Climate change presents an existential threat - and a challenge that's going to require transformative action by governments and polluting industries across the globe. What actions can we, as individuals take? In the second of a series of extracts from his contribution to the upcoming book Climate Aotearoa: What's happening and what we can do about it, edited by former prime minister Helen Clark, Herald science reporter Jamie Morton looks at climate-friendly diets.
Should we take red meat out of our diets? Let's look at what we know.
Today, agriculture covers nearly 40 per cent of global land, making agroecosystems the largest terrestrial ecosystems on the planet.
Food production is responsible for up to 30 per cent of global greenhouse gas emissions, and nearly three-quarters of freshwater use.
As we in New Zealand know all too well, land conversion for food production is the single most important driver of biodiversity loss.
Ditching animal protein is seen by an increasing number of people as the only way to deal with the fact that, by 2050, the world's population will hit 10 billion, rendering the demand for meat higher than the industry's ability to supply it.
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As prominent New Zealand science communicator Associate Professor Siouxsie Wiles has previously pointed out to the Herald, studies suggest that climate change is going to lower the yields and nutritional value of staple crops like corn and wheat.
At the same time, it will expand the areas where crop pests can survive, and make it more difficult for farmhands to work at certain times of the day due to the heat.
"In other words," she says, "we simply can't rely on our current land-hungry, water-thirsty, pollution-heavy and extinction-inducing ways of producing food if we are to feed the ever-growing human population as our environment changes around us."
Science is also increasingly telling us about the health benefits of a more climate-friendly diet, consisting of less red meat.
Otago University researchers have found that eating less red meat could be key to New Zealand not only significantly slashing emissions but also saving billions of healthcare dollars over coming decades.
Specifically, they showed a population-level shift to diets rich in plant foods such as vegetables, fruits, whole grains and legumes could — depending on the extent of changes made — cut diet-related emissions by between 4 and 42 per cent annually.
More strikingly, if all Kiwis adopted an exclusively plant-based diet tomorrow, and avoided wasting food unnecessarily, we'd achieve what would be equivalent to a 60 per cent drop in emissions from cars.
As a bonus, Kiwis could collectively enjoy up to 1.5 million more "life years" — that's those equivalent to a year of optimal health — and save our health system between $14 billion and $20b over the lifetime of our current population.
There are already plenty of signs that a green shift is happening.
By 2016, the proportion of Kiwis who stated that all — or almost all — of the food they ate was vegetarian had grown by nearly a third from four years earlier.
The sharpest rises came from among 14- to 34-year-olds, North Islanders and, perhaps surprisingly, men.
More recent polling by Colmar Brunton indicates that about one in 10 of us is now largely shunning meat, amid a growing shift to sustainable lifestyles.
Industry data similarly indicate a downward trend of red-meat consumption in New Zealand over the past 10 years, with beef, lamb and mutton down 38 per cent, 45 per cent and 72 per cent respectively.
Rates of vegetarianism do tend to drop away among Kiwis in their 30s and 40s — likely because parents with kids to feed find it tougher to stay meat-free.
However, veganism, once considered a radical-fringe movement, is also on the rise.
An intriguing study by online cookbook Chef's Pencil on the countries and cities where veganism was most popular put New Zealand — an agricultural nation which we might think of as a carnivore's paradise — in third place.
The online cookbook used Google Trends to analyse the search-interest level — trawling for terms like "veganism" and "vegan restaurants" — across the world.
Supermarket chains have certainly noticed this trend, and have responded by stocking their shelves with more vegan, vegetarian and flexitarian - people who are primarily vegetarian but occasionally eat meat or fish.
You'll now find vegan chewing gum and vegan "fried eggs", along with plant-based sausages, hot dogs, patties and mince, and curious items such as "bacon-style rashers" and "chicken-free chicken".
In terms of sustainability, we do need to consider whether it is fair to compare New Zealand's meat sector with its overseas counterparts.
Beef + Lamb New Zealand argues that our farming systems, which make efficient use of land unsuitable for horticulture or arable production, are often unfairly compared with grain-fed, factory-farming models seen in the US.
Nearly half of our emissions come from agriculture — the bulk of that being methane from ruminant animals such as cows and sheep — and some farming models like intensive dairying do generally emit more greenhouse gases.
But the footprint of the sheep and beef industry has a different profile.
Sheep and beef emissions have fallen by a third since 1990, in step with falling stock numbers, and, with some 2.8 million hectares of forest on its land, the industry holds the largest collection of native bush outside the conservation estate, bringing some carbon-offsetting benefits.
• This extract series continues tomorrow, as part of the Herald's Covering Climate Now coverage, with a look at sustainable transport.
• Text extracted from Climate Aotearoa: What's happening and what we can do about it, a new book from a range of leading New Zealand climate scientists and commentators, edited by Helen Clark. Published by Allen & Unwin NZ. RRP$36.99. Available in stores from Monday, April 19