Land/built-up
Using 'population' data to estimate built-up land
Some inner cities can be quite dense, but even the less-dense suburbs are still fully built-up, as none of the land is truly wilderness
Let's estimate the minimum population density that might be considered fully built-up land:
Do Minimum Lot Size Rules Matter? - Strong Towns www.strongtowns.org › journal › do-minimum-lot-size-rules-matter
This is just an educated guess, so if you have actual data, please say it in the discussion.
(calculation loading)
So, any land with more people than this, would be considered 100% built-up land in our analysis.
Any land with fewer people, will be counted proportionally. So if the population density is 10% of the threshold, we say the area contains 10% built-up land. This might be the case of a small family farm, where 90% of the lot is farm land, and the last 10% is housing and driveway.
Technically, there could be fully-built-up areas below this population threshold - such as industrial areas - but those are probably uncommon enough.
Let's test out our threshold using the image generator:
pop << data/population.data-float64-8640x4320 # population counts pop @@ quantity_to_density # convert to 'people per km^2' pop /= 2583.3385 # threshold for land to be considered 'fully built-up' pop <= 1 pop @@ density_to_quantity pop @@ stats
Which gives the result:
Dimensions: 8640 by 4320 Sum: 2708207.986793 Average (Mean): 0.072558 Standard Deviation: (+/-) 0.651528 Minimum: 0.000000 at [0,0] Maximum: 21.466134 at [3093,2159]
The Sum: 2708207.986793
is the number of km2 of built-up land on Earth.
This is actually quite a lot higher than official estimates. OECD data says there's 784841 km2 of built-up land globally, and OurWorldInData says there's about 1.5 million km2.
Either way, built-up land is a tiny fraction of Earth's surface510 million km2, according to the same OurWorldInData source, especially compared to farm land43 million km2, according to the same OurWorldInData source.