Low Carbon Footprint Baking – Lime and Courgette Cake By Sarah Dunkerton

We are all aware of the impact human activity has on greenhouse gas emissions. While it’s easy to tweak some areas of our lives to reduce our impact, such as choosing to walk instead of drive, it’s easy to forget that every area of our life has an impact.

The majority of our food based environmental discussion is limited to the meals served around the dining table. The impact that our bowls full of spaghetti Bolognese, our potato’s covered in meat stew, and our roasts of lamb and beef are vastly known to us.

Red meat has an undeniable effect on the environment, with cows being responsible for 10% of the anthropogenic greenhouse gas emissions through producing methane.

However, there is significantly less attention granted to other cooking practices, such as baking. If you’re anything like me, cake doesn’t stay around for long enough to dwell on its environmental impact! So, I decided to intentionally examine the carbon footprint of my favourite cake to see the damage I’ve been doing.

My cake of choice is lime and courgette with a cream cheese frosting. It sounds completely unappealing to many but trust me when I tell you it’s carrot cakes more attractive cousin!

I began by using an online website to calculate the carbon emissions for each ingredient and I was shocked! The total carbon emissions the whole delicious cake is the same as driving my car for 21 miles! (2.63 miles a slice!!!)

Lime and Courgette Cake with Cream Cheese Frosting Carbon Emissions

IngredientQuantityCarbon Emission (kg CO2 e)
Caster Sugar150g0.16
Self-Rising Flour225g0.22
Bicarbonate of Soda1/2 tsp.
Courgette250 g0.43
Cream cheese400g4.96
Icing Sugar175g0.19
Lime juice2 tbsp0.05
Oven1 hr1.87
  = 9.86

Total: 9.86kg CO2 e (28 miles in a petrol car / recipe)

As expected, the largest culprit for CO2 emissions was from the dairy ingredients, with the cream cheese contributing over half the total value! The other significant contributor was the hour needed to cook in a gas oven.

Rather than being completely gutted that my favourite cake had such a footprint, I decided to trial changing the ingredient and style of cake. The recipe I came up with is below, along with the reduced emissions!

Method for a Lower Carbon Emission Lime and Courgette Cake


  • Weighing Scales
  • 1 large Sized Mixing Bowl
  • 1 Medium Sized Mixing Bowl
  • 1 Sieve
  • 1 Grater
  • 1 Juicer (can be done by hand!)
  • 1 Chopping Board
  • 1 Sharp Knife
  •  1 Electric Whisk
  •  1 Muffin Tray
  • 12 Cupcake Cases
  • 2 Large Spoons
  • 1 Cooling Rack



  • 3x Medium Eggs
  • 125 ml Vegetable Oil
  • 150g Caster Sugar
  • 225g Self-Rising Flour
  • ½ tsp. Bicarbonate of Soda
  • ½ tsp. Baking Powder
  • 250g Courgette
  • 1 Tbsp. Zest


  • 175g Icing Sugar
  • 2 Tbsp. Lime Juice
  • 1 Tbsp. Lime Zest


1. Preheat the oven to Gas Mark 4 (180*C, 160*C fan)

2. In the large mixing bowl, beat together the eggs and sugar until the mix is creamy. Sift in the flour, bicarbonate of soda and baking powder and beat well.

3. Grate the courgettes and zest the lime. Stir these ingredients in until well incorporated.

4. Divide the mixture between the 12 cupcake cases and cook for 20 minutes.

5. Remove the cupcakes from the oven and transfer onto a cooling rack until cool.

6. Whilst the cupcakes are cooling down, make the icing. Sift the icing sugar into the medium mixing bowl and beat in the lime juice and zest until the mixture is smooth. (You may need to add in more juice / icing sugar depending on the texture you like!)

7. Spread the icing onto the cupcakes, serve and enjoy!!

Updated Lime and Courgette Cake with Lime Juice Glaze Carbon Emissions

IngredientQuantityCarbon Emission (kg CO2 e)
Caster sugar150g0.16
Self-Rising Flour225g0.22
½ tsp. Bicarbonate of soda½ tsp.
½ Tsp. baking powder½ tsp.
Icing Sugar175g0.19
Lime juice2 tbsp0.05
Time in oven20 minutes0.62
  = 2.79

Total: 2.79kg CO2 e (7.5 miles in a petrol car / recipe)

As you can see, a few small tweaks of the recipe significantly lowered the overall carbon emissions of the recipe to almost a quarter! Changing the butter to oil was very simple and made the cake moister in my opinion!

The updated topping from a cream cheese icing to a lime glaze not only cut calories but also intensified the lime flavour. I’d also never considered converting this cake into cupcakes, but it was another adaption which worked very well.

Simple changes like these in the kitchen can result in substantial carbon emission cuts in a household.  They are easy and often cheap to implement and mean you can enjoy your favourite food without concern for the high environment effect!

Everyone’s happy. 

* All emission figures have been calculated using https://www.foodemissions.com/Calculator

For more recipe ideas from MetMUnch go to www.metmunch.com/cook and follow us on InstagramTwitter and Facebook.

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