Air travel and carbon footprint

A bi-annual vehicle emissions test got me thinking about my personal carbon footprint. A lot broad-brush numbers and calculators exist out there to calculate one’s footprint, but I’ve never found them to be very reliable because they have to generalize across a very heterogeneous population in terms of location, type of dwelling and size, family size, and fuel sources.

For example, when I had my home energy audit done last year, the report came back that our home could reduce its GHG emissions by 3.1 tonnes if we reduced our energy consumption by 31%. This is based on inputting data about our house into a model from Natural Resources Canada, and it is complete bunk. It may well reflect national averages or something like that, but we only have a small gas fireplace, whereas the main components of our energy use, space and water heating, are electric powered (which in BC is 90% hydropower).

Lo and behold, when I downloaded our gas consumption history from the utility, I came up 0.43 tonnes per year. On the vehicle side, we try not to drive the old gal too much (20-year old Corolla; hoping to replace it with something fully electric at some point). Our AirCare inspection gave us a report back that we had emissions of 2.6 tonnes per year. In both cases these were averages over the past two years.

So 3 tonnes per year for the household, which amounts to 1 tonne per person (hooray for household economies of scale), that is, me, in terms of direct emissions attributable. And on this score I’m looking pretty good, as per capita direct emissions for BC are 3.5 tonnes, and for Canada, 4.5 tonnes.

This does not count the GHGs embodied in the goods and services I consume (typically about double the direct emissions, though data are very high level). Of particular import, I flew four times last year for work and leisure. These “indirect” emissions can really add up and turn the tables. So I went to figure out my airplane footprint, based on data from the Airline Data Project and standard emission factors. These are data for US carriers but include international departures as well as domestic and regional flights. Spanning 546 million passenger-flights in 2010, and 13.7 billion gallons of fuel, I have not seen any equivalent Canadian data so I’m assuming the US averages are valid for Canada.

Factoring in air travel distances, a typical round-trip from Vancouver to Toronto weighs in at 0.66 tonnes CO2e, Vancouver-London, 1.5 tonnes, and Vancouver-Sydney, 2.4 tonnes. These are based on “available seat miles” (converted to km) but one could also calculate based on “revenue passenger miles”, but I chose the former because it better reflects the average impact of a seat on a plane, whether or not a bum is in it or not (in recessions, for example, the load on any given flight may drop somewhat).

My 2010 total comes to 3.7 tonnes, or “ouch”, and I’m not even close to being Elite or Super-Elite. Ironic fact: most well-known climate activists fly way more than I do, and longer distances. How does that compare? Total US population is about 313 million, so in 2010, that number divided into 546 passenger-flights equals 1.8 flights per capita; not quite one round-trip per person. On average that works out to 0.3 tonnes per passenger-flight; so roughly half a tonne per person per year. Alas, we know little about the distribution of air travel by income class; clearly, some professionals and executives fly all the time, other people, not at all or rarely.

Altogether, my 4.7 tonnes is still under an estimated Canadian average of 5 tonnes per capita of home, vehicle and air emissions. All the biking to work and trying to keep a low emissions profile for driving and the home basically get swamped by flying. Which sucks because I really like to travel. At $200 per tonne of externalized costs, I incurred $940 of damage imposed on others that I am not expected to pay. I think I’ll up my annual donations to projects supporting adaptation in developing countries.

Should we then all choose to stop flying? These are big structural systems, and the marginal impact of me or anyone else not flying is zero, because those planes are still flying even if they have an extra empty seat. It would take a large share of the population to say no before it affected emissions, but like fair trade or green consumerism only a fraction of the population are going to make that choice voluntarily.

Structural solutions to cut air emissions close to zero would imply some combination of absolute reductions in travel, switching to cleaner modes like rail where possible, and switching to clean fuels where we must use aircraft. The latter may have some long-run prospect in the form of biofuels, maybe hydrogen, though it is not clear that a whole aviation system as we know it could be powered on biofuels, and we’d also have to consider knock-on effects on food supply and other land uses. High-speed rail (and perhaps zeppelins) is an obvious solution for shorter distances, but it will still take a couple decades of major infrastructure investment in North America to make a major dent in short-haul air travel. And the system must be powered by renewable electric power, which has its own infrastructure build.

What’s left is absolute reductions in air travel: the week-long golfing trip to Mexico; the academic conference; the overnight business trip. Perhaps down the road we would need some form of quota system that gives each person the right to one return trip per year, though the exact parameters would depend on progress in the other areas. In the absence of something like that there is always going to be an internal battle between what we know is needed in the long run, versus what benefits us in the short run. This also creates a demand for the arguments of climate deniers, because it means we do not have to give up our “entitlement” to progress fundamentally intertwined with the combustion of fossil fuels.

As much as I have been beating up on Enbridge and oil and gas companies for making odious profits, at the end of the day they are just producing the fuel that powers what we consumers want: heat; mobility; cool gadgets; and a week of sun and surf in the dead cold of winter. We have met the enemy, said Pogo many a decade ago, and he is us.