Greenhouse gas emissions from dairy farming have increased to an all time high, according to Stats NZ.
But emissions from the dairy cows themselves have dropped year-on-year, according to Ministry for the Environment, which the industry says is the best measure to look at. It said statistics which show dairy farming emissions have increased capture too many irrelevant categories.
Stats NZ figures show dairy cattle farming emissions rose 3.18 percent (up 546.2 kt CO2-e to 17,719.4 kt CO2-e) between 2018 and 2019, the most recently reported year. This is the highest figure on record, dating back to at least 2007.
The Stats NZ figures count all emissions produced on dairy farms, regardless of what the emissions stem from.
Two industry groups - Dairy NZ and Federated Farmers - said they monitor a slightly different set of statistics from the Ministry for the Environment, which show a decrease in dairy cattle emissions of 0.4 percent (down 73.8 kt CO2-e to 18,460.1 kt CO2-e).
Ministry for the Environment (MfE) dairy cattle figures count emissions produced only by dairy cows, but not from other sources on the same farm.
Federated Farmers national president and climate change spokesperson Andrew Hoggard said he was aware of MfE figures, but hadn't seen the Stats NZ figures.
He said year-on-year comparisons didn't necessarily tell the whole story.
"To me, you don't want to look at it in one year. That's a very short time period, lots of things can change. It may have been a good year, it may have been a bad year. I think what you want to look at is the total trend. And to me the total trend, particularly for methane, has been since 2006 emissions haven't increased - in fact they've gone down."
Nationwide methane emissions from all sources fell 4.7 percent since 2006. But other emissions from dairy, namely nitrous oxides which are emitted from manure and synthetic fertiliser, have increased since then.
In any case, Hoggard said it was less important to focus on dairy, and more on total agriculture emissions.
"Land use changes between dairy and sheep and beef and horticulture and arable - farmers are constantly changing farm systems. The key one to look at is total farm emissions reductions, not worry about whether it's dairy or sheep and beef."
Total agriculture emissions were slightly higher in 2019 than they were in 2006, according to MfE. Since the 2000s, sheep and beef farming has declined, while dairy farming has increased. Agriculture accounted for 48 percent of New Zealand's total carbon emissions in 2019.
The thing that matters most was New Zealand farmers were among the most efficient in the world at producing milk and meat, Hoggard said.
"To me, that's the important thing, because it's not New Zealand warming, it's global warming. It makes zero sense for us to reduce production here in New Zealand and just have it replaced offshore where they do it at a higher [carbon emissions] footprint."
Dairy NZ, another industry group, also does not use the Stats NZ figures because it includes all emissions on dairy farms, including those from beef cattle and sheep which also live on what are predominantly dairy farms. (By way of example: if a farm has 90 percent dairy cows and 10 percent beef cows, Stats NZ would count all emissions from that farm as dairy farming emissions, while MfE would count only the dairy cows' emissions.)
Greenpeace said the Stats NZ figures - showing an increase in emissions - gave a fuller picture by including emissions from synthetic nitrogen fertiliser, on-farm vehicles and other activities.
Greenpeace campaigner Steve Abel said the industry was intentionally excluding some of its emissions in an effort to hide its true carbon impact.
"The dairy industry itself wants to make that look a lot better than it actually is. And they do that by a trick of statistics - they exclude a whole lot of the things and activities that they're doing so as to make it look like they're not as bad as they actually are."
These figures - even the ones that show rising emissions - ignored some large emitting processes in the dairy industry, he said.
"The burning of coal for dehydration of milk powder by Fonterra is not counted as a dairy emission, but for most people that's illogical, because of course it's part of the dairy industry's activity and it should be considered part of their emissions."
By far the largest contributor to the country's agricultural emissions - about 75 percent - is the methane (CH4) produced when livestock digest their food. Hoggard said that's a fixed amount per animal, and not able to be reduced without reducing stock numbers.
"Whether it's a sheep or a cow, if you put in one kilogram of dry matter, you'll get, pretty much, 22 grams of methane out. So if you're wanting less emissions it's basically less feed," Hoggard said.
He didn't explicitly agree that cow numbers should be reduced.
"We produce food for approximately 40 million people. If we're not producing it, someone else is producing it [at a] higher footprint, or someone isn't producing it and people are going hungry."
There are small emissions improvements that could be made on farm - a couple of percent, Hoggard said - but beyond that it's technology, like a methane-reducing feed additive which would be a breakthrough in reducing emissions. The problem is it needs to be present in each mouthful to be effective, which wouldn't work for our pasture-grazed animals. A methane-reducing vaccine is also being worked on.
Abel said there was no debate: the number of cows needs to come down.
"The United Nations tells us that methane is a major climate heating gas. We have to cut it if we're going to deal with climate change. Over a 20 year period it's over 80 times more potent than carbon dioxide."
Abel said there were a lot of farmers doing good work to reduce their environmental impact, but these were overshadowed by those who don't, so the government needs to regulate.
"It is the only way we're going to solve the problem, because these voluntary measures don't work. I think the dairy bosses really laugh in our faces when we agree to these voluntary measures."
There were sustainable, economically viable solutions, he said.
"We need to phase out synthetic fertiliser, lower stocking rates and support those willing farmers to move to regenerative, organic farming that is farmgate profitable, but promises us healthy climate, healthy rivers and healthy people."
When people consider what type of world they'll leave for their kids, Abel said, they're more willing to making change.
"When presented with the option of a future that will be absolutely miserable for our grandchildren, or taking some tougher choices now, when they think about it I would say 90 percent of people say 'yep, we've got to take the tough choices, it's the right thing to do, because I don't want my grandchildren living in a miserable, climate change destroyed world'."
Dairy NZ principal policy advisor Roger Lincoln said the organisation used MfE statistics because Stats NZ data "captures a much broader set of emission sources under a dairy business, which might include horticulture, cropping, other non-dairy stock and the like".
"Therefore, the data is particularly broad - capturing dairy-owned sheep and beef, for example. Ministry for the Environment data is what industry and government use.
"Overall, agricultural emissions are relatively stable in both the StatsNZ inventory and MfE inventory."
Farmers are reducing fertiliser use and supplementary feed as well as planting trees to reduce emissions, he said.
"To deliver on the Zero Carbon Act commitments there's a lot of work underway to help farmers reduce emissions, through He Waka Eke Noa - a partnership between the primary sector, government and Māori.
"DairyNZ, with many other partners, is investing millions researching different farm system options, such as feed types and use, improved fertiliser and effluent use, and options for on-farm sequestration of carbon."
Farmers are required by the government to reduce methane emissions by 10 percent from 2017 levels by 2030. New Zealand's total greenhouse gas emissions rose 2.1 percent between 2018 and 2019. 2020 figures will be released in 2022.