Table 1.

Variables Synthesis.

Acronym	Variables Selected	Source
GHG pc/area	Greenhouse Gases per capita by surface area (sq. km)	Eurostat
LEdu pc/area	The percentage of the working-age population with an advanced level of education, per capita, and per area	World Bank
GDP pc/area	Gross domestic product per capita (pc) and per area	Eurostat
GDP pe2/area	Gross domestic product squared per capita and per area
Euse/area	Energy use (kg of oil equivalents) per capita and per area	World Bank *
Elect/area	Electricity production from oil, gas, and coal sources (% of total) per capita and per area	World Bank *
CO2 pc/area	Volume emissions of carbon per capita and per area	Eurostat/World Bank *
CH4 pc/area	Volume emissions of methanol per capita and per area
N2O pc/area	Volume emissions of nitrous oxide per capita and per area

Notes: * Ratios were computed by the authors using original data from the cited sources. All variables are in the natural log form. The volume of emissions of carbon per capita (CO₂), emissions of methanol per capita (CH₄), and emissions of nitrous oxide per capita (N₂O).