Quitting meat and dairy is not the only way to lower your carbon footprint - a few simple swaps in your food shopping can have a dramatic effect.

Switching whole milk for skimmed, processed burgers for make-your-own, and greenhouse tomatoes for overseas varieties grown in the sun can all make the difference - making a whole basket of swaps can be the equivalent to the carbon absorbed by four trees in one year.

These surprising findings come from food data firm CarbonCloud who were commissioned by natural energy drink TENZING to investigate carbon footprints of the average shopping basket. The two companies have joined forces for the second annual Knowvember - a month-long campaign bringing carbon transparency to the high street.

To encourage Brits to make educated choices, researchers have compiled two typical food baskets of goods, where simple swaps can reduce carbon footprints - or “carbon calories”.

The ‘high carbon’ basket contains a number of carbon-heavy products such as feta and goat cheeses, which demand huge amounts of water in production. Swapping these items for mozzarella or halloumi reduces the carbon by more than half.

Similarly, making your own burger with ground beef instead of opting for a processed hamburger can reduce your emissions footprint by 25%.

Swapping a chocolate bar for a packet of Haribo-style sweets cuts the carbon by 70%, and greenhouse grown tomatoes for sunshine grown ones cuts the carbon in half.

CEO of TENZING Huib van Bockel said: “These simple swaps show how easy it is to cut your carbon footprint once you have the knowledge. For example, coffee produces seven times more carbon than a TENZING, so making that simple swap will save both carbon - and money. But it shouldn’t be down to shoppers to work out the carbon impact of what they are buying.

“Across the board, food brands should know their footprint and show this on their packaging. What have they got to hide?

“TENZING is proud to be at the forefront of carbon labelling and we want other companies to join us and put customers in the Know.”

Erik Edlund, PhD in Data Science and VP of Science at CarbonCloud, said: “Carbon labels prove how easy it is to choose climate-smart with the necessary information. Starting by making simple switches to plant-based alternatives as often as they can has a great impact.

“Carbon footprints are one side of the story. Greenhouse gas emissions do not always correlate with other sustainability factors, such as organic farming or water use. However, the worse climate change gets, the worse other environmental issues will get as a result.

“For example, a UK tomato grown in the UK that has travelled less but is greenhouse-grown has a higher climate footprint than the Spanish tomato, not grown in a greenhouse.

“This is just one example of how the food we perceive to be more artificial and processed doesn’t always have a higher footprint.

“If you are curious about the carbon footprint of other foods head to https://apps.carboncloud.com/climatehub”

The campaign wants to educate consumers on the environmental impact of their purchases and urge brands to display emissions on packaging. Businesses wanting to join the carbon labelling movement and consumers eager to learn more can visit Knowvember.org.

Supporting members of Knowvember include: Little freddie, Ombar, When In Rome, Dame, Rubies in the Rubble, Oatly, Future Farm and more.