The responsibility of demand: air travel projected to create net increase in greenhouse gas emissions

There are many ways that individuals can make lifestyle changes to aid in the global mission of reducing greenhouse gas concentrations in the atmosphere.  Just to name a few…eat less meat, drive less, monitor air conditioning/heating and improve insulation, buy compact fluorescent bulbs and energy-efficient appliances…all these can help.  But perhaps the single most important behavior change is to fly less.

The graph above, taken from an IPCC report, indicates that airplanes account for the highest emissions per passenger-kilometer across all major modes of transportation.  An interesting side note – rail systems have a great variability in emissions but possibly the greatest potential for low-emissions mass transportation.  Also, airplanes emit CO2 at high altitudes which leads to more chemical reactions that amplify the warming effect twofold to fourfold.  Globally, we use over 5 millions barrels of oil per day for flights.  Given all this data, it’s crucial that we reduce emissions from aircraft to reach our emission reduction goals set for 2020 and beyond.

Unfortunately, a recent literature review in Atmospheric Environment indicates that demand is largely outpacing any emissions reductions that are occurring due to technological improvements.  The authors pored through previous research to collect all available information about forecasting ticket demand and emission levels.  Their summary indicates that ticket demand will strongly increase in the years to come.

To combat this increase in demand, the authors looked at two general sources of emissions reduction – policy/legal measures and technological/operational measures.  The latter will come from more energy efficient fuel sources and engines that market forces will promote to reduce fuel consumption and costs for airlines.  Airlines will be more than happy to work hard to improve this area.  But the authors emphasize that this cannot be the only method of emission reduction, as market forces do not ‘see’ far enough into the future to reduce emission to quickly enough to level to keep temperature increases in the 2 degrees Celsius range.


This reasoning does not just apply to air travel – in all arenas, market-based economies are not properly pricing the cost of carbon emissions (known as an externality in economics lingo).  Rather, the costs go to a third party not necessarily receiving benefits from the good or service.  It is well known among economists that capitalistic markets suffer from this shortsightedness!  This is the whole reason for policy-making and government intervention and subsidy regarding renewables.  It’s quite unfortunate we do not have this type of dialogue often in the mainstream media, in which subsidies and the like are called an affront to capitalism (and probably un-American on some channels).  There have been some interesting discussions about how to incorporate externalities into market economies, however.

Anyway, rant aside, this means that the other source of emissions reduction beyond technological improvements is legal and policy decisions.  The authors indicate that only policy changes will force the speed of implementation and the appropriate strictness of mandates to meet reductions dictated by societal standards, not market forces.

The authors are pessimistic that even policy will not prevent growth rates from outpacing emission rates, and therefore call on individual behavior change as the major path to reduced emissions.  A reduced demand for air travel seems to be the best solution in this case – we can all help with this!  I often think about this cost of air flights – even if I take the bus to work every day, eat vegetarian, turn off the AC – my one flight to a conference each year does much to cancel out these other daily intentions.

One economic way to reduce demand is to increase ticket prices (basic economics 101).  The article does discuss this possibility, but only to point out its lack of feasibility.  Their calculations indicate that, if ticket prices were increased to the point where demand would lower enough to reduce emissions, the monetary value of the related CO2 emissions would be 7-100 times greater than its valuation in other settings, like other fossil fuel-based emissions.  This seems a bit unrealistic!

So once again, the responsibility rests on each individual citizen to change behavior to reduce emissions.  Maybe think about driving to your next vacation destination!



Matt Grote, Ian Williams, John Preston (2014). Direct carbon dioxide emissions from civil aircraft Atmospheric Environment

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