Flying High

Do you fly? Me too.

Whilst we have attractive sustainable options for terrestrial and aquatic travel, there are no realistic low carbon alternatives to air travel. We could take ships for international travel but that’s not very practical and only marginally more sustainable. At present if we want to fly, we’re stuck with the associated emissions. With 2% of global greenhouse gas emissions coming from the aviation sector, they’re significant too. We could choose to offset our emissions but how effective and viable is that?

Some jurisdictions have chosen to implement emissions control measures for the airline industry. In 2012 the EU implemented an airline emissions trading scheme which came with the obligatory resistance we’ve come to expect with environmental policies. This is certainly a positive measure, but is tokenistic considering the ambitious emission reductions required to avoid catastrophic climate change, and which were ignored in last years COP21 Climate Summit in Paris.

There are ways of increasing the sustainability level of air travel. The last decade has seen many airlines experiment with the use of biofuels but none are using it regularly on main routes. The effectiveness of biofuels is also contentious, with emissions forecast to rise if natural woodlands are used for fuel conversions. Not to mention the ethical dilemma of burning fuel made from food-stocks. Then there are carbon offsets. Essentially, you pay someone to plant trees for every tonne of carbon emitted by your flying activities. Since these programs are opted in to (rather than out of) they aren’t very effective. According to this Conversation article, only around 5% of passengers opt in. Even if the offset option is selected, tree plantations are far from sustainable, with many affecting local irrigation cycles for the worse.

Considering the amount of flying we do, though, it is important we look in to viable alternatives. That’s exactly what Bertrand Piccard and Andre Borschberg of Solar Impulse are trying to show, having last week completed a round-the-world flight powered only by the sun and determination. Of course, there is significant embodied energy in their aircraft and the hefty crew needed to ensure the expedition went to plan but we have to start somewhere.

Solar Impulse 2
Their second aircraft, Solar Impulse 2 was first flown in 2014 so let’s compare the flying emissions of their flights to all of mine over the last two years.

CO2 (tonnes) 2014 – 2016
Solar Impulse 2 0
Darius 40.5

40.5 tonnes – is that a lot? It’s the equivalent of planting around 200 trees at a total cost of over $2000. It’s the cumulative impact of almost 40 flights and over 200,000 km travelled. I’ve graphed them chronologically with cumulative distance covered.

Darius’ Flights 2014 – 2016 *

The graph above illustrates two things: 1. I need to cut down on the flying and 2. International flights release way more CO2 in to the atmosphere than domestic flights. What’s more, these are the flying habits of a budding environmentalist! Imagine those of a business frequent flyer. If all passengers chose to offset their emissions we’d end up completely covering the planet in trees, so obviously carbon offsets are not a long-term solution. The aforementioned short-comings of carbon offsets are why I have chosen not to off-set my flights.

What we really need is an economic system which accounts for all negative externalities in the aviation cycle. That is, the environmental costs of flying need to be factored in to the cost of the ticket. Currently, we’ve gone the other way, with many flights subsidised to promote international business. This may be great for the global economy, but at an enormous environmental cost. Accounting for all negative externalities in the process would have a cyclical impact because the increased financial cost would mean fewer folks would fly.

Unfortunately, it’s very unlikely any politician would implement such measures and alternatives to carbon offsets are limited until Betrand and Andre build a commercial airliner powered by the sun. While you wait, consider taking a sailing holiday or conducting business meetings via Skype.

*Email me for a copy of my Excel-based flight calculator.

NB. I’ve used CO2 emissions as the main metric for assessing flight environmental impacts. This has some significant deficiencies:

  • Burning of AvGas and Jet Fuel releases all sort of particulates in to the atmosphere, not just CO2. Since trees do not absorb these particulates this is another reason why carbon off-sets are ineffective.
  • Aviation emissions are released at altitude. This means that global cooling takes place during the day when solar radiation is reflected back to space, and the greenhouse effect is exacerbated at night as heat is trapped in the Earth’s atmosphere. This is a phenomenon called Global Dimming.

2 thoughts on “Flying High

  1. I fly a lot, and chose the carbon offset when booking my tickets. I’m sure it’s not the most effective method of reducing my carbon footprint, but I feel like it’s better than nothing! At the very least, I feel like I’m letting the airlines know that this is an important issue for me

    Liked by 1 person

    1. Nice one Tegan! You make a valid point – by making the extra investment in off-setting your flight you’re definitely sending the right message. Keep fighting the good fight!


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