Why do different carbon calculators give different results?
Flight calculators may use different techniques to measure the distance an aircraft travels, and include different estimates of the climate change impact of high altitude flights. The UK government calculator, for example, automatically adds to the flight distance to account for airport congestion. Carbon Clear calculates distance using the actual latitude and longitude of specific airports, plus an increment to account for airport congestion and indirect routes. Uncertainty about the additional global warming impact of high-altitude aircraft also leads to different calculator results. The Intergovernmental Panel on Climate Change estimates that flight emissions have up to 2.7 times the global warming impact of ground-level emissions, and at least one calculator claims that aircraft emissions have four times the impact. The UK Government recommends a multiplier of 1.9, but has tended to use a multiplier of 1.0 on its own calculator. Carbon Clear has traditionally used the same 1.0 mult
