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ScienceSeptember 20, 2019

Does saving the planet mean the end of the sausage sizzle?

Photo: Getty Images
Photo: Getty Images

Covering Climate Now: Just how much of an impact would a shift to vegetarian diets have on the battle to halt climate change, asks Mirjam Guesgen.

The Spinoff’s participation in Covering Climate Now is made possible thanks to Spinoff Members. Join us here!

Kiwi cuisine is replete with meat: fish and chips, meat and three veg, steak and cheese pie. But eating meat is starting to get a bad reputation. This time, not just from animal rights groups but also environmentalists and intergovernmental panels. Our carnivorous habits are partly to blame for climate change, they say, and going green on our plates is one way to curb our ever-rising emissions.

So how much of an impact does ditching the deli-meat really have? Turns out, quite a bit. But for Kiwis, it’s less about what we’re eating and more about what we’re exporting overseas.

Agriculture is a double-whammy in terms of climate impact. For one, the process of making and transporting food makes greenhouse gases: carbon dioxide from running machinery, methane from cow burps and nitrous oxide from fertiliser or cow urine.

Second, the land needed to raise those potatoes or pork is all land that could be full of trees which help pull greenhouse gases out of the atmosphere. Cutting down those trees causes them to let go of their stored carbon dioxide and release it into the atmosphere.

In New Zealand, agricultural emissions makeup almost half of our total emissions and are the biggest contributor to our emissions total.

When comparing the emissions from meats like beef or pork with vegetables like potatoes or carrots, meat comes out on top. Beef is particularly bad because cows are huge animals that need a lot of land and feed to grow (which also has to be grown, somehow). Their size also means they burp out more methane.

Diets that are more plant-based can significantly reduce those emissions. Generally, the more plant-based, the fewer emissions. Even making a relatively modest change of eating low-emission meats (like chicken) and eating more fruit, veg and cereals can make a substantial difference.

Replacing meat with faux-meat also helps, especially if the product is insect or soy based. Lab-grown meats sound appealing, but their overall environmental impacts (not just greenhouse gas emissions) can be quite high because of the energy needed to make them. And of course, not everyone is keen on the sometimes-rubbery, overly-salted meat alternatives.

And being choosy about the food you eat isn’t accessible to everyone. Low income households don’t have the luxury of affording steak dinners but they also often don’t have the luxury of fresh produce, especially if the food they get is from a food bank.

Source: The Impacts of Dietary Change on Greenhouse Gas Emissions, Land Use, Water Use, and Health by Lukasz Aleksandrowicz, Rosemary Green, Edward J. M. Joy, Pete Smith, Andy Haines (2016)

But maybe the biggest issue for New Zealand is that most of its agricultural emissions come from making food for other people, not for Kiwis.

Methane emissions from dairy cows almost take the biggest slice of the greenhouse gas emissions pie, on par with carbon dioxide from transport. But even if everyone suddenly became dairy-free, that would only account for 5% of the milk New Zealand produces. Same goes for lamb and beef.

Between 90% and 95% of these foods get exported overseas to places like China, the United States and the United Kingdom.

So going vegetarian, vegan, or even just swapping out the saussies a few times a month can help the planet out. But reducing emissions is a global game. Our international trade partners would need to follow suit and then we’d need to set forth on the mammoth task of figuring out what will hold up our economy.

The greenhouse gases

Carbon dioxide isn’t the only player in the climate change game. Methane and nitrous oxide also contribute, especially when talking about agricultural emissions.

And not all greenhouse gases are created equal. Carbon dioxide has the biggest impact, because it hangs around in the atmosphere for thousands of years. Methane doesn’t stick around as long, about a decade, but it keeps more energy trapped within the atmosphere which heats the Earth. Nitrous oxide is somewhere in between, sticking around for a century or so and overlapping with carbon dioxide in terms of its heating ability.

Where do agricultural emissions come from?

Carbon dioxide:

  • Fuels used to run tractors and other machinery
  • Fuel for transporting food by trucks or planes
  • Fuel to bring farming materials (fertilisers, food, seeds) to the farm itself
  • Generating electricity to power hothouses, irrigation pumps, lights or fans in barns
  • Refrigerants leaking from cold storage facilities


  • Microorganisms in the water of rice fields that “breathe out” methane
  • Microorganisms in the guts of sheep and cows that digest their food (methane is burped out but can also be found in their manure)

Nitrous oxide:

  • Making fertilisers
  • Microbes in the soil turn nitrogen from fertilisers and cattle urine into gas

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