Wednesday, September 5, 2018

Steven Cranston: NZ should lead on smart agricultural emission accounting

The Zero Carbon Bill is an opportunity for New Zealand to lead the world on smart agricultural emissions policy. James Shaw has regularly touted his wish to see our country as international leaders on climate change and is trying to break new ground by bringing biological emissions into the ETS. To be leaders however, we must look forward and not backwards.

The issues with the current Global Warming Potential (GWP) accounting system for methane are now widely publicised and understood. Anyone who cares to investigate the origins of GWP accounting will find it was actually created by a group of climate scientists to demonstrate the flaws in comparing short and long-lived greenhouse gases. To their surprise, the IPCC saw things differently and adopted it as the international standard. So although GWP is now the accepted way to compare different GHG emissions, people should not be fooled into thinking it got there on scientific merit.

The flaws with GWP create significant policy issues for the Zero Carbon Bill. The goal of the Paris Agreement is specifically to stop warming, yet the Government response to this is to propose a simplistic tax on methane emissions. The Government currently has no way to calculate the warming effect from steady flow methane emissions so cannot even say if the tax is successful in its’ goal or not.

This point is compounded by the fact MfE has recently confirmed they do not know if NZ agriculture is contributing to warming or cooling as of 2018. Surely a world leader in agricultural climate change policy should be able to answer this basic question?

No one would argue with the fact a ton of methane emitted into the atmosphere will cause warming, that’s just a fact. That’s not how farms work however, they emit a steady flow of methane over time and if that flow is stabilised, any ongoing warming effect is thought to be ‘very minor’. This is important for our industry because 2016 methane emissions were only 4% above 1990 levels and are declining. The warming effect from methane is probably zero but farmers have no agreed way to demonstrate that yet.

If New Zealand really does have ambitions of leadership in this important global issue we will need to do things differently. Finding way to account for methane that directly correlates to warming is an absolute must for our ETS to have scientific integrity. Prominent climate scientists like David Frame from Victoria University have identified this as an issue and are promoting solutions such as the GWP* metric.

The other aspect holding us back from a leadership position on agricultural emissions is our lack of understanding on carbon sequestration. All the research funding has gone into the emissions side of the equation and almost none into understanding how much carbon is locked up annually on agricultural land. How can farmers possibly complete an individual farm GHG budget with only half the information? We now know thanks to the good work of Beef and Lamb that their farmers alone possess 1.4 million hectares’ of woody vegetation.  Although the detail on actual sequestration rates is still being worked out, much of this area will be regenerating native bush which will continue sequestering carbon for hundreds of years.

This give’s New Zealand its’ next big opportunity to innovate and show leadership. Satellite senor technology is now so advanced that we can accurately measure above ground biomass accumulation. Instead of using rough estimates of carbon accumulation using farm maps and sequestration rate tables, we should be assessing properties annually and giving farmers credit for their annual measured carbon accumulation. Sure, it will take a couple of years to develop and calibrate this type of system, but any country trying to claim a leadership position cannot ignore this technology.

The future of agricultural emissions accounting is to link satellite biomass data with individual farm GHG budgets using a model such as Overseer. We must also use a smarter way to account for methane which directly correlates to warming. If we can achieve this, we will not only be world leaders in accounting for agricultural emissions, but we might very well have created the world’s first verifiable ‘warming neutral’ agricultural industry. The Paris Agreement allows us the flexibility to innovate and do things better so as Jacinda Ardern would say, “lets’ do this!”
Steven Cranston is a Hamilton-based Agricultural and Environmental Consultant, who blogs at


Ancient Dan said...

One should question the first premise. Why should New Zealand take any action in relation the the Paris Acord.
We are .17% of world Carbon dioxide Emissions.
The entire exercise is therefore pointless.

Allan said...

Why is agriculture the bad boy regarding GHG?
Answer; because global government decree that South America should be the producers of agricultural product, so they will pay nothing for their animal emissions NZ grows pine trees faster than any-where else on earth, so our destination is forestry & tourism.
Now please tell me why, no matter where you are, humans are not charged for their flatulence or exhaling..

Unknown said...

If we account for trees growing and sequestering CO2, why do we not account for the grass growing and absorbing CO2?
they are both crops and both farmed.