Dietary changes could help NZ reach climate targets

Red and processed meat (35%) and dairy products (19%) were responsible for over half of dietary greenhouse gas emissions associated with New Zealand households' food purchases in 2019, according to an analysis of data from almost 2,000 households and two million purchases.

“Kiwis who want to reduce their carbon footprint can make a significant difference by changing their diets,” says lead author University of Auckland honours student Eli Kliejunas.

New Zealand has committed to a 50 percent reduction in greenhouse gas  emissions from 2005 levels by 2030.

Food production is estimated to account for one-quarter to one-third of global greenhouse emissions.

This study used data on greenhouse gas emissions for various foods through  the production cycle from farming, to processing, transport, and refrigeration,  up until the point of purchase.  

“We have previously done work looking at the healthiness of food purchases  and we wanted to look more broadly at the environmental impact of our food purchases in New Zealand,” says Dr Kathryn Bradbury, senior author.

Age group of the primary household shopper and household size were  significant predictors of per capita dietary emissions.

Households with older primary shoppers had higher per capita dietary  emissions, while larger households had lower per capita dietary emissions.

The inverse relationship between household size and per capita dietary emissions could be attributed to increased energy efficiencies and reduced food waste associated with larger households.

This research highlights the importance of dietary choices in mitigating climate
change and provides a basis for targeted interventions.

“We know that food products that come from ruminant animals, such as beef, lamb and dairy products, generate a lot of greenhouse gas emissions,” says Kliejunas. “This is because ruminant animals produce methane, which is a particularly potent greenhouse gas over the short-term.

“Global recommendations for red meat intake are generally to eat meat no more than three times a week for health reasons. So, making sure you are not eating more than that will also mean you are reducing your carbon footprint.

“Agriculture accounts for about half of the greenhouse gas emissions we produce in New Zealand, and we export a lot of our meat and dairy products offshore. Policymakers need to work towards reducing both national and global consumption of meat and dairy.”

• See: Quantifying the greenhouse gas emissions of New Zealand households’  food purchases: An analysis by demographic  variables. Journal of Cleaner Production.

'Vegetarians' fewer than previously estimated

Meanwhile another study led by Dr Bradbury shows the accurate percentage  of vegetarians in New Zealand is more likely to be two percent than the 20 percent previously cited in market research.

The University of Auckland-led study used data from recent NZ Health Surveys, capturing answers from about 20,000 Kiwis, but unlike earlier surveys asked whether they excluded meat and dairy.

“There have been some market research that have asked whether people  identify as being a ‘vegetarian’, which is likely to overestimate the proportion of people who are vegetarian,” says lead author Dr Bradbury from the  Department of Epidemiology and Biostatistics in the School of Population  Health.

Fewer than one percent of New Zealanders are estimated to be vegan.

“This is important because government guidelines recommend a plant-based diet, with moderate amounts of animal-sourced foods.

"Although our study  estimated the proportion of NZers who never eat meat and dairy products, we are calling for a comprehensive national nutrition survey, which would give us information on the actual amount of red meat and other animal-source foods that the NZ population currently consumes, and see the extent to which NZers are meeting our dietary guidelines,” Dr Bradbury says.

“What we eat is one of the major risk factors for chronic disease in NZ, and we  don’t have good up-to-date information on what we are eating, and so we don’t know which dietary-related policies we should implement and whether any policies we have or are planning would help to reduce chronic disease in our population.”

• See Journal of Public Health Nutrition.