Opinion: If people are prepared to dig deeper they'll find that reducing livestock numbers is not the way to combat climate change, Dr Jacqueline Rowarth writes.
Most people do not think that New Zealand needs to reduce livestock numbers to combat climate change.
Most is 50.4 per cent. Twelve per cent didn't know enough to decide, and 37.6 per cent thought "yes", which possibly indicates that they don't know the facts, but have been swayed by the vocal anti-farming lobby.
The question was asked by Newshub Reid Research in February.
The results were welcomed by farmers who are feeling societal pressure to do better by producing food with lower environmental impact that is also cheaper to purchase.
The vocal activists appear not to understand the realities or the science. For example, the latest missives from Greenpeace in response to the IPCC report on climate change states that "Industrial dairy is to New Zealand what coal is to Australia."
Industrial agriculture is generally considered to involve feedlots or barns where food is brought to the animals. New Zealand has animals outside grazing pasture most of the time.
More worryingly, there seems to be confusion about the impact of the greenhouse gases (GHGs) emitted by the sectors. Dairy cows, like all ruminants, belch methane.
Methane is a product of the digestion of plant material by organisms in the rumen. It is a potent but short-lived GHG, with approximately 60 per cent of the burp having decomposed to carbon dioxide in 12 years.
In stark contrast, combustion of coal puts carbon dioxide in the atmosphere that has been sequestered (out of circulation) for millennia.
Comparing the two takes focus away from fossil fuels.
In New Zealand, transport-related GHGs have almost doubled since 1990 and energy use has increased 44.3 per cent. In contrast, agricultural GHGs have increased by a much smaller 17.1 per cent and appear to be stabilising.
In the context of the fossil fuel impact, a focus on what is known worldwide to be efficient agriculture in New Zealand is a distraction.
Despite this, Greenpeace is yet again calling for a shift in New Zealand to "plant-based, organic regenerative farming".
Making the shift could result in agricultural GHG problems becoming worse.
Research has clearly shown that per unit of food production, losses to the environment (water and atmosphere) are higher from organic systems than conventional. Part of the problem is feed quality and the growth and production of the animal.
Research at Lincoln University in 2020 determined the lifetime intake of feed for beef production in different New Zealand spring calving systems.
The animals varied in time to slaughter weight (to produce a 300 kg carcass) from 18 months to 30 months.
From this research, and using published data on metabolisable energy and nitrogen inputs in the feed, the lifetime methane and nitrogen outputs (both GHG and urinary nitrogen) could be calculated.
An animal that took 18 months to reach a 300 kg carcass weight emitted half the methane and nitrogen emitted by a slower-growing animal that took 30 months to reach target weight.
Dr Jim Gibbs, a Lincoln University animal scientist, has stated that "Regenerative systems involving animals reaching weight at 30 months (and most in New Zealand will be 36 months) were comfortably the highest in both methane and N output."
Gibbs would like the importance of slaughter age and carcass weight to be made more explicit in public discussions of regenerative systems.
"No possible 'rumen or soil magic' in a regenerative system could ever redress the 100 per cent+ increase per kilogram of slaughter weight in methane and nitrogen waste outputs in regenerative systems where older stock were being slaughtered," he says.
He concludes: "If New Zealand genuinely wanted to rapidly and significantly reduce ruminant GHG and nitrogen outputs, it could. A premium price on early slaughter age (<18 months) that resulted in only half the current slaughter numbers achieving the premium requirements would still reduce GHG outputs from beef by 25 per cent. This could be done in a single year. The same structural realities apply to lamb production. This will never happen with regenerative systems."
Many organic production systems also suffer from slow growing and lower yields.
The premium associated with organic food sometimes compensates for the lower yields that are typically realised.
Higher prices do not however account for the greater environmental impact – a fact rarely mentioned.
Listen to Jamie Mackay interview Dr Jacqueline Rowarth on The Country below:
The 50 per cent of people who said that New Zealand does not need to reduce stock numbers to combat climate change probably understand that our farmers are world leaders in production efficiency (smallest GHG footprint per kg of food produced).
They might also remember that the Paris Agreement of 2015 stated that countries should do everything they can to reduce GHG without reducing food production, with developed countries taking the lead.
New Zealand has been doing its part, with scientists supporting the farmers and developing ideas, some of which have come from farmers, into practical solutions.
Many New Zealanders know that farmers are trying to reduce GHG even further without compromising food production, but the vocal and often politically motivated minority persist in spreading messages that sound good on the surface.
Digging deeper uncovers the reality.
- Dr Jacqueline Rowarth, Adjunct Professor Lincoln University, is a farmer-elected director of DairyNZ and Ravensdown. The analysis and conclusions above are her own. jsrowarth@gmail.com
