The study, published in Environmental Research: Food Systems, found the UK's current level of meat consumption is 2 to 3 times higher than recommended guidelines. The researchers wanted to explore the climate impact of five different options:
- Business as Usual (BAU) – continuing our current diet trends
- REDUCE - reducing the amount of protein eaten through lowering meat and dairy products consumed
- SWAP - replacing beef with salmon once a week
- NHS Eatwell – following the NHS dietary guidance
- Planetary – the EAT-Lancet Planetary Health Diet
Using data from 4,000 UK households in the Family Food Dataset, the team modelled outcomes from 2021 to 2050 and estimated the corresponding carbon emissions savings.
They found that should trends continue at the same rate as they did between 2001 and 2021, the BAU diet would see a reduction in food-related carbon emissions of 15% from 2021 to 2050 – the equivalent of a return flight from London Heathrow to Madrid, Spain (2,486 km).
But by swapping one portion of beef steak for UK-sourced salmon, the effect was nearly doubled, seeing carbon emissions reduced by 28% long-term - the equivalent of a return flight to London Heathrow to Marrakech, Morocco (4,583 km).
The REDUCE option had a reduction of 39% emissions, which equates to a return flight to Cyprus (6,565 km), the NHS Eatwell diet reduced emissions by 42% - enough to fly to Tel-Aviv, Israel and back (7,186km), and the Planetary diet would reduce emissions by 49%, which compares to a return flight to Baku, Azerbaijan from Heathrow (8,024km).
The researchers suggest implementing diet changes such as these would be highly advantageous in contributing to national targets of reduced carbon emissions.
Lead author Dr Jenny Baverstock, Honorary Research Fellow in Bristol's School of Biological Sciences and previously Principal Enterprise Fellow at the University of Southampton said: "Taking forward simple changes in our diets and also following existing recommendations from the NHS Eatwell guide could see important reductions in carbon emissions that are necessary for environmental sustainability.
"Our simple swap offers a nutritional/health advantage as well as an environmental one which is ideal as these two need to go hand in hand and not be traded off against each other".
Globally, the food and agricultural industry accounts for 26% of human-caused emissions, in the UK the figure is 20%. Emissions have been falling and could fall further with dietary changes, potentially playing a significant role in achieving the UK Government's target of net-zero emissions by 2050.
Animal agriculture is responsible for 82.5% of global food industry emissions. High environmental impact proteins of red meat, like beef, lamb, and pork, contribute significantly to these emissions. Protein sources such as fish, chicken, and legumes, also known as the pea or bean family, provide alternative protein sources with a lower environmental impact.
Beef and salmon steaks were chosen as a more practical dietary change that could realistically be adopted by the UK public, using familiar foods that are mainly produced within the UK.
Modelled to 2050, this single substitution switch had a reduction in carbon emissions of 7.30 kg CO2 emissions/person/week, a significant reduction in emissions just from a small dietary change.
The researchers recognise that changing population-wide dietary habits is challenging and involves trade-offs, requiring measures to mitigate impacts on traditional livestock farmers and sustainable production in the fishing industry.
However, the UK currently eats 31% less seafood than is recommended by government guidelines, and there is strong evidence that the consumption of meat, particularly processed meat and unprocessed red meat, is a risk factor in developing type 2 diabetes.
Professor Guy Poppy, Pro Vice-Chancellor for Research and Innovation at the University of Bristol and co-author on the research paper, said: "Given the public concern about planetary health this substitution of salmon for beef may gain traction with the public if, as well as promoting individual health there is more awareness around eating more sustainably. This offers an easy choice for people whom want to reduce their environmental footprint.
"In 2026, we face unprecedented trade challenges with the turbulence of the trade tariffs levied by the US and counter responses globally which raise questions around national food security and the role of a global food system. This might create additional opportunities for the UK to examine the domestic supply of fish for future stability, in particular, protein security."
Paper:
'Adapting the source of protein in diets to reduce carbon emissions: a UK case study exploring aquaculture' by J. Baverstock, D. Romero-Saavedra and G.M. Poppy in Environmental Research: Food Systems [open access]
