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Aligns with articles 1, 3 and 7 in the Terra Carta mandate

Sustainable Consumption

Measuring the sustainability of supermarket food products and how policies can enable shifts to more sustainable societies and consumption. 

By Dr Emma Garnett


Reducing the Environmental Impact of Diet

Food production has arguably transformed our planet more than any other human activity and is the leading cause of natural habitat loss and species extinction. Food production takes up half of the Earth’s habitable surface and is responsible for approximately 26% of anthropogenic greenhouse gas emissions, 70% of freshwater withdrawals and 78% of water pollution. Consequently, sustainable food choices are one of the most powerful ways in which individuals and organisations can affect positive environmental change. 

Reducing both the environmental footprint of diet and the land use of our diets is essential for restoring wildlife and for enabling nature-based solutions to climate change. However, we cannot simply ‘tree plant’ our way out of climate change. Nature-based solutions alone are not sufficient: stopping the burning of fossil fuels and reducing inequality is essential. 


Dr Garnett researches which interventions work to reduce the environmental impact of diet. These projects span the natural and social sciences as well behavioural psychology. Acknowledging the critical nature of understanding these interventions, Dr Garnett is working in two main areas: 

  • Measuring the sustainability of supermarket products, considering the impacts on climate change and land use. This information could then be used to inform supermarkets’ sourcing decisions and communicate to customers about foods’ sustainability.  

  • Pitfalls and promises of carbon labelling. This information contributes to understanding sustainable consumption drivers through both analysis and perspective pieces on the challenges and opportunities of environmental footprint labelling. 

I think David Bowie put it perfectly: I demand a better future. Society could be so much greener and more equal. It’s going to take every sector of society to build the future we want.


Transformational change is required to reverse the decline of nature and mitigate climate change, which will require a dramatic shift in corporate business models. Technical innovation isn’t enough by itself: we also need social innovation and reductions in demand to decarbonise, protect nature and reach net-zero. But what systemic changes, policies and approaches do we need to enable social innovation and more sustainable societies? Research and data is needed to advance the development of sustainable solutions. 

Influencing Systemic Change


Often feeling like an uphill struggle, reducing our impacts on climate change and biodiversity is of great importance for many citizens, but is this at odds with our expectations of choice and year-round product availability. Bananas, coffee, cocoa and tea—once luxury products—are now staples found in almost every supermarket basket. Supermarket retailers have evolved to meet this customer demand, offering large product lines and ensuring such products are available and affordable. In the process, customers have arguably become disengaged from the production journey, whether it be intensively reared salmon or bananas shipped halfway around the world on atmosphere-controlled ships. 

Addressing these challenges, Dr Garnett is researching how supermarkets and other actors can implement policies and create an enabling environment which make sustainable behaviours easier to achieve. Supermarkets are powerful actors and their decisions can shape our purchasing behaviour and determine which products we have ready access to. Supermarkets are also key sustainability policy makers for critical climate-damaging sectors, including food production, food waste and transport. 

Alongside favourable policy frameworks, organisations play a vital role in catalysing action to protect nature, climate and human health. Environmental action is often framed as the responsibility of individuals or national governments. While both individual and system change are needed, organisations such as businesses—which are intermediate in size and influence—have enormous potential to deliver effective policies around more sustainable diets.  

How to engage consumers in sustainability? We continue to grapple with this question and welcomed the chance to experiment further with CISL. Forming that connection – between consumer and producer – lies at the heart of the solution in our view.


Understanding these complex dynamics is the key to successfully navigating the low-carbon transition. But the risks can only be estimated if companies and governments provide transparent information about their exposure to fossil fuels. Climate-related disclosures are essential for understanding and estimating climate-related risks. As more companies and governments start to disclose their information, the market will be able to adjust, thereby allowing the creation of measures for building resilience. Such an approach will be the only way that we can ensure a just and orderly transition, one which protects the most vulnerable while the economy is decarbonised at a speed that is compatible with the goals of the Paris Agreement.  

about the author

Dr Emma Garnett is the Prince of Wales Global Sustainability Fellow in sustainable consumption, supported by Sainsbury’s supermarket. Her work focuses on reducing the environmental impact of diets.

She holds a PhD from the University of Cambridge in Zoology, testing which interventions were the most effective at reducing meat consumption and increasing vegetarian sales in university cafeterias.

She has previously worked with several different academic institutions, NGOs and businesses including the University of Kiel (Germany), Microsoft Research (UK) and Zoological Society London (UK).

Learn more

This case study was prepared by the University of Cambridge Institute for Sustainability Leadership (CISL) and aligns with articles 7, 3, and 1 in the Terra Carta mandate.