How close are we to a sustainable planet?

How close are we to a sustainable planet?

April 24, 2023

Written by Alice Dutton, Cameron Kerr, Luca Bisio, Vignesh Iyer and Anjila Hjalsted 

What makes an item produced in today’s global economy ‘sustainable’? We took the world’s carbon budget, divided it between the global population and tried to understand how close (or far away) we are from a sustainable planet.

As more corporates join the global race towards Net Zero and a more sustainable world, the question remains: how will we know when have we done enough? The Planetary Boundary Framework (see below) gives us a scientific, state-of-the-art picture of how much we can strain the planet in nine different environmental areas, as well as a snapshot of how much we already have strained the planet in each. The planetary boundaries quantify this strain in areas such as biodiversity, freshwater reservoirs and climate change, before these reach critical threshold (also known as tipping points).

The ‘safe operating space’ (SoS) is the wriggle room humanity has within each of the planetary boundaries. As an example, the SoS for ozone depletion represents the number of ozone-depleting chemicals humans can release before this protective layer is broken down irrevocably and poses a threat to life on our planet.

chart biosphere integrity


What is absolute sustainability?
Now that we have a framework that quantifies the environmental impact of humans using the concept of SoS, a tricky question appears. How do we share the SoS between the global population equitably? This is a question which the new field of ‘Absolute Sustainability’* addresses. If an activity can continue to occur without breaching the nine planetary boundaries (now, or for current generations) then scholars have introduced the term ‘absolute sustainability’ to describe it.

Let’s take climate change as an example: to understand what could be considered as sustainable in absolute terms, we would need to divide a predetermined carbon budget between all human activities to see how much each one would be allowed. Impossible? No, but certainly challenging.

In this blog, we have used food as an example to understand how close we are to consuming food products that meet the goal of ‘absolute sustainability.’* For more information on absolute sustainability, including a short TEDx Talk on the topic, see this ClimatePartner blog post. The concept is relatively new, but has also gained enough traction to merit a flourish of academic literature and a department of its own at a high ranking Danish university.

For a more detailed breakdown of our approach and calculations, please contact us for a technical annex.

1. Why did we look at food? The food industry is a significant contributor of greenhouse gas emissions (24% of global GHG emissions, according to Project Drawdown.) Moreover, food is an essential human need and human calorific/nutrient requirements are well documented.

2. Why did we look at climate change? Climate change is highly intertwined with the other planetary boundaries. More importantly, it has the potential to significantly alter planetary functioning in a diverse range of ways, so understanding how we can exist within our means is crucial.

To determine whether a food product is sustainable in absolute terms with respect to carbon emissions, we first had to determine some key variables:

1. What is the safe operating space for carbon emissions? How much can we release?  To start using a simple analogy that will help, we could imagine wanting to divide a cake between people at a party. This step would be working out the size of cake.

2. Who wants to share the safe operating space? The global population, including future generations. For our analogy, how many people are at the party? Once we agreed on these metrics, we then worked on the following, more challenging question:

3. How do we share the safe operating space? How do we split the remaining carbon budget between individuals, both those who exist now and those of the future? Back to the analogy, this would be working out how we share the cake with everyone at the party (and others who might turn up to the party later).

So, how did we apply this?

1. What is the safe operating space for carbon emissions? The SoS can vary depending on how you measure it, so it is important that it is clearly defined. We decided to present two alternative remaining carbon budgets in this blog post (budgets to remain under 1.5 oC and 2 oC global warming since pre-industrial times.) We also assumed that we have 30 years to use this carbon budget (by which time we hope to be living in a Net Zero world, where carbon budgets are no longer necessary!) Then, we defined how much of the carbon budget should be allocated to global food production. Given that the current contribution of food systems to carbon emission levels is approximately 25%, we worked with the assumption that this would continue to be the case.

2. Who wants to share the safe operating space?
We took the global population in 2020 and assumed it would plateau over the next 30 years.

3. How did we split the food budget between the global population? You could split these budgets in a multitude of ways. We used two principles (developed in the academic literature) that could generally be viewed as fair approaches:

Equal per capita - every person gets an equal share of the global food budget.

Ability to pay - those from nations with lower levels of industrial development, and thus having contributed less to climate change historically, get a greater share of the food budgets. Using the UK as an example, we took its GDP per capita as a proxy of development. Once we determined one adult global citizen’s annual carbon budget, we drilled down to estimate their daily budget for food and then a value for maximum carbon emission per daily calorie (assuming a daily requirement of 2500 kcal).

carbon budget per day

So, what does this mean for the average person in the UK who wants to know if they are eating within their ‘absolute sustainability’ carbon budget?
We chose to look at a couple of meals from the recipe box company, Mindful Chef, because we have worked with them to understand the carbon emissions associated with their recipes (aka a recipe carbon footprint) and because they have designed their meals to be perfectly nutritionally balanced so there are no ‘non-nutritional’ calories in the meal.

Firstly, let’s look at a meal which has a lower than average carbon footprint for the UK: red lentil dahl with turmeric tender stem broccoli. It is plant-based and therefore isn’t associated with the high emissions we know to arise from meat production. If we take the ‘equal per capita’ approach with a 2oC budget, then we can see that the meal is above the limit —but could achieve absolute sustainability status with a 33% reduction in emissions. If we were to adopt an ability to pay approach, then we would be emitting over 12x the desired emissions. If we take a meat-based meal, like beef koftas, then we are much further away from our goal.


Emma Detain, Mindful Chef's Sustainability Manager, says: "These findings by ClimatePartner confirm that we need to work collectively to decarbonise the food system from farm to fork to achieve a truly sustainable meal. As a brand we are committed to minimising our carbon footprint as much as possible and have set short, near term targets to monitor our progress. We have a holistic reduction plan which includes both changes to our own operations, as well as projects to support and drive reductions down our supply chain, as we recognise that is where most of the work needs to be done. "

The key takeaway here is that our global food system needs to undergo radical change as quickly as possible, decarbonising whilst ensuring it can supply sufficient, healthy food to feed the global population.

This systemic shift needs to be addressed from the angles of food production and consumption. Below, we summarise what we believe to be the crucial enablers to decarbonising our global food system.

Consumption of food:
1. Switching to plant-based diets
Substituting high-carbon meat-based meals with low-carbon plant-based meals is the most impactful choice we can make to facilitate the shift to a more sustainable global food system, as well as lowering our own carbon footprints (see graph below). Animal proteins, especially ruminant proteins such as beef and lamb, have up to 10 times more carbon impact than alternative plant-based proteins (McKinsey, 2020).

Whilst not everyone is able commit to a 100% plant-based diet, our calculations are a demonstration that plant-based meals are significantly closer to being sustainable in absolute terms, meaning an individual’s choice to switch to plant-based meals several times a week would have an impact. As the food system decarbonises further, these plant-based meals will likely then be the first meals that fall within the boundaries of absolute sustainability. The WWF also identified plant-based meals as being the best option for having a low carbon impact whilst ensuring nutritional and dietary meals are met. So, when it comes to your next meal, could you consider swapping a ‘meat-centred’ meal with a ‘plant-centred’ meal?

Reducing the size of meat portions within meals can also be impactful. The recommended daily protein intake for an average adult is 45g (female)/56g (male). The UK National Diet and Nutrition Survey suggests adults are eating 45-55% more protein than their body needs per day.

greenhouse gas

2. Reducing food waste
Around 33% of food produced globally is never consumed (Mckinsey, 2020). The causes are two-fold: food loss and food waste. Food loss occurs early in the supply chain, in stages like production, transportation and storage, and is caused by lack of access to technologies such as cold storage. Food waste occurs at the retail and consumer stage, particularly in higher-income countries, and stems from aesthetic preferences for the food we eat as well as discarding excess food in the home.

Whilst it’s evident those involved in food production need to shift to practices to ensure food loss is reduced, it is also clear we as consumers also need to consider how we can also reduce waste. Practices such as meal planning can be an easy and cost-effective way to reduce our personal food waste.

Would you like to know your daily carbon budget? Would this help you make climate-conscious choices? Get in touch.

The concept of absolute sustainability can help determine whether something is or is not sustainable in absolute terms. Understanding what absolute sustainability looks like is the first step to achieving it. To get there, we need to take bold action and remember that better is not always good enough.