This takes into consideration the trend in total and diffuse greenhouse gas emissions per capita per country in equivalent tonnes of CO₂. The value of the ratio whose variation is being compared is the result of dividing the total and diffuse GHG emissions of each country, for each year taken into consideration, by the total of its population on the last day of that year.

The data from the Basque Country comes from the Greenhouse Gases Inventory and data from the other countries, both from EUROSTAT and the Secretariat of the United Nations Framework Convention on Climate Change (UNFCCC) and the EU Emissions Trading System (European Environment Agency) .