The carbon footprint accounts for all greenhouse gas emissions associated with an activity: CO₂, methane, N₂O, converted to CO₂ equivalent (CO₂e) by global warming potential. The global average is ~4.7 t CO₂e/person/year; Spain ~5.5 t; USA ~14 t.
Meteorology helps calculate footprints: solar radiation, wind, and temperature data determine heating/cooling emissions and renewable energy potential. Reducing the global footprint to 2 t/person by 2050 is needed to meet the Paris Agreement and limit warming to 1.5–2 °C.