Jeanette Fitzsimons said it was not reasonable to expect the farm sector to face a carbon price for all its emissions.
That is because there is no way at present to reduce emissions of the methane belched by ruminants other than by reducing stock numbers.
But dairying was growing so fast it posed a threat not only to the Crown's Kyoto liability but also to the availability of water in some parts of the country and it was polluting waterways, she said.
The Greens would place a liability for the growth in dairy emissions since 1990 on Fonterra and other dairy processors, rather than farmers directly.
The beef and sheep sector would be exempt since its emissions have fallen, but the deer industry would face a liability.
Climate change officials currently estimate the agriculture sector's emissions over the 2008 to 2012 period will be 38 million tonnes of carbon dioxide equivalent higher than they were in 1990.
At the carbon price the Treasury is using of $14 a tonne that would would be a cost of $532 million, most of which would fall on Fonterra.
Fonterra's sustainable production manager, John Hutchings, said it was still very early to be thinking about the detail of any pricing policy.
The Government has promised the farming sector it will face no price measures before 2013.
Greens' policy
* Companies that mine or import fossil fuels will have to buy credits to cover the carbon emitted when the fuels are burned.
* Electricity companies would buy credits for fossil fuels they burned.
* The agriculture sector would buy credits to cover any emissions - from animals burping and farting - above 1990 levels.
* Foresters would receive some benefit from the carbon stored in their trees.
