5 acres for every person

What if we were to split up the earth evenly, each person getting their ‘fair’ share? When we think about the earth, it seems so incredibly massive that many people have a hard time believing the amount of impact that humanity is having on the planet. One way to think about how we occupy the physical space of the world is to break it down in terms of the amount of different types of land there are for each person. While the world is more than 2/3 oceans, the ocean provides relatively little to our food and resources compared to the production on land, so we’ll focus on land area alone for this thought experiment. There are 37 billion acres of total land area on earth across all land types. As of early 2018, there were 7.6 billion people on the planet. Put together, this means that there is a bit less than 5 acres of land per person. Depending on whether you have an urban or rural perspective about land, this may or may not sound like a lot. We would argue that once one accounts for all of the resources that we rely on that come from natural ecosystems and agricultural land that this really isn’t all that much. See the table and pie chart below for a breakdown of how that land is actually distributed (the same information is in each).

Land typePercentageAcres/personMeters²/person
Mostly uninhabitable –
deserts, mountains,
glaciers
211.04140
Forests341.76700
Grasslands and rangelands281.45520
Crop lands130.62560
Inland fresh water – lakes, rivers, wetlands30.1590
Urban areas – buildings,
roads, etc.
0.50.090
Total1004.922160

data from https://ourworldindata.org/land-cover

Imagining each person had a homestead that included their proportional share of the world’s land types gives an idea of what kind of resources are available to support humanity. As things actually work out in our unequal world, some are of course utilizing much larger or smaller amounts than this. A five acre spread laid out as a square of land would be about 460 feet (140 meters) per side, around 5 football fields of space.

  • Uninhabitable land – One acre. Right off the bat, about 20% of land area isn’t very useful in supporting people’s needs, as it is made up of deserts, high mountains, and glaciers such as those covering Antarctica. People do travel through these landscapes to some extent, but very few stick around for any length of time.
  • Forests – 1.7 acres. About one third of all land is forested. Here in southeastern Canada, this amount of land could support one to two hundred trees of larger sizes, those with trunks bigger than about one foot in diameter (30 cm), along with all of the smaller trees, undergrowth, and wildlife. These trees grow at a rate of about 2% per year, so each person’s share of wood needs to come from something like 3 or 4 decent sized trees per year. That wood is needed to construct all the buildings, all the wooden furniture, make all the paper products and cardboard, firewood, pallets and shipping materials. Construction of a typical home might require the wood of 100 trees or more. While in much of North America forests are growing faster than they are being cut, the tropics are being deforested at unsustainable rates. Could your needs all be met from 4 trees per year?
  • Grasslands – There are about 1.4 acres of grasslands for each person. There once was much more grassland than today, but most of the areas that have enough moisture available have been converted into cropland. The grasslands that exist today tend to be on terrain that is too rough or too arid for crops. When it comes to providing for human needs, the primary use of grasslands is for grazing animals. This mostly means cows in North America, though there are numerous other domestic grazing animals such as sheep. Americans eat a lot of meat, roughly 200 pounds per year. The most productive grasslands, those that are wetter and more fertile, could provide 200 pounds of beef on each person’s one and a half acre plot, but most of the world’s grasslands are much less productive because they are drier and don’t grow nearly as much grass and other plants. Eating only grass and other forage, there simply isn’t enough grass on earth for the whole world to eat meat the way that Americans do. Of course livestock currently get more of their nutrition from farmed crops rather than from pasture (see next section).
  • Croplands – About 10% of the earth’s surface is in crop fields, or just over half of an acre for each person. This land produces enough to supply all sorts of needs. It is our fresh vegetables, grain for bread and to feed to livestock, cotton for clothing, and the base materials for chemical products, especially biofuels. Before agriculture, these were some of the world’s most prolifically producing natural ecosystems, having some of the best conditions for growing plants and all of the other life that depends on them. Fields were carved out of forests, grasslands, and wetlands, and these areas are still very productive today. Just 55% of this area grows food that is directly eaten by people, 36% goes to feeding livestock, 10% to biofuels. This direct food portion would be a garden about 100′ long and 100′ wide. That quarter acre plot of land has to provide about 80% of all of a person’s calories (the rest coming from meat). Homesteaders may have gardens this size and directly produce much of their own food, but most farms today are heavily mechanized with each farmer tending hundreds or even thousands of acres of cropland.
  • Waterways and wetlands – The portion of each person’s little plot that has water on it would be only .1 acre, which would be a square about 80 feet (25 meters) on a side. That includes your entire portion of all the streams, rivers, lakes, swamps and marshes. Taken at that individual level, this isn’t a lot of water for each person, and we need that water for so much. It provides drinking water, irrigation for crops, it carries away our wastes, transports people and goods, provides fish and recreation, and is critically important for natural ecosystems. We are doing better than we once were at taking care of waterways and wetlands, but the health of these systems still needs improvement.
  • Urban space – Urban areas actually make up a pretty small portion of the world, less than 1% of land area. This adds up to about 1000 square feet per person, the size of a comfortable two bedroom apartment. This number includes not only our homes, but also all of the roads and parking lots, commercial and industrial buildings, everything within our towns and cities. Over half the population worldwide live in urban areas, with the US and Canada over 80% urban, and urban areas are continuing to grow at the expense of rural populations. With how tightly packed things are in many urban cores, it is perhaps no surprise that over half of people are packed into under 1% of the space.
The grassy area visible in this photo, not including the forest, is very close to 5 acres of land. From the Farm at Manitou Bay.

One of the main points to writing a piece like this is to show how finite the world is. Compared to how many people there are today, there isn’t much for ‘extra’ space, as we’re already occupying almost all parts of the world and don’t have much for new frontiers to push into. This means that what we really need is to be the best stewards that we can of the places that we inhabit and use. We need to be more efficient in our use of resources, and to maintain our landscapes more sustainably. We have the solutions in hand to do better, whether we are facing problems like erosion, deforestation, or species loss, and we need to implement them.

This piece also gives a good opportunity to think about allowable carbon dioxide emissions. As discussed here, we need to get North Americans from close to an annual 20 tons of CO2 per person down to 2 tons to maintain climate stability. So where does that 2 tons figure come from? This is how much CO2 can be absorbed by each person’s share of the land and sea. Each person’s 5 acres of land (and their share of the ocean), can absorb an extra two tons of CO2 per year through natural processes. Some CO2 is put into tree trunks and other biomass, some into the ground as soil carbon, some is locked up in chemical processes. Quickly growing forests or healthy soil-building prairies may sequester several tons of CO2 per acre per year, while other landscapes may actually be releasing more than they absorb. The earth can process a lot of the wastes that we humans create, but we need to work within the limits of the biosphere.