The potential effects of climate change, plus an increasing world population with a growing proportion improving their standard of living (with less in poverty) mean that it is essential to consider how we produce food and how we consume it.

Regardless of anything else, too many people eat far too much – a lot more than they need to and too much for good health.

Newsroom:  Changing our diets to save the world

Can we grow enough food to feed us all in a changing climate? And can New Zealand thrive as a dairy exporter without worsening climate change? Eloise Gibson spoke to IPCC food security and farming experts and found them surprisingly upbeat.

Newsroom specifically wanted to know what the experts thought of New Zealand’s prospects of thriving as a meat and dairy-exporting nation, in a future where people eat less meat and milk.

We talked through the issues with five experts, whose readiness to answer suggested we were not the first to raise it since they reached our shores.

Based on their research in climate modelling, food security and farming methods, all of them agreed that eating and farming patterns need to change a lot if we’re to feed more people in our new and altered climate. That means raising fewer livestock and sharing the meat and milk we still eat more fairly between nations.

“Sharing the meat and milk we still eat more fairly” should be contentious. Who decides what is ‘fair’? How could it be enforced?

Right now, people in rich countries over-consume, despite the hefty climate impact of their livestock-heavy habits, says Pete Smith, a climate change and soil professor at the University of Aberdeen.

“We can’t have nine or ten billion people consuming the way people do in the Western world. But that’s not to say we don’t still have livestock in the system, we certainly do. But we can’t continue at the rate we are. Although consumption has to come down, there are still going to be global markets.”

Those markets are likely to change significantly.

Holding the pre-Easter IPCC meeting in Christchurch signaled global recognition of what most Kiwis know already – that, among developed nations, our greenhouse gas emissions are uniquely skewed towards farming.

Our problem is mostly cows, with their methane-laced burps and gas-producing urine, both of which New Zealand spends millions trying to solve.

But when these researchers talk about the climate costs of food growing; they’re looking much wider than reducing cow burps.

They’re discussing wholesale changes to the food system. “This is first time really that the IPCC has tackled food, as opposed to agriculture, in a big way,” says Tim Benton, who studies food security in his job as Dean of Strategic Research Initiatives at the University of Leeds. “I’m really hoping that, for the first time, people will start to pay attention to the impact our food systems have on climate and the impact climate has on our food systems.”

Globally, agriculture ranks second only to fossil fuels as a source of greenhouse gases.

Smith, from the University of Aberdeen, lists the numbers:

“Direct emissions from crops and livestock are about 14 or so percent of global emissions, if you include deforestation it’s 24 percent, and if you add things like transport for moving food around and the embedded emissions in the agri-chemicals, you’re probably talking 30 per cent. We can’t meet the Paris targets without it.”

Farming faces a circular problem. Growing food creates a lot of greenhouse gases, and greenhouse gas is threatening the world’s food-producing capability. “If we don’t tackle climate change, the impacts on the food system will be such that there’s no guarantee we could feed 11 billion people at the end of the century,” says Benton.

Even cows are not immune. “Dairy cows really do not like warmer temperatures, it decreases milk production and fertility,” says Cynthia Rosenzweig, a senior climate scientist at the NASA Goddard Institute for Space Studies.

Mitigation, Rosenzweig, Smith and Benton each explained, has to include rearing less livestock, especially our burping cows. “We need to think about what we’re eating and how much. Because large-scale animal production, especially industrial animal production, has a very large carbon footprint,” says Rosenzweig.

None of them suggests everybody goes vegan, because most of us will not, they say.

“It’s just unrealistic to think that everybody is going to give up meat tomorrow,” says Rosenzweig. “So we need to realise there’s probably a pathway of healthy diets that is not no meat at all, but reduced meat consumption.”

Dairy has a lower greenhouse footprint than beef, but it remains considerably higher-emitting than producing vegetable products.

Still, no-one expects a quick switch. “New Zealand has an important livestock sector and I don’t think these people are about to start growing carrots tomorrow. It’s about finding pathways to sustainable production,” says Rosenzweig.

Benton agrees. “On an existential basis, I don’t think any country needs to be particularly worried, because we’re talking about changes over a number of years,” he says. “If you look back 30 years, our agricultural industry was very different to what it is today and in 30 years’ time it will be different again.”

Major change is certainly needed, says Benton.

There will have to be major change in food production in New Zealand, eventually at least. The world market is likely to demand it.

If the current Climate Change minister James Shaw has his way there will be major change much sooner.

Rosenzweig, the impact modeler, sums up those trade-offs and farmers’ tricky conundrum. “The challenges for agriculture everywhere are to simultaneously be reducing their emissions of greenhouse gases and be adapting to a changing climate,” she says. To do it, they will need our help, and that includes changing our diets. “That’s why there’s a role for people changing what we eat. Because as we go from 6 or 7 billion people to 9 or 10 billion, how are we actually going to do that?” she says.

In New Zealand and elsewhere in the developed world eating less will be better for our health – but won’t that increase the population more if we live longer?