Making one simple change to the average UK diet—swapping a beef steak for a piece of salmon once weekly—could cut each person’s emissions by 7.3 kilograms of CO2 per week, adding up to enough to offset the emissions of an international return flight.
Among several options examined in a new study to reduce personal dietary footprints in the UK, this was identified as a small, simple adjustment with outsized power to bring about real change.
The study compared this beef-for-fish protein swap with four other measures, looking at how each one would shift dietary emissions in the UK if applied at the population-scale and modeled out from 2021 to 2050. The other measures were business-as-usual, meaning the country would continue on its current dietary trajectory; a measure to reduce the UK’s overconsumption of protein; another to align national diets with the UK National Health Services’s (NHS) recommended ‘Eat Well’ diet; and a final one to transform the country’s consumption patterns in line with the globally-recommended, plant-forward EAT Lancet Planetary Diet.
The biggest surprise came from the protein-swap scenario, where just one portion of beef a week would be exchanged for a UK-sourced fish like salmon. Played out to 2050, this would bring down each person’s emissions from 26.38 kg CO2 to 19.07 kg CO2 each week, tallying up to a 28% long-term reduction in food-related carbon emissions by 2050.
Equating this to flight emissions, the researchers say that’s the equivalent of a return flight from London to Marrakesh. This could be achieved with what the researchers define as “a simple and consumer-possible change”.
Moving on to the other measures, they found that surprisingly, even continuing with normal diets up to 2050 would result in relative food-related carbon reductions of 15% in the UK by 2050, assuming that the consumption pattern continues as it did between 2001 and 2021. Nevertheless, this was still only half the savings generated by switching a portion of beef for salmon.
From here, the emissions savings only ramped up. The reduced protein pathway revealed that currently the UK consumes 33% more protein than it needs. If countrywide meat and dairy consumption were cut by a third to handle that excess, personal CO2 emissions would go down by over ten kilos per person per week, resulting in a long-term reduction of 39%. Meanwhile the NHS and EAT Lancet diets reduced emissions up to 2050 by 42% and 49%, respectively.
While swapping beef for fish doesn’t produce the biggest savings in this mix, this option probably has the greatest chance of actually being adopted, the researchers reason, because it doesn’t require an ambitious dietary change from the public. Also, fish like salmon is already a familiar option in the UK. And, the country consumes less oily fish than health professionals recommend, so there’s already a national incentive to get more fish onto British plates.
If that can be achieved by simultaneously replacing some beef, it would tackle two challenges in one: health and emissions.
There are some caveats to eating more fish, the first being that aquaculture may need to increase in scale and output to supply enough fish to sate this new appetite, and salmon aquaculture in particular doesn’t have a glowing environmental track record. The researchers recommend further research that looks at alternative oily fish to supply this demand more sustainably.
Ultimately, their work puts a straightforward solution on the map, and shows just how much can be achieved with small, incremental changes.
Baverstock et. al. “Adapting the source of protein in diets to reduce carbon emissions: a UK case study exploring aquaculture.” Environmental Research Food Systems. 2026.
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