New Zealand's biggest emitters for 2023 revealed

New Zealand's top 10 emitters still make more than half the country's greenhouse gases, with Fonterra taking out the top spot for the third year running, followed by the three biggest petrol retailers.

Overall, the top 10 have reduced their tallies slightly, by a collective 2 million tonnes from the previous year.

Petrol companies Z Energy, BP and Mobil remain in the next three spots after Fonterra, but Mobil has overtaken BP to take third spot.

Rounding out the top 10 are various meat companies (Silver Fern Farms, Alliance and AFFCO), two gas field operators (Todd and OMV) plus NZ Steel and Open Country Dairy (tied on 1.4 million tonnes).

The figures are for the year ending 30 June 2023 and were published by the Environmental Protection Authority (EPA), using data companies have to supply by law.

Although the figures are only a partial picture of the companies' impacts, they are one of the few ways to compare companies which choose to publish their greenhouse gases with ones which do not.

They cover the country's biggest emitters in coal, gas, petrol and farming.

For context, at last count, New Zealand's entire annual greenhouse gas output was 76.8m tonnes, although this was calculated using different methods and was not directly comparable.

The top 10 companies collectively reported 43.4m tonnes of emissions in a year to the EPA.

How the top 10 fit in

Overall, there was little change, either in the rankings, or in the climate pollution.

Despite some shuffling of places, the three big fuel retailers' combined emissions were similar to the previous year, at a little over 16m tonnes.

That compares to Fonterra's 12.8m, which was down slightly from 13.1m in the year to June 2022. (This is not the co-operative's whole impact, which is closer to the combined fuel retailers' emissions once sources not counted by the EPA are added.)

The biggest drop in emissions in the top group was recorded by meat exporter Silver Fern Farms, however when RNZ asked about this, the company said that was likely down to a change in the way emissions were accounted for rather than a big operational change.

The EPA said it could not comment on individual companies.

An even larger drop - from 2.5 to 1.1m tonnes - saw Genesis Energy drop out of the top 10 since last year. The power generator and retailer was able to drastically cut its coal imports when rain refilled its hydro dams, reducing the need to run Huntly's coal-fired generators. Again, Genesis' true, self-reported impact was higher than the EPA tally, though also moving down.

The industries in the top 10 were the same ones dominating national totals.

Like the country as a whole, the EPA tally was dominated by dairy and meat (producing mainly methane and nitrous oxide) followed by petrol and diesel vehicles (making carbon dioxide) and heavy industry (also making carbon dioxide, burning from coal and natural/fossil gas).

There was one New Zealand company which was not a big player in either the EPA list or the national inventory, but only because its main impacts happen overseas - Air New Zealand.

The airline voluntarily reveals its emissions, and its own latest report puts its annual climate impact at 3.7m tonnes (3.4m of that from jet fuel, mainly from international flights). That would put the airline 5th on the list, if the emissions happened in New Zealand.

What gets counted and why

The EPA figures were often smaller and different from totals reported by companies themselves.

However they were the only way to compare and track emissions changes year-on-year, between companies that report climate impacts themselves, and those that do not.

That is because climate disclosure laws do not require most privately-owned companies to publish their climate impacts in a standardised way, and several of our biggest polluters choose not to reveal any totals themselves.

The EPA list was possible because big players in the Emissions Trading Scheme (ETS) have to report a total to the authority every year, so they can be charged a carbon price. (Despite this, many exporters, such as NZ Steel, receive most of their credits free on the basis they would otherwise lose business overseas.)

Big agricultural companies (dairy, meat and fertiliser) also have to report their emissions to the EPA, in their case methane (from cow and sheep burps) and nitrous oxide (from concentrated animal urine and fertiliser). But they do not have to pay for these.

Companies' tallies were calculated using fairly crude estimates based on taking quantities of meat or milk processed or coal, gas or petrol imported or purchased, and multiplying that by how much global heating was estimated to be caused over 100 years.

The company at the top of the supply chain was responsible for everything underneath - so emissions from beef farms were allocated to the meat processor and exporter, not the farmer, for example, while petrol in a motorist's car was listed under the name of the fuel retailer who imported it, not the motorist.

There can be big differences when companies tally their own emissions.

For example, Fonterra's latest EPA total is 12.8m tonnes but its own reported hoofprint is more like 16m tonnes, which includes overseas activities.

Fonterra does not have to report to the EPA about the coal it burns to dry milk powder, or the diesel in its tankers, because they come under the company importing the fuel or supplying the coal. But Fonterra's own reports include these kinds of sources. (As of May, Fonterra told RNZ its coal use produced about 0.8m tonnes of carbon dioxide a year.)

Likewise, Z Energy's latest EPA tally of 7m tonnes (for the fuel it imports) was much lower than its self-reported total of about 10m tonnes (which also covers a different period).

EPA total reported emissions, 2023 versus 2022