Data.
Population 1975–2030:
GHSL GHS-POP R2023A, European Commission Joint Research Centre, CC BY 4.0.
10,000 BC–1840:
HYDE 3.3, Kees Klein Goldewijk, Utrecht University / PBL, CC BY 4.0 (fetched from a
Kaggle mirror).
1850–1970 and the 2035–2100 scenarios:
ISIMIP (ISIMIP3a histsoc, a HYDE-based reconstruction; ISIMIP3b SSP1, SSP3, SSP5), CC0.
Towns and capitals:
GeoNames, CC BY 4.0.
Coastlines:
Natural Earth via
world-atlas.
Drawn with
d3 and topojson-client.
The story starts in 10,000 BC because that is where HYDE starts. Before 1850 the steps are HYDE’s own (a thousand years, then a hundred, then ten) and the timeline squeezes them into its left end. Nobody lived in towns in 10,000 BC, so that year has no city/country split. Distances are great-circle; the Earth is a ball of radius 6,371 km. Everything before 1975 is modelled, 2025 onward is projected, and the joins between sources are drawn as seams rather than smoothed over.