Flight emissions calculations

Understanding the global heating effect of a flight can be useful to help you plan your own climate emergency response. 

But specific footprint calculations should not entice us into thinking that emissions from one source are ok because those from another source have been reduced. We need to reduce all emissions to zero within ten years or so. If we don’t, there is an unacceptable risk that ongoing emissions will trigger catastrophic global heating.

What’s being measured?
Calculators

For any given source — cars, power generation, aviation, food production, domestic household, etc — the footprint can vary because, for example, not all cars generate the same emissions. A “Household” can vary in size, a “Bus” can have different levels of occupancy. Their engines can operate at different levels of efficiency and with different fuels. And when embedded emissions (such as those created in the process of producing cars) are included, the specific footprint again varies. 

Some footprint calculators use carbon dioxide emissions alone as their warming measure. Other use just carbon emissions. Still others use carbon dioxide equivalent emissions (CO2-e) as their measure. A CO2-e footprint is a measure of the heating of all emissions from a source, not just its CO2 emissions. It is represents the amount of CO2 emissions that would have the equivalent heating effect as that of all emissions, CO2 and non-CO2.

For short-lived non-CO2 emissions, like those from aviation, there is a new, arguable more accurate, way to assess their ‘global warming potential’

The total warming effect of a litre of jet fuel burnt at altitude generates 3 times the warming of the CO2 emissions alone. So, when comparing the CO2 footprint of other activities in your life, with that of flying, flying’s CO2 measure needs to be tripled. 

As a consequence, we can unequivocally say that flying has the most damaging effect on the climate of all transport modes, per kilometre travelled. One return flight to London increases your annual emissions by a staggering 40%. An A380 Airbus, 80% full creates 8.5 tonnes CO2e, per economy passenger, compared to the 22 tonnes CO2e figure for Australia’s total emissions in 2016 divided by the population. 

A number of emissions footprint calculators exist online. Here are just a few:

• flightemissionmap.org
Includes CO2 emissions from production and distribution of aviation fuel, and multiplies aviation CO2 emissions by 3. 

• chooseclimate.org/flying
Multiplies aviation CO2 emissions by 3. 

• atmosfair.de/en/
Calculation approximates x3 multiplier

• carbonindependent.org/index.html
Multiplies aviation CO2 emissions by 2.

• foe.ie/justoneearth/carboncalculator/
Calculates just aviation CO2 emissions.

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