Active transportation such as cycling has many benefits that helps to reduce greenhouse gas emissions, but researchers say we need to think about what people eat in order to fuel their cycling.
In a paper published in the international journal, Scientific Reports, the researchers say people who have shifted to cycling as their main means of transportation, will have higher energy needs, which could lead to an increase in food-production related emissions.
The study is understood to be the first international estimate of greenhouse gas emissions associated with the extra food intake required per mile travelled by active transport.
Lead researcher Dr Anja Mizdrak from the University of Otago, Wellington, says producing the food required to fuel cycling does come at a cost.
“We have a conundrum — but a solvable one. To maximize the benefit on greenhouse gas emissions achieved by increasing active transport, we need to also address dietary patterns. Emissions associated with active transport will be lower if cycling are powered by low-carbon dietary options.”
The research estimates that the additional energy expenditure required to travel one mile ranged from 25 to 40 calories for cycling.
“If this energy is compensated with extra food intake, traveling an additional mile in the most economically developed countries could result in an increase in greenhouse gas emissions by 0.26 grams CO2-equivalents per mile for cycling.”
Dr Mizdrak says there is a significant difference in greenhouse gas emissions related to food production between the most and the least economically developed nations.
“There is a wide variability in emissions required to compensate for cycling between countries, representing an almost five-fold difference between the most and the least economically developed countries.”
Dr Mizdrak says active transport has many advantages including more pleasant urban living, reduced air pollution, and a reduction in chronic diseases like cancer and heart disease.
“But to maximize the effect on greenhouse gas emissions achieved by increasing active transport, we need to address dietary patterns too. Emissions associated with active transport will be lower if cycling is powered by low-carbon dietary options.”
Dr Cristina Cleghorn, a nutrition researcher at the University of Otago, Wellington, and co-author of the research paper, says reducing meat consumption and shifting diets away from processed food and towards more vegetables, legumes, whole grains and fruits are likely to have health and environmental co-benefits.
“Given emissions associated with different food groups range widely — from 0.02 for legumes to 5.6 grams CO2-equivalents per calorie for beef and lamb in one global study, consumers switching to foods with lower emissions could reduce overall dietary emissions by up to 80%.”
Dr Cleghorn says in high income countries, reductions in greenhouse gas emissions are largely proportional to the magnitude of meat and dairy reduction.
“In order to reduce greenhouse gas emissions we need to encourage changes in what we eat, as well as how we travel.”
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