Climate change benefits of substituting meat from the average New Zealander’s diet would only lead to a 3-4 percent decrease in an individual’s lifetime global warming impact and could risk individuals missing out on key essential nutrients, such as iron, according to independent research by some of the world’s leading scientists.
The peer-reviewed research paper was developed by climate, nutrition and environmental scientists from the University of Oxford, Massey University, University of Auckland, the New Zealand Agricultural Greenhouse Gas Research Centre, the Riddet Institute, Victoria University of Wellington Te Herenga Waka and the Ministry for Primary Industries. It has been published by the Switzerland-based Multidisciplinary Digital Publishing Institute (MDPI) in the Sustainability Journal.
Reducing or eliminating meat consumption is often billed as one of the most effective ways for an individual to lower the climate impact of their lifestyle. However, methane is a short-lived gas, whereas carbon dioxide is long-lived and, therefore, accumulates in the atmosphere.
Cutting meat out of the diet offers greater benefits for the climate in the short term, but over the long term, most of these benefits reduce because of the accumulation of carbon dioxide created by the alternative foods people would eat, and the eventual removal of methane over the rest of their lifetime.
The research sought to analyse the cumulative atmosphere warming impact of following the national dietary guidelines and the substitution of meat.
The team used a new metric known as GWP*, as well as the current 100-year global warming potential (GWP100) metric, as GWP* better reflects the global warming dynamics of methane arising from the different diets.
As far as the researchers are aware, it is the first study to use GWP* to explore cumulative climate impacts of dietary transitions.
“We welcome this research because it assesses dietary impact within the context of lifetime emissions and suggests that ‘meat-free’ is not the silver bullet it is often made out to be,” commented Fiona Windle, Head of Nutrition at Beef + Lamb New Zealand Inc.
“Whilst current environment footprint studies do not usually take into account the nutritional composition of foods, this paper highlights if you eliminate meat from the diet, then you are more likely to miss out on key nutrients such as iron, which is of great concern when we already have an iron deficiency challenge in New Zealand.”
Windle explained that the researchers were able to model a selection of micronutrients, based on available data and encouraged further research to broaden the analysis to better understand nutritional implications and climate change trade-offs in changing diets, such as sources of all the essential amino acids (found in quality protein foods).
“It is important anyone transitioning to a new diet ensures it is sustainable from an affordability, nutritional and climate perspective,” Windle concluded.
Beef + Lamb New Zealand is pleased this study helps to better understand the impact that emissions of short-lived gases such as methane have on global temperature, and this will help policymakers make more informed decisions.
The research paper can be found here