Experts call on policymakers to consider the urgent global climate implications of generational differences in diet for public health and food systems.
Teenagers and young adults tend to have the highest individual environmental impact from their diets, but population ageing is driving total global carbon emissions - not because older people eat worse diets, but because of increasingly aging populations.
Publishing their findings in Nature Food, an international research team led by the University of Birmingham, calls on policymakers to consider the urgent implications for public health and food systems.
The study highlights that rising emissions are often linked to poorer diet quality, creating a dual crisis of climate pressure and worsening nutrition outcomes. There is also a global inequality dimension, as in Low- and Middle-income Countries (LMIC) higher-emission diets often coincide with improving nutrition.
Our findings challenge the dominant narrative that older populations are the most carbon-intensive consumers and prompts policymakers to face some tough challenges. In emerging economies, rising incomes are driving increased consumption of animal products, sharply increasing emissions among younger populations. This creates a growing dilemma for policymakers, namely, how to reduce emissions without undermining nutrition.
After analysing diets across 149 countries and 22 age groups – using data from 2000–2019 - researchers found that adolescents (11–19) and young adults (20–29) produce the highest per‑capita food-related greenhouse gas (GHG) emissions worldwide.
The study reveals an important second trend: seniors (60+) are now the fastest-growing contributors to total dietary emissions, particularly in high-income countries, due to population ageing.
Researchers' key findings included:
Young people (11–29) have the highest carbon-intensive diets globally, driven by greater consumption of meat, dairy, and processed foods.
Seniors (60+) are now the fastest-growing source of total emissions, particularly in high-income countries with ageing societies.
Global dietary emissions rose by 2.1 GtCO₂e between 2000 and 2019, with seniors contributing the largest share of that increase (25.4%).
Rising meat consumption, especially red meat, is the single biggest driver of dietary emissions growth worldwide - coinciding with worsening nutritional quality.
Corresponding author Professor Yuli Shan, from the University of Birmingham, said: “Our findings challenge the dominant narrative that older populations are the most carbon-intensive consumers and prompts policymakers to face some tough challenges.
“In emerging economies, rising incomes are driving increased consumption of animal products, sharply increasing emissions among younger populations. This creates a growing dilemma for policymakers, namely, how to reduce emissions without undermining nutrition.
“We must rethink climate responsibility or face a policy blind spot if interventions focus on only one age group - identifying clear intervention points by age group, whether children and adolescents, young adults, or seniors.”
The study challenges ‘one-size-fits-all' climate solutions focused on diet alone, calling instead for targeted strategies tailored to age groups and development stages:
For high-income countries, these blueprints should focus on low-emission, nutritionally adequate diets for ageing populations - addressing rising emissions linked to demographic change.
For younger populations globally, policymakers should prioritise education and behavioural change – reforming school and youth food environments.
In LMICs, we must balance nutrition needs with sustainable transitions, whilst investing in local food systems, productivity, and access to diverse diets.
“Food systems already account for around a third of global greenhouse gas emissions. Our research shows that - with the global population both growing and ageing - who we are, as much as what we eat, is becoming a defining factor in future climate trajectories,” said Professor Shan.
The rise in food-related emissions linked to older people is mostly due to there being more of them, not because their diets are especially harmful. Most of the rise in emissions among older people is simply because people are living longer and having fewer children.
In high‑income regions, older adults now account for the largest share of diet‑related emissions, reaching 22–29% of national totals across countries such as the U.S., Western Europe, and Japan. The increase is driven by population ageing rather than more carbon‑intensive diets.
Teenagers and young adults tend to eat more foods that have a high environmental impact such as meat, dairy, sugary foods, and drinks. In developing countries, as incomes rise, young people are eating more food overall, which increases emissions further.
For more information, please contact Tony Moran, International Communications Manager or call +44 (0)7827 832312
‘Youth lead current dietary emissions while seniors increasingly drive total emission growth’ - Yanxian Li, Jin Yan, Pan He, Prajal Pradhan, Shuai Fang, Yuli Shan, Franco Ruzzenenti, and Klaus Hubacek is published in BMJ Global Health.
About the University of Birmingham
The University of Birmingham is ranked amongst the world’s top 100 institutions. Its work brings people from across the world to Birmingham, including researchers, teachers and more than 40,000 students from over 150 countries.
England’s first civic university, the University of Birmingham is proud to be rooted in of one of the most dynamic and diverse cities in the country. A member of the Russell Group and a founding member of the Universitas 21 global network of research universities, the University of Birmingham has been changing the way the world works for more than a century.
Participating institutions: University of Birmingham, UK; Chongqing University, China; Fudan University, Shanghai, China; The University of Hong Kong, China; Cardiff University, UK; University of Groningen, the Netherlands; Potsdam Institute for Climate Impact Research, Germany; and Soochow University, Suzhou, China.
Professor in Sustainability
Professor Shanis an expert in Climate Change and Sustainable Transitions. His research aims to reveal how human activities affect global and regional climate change.
