Covering climate now series: Why cow burps are NZ's biggest climate headache

George Moss hopes scientists will help his cows produce less methane. Photo / Alan Gibson

Every time one of George Moss's cows belches, it adds to New Zealand's biggest climate change headache.

It's not the Tokoroa dairy farmer's fault that these, and any other of the millions of ruminant livestock that graze our pastures, are methane-making machines.

It starts when they munch on carbon-carrying grass. As this gets digested by microbes in their stomach, some of the carbon is converted to methane.

When it's belched, it rises into the atmosphere where it helps to trap heat, before finally breaking down into carbon dioxide.

Moss and wife Sharon, like many farmers, have tried to minimise their climate change footprint over their nearly four decades farming together.

"We try to keep imported feeds to a minimum and use industry support tools extensively, including private consultants."

They stock their paddocks at a lower than average rate, instead striving for above average profit and performance for each cow.

The bigger picture, however, is an inconvenient one.

Although a shorter-lived gas than CO2, methane accounts for nearly a third of New Zealand's emissions. Levels of it have risen by about 10 per cent since 1990, in line with a shift toward more intensive farming.

It's not the only source of climate pollution from our farmlands – there's also nitrous oxide, mostly borne from nitrogen fertiliser and livestock urine and dung – but it remains the sector's biggest climate challenge.

Methane - mostly belched from cows and other ruminant animals - make up about a third of New Zealand's total greenhouse gas emissions. Photo / Supplied

Although some inhibiting agents have shown promise, and scientists have made strides toward a climate-friendly cow, there's still no silver bullet for farmers like Moss to use.

And policy makers aren't waiting for one.

Environment watchdog Simon Upton has suggested methane emissions need to drop by 10 to 22 per cent below 2016 levels by 2050, with further cuts by the end of the century.

The Government is proposing its own targets.

Its Zero Carbon Bill, which takes a somewhat softer stance on biogenic emissions, like methane, than CO2, is looking for cuts somewhere between 24 and 47 per cent by mid-century. The industry is asking that the final figure sit toward the bottom end of that range.

Around 10 per cent of that would have to come by the end of the next decade.

On top of that, farmers are finally about to join other sectors in having to pay a price for their emissions.

Critics point out it won't be much - with a 95 per cent discount, for instance, dairy operations will be coughing up just one cent for every kilogram of milk solids - but it nonetheless represents a big step forward for our biggest-emitting industry.

"[Emissions pricing] will not be what drives ours or other farmers' behaviour - just as fuel pump pricing rarely changes driver behaviour."

In some cases, he thought the move would be counter-productive.

"It penalises those, such as organic farmers, who have very limited ability to make further reductions and those farmers who are higher emitters, either intentionally or inadvertently, will just absorb the cost."

Tokoroa's George Moss says farmers are keen to do the right thing when it comes to climate change. Photo / Alan Gibson

Moss said he'd rather see a levy, as suggested in an alternative proposal put forward by DairyNZ and other sector organisations.

"If there was to be one based on livestock numbers, this would send a signal about driving efficiencies. If we can achieve the same or a similar amount of milk from fewer cows and less inputs, there will a greenhouse gas footprint reduction."

He suspected this would be easier said than done - and to gain the required efficiencies on farm will require a huge amount of industry support.

"You do not know what you don't know, and huge up-skilling will be required and change can be challenging, especially if viability is any issue for some farmers."

As it stood, farmers were frustrated over how few tools were available to them, he said.

Achieving that first 10 per cent reduction over the next decade would not be about big transformations, but efficiencies in small but incremental gains.

Beyond that, he hoped that scientists would by then have delivered a methane-inhibiting vaccine.

Nonetheless, he felt farmers, facing some of the worst climate impacts themselves, were committed to do the right thing.

"This has to be of concern to all of us."

• TOMORROW: What rising seas mean for New Zealand.

This story is part of the Herald’s contribution to Covering Climate Now, an international campaign by more than 170 media organisations to draw attention to the issue of climate change ahead of a United Nations summit on September 23. To read more of our coverage go to nzherald.co.nz/climate