Sources and method
- Atmospheric CO₂: NOAA Global Monitoring Laboratory; EPA compilation of ice-core records (ice-core values sampled by decade before 1960; five-year averages) — via Our World in Data.
- Farmland (cropland plus grazing land): HYDE land-use database — via Our World in Data.
- Wildlife: WWF/ZSL Living Planet Index, 1970–2020, with its confidence interval — via Our World in Data.
- World GDP: Maddison Project Database, inflation-adjusted — via Our World in Data.
- Human quality of life: Augmented Human Development Index, Prados de la Escosura, 1870–2020 — via Our World in Data. It combines life expectancy, schooling, income and civil liberties; plotted in the top panel from 0 at 1900 to its 2020 value.
- Life expectancy: Riley and UN World Population Prospects — via Our World in Data.
- Data retrieved —. The top panel is a conceptual illustration, not a projection, and nothing on this page describes investment performance.