The following article was written by Servants member Tom.
As a Servants member, some of the trickiest decisions I make are ‘to fly or not to fly’. I deeply value my life in India, and appreciate that flights are necessary for this. But I am also passionately concerned about climate change, and deeply discomforted by the fact that one return flight to Australia causes emissions greater than many of my poor neighbours would produce in a year.
My dad and I recently wrote a book, Low Carbon and Loving It, weaving together our stories of life in India and an analysis of climate change. I wrote this article just after it was published.
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At our book launch yesterday, I was asked a curly question: “Flights go everyday from Sydney to Johannesburg. Whether or not I book a ticket and get on that plane, it will go. So what difference does it make whether or not I fly?”
Many of us will have wondered similarly ourselves. This is indeed a tempting line of thought, as it allows us to minimise responsibility for our actions. However, as I’ll attempt to demonstrate in this article, our choice to fly or not to fly does make a difference.
The easiest way to show that an individual boarding a plane does make a difference was put forward by Professor David Hood, on the night. He noted that the plane’s weight directly relates to how much lift is required, and hence to the rate of fuel consumption. Having you – rather than an empty seat – on a plane will cause more emissions.
Professor Hood’s argument is indisputable, but it is also inadequate. When a typical plane takes off, passengers and their baggage account for 20-25% of the total weight of the plane – which includes the aircraft and the fuel. Put differently, a typical 260 seat plane weighs 100 tonnes without passengers or fuel – almost 400 kg per seat. Consequently, if we view our carbon footprint from flying as arising purely from the additional weight we add to the aircraft, we will significantly underestimate our emissions. If each passenger viewed themselves as non-responsible for the half a tonne of aircraft and fuel that it took to support and propel their seat, we would seriously under-count the emissions.
There is a more complex, but more accurate, argument which demonstrates how we add to the world’s carbon emissions when we fly. By booking tickets, we economically support an airline company and the routes it operates, increasing aviation’s emissions over time.
Consider a daily flight route that is running at an average of 80% capacity – that is, the average plane on that route has 4 out of 5 of it’s seats occupied. Suppose that a small but significant proportion of passengers, over a period of time, decide to not fly, but instead use other forms of transport or travel less. The average capacity drops to 70%. The airline’s profits are drastically cut – it still costs roughly the same amount to fly the plane, but their revenue has declined. Consequently, they reduce the frequency of flights to 6 times a week. A few passengers need to travel on a different day of the week, the average capacity rises again, and emissions drop.
The opposite happens if more people start flying that route. The average capacity rises to 90%. Popular days (perhaps weekends) start to get fully booked out. The airline company realises that this is revenue foregone – people who would fly if they could, but there aren’t enough seats available at the right time. To make more money, they increase the flight frequency to 8 times a week. More people can fly, the average capacity drops again, and emissions rise.
My questioner was right: buying a ticket will have no impact whatsoever on whether this particular plane flies out today, as airlines do not cancel at late notice simply if a flight is under-booked. But it does affect the likely number of future flights. If this still seems counter-intuitive, consider an example from a different area of life.
When you buy chicken from the supermarket, there is no way that your purchase resulted in the death of that particular chicken. That chicken was killed before you purchased it, and causality cannot run backwards in time. Put differently, that chicken was dead long before you walked down that supermarket aisle, and, if you decide not to purchase it, that won’t bring the chicken back to life. But does this mean that there is no link between buying a chicken in a supermarket and chickens being killed in slaughterhouses. Of course not!
In buying the chicken, your money goes towards raising, transporting, killing and processing chickens. If many people stopped buying chicken, the price of chicken would drop, and it would no longer be profitable to produce as many chickens. The supply would drop to meet the demand. Conversely, if people buy more chicken, more chickens will be slaughtered to meet that demand. Buying a chicken does not cause that particular chicken to die, it does cause another chicken to die in the future.
In much the same way, my decision to fly does not affect whether or not this flight goes (and hence, doesn’t affect its emissions, except for the additional weight). But it does increase the probability of more flights along that route in the near-term future. The best way to approximate the carbon footprint of flying is to divide the emissions from the plane by the average number of passengers on that route (though business and first class passengers bear a higher responsibility, as they are paying more and occupying a larger area of the plane).
In summary, though it is tempting to trick ourselves into believing that we have no (or little) responsibility for emissions from flights we take, the facts are to the contrary. Much to my own sadness, a return international flight can cause around 2 tonnes of carbon dioxide equivalent emissions – an individual’s sustainable fair share for the year. Tomorrow, I will be burning roughly 4 months of my fair share carbon footprint, in just one day, as I return to India. There are many ways I should, and do, respond to this – by trying to reduce the frequency of my flights, by traveling some of the distance overland, by carbon offsetting. But an attempt to deny my responsibility is not one of them.
REFERENCES:
https://howthingsfly.si.edu/ask-an-explainer/how-much-weight-can-average-size-airplane-hold
http://www.airbus.com/aircraft/previous-generation-aircraft/a300-600.html
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