Britons are used to checking traffic light scores to compare the calorie, fat, sugar or salt content of different foods, but will a new environmental label make them think about the planet’s health too?

The Foundation Earth label means meat eaters and vegans are now able to compare the environmental impact of their food, whether it is a fry-up of bacon and sausages or plant-based no-chicken goujons.

“I want consumers to be able to say very, very confidently: ‘I know what I’m buying. I know what nutritional score it has but I also know what environmental impact it has’,” said Cliona Howie, Foundation Earth’s chief executive. “Some people think if the nutritional score is high, it doesn’t matter about the environmental impact.”

The label rates food on a sliding scale from A+ (great) to G (not good) in an ambitious attempt to give consumers the power to re-engineer a food industry that contributes up to 37% of global greenhouse gases.

Food groups and retailers including Nestle, Tesco, Sainsbury’s and Marks & Spencer are among the big names working with Foundation Earth to explore how environmental labelling can work as the clock ticks down to November’s Cop26 climate summit in Glasgow.

The initial resistance from some brands to the front-of-pack nutrition labels or “traffic lights” introduced more than a decade ago would suggest a likely reluctance to carrying a G rating, but Howie says some companies are willing to run with low scores.

“This is not about naming and shaming for brands or consumers,” she said. “This is all about progress for companies, saying, ‘OK, we’re going to score an E but how do we get to a C, or how do we turn a C into an A?'”

With transport a big factor, Howie hopes companies will seek more local solutions if products score badly. “In northern Spain where I live, people are starting to grow things they didn’t used to grow such as avocados, and kiwis,” she said.

Any food labelling system succeeds based on how easy it is for consumers to grasp and there are numerous complicated schools of thought on how to measure environmental impact.

The Foundation Earth “enviro score” is based on four measures: carbon, water usage, water pollution, and biodiversity. Shoppers can read detailed explanations of a product’s score on the non-profit organisation’s website.

The bounty found in supermarket produce departments means Britons munch on avocados and blueberries all year round. But while some consumers clock the food miles in their shopping trolley, others are unaware.

The meat group Finnebrogue, which owns a number of brands including Naked bacon, is putting the labels on its packs despite a set of results that range from A to D.

Its chief strategy officer, Jago Pearson, said the scoring process threw up some surprises for the company, which is based in Downpatrick in Northern Ireland. Some plant-based products fared worse than expected, while its 100% grass-fed wagyu burgers got a D.

However Pearson is adamant that the ratings will be a force for good. “Putting honest scores on packs will get away from the polarised debate between meat and plant-based, local and international, and ascertain the reality and communicate that,” he said.

Another Northern Irish company, Mash Direct, which makes convenience fare such as mashed potato from vegetables grown on its farm in County Down, is also on board.

It happily scored As and Bs but Jack Hamilton, the chief executive, says they would have embraced less flattering ones too and hopes the scheme will encourage producers to be more open about where all their ingredients come from.

“While we can grow potatoes incredibly well in County Down there are still loads of potatoes that are imported,” he said. [With eco-scores] you can then see the impact of somebody who is maybe taking shortcuts.”

“So it will be interesting to see the consumer response to having two packs in front of them: one has the front-of-pack labelling and the other one doesn’t. I think it’s the one that doesn’t have it that will trigger questions in their mind about what values that company has.”

By the end of this year, hundreds of products will carry the label. Prof Chris Elliott, who chairs Foundation Earth’s scientific advisory board, said the scoring was based on “hard science” and likened the level of interest in it to a “runaway train”. He has recently spoken with the ambassador of a South American country who wanted all its exports to be scored.

“When companies come to get their products scored we know some of them will be pretty bad and they might not want to advertise at that time, which is absolutely fine,” he said. “But they will know what they’re going to have to look at: how do we were reduce water? How do we increase biodiversity? Hopefully they’ll come back to be re-scored so it will drive good behaviour in the food industry.”

For Foundation Earth to succeed, however, it all comes down to how consumers react. “From what we have read, people do look at labels and make decisions around [them],” he said. “The consumer will make the system, win or lose.”