COMMENT: I can now say with confidence that the conversation around agricultural emissions is in for a major shake up.

Policy makers who have long criticised agriculture's contribution to global warming are now realising it was all a bit of a misunderstanding. The truth is, New Zealand agriculture is almost certainly not adding to any further warming of the atmosphere as of today. This means farmers are already meeting their Paris Agreement obligations of keeping warming under two degrees, thus negating any moral argument to pay a tax under the Emissions Trading Scheme (ETS).

So what has changed?

There have been two major developments in the last three months which have allowed the discussion to move past the endless debate on the physics of methane, to a more substantive discussion on what agriculture must do to avoid further warming.

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The first was the release of the recently created metric called GWP*. This metric effectively zeros agriculture's methane emissions at warming neutral. This has been calculated to be on average, a 0.3 per cent annual reduction.

If emissions go up, GWP* puts a CO2 equivalent warming value on that. Also critically, if emissions go down this metric will put a CO2 equivalent cooling value on that.

Many people are still waking up to the fact a greater than 0.3 per cent reduction in methane emissions will result in a cooling trend. The Productivity Commission was impressed by the potential of this new metric stating, "GWP*'s greater accuracy would justify its use to guide policy decisions about relative mitigation efforts between short- and long-lived gases".

The second development was the release of Simon Upton's PCE Report which confirmed that a 10 to 22 per cent reduction by 2050 will offset any warming from methane.

Listen to Steven Cranston talk to The Country's Jamie Mackay about agriculture and the ETS below:

The 10 per cent figure assumes moderate mitigation action from other counties and would be a fair starting point given international action to date has been very limited. A 10 per cent reduction might sound significant, but this correlates exactly to the 0.3 per cent annual reduction used in GWP*.

Most interesting was what the Upton Report failed to include. Agricultural emissions have reduced a combined 2.9 per cent in our last two years of available data, without any taxes or forced land use change. The short story is, agricultural methane emissions can effectively be stabilised at current levels without adding to warming. How the report managed to conclude 1.3 to 2.8 million of hectares of farm land must be converted to forestry to stop warming is a worthy discussion for another day.

With clear evidence agricultural methane is not adding to warming, the question then becomes, what is?

Nitrous oxide is a long-lived gas and makes up around 15 per cent of agriculture's total emissions. Some very basic maths would suggest all of these N20 emissions can be offset with around 870,000 ha of typical native bush. Sheep and beef farmers alone are estimated to have 1.4 million ha of woody vegetation on their properties. It would be very difficult to conclude anything other than the fact NZ agriculture creates no additional warming.

Some will try and claim that farmers should not get credit for their pre-1990 trees. The 1990 rule related specifically to the Kyoto Protocol, the updated Paris Agreement allows each individual country to make their own decisions on this. Farmers have every right to expect the government to give them full credit for the provable carbon sequestration occurring on their land.

So where to from here?

Industry good bodies like DairyNZ and Beef & Lamb NZ are in an excellent position to turn the Carbon Zero Bill into a major boon for agriculture by leading in the development of a smart ETS. We now have the tools to demonstrate NZ agricultural products are 'zero warming'. Every block of butter and leg of lamb that leaves these shores should be proudly branded as such. If we can extract just a 2 per cent price premium across all our exports, our farmers would collectively receive an additional $400 million a year.

A smart ETS is exactly what our industry needs to compete internationally against synthetic protein makers and the increasingly vocal anti-milk-and-meat brigade. It will also go a long way to improving public opinion, which has been damaged by repeated attacks from activist groups with limited understanding of agricultural emissions.

The idea that agriculture is 46 per cent of New Zealand's emissions is only true if we use the outdated GWP100 accounting system. If New Zealand really wants to be world leaders in this space, it is time we started using an accurate metric that correlates to actual warming. Again, there is nothing in the Paris Agreement that would prohibit us from using more advanced metrics. Farmers should accept nothing less.

The definition of net zero emissions has not even been defined by government yet, both option two and option three can be considered net zero. This zero warming concept is effectively option two and will still comply with the Government's 2050 target.

The entire submissions process will in hindsight be viewed as a massive waste of government resources. At no point did the government explain to the public that stabilised methane emissions do not cause further warming. Why the public was asked to make submissions without having all the information is not yet clear.

There is a very important point in this debate that farmers and the general public need to understand - no policy maker or climate scientist with any credibility will come out and say agriculture is adding to further warming.

They have simply worked out that if they can force farmers to reduce their emissions, then the rest of the country can keep on warming for longer.

I will let you decide if you think that is fair.

Steven Cranston is an agricultural consultant for Cranston Consulting based in Hamilton.