Produced in Association with


SERIES 23 / Module 02 Net Zero


Space on the planet per head of population:


● 6 football pitches of sea, +


● 1 football pitch of inhospitable land, +


● 2 football pitches of more habitable land


sea sea sea sea


year; or a recent record-distance test commercial flight from New York to Sydney at around 16,000km- and the world starts to feel pretty small. Perhaps a little more like a goldfish bowl than it might at first appear. These numbers hopefully feel easier


to grasp than the ‘number of planets’ headlines, giving a clear sense of how essential it is to find a way to live within the carrying capacity of our relatively delicate natural systems. If you take the exploration a little


further, then you can make a basic version of a global sustainability metric by working out the amount of space available on the planet per head of population. This seems like a useful reference point – i.e. how much space do we have to support our modern lifestyles? Referring back to the diameter of


the earth given above as ~12,500km, and keeping hold of the ambition to develop the numbers intuitively, most people know some kind of global number that helps to sense check this. For example, I have cycled Land’s End to John o’Groats, which is approximately 850 miles. Another reference point could be the number of air miles from say London to New York. If you take your global reference point for planetary scale and use it to explore on Google Earth, then you can come to a first pass estimate of the diameter of the earth. Doing so, you will be joining a rich history of people seeking to understand the scale of the planet over the past 2,000 years. Doing this helps to confirm that an estimate of the planet’s radius of around 6,400km is a reasonable starting point. A quick Google will then confirm that the surface area of a sphere is given by


Produced in Association with


4πr2, and running the numbers gives a surface area of the planet of around 515 million km2. Another quick Google gives the


population of the planet as being approximately 8 billion people, and dividing these numbers through gives an estimated global population density of around 16 people per km2 (including land and sea), or around 52 people per km2 if you just count the land and assume that ~70% of the planet’s surface is sea. These numbers still don’t feel very


intuitive though, so let’s break them down a little further. A seemingly easy reference point


would be the number of football pitches of space per head of population, until you realise that there is no standard size for a football pitch. Let’s reference the calculation against Wembley’s football pitch. Running the numbers gives a result that each person on the planet has ~9 football pitches of space, split out as ~6


Table.1


Fundamental drivers of human impact:


Combined impact: ~160 times higher


Ready reckoners for a sense of scale.


Read up in more detail for further context, search “I=PAT”.


1) Population size ~8 times higher


2025: ~8 billion 2000: ~6 billion 1975: ~4 billion 1950: ~2.5 billion 1900: ~1.6 billion 1800: ~1 billion


2) Consumption per head of population


~20 times higher


A proxy being GDP per capita (in current US$)


2020: ~$10,900 2000: ~$5,500 1980: ~$2,600 1960: ~$450


3) Efficiency of production


~1 times higher


Harder to quantify succinctly.


Let’s make a starting assumption that it remained flat.


football pitches of sea and 3 football pitches of land. A final step is to split the land up by


assuming that around one third of it is inhospitable, as some sort of sandy or icy desert, etc. So, an intuitive grasp of planetary


scale can be reached through these calculations, which give the amount of space on the planet per head of population as summarised below:


Space on the planet per head of population: ● 6 football pitches of sea, plus ● 1 football pitch of inhospitable land, plus


● 2 football pitches of more habitable land


Exploring these numbers


through the Brundtland definition of sustainable development, which is the ability to “meet the needs of the present without compromising the ability of future generations to meet


their own needs”, it is possible to imagine sustaining a healthy lifestyle from six football pitches of sea, one football pitch of desert, and two football pitches of habitable land. However, these numbers also


feel like they confirm that a modern ‘American’ lifestyle couldn’t be sustained in this amount of space, i.e. making the four planet claim explored at the start of this article feel credible.


The three fundamental sustainability levers: There is one other perspective which can be useful when seeking to understand sustainability from the global perspective. This relates to the three fundamental drivers of human impact on the planet, namely: the population size, the consumption per head of population, and the efficiency of production in supporting this consumption. When viewed in aggregate, a starting interrogation of these numbers


20


EIBI | JULY � AUGUST 2025


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36