Countries were assessed based on an equally weighted average of two subcategories: Land & resource sustainability and natural amenities.
The land & resource sustainability category comprises five factors: carbon emissions (the volume of greenhouse gas emissions per capita, expressed in CO2 equivalents, deforestation (the percentage change in forest land area from 2000 to 2025), protected areas (the percentage of the total territorial area designated as terrestrial and marine protected areas), sustainable trade (the value of sustainable, biodiversity-based trade, expressed as a percentage of GDP), and water stress (the ratio of total freshwater withdrawn to total available renewable freshwater resources).
As for natural amenities, factors that are measured included air quality (the average concentration of PM2.5 particulate matter in urban areas, weighted for population), light pollution (the percentage of land area experiencing the maximum measurable intensity of nighttime light, natural attractions (the number of global Wikipedia pageviews for a country's national parks per 1,000 residents over the last year, species richness (the number of non-extinct local breeds per 10,000 square miles of surface area), and urban green space (the percentage of green space within built-up urban areas, weighted for population).
