CO2 emissions from aviation fuel are 3.15 grams per gram of fuel [1], which gives CO2 emissions from a Boeing 737-400 of 115 g per passenger per km. At a cruising speed of 780 km per hour [Wikipedia, 28.2. 08], this is equivalent to 90 kg CO2 per passenger per hour.

The carbon footprint of an airplane is significant, though it varies by aircraft type and flight duration. On average, a modern commercial jet produces about 90 kg of CO2 per passenger per hour of flight. For a short-haul return trip (e.g., London to Rome), a single passenger accounts for roughly 234 kg of CO2. On a long-haul flight like London to New York, that figure jumps to approximately 986 kg of CO2 per person. To put this in perspective, in many developing nations, the average citizen emits less than 1,000 kg of CO2 in an entire year. Aviation currently accounts for about 2% to 3% of global CO2 emissions, but its "warming effect" is often doubled due to non-CO2 factors like contrails and nitrogen oxides released at high altitudes. In 2026, airlines are increasingly using Sustainable Aviation Fuel (SAF) and carbon-offset programs to mitigate this, but flying remains one of the most carbon-intensive activities an individual can undertake, contributing heavily to an individual's total annual environmental impact.