There are problems with making pie charts that have, for example, a slice for mountain and a slice for desert. The categories often overlap, e.g. the Great Basin Desert, https://www.britannica.com/place/Great-Basin , contains mountains.
The UN page “United Nations Decade for Deserts and the Fight against Desertification”, https://www.un.org/en/events/desertification_decade/value.shtml has useful basics on the definition of dryland and desert, their subcategories, and the amounts of each. Unfortunately, it expresses these as percentage of land area, but doesn’t say what its definition of that is. For example, does it include icesheets?
There is a section at the end on land degradation, which makes me think we should do a page on that.
There is a 2021 UN page on rangelands, “New atlas reveals rangelands cover half the world’s land surface, yet often ignored despite threats”, https://www.unep.org/news-and-stories/press-release/new-atlas-reveals-rangelands-cover-half-worlds-land-surface-yet . We should mention these. They’re not explicitly listed in the land-cover types I used from the Copernicus project: its categories probably overlap them.
Yet another categorisation, which cuts across that, is by landform. That is, by morphology, see https://en.wikipedia.org/wiki/Landform , though that one is not a good article. There’s an interesting paper “Classification and Characterization of Planetary Landforms”, https://www.researchgate.net/publication/308905939_Classification_and_Characterization_of_Planetary_Landforms , which explains why their classification is difficult. It also shows how badly the taxonomy differs between researchers, making results hard to compare. Kenneth Gregory’s “Recognizing the Land Surface”, https://www.sagepub.com/sites/default/files/upm-binaries/32897_01_Gregory_CH_01.pdf , has some useful info.
Yet another classification is by biome, https://www.nationalgeographic.org/article/five-major-types-biomes/ .
Total Land Area
Total land area in 2017 was 147,135,404 square kilometres. This includes inland lakes and other permanent bodies of water. Estimates vary slightly: this one is from the source noted below. [ Note: the land-area percentages in those results, which I use in the next section, sum to only about 90% of this total. The source, the Copernicus Project, is reliable, so I need to check this with them and ask why. ]
For each person in the 2017 population of 7.509 billion, this is 19,594.5 square metres, or 0.0196 square kilometres. For a population of 10 billion, it would be 14,713.5 square metres, or 0.0147 square kilometres. For 12.5 billion, it reduces to 11,770.8 square metres or 0.0117 square kilometres.
To visualise this, here is what each of ten billion people would get, if set around the Brandenburg Gate in Berlin:
It is 121 metres on a side, just under twice the width of the Gate, 64 metres:
The slice for 7.5 billion would be 139 metres on a side; that for 12.5 billion would be 108 metres.
Slicing out Cones, Walking Your Area
We can think of these slices as cones. Each person gets a cone with its point at the Earth’s core, and a big end which — depending on the population — is not very much bigger on each side than a famous monument in Berlin.
Assume that the average person walks 1.4 metres per second. Then it would take 6.7 minutes to walk round the 2017 slice of land; 5.8 minutes to walk round the 10-billion population’s slice; and only 5.2 minutes to walk round the 12.5-billion’s slice.
Land Cover by Area
|Bare or sparse vegetation||15.33%|
|Permanent water bodies||2.05%|
|Snow & Ice||1.44%|
|Moss & Lichen||1.06%|