To expand on THelper's answer, and to provide an answer to just one part of the question:
How much land would each person have if everything were distributed evenly?
The back-up research to the Footprint Calculator is found primarily in two documents:
The second of these two resources gives 2007 figures (and cites sources) for land in five different categories, and the total amount of land available:
- Grazing land (for livestock)
- Forests (for timber and forest products, and CO2 uptake)
- Fisheries (including inland freshwater and continental shelf)
- Built-up land (cities, roads, bridges, etc)
Totals and per capita
If we bring all of this data together, here is how it breaks down per person (using land data from 2007 and a population of 6.6708 billion):
Land type ha (mil.) EQF gha (mil.) ha per capita gha per capita
--------- --------- --- ---------- ------------- --------------
Cropland 1,560 2.51 3,905 0.24 0.61
Grazing land 3,377 0.46 1,552 0.52 0.24
Forest 3,944 1.26 4,962 0.59 0.75
Fishing 2,840 0.37 1,049 0.43 0.16
Built-up 174 2.51 426 0.03 0.06
TOTAL 11,895 11,895 1.81 1.81
- ha (mil): million hectares.
- EQF - equivalence factors. The EQF is used to cmpare different types of land, based on how much human-useful resources can be produced from each type. It assumes that the most productive land is cropland, followed by forests, then grazing land. The calculation then looks at yields to determine how much crops could be produced if grazing land were converted to cropland, forests to cropland, etc. Fisheries are equated through protein yields compared to grazing land, and built-up land is compared to crop-land, as it is assumed that the majority of built-up land (cities) would make suitable crop-land. Ultimately, area times EQF equals global area.
- gha (mil): million global hectares.
- A note on totals: The values in the bottom row include more precise figures than what's shown in the table, so the sum of the rows as shown may not add to the totals as shown.
- YF - yield factors (not shown). To compare nation to nation, yield factors (YF) compare productivity between nations, within each category. For example, grazing land in New Zealand is more productive than world average grazing land, due to precipitation and other factors. The YF is baked into the calculations in the tables from the Footprint Atlas, but I was not able to find a listing of the YF per category, per country.
A real-world example
If, like me, you don't have much concept of a hectare, Wikipedia is quite helpful: The grass area inside a standard outdoor athletic track is equal to one hectare.
By IlliniGradResearch - Own work, CC BY-SA 3.0, Link
Thus, each person gets just under two of these. A family of five would get a hair over nine. Here's how their land use would break down:
These numbers are in absolute (not global) terms, thus related to the actual land usage, not the productivity of the land.
So, roughly speaking, this family would have:
- Four fields for crops and animal pasture
- Three fields forested
- Two fields filled with lakes for fishing
Housing, barns, workshops, etc would be spread throughout all areas.