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Thursday, 12 August 2021 09:55

Farm emissions misrepresented

Written by  Steven Cranston
Steven Cranston Steven Cranston

OPINION: There has been a lot of talk about agricultural emissions lately, but very little honest conversation.

The Government repeats, at every opportunity, that agriculture must dramatically reduce its emissions to stop further climate change.

If addressing climate change was indeed the primary objective of this rush to put a tax on farm emissions, would it not be reasonable to expect the Government to be measuring agriculture’s impact on climate?

Astonishingly, this is not the case. This fixation on emissions has been a convenient way for the Government to draw attention away from the real issue – which is warming.

Not all greenhouse gasses are created equal. Some are long-lived like CO2, others like methane are short-lived and naturally decay in the atmosphere after about a decade. Both are GHGs that New Zealand produces plenty of. But the key difference is CO2 needs to reduce to zero to avoid any further warming of the atmosphere while methane emissions only need to stabilise at their existing level. Or more precisely, reduce by a minuscule 0.3% per year owing to some residual GHGs left behind in the decay process.

In basic farming terms, if you have the same number of livestock each year and keep feeding them around the same amount, your methane emissions will not be adding to climate change. At an industry level our methane emissions have remained relatively stable over the past 10 years, meaning little if any warming is being produced.

But why is warming effect so important? New Zealand’s climate policy is a direct response to the Paris Agreement objective of limiting warming to 1.5 degrees Celsius above pre-industrial levels.

The Climate Commission references this warming target dozens of times in its reports. Yet oddly it never refers to agriculture’s warming effect either.

The standard CO2 equivalents metric (GWP100) we currently use to account for methane has no relationship to year-on-year warming impact. It is only useful when looking at a single pulse of methane emitted in isolation. Given farms emit a steady flow of methane over time, GWP100 is not fit for purpose. This effectively means agriculture has no way to measure success against the very document that our climate policy is based on. Quite absurd!

According to the science, our methane emissions must reduce 10% by 2050 to have zero warming effect. The Government target for methane reduction is 24% to 47% by 2050. The Government seems to expect farmers to reduce their methane emissions at least two and a half times more than what was intended under the Paris Agreement.

This is a major anomaly that requires an explanation.

The more charitable among you might be willing to give the Government the benefit of the doubt. Maybe they just forgot to create a working group to check that their targets were science based? I am less charitable. You see, measuring methane’s warming effect is not some arduous and impractical task. It is not that the Government can’t do it, they simply choose not to.

Several years ago, a new metric was created called GWP*. This metric was designed specifically to account for methane relative to warming effect. Given 40% of New Zealand’s total emissions are methane, you would think the Government would be hailing this breakthrough.

The Productivity Commission went as far as saying it was a more appropriate metric to guide policy decisions. Not a peep on it from this Government, however. They have quietly swept GWP* under the rug in the hope no one else will find it.

The message is clear, farmers are not supposed to measure themselves by warming impact because they might find out how insignificant it really is.

The accounting shenanigans unfortunately do not stop there. The Government is a big fan of planting trees on farmland; they expect another 680,000 hectares to be planted by 2030. What they are much less enthusiastic about is giving farmers credit for the trees they already have.

New Zealand farmers collectively have over 2 million hectares of woody vegetation on their properties.

Most of this is actively sequestering carbon and reducing agriculture’s overall footprint.

Let’s cut to the chase, if NZ agriculture was measured based on net warming impact, it would be next to nothing.

The agricultural emissions scheme is not about saving the climate from farmers, it is about using the comparatively less costly emissions reductions from agriculture to help the Government meet its national emissions targets.

Steven Cranston is a Hamilton-based agricultural and environmental consultant.

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