But, surely the target for methane should be set at what the zero carbon equivalent is, meaning what amount of reduction is required by 2050 to give you the same outcome as net zero carbon dioxide and net zero nitrous oxide at 2050.
Or maybe a simpler way to look at it is what reduction is required to ensure no additional warming is being caused by methane from NZ agriculture.
There needs to be a separate target for methane because it is a short-lived gas that quickly flows in and out of the atmosphere.
Unlike long-lived gases, such as carbon dioxide and nitrous oxide, methane does not need to be reduced to a net zero level to have no impact on climate change going forward.
The currently used metric of GWP100 was never intended to be used as a long-term regulatory tool and inflates the impact of short-lived GHGs.
Read more from Federated Farmers here.
There are more accurate metrics out there such as GWP* (GWP star) but it appears politically easier to set a separate target for methane, rather than to lead the world and upgrade the way we measure all greenhouse gases.
Now James Shaw will point to the Intergovernmental Panel on Climate Change report from last year and say we have already been given a number, give me a good reason why I should ignore the world experts.
Well, the first reason would be in the report itself, which says these numbers should not be used as individual country targets, it's a global target.
Second point, the bill already ignores the experts and calls for tougher carbon dioxide and Nitrous Oxide targets.
Third point, the experts modelled 90 pathways that would achieve the 1.5 degree warming target, and in some of those they actually had the amount of biogenic methane from agriculture increasing.
What they then did was give all those pathways to economists, who then worked out what was least cost to the globe.
We have no clue whether what is least cost to the globe also equals least cost to NZ.
We have an economy that still has agriculture as the backbone, a power supply that is largely renewable - we are very different to the rest of the world. So surely we need to run the scenario the IPCC did with the NZ context in mind.
The Meat Industry Association and Dairy Companies Association did just that.
They commissioned researchers from Oxford University to run the NZ long-lived gas targets through the IPCC models, and determined what is the amount that biogenic methane needs to reduce by to achieve the 1.5 target.
The answer was 7 per cent by 2050, or if we wanted to do it all by 2030, then 4 per cent.
Other papers have stated that biogenic methane needs only to reduce 0.3 per cent per year to have no additional warming impact.
The same scientists say that if the CO2 emissions reduce substantially globally, then the methane reductions will need to increase.
So surely the answer is that we ensure that the Climate Change Commission has access to a solid range of scientific knowledge on this subject, that they themselves calculate this number using the most up to date understanding, and then review on a regular basis.
Once we have those numbers we can look at the economic and social impacts, what's possible and what isn't.
Some people may point to studies and the promise of new technologies showing that we could have far greater ambition than just 7 per cent by 2050, or 0.3 per cent per year.
But I would argue that we need to be abundantly transparent with what we are asking the agriculture sector to achieve.
While there are some in the Ag sector who seem to think 24 per cent reduction is an okay number because we are likely to achieve it, it's not a number based on science.
If we can do more than what is scientifically required, then we are having a positive impact, and just like planting a tree that should be rewarded.
By just going for what we might be able to achieve if we really push ourselves, then all it's doing is putting farmers on a treadmill, hopefully just getting there, rather than allowing recognition of going above and beyond.
The government has pointed to the industry-led research into what may be achievable, as a signal that their proposed targets are all good.
Again they miss all the caveats, like the fact that none of the mitigations looked at considered economic factors.
Given that most of the mitigations mentioned are yet to be invented or commercialised, we had no idea whether they would be economically viable.
Also, just because a mitigation is available doesn't mean it will work on all farms.
For example, the feed inhibitor close to being released looks very likely to be able to make big reductions on my farm (if it's economically viable) but that is because I have the ability twice a day to put that feed additive in front of my cows in a regulated dose thanks to in-shed feeding.
My sheep and beef neighbours have no ability to do likewise.
