The trouble with jets

Giant spider

Air travel is one of the trickiest ethical issues, when it comes to climate change. In most situations, the difference between a high carbon option and a zero carbon alternative is essentially a matter of cost. If we are willing to spend enough, we can replace all fossil fuel power with renewables. We can get electricity, heat, ground transport, and energy for industry from sources that do not contribute to climate change. Air travel is different. Even for one million dollars a ticket, there is no way to get someone from New York to London in about eight hours that does not release greenhouse gases. Likewise, there is no feasible way to capture those gases for later storage.

Let’s consider a series of propositions:

  1. Climatic science strongly suggests that allowing global greenhouse gas concentrations to rise beyond 500-550 ppm of carbon dioxide equivalent will have very adverse affects. These will be concentrated in the poorest states. It is highly likely that exceeding these limits will directly lead to large numbers of deaths, especially in the developing world. (See: these Stern notes)
  2. At present, per-capita emissions in developed states are far higher than those in developing states. Canada’s emissions per-capita are about twenty times those in India.
  3. Essential human activities, from heating to agriculture, produce greenhouse gasses.
  4. People have equivalent moral claims to the basic requirements of survival.

If we accept these claims, we find ourselves in a tricky spot. To stabilize the level of a stock, you need to reach the point where inflows are equal to outflows. Even if we ignore how global warming is reducing the ability of the forests and seas to absorb carbon dioxide, it is clear that such stabilization requires deep cuts in total emissions. At the same time, taking the last two points seriously means acknowledging that developing states do have the right to comparable per-capita emissions. As such, the only option that is fair and capable of stabilizing overall concentrations requires very deep cuts in developed states.

Aside from being inextricably linked to fossil fuels, modern air travel compounds the harm done by the burning of that kerosene. This is partly because of where in the atmosphere it is deposited. It also seems likely that jet aircraft affect clouds in ways that increase their impact on climate change.

Imagining a world stabilized at 500 ppm, with reasonably similar per-capita emissions for all states, it seems quite impossible that there can be air travel at anything like contemporary levels. It is possible that some miracle technology will allow high-speed flights to occur without significant greenhouse gas consequences, but no such technology is even within the realm of imagination today.

As someone who has long aspired to travel the world, this is a very difficult conclusion to reach. It now seems possible that air travel bears some moral similarities to slavery. Before people become overly agitated about the comparison, allow me to explain. Just as slavery was once a critical component of some economies, air travel is essential to the present world economy. Of course, economic dependency does not equate to moral acceptability. If our use of air travel imperils future generations – and we are capable of anticipating that harm – then flying falls into the general moral category of intentional harm directed against the defenceless. After all, future generations are the very definition of helplessness, in comparison to us. We can worsen their prospects by fouling the air and turning the seas to acid, but they will never be able to retaliate in any way. (See: these Shue notes)

While I personally fervently hope that some solution will be found that can make continued air travel compatible with the ethical treatment of the planet, nature, and future generations, I must also acknowledge the possibility that people in fifty or one hundred years will look upon us as sharing some moral similarities with plantation owners in the United States, prior to the civil war.

Author: Milan

In the spring of 2005, I graduated from the University of British Columbia with a degree in International Relations and a general focus in the area of environmental politics. In the fall of 2005, I began reading for an M.Phil in IR at Wadham College, Oxford. Outside school, I am very interested in photography, writing, and the outdoors. I am writing this blog to keep in touch with friends and family around the world, provide a more personal view of graduate student life in Oxford, and pass on some lessons I've learned here.

37 thoughts on “The trouble with jets”

  1. Oleh says

    Last week’s edition of the Georgia Straight had at its cover story how air travel conributes to carbon emmissions. One of the challenges is that bio fuels are more difficult in air travel because they would gelinate at the the tempeatures occuring in flight. Airlines are offering the opporunity for the traveller to add buy offset credits. I had cut out the article to send to you.

    In many ways your general comments are consistent with much of our activity in developed countries. An illustration for me was when I decided to take the car to work today instead of the bicycle. There was no particular reason to do so as the weather was good and although I had a heavy load to carry my panniers would have sufficed. This was especially a problem when on my return I was stuck in horrendous traffic and I thereby even further released carbon emissions. The irony was that on the bike I would have , because of the traffic conditions, been home much faster.

  2. Biofuels might be a mechanism for de-carbonizing air travel eventually, but two major sets of hurdles need to be overcome.

    The first is the inappropriateness of today’s biofuels for use in aircraft. One problem is how they become gelatinous at low temperatures – a characteristic that completely bars the possibility of their use at altitudes where planes now operate. There may be a technical solution to this. For instance, I have read that repeatedly freezing and thawing them can eliminate this characteristic, but doing that for millions of gallons of jet fuel would at least be very expensive, and may eliminate much of the environmental benefit.

    The second is the sources of biofuels. Biofuel made from food crops uses arable land and water. Fertilizing those crops pollutes rivers with nitrates and sulphates that cause eutrophication and algae blooms. Even worse, a major contemporary source of biofuels is palm oil. Cutting down the rain forest and replacing it with palm plantations is hardly a strategy that will help stabilize greenhouse gas concentrations.

    What I meant to stress in the post above is how air travel is fundamentally different from choices about whether to drive or cycle. There is no reason for which zero emission land vehicles are impossible today – they are just expensive and impractical. That said, the psychological tendency to choose the easier option is shared between the two choices.

  3. “I must also acknowledge the possibility that people in fifty or one hundred years will look upon us as sharing some moral similarities with plantation owners in the United States, prior to the civil war.”

    Plus they’ll probably look on us more critically because we generally benefited from slavery, while they’ll be harmed by our greed.

  4. “Plus they’ll probably look on us more critically because we generally benefited from slavery, while they’ll be harmed by our greed.”

    Who is the ‘we’ there? Slaves didn’t, presumably, and I think that the trade was generally pretty devastating for the societies from which the slaves were taken. Also, there is a half-decent argument that slave labour keeps wages down, and stunts economic growth – because as long as enough surplus is extracted, structurally there’s no incentive to either the conditions of the slaves or the productivity of whatever it is they do. So whether white northerners benefitted from it generally may not be clear. Also, there may be economic benefits from air travel; the Spanish certainly seem like they would have been buggered without it.

  5. Doesn’t this help to explain a bit why the ‘debate’ about the reality of global warming continues? As long as people can say to themselves, others, and hypothetical future generations that the consequences of carbon emissions were unknown, they cannot be held culpable for them.

  6. Regular oil cleaner than ethanol

    A new study in the journal Science ($ub req’d) validates what many have been saying here in Gristmill: Biofuels, especially those from the tropics, are far worse for the planet than regular old crude oil.

    The study finds that we could reduce global warming pollution two to nine times more by conserving or restoring forests and grasslands than by razing them and turning them into biofuels plantations — even if we continue to use fossil fuels as our main source of energy. That’s because those forests and grasslands act as the lungs of the planet. Their dense vegetation sucks up far more carbon dioxide and breathes out far more oxygen than any biofuel crop ever could.

    When you destroy that wilderness, much of the carbon stored in its living matter is either burned or otherwise oxidized — which is why the destruction of tropical forests accounts for more than 20 percent of global greenhouse-gas emissions (more than China produces). Meanwhile, we’d be saving all the creatures that rely on those wildlands for habitat. The scale is huge: replacing even 10 percent of our gas with biofuels would require 43 percent of U.S. arable land.

    Are you listening George Soros? What about you, Center for American Progress? And you, Barack Obama?

  7. Doesn’t this help to explain a bit why the ‘debate’ about the reality of global warming continues? As long as people can say to themselves, others, and hypothetical future generations that the consequences of carbon emissions were unknown, they cannot be held culpable for them.

    With all the reports that have come out, this is vincible ignorance, at best.

  8. The climate impacts of different anthropogenic emissions can be compared using the concept of radiative forcing. The best estimate of the radiative forcing in 1992 by aircraft is 0.05 Wm-2 or about 3.5% of the total radiative forcing by all anthropogenic activities. For the reference scenario (Fa1), the radiative forcing by aircraft in 2050 is 0.19 Wm-2 or 5% of the radiative forcing in the mid-range IS92a scenario (3.8 times the value in 1992). According to the range of scenarios considered here, the forcing is projected to grow to 0.13 to 0.56 Wm-2 in 2050, which is a factor of 1.5 less to a factor of 3 greater than that for Fa1 and from 2.6 to 11 times the value in 1992.

    IPCC report on aviation

  9. Biofuel trial flight set for 747

    Air New Zealand says it plans to mount the first test flight of a commercial airliner partially powered by biofuel.

    The 747 flight is one part of a deal signed by the airline, engine producer Rolls-Royce and aircraft manufacturer Boeing to research “greener” flying.

    One of the four engines will run on a mixture of kerosene and a biofuel, and is set for late 2008 or early 2009.

  10. EasyJet CEO advocates ban on old, polluting aircraft

    EasyJet CEO Andy Harrison said Monday that Europe should scrap its 700 oldest and most-polluting aircraft to limit emissions and aviation’s effect on the environment.

    But during its bid to please environmentalists, the company also announced three new routes out of Scotland.

    Harrison is hoping to burnish easyJet’s environmental credentials by pointing out the company’s 137 aircraft are on average just over two years old.

    “I think global warming is a real issue and this generation has to do something about it,” Harrison said. He also noted that easyJet reduces the price of plane tickets by using online booking and having its crews clean their own aircraft.

    Harrison called for airlines to jettison all planes manufactured before 1990 by 2012. He also advocated changing the existing flat-rate air passenger duty to a tax that would target the worst polluters. “One-third of current aircraft are of the older generation and are 20 percent less fuel-efficient,” he said.

    EasyJet plans to nearly double its fleet by adding 120 new Airbus planes by mid-2012

  11. The climate is already changing and we need to find urgent ways to mitigate that change immediately and maintain as much biodiversity on the planet as possible. The most positive but realistic thing that governments could agree in Bali is to halt the cutting down of virgin tropical rainforests with immediate effect and agree a method by which the major economies, big multinationals and other carbon offset groups could pay for it. Why is this so important? The next five years of carbon emissions from burning rainforests will alone be greater than all the emissions from air travel since the Wright brothers first flight in 1903 until at least 2025.

  12. The answer depends on whom you ask
    How much global warming results from air travel?
    Posted by Clark Williams-Derry at 1:49 PM on 18 Dec 2007

    Over the past few days, I’ve been trying to pull together some data on how airplane travel affects global warming, as part of a broader project on transportation and climate change.

    My stunningly obvious conclusion: it’s complicated. Worse, different calculation methods yield wildly different results…

    “But on average, the IPCC recommends multiplying the CO2 emissions from fossil fuels by 2.7 to get the total global-warming impacts from a given flight. That is, the comprehensive global warming impacts (counting contrails, clouds, and trace gases) of flying are about 2.7 times as high as the CO2 alone.”

  13. “For the second tack, the Stockholm Environment Institute recommends Atmosfair, since it has the broadest and most comprehensive assessment of the climate impacts of flying — covering not just CO2 emissions, but also other gases, contrails, and the like. As a consequence, Atmosfair tends to give a higher estimate of climate impacts than the other flight calculators — depressing, but probably pretty accurate.”

  14. Airbus predicts air travel boom

    European plane maker Airbus expects global passenger traffic to grow at an average of 4.9% a year, almost trebling over the next two decades.

    It forecasts that 24,300 passenger and freight aircraft worth $2.8 trillion will be ordered between now and 2026.

  15. Planes

    “Half of the work done by a plane goes into staying up; the other half goes into keeping going. The fuel efficiency at the optimal speed, expressed as an energy-per-distance-travelled, was found in the force (C.18), and it was simply proportional to the weight of the plane; the constant of proportionality is the drag-to-lift ratio, which is determined by the shape of the plane. So whereas lowering speed-limits for cars would reduce the energy consumed per distance travelled, there is no point in considering speedlimits for planes. Planes that are up in the air have optimal speeds, different for each plane, depending on its weight, and they already go at their optimal speeds. The only way to make a plane consume less fuel is to put it on the ground and stop it. Planes have been fantastically optimized, and there is no prospect of significant improvements in plane efficiency.”

    Possible areas for improvement of plane efficiency

    ‘Laminar flow control’ (cunning trick for reducing drag a little). Flying wings: said to be 25% more fuel efficient. Propfans instead of turbofans? Said to be 12% more efficient for short journeys (less than 3000 km), but not for long journeys. They’re more efficient because the engine efficiency is greater.

    Formation flying in the style of geese could give a 10% improvement in fuel efficiency (because the lift-to-drag ratio of the formation is higher than that of a single aircraft), but this trick relies, of course, on the geese wanting to migrate to the same destination at the same time.

    Optimizing the hop lengths: long-range planes (designed for a range of say 15 000 km) are not quite as fuel-efficient as shorter-range planes, because they have to carry extra fuel, which makes less space for cargo and passengers. It would be more energy efficient to fly shorter hops in shorter-range planes. The sweet spot is when the hops are about 5000 km long, so typical long-distance journeys would have one or two refuelling stops. Multi-stage long distance flying might be abou”

    “Earlier in this chapter, however, our cartoon made the assertion that the transport efficiency of any plane is about

    0.3 kWh/tonne-km.

    According to the cartoon, the only ways in which a plane could significantly improve on this figure are to reduce air resistance (perhaps by some newfangled vacuum-cleaners-in-the-wings trick) or to change the geometry of the plane (making it look more like a glider, with immensely wide wings compared.”

  16. Crash Landing
    Posted May 22, 2009

    As BA reports massive losses, isn’t it time to scrap the airport expansion programme?

    Aviation accounts for 0.78% of total business turnover in the UK. Yet it is responsible for 13% of the country’s total greenhouse gas emissions. Any fair pricing of greenhouse gases would make flying prohibitively expensive.

    Aviation and global climate change in the 21st century

    David S. Lee et al.
    Atmospheric Environment. Received 19 November 2008; revised 7 April 2009; accepted 8 April 2009. Available online 19 April 2009.

    Aviation emissions contribute to the radiative forcing (RF) of climate. Of importance are emissions of carbon dioxide (CO2), nitrogen oxides (NOx), aerosols and their precursors (soot and sulphate), and increased cloudiness in the form of persistent linear contrails and induced-cirrus cloudiness. The recent Fourth Assessment Report (AR4) of the Intergovernmental Panel on Climate Change (IPCC) quantified aviation’s RF contribution for 2005 based upon 2000 operations data. Aviation has grown strongly over the past years, despite world-changing events in the early 2000s; the average annual passenger traffic growth rate was 5.3% yr−1 between 2000 and 2007, resulting in an increase of passenger traffic of 38%. Presented here are updated values of aviation RF for 2005 based upon new operations data that show an increase in traffic of 22.5%, fuel use of 8.4% and total aviation RF of 14% (excluding induced-cirrus enhancement) over the period 2000–2005. The lack of physical process models and adequate observational data for aviation-induced cirrus effects limit confidence in quantifying their RF contribution. Total aviation RF (excluding induced cirrus) in 2005 was not, vert, similar55 mW m−2 (23–87 mW m−2, 90% likelihood range), which was 3.5% (range 1.3–10%, 90% likelihood range) of total anthropogenic forcing. Including estimates for aviation-induced cirrus RF increases the total aviation RF in 2005–78 mW m−2 (38–139 mW m−2, 90% likelihood range), which represents 4.9% of total anthropogenic forcing (2–14%, 90% likelihood range). Future scenarios of aviation emissions for 2050 that are consistent with IPCC SRES A1 and B2 scenario assumptions have been presented that show an increase of fuel usage by factors of 2.7–3.9 over 2000. Simplified calculations of total aviation RF in 2050 indicate increases by factors of 3.0–4.0 over the 2000 value, representing 4–4.7% of total RF (excluding induced cirrus). An examination of a range of future technological options shows that substantive reductions in aviation fuel usage are possible only with the introduction of radical technologies. Incorporation of aviation into an emissions trading system offers the potential for overall (i.e., beyond the aviation sector) CO2 emissions reductions. Proposals exist for introduction of such a system at a European level, but no agreement has been reached at a global level.

  17. “The controversy stems from the fact that high-altitude emissions – from nine to 13 kilometres up for subsonic flights and higher for supersonic – cause disproportionately more warming than those at ground level, anywhere from 50 per cent to four times as much, making its global-warming role more significant than its emissions tally alone would indicate.

    Part of the worry is due to contrails, the thin vapour trails from jets that crisscross the sky above many of the world’s most-travelled air routes. Contrails resemble artificial cirrus clouds, trapping heat, although there is no scientific consensus about the size of their leavening effect on global warming.

    Air travel was given a little-publicized loophole in 1997 under the Kyoto Protocol, one of only two industries, the other being shipping, exempt from the greenhouse-reduction pact. When the protocol was negotiated, there was no agreement on who should shoulder responsibility for emissions due to international travel.”

  18. “This dust cloud isn’t that kind of tragedy. Nevertheless, the eruption of Eyjafjallajokull could continue into next week, next month, or next year. That would turn the volcano into one of those inexplicable natural events, which, like earthquakes and tsunamis, change the economics and politics of an entire region. No wonder we suddenly feel the need to focus on the scientific and mystical significance of wind patterns, magma, and dust.

    Already, the events of the last several days have revealed that we rely on air travel for far more things than we usually imagine. Things like supermarkets—all that fresh fruit—and florists. Things like symphony performances, professional soccer matches, and international relations. In fact, “European integration,” as we have come to understand it, turns out to be utterly dependent on reliable air travel. Over the last two decades—almost without anyone really noticing it—Europeans have begun, in at least this narrow sense, to live like Americans: They move abroad for work, live for a while in one country, and then move to another, eventually going home or maybe not. They do business in countries where they don’t know the language, go on vacation in the Mediterranean and the Baltic, visit their mothers on the weekends. Skeptics who thought the European single market would never function because there would be no labor mobility in Europe have been proved wrong.”

  19. US airlines begin powering flights with biofuels

    US airlines are attempting to demonstrate their clean energy credentials, scheduling flights partially powered by biofuels

    Do not be alarmed if your aircraft begins to smell suspiciously like a fast-food restaurant ñ or pond scum for that matter.

    US airlines were racing this week to demonstrate their clean energy credentials, scheduling a number of flights powered partially by biofuels.

    First United Continental announced the departure on Monday morning of Flight 1403 from Houston for Chicago ñ or the ‘Eco Skies test flight’ as the airline called it ñ using a mix of 60% conventional jet fuel and 40% algae-based fuels.

    Alaska Airlines then announced it would operate 75 flights using a mix of 80% conventional jet fuels and 20% biofuels starting on Wednesday. Instead of algae-base, the airline is using used cooking oil or fast-food restaurant throwaways, said Robert Ames, vice-president of Dynamic Fuels, which produced the fuel.

    “We can use vegetable oil. We can use used cooking oil,” he said. “A good mental reference is McDonald’s used fryer grease.”

  20. “The cooking oil substitute cost six times as much as conventional jet fuel, said Egan. That makes a permanent switch prohibitively expensive ñ unless production increases and prices come down.

    Dynamic Fuels, a joint-venture between Tyson Foods Inc, the world leader in chicken, beef and pork production, and Syntroleum Corporation, is the only producer of this type of fuel in the US. The plant has been operating just over a year, and has an annual capacity of 75m gallons.”

  21. Jet pollution

    SIR – Your article on China’s objections to European efforts to curb airline emissions downplayed how bad the International Civil Aviation Organisation (ICAO) has been in sorting out aircraft emissions (“Trouble in the air, double on the ground”, February 11th). You mentioned that the ICAO ruled out the introduction of a global emissions-trading scheme in 2004. But it also ruled out kerosene taxes as early as 1996 and again in 2001, and emissions charges in 2004. It even ruled out developing a fuel efficiency standard for aircraft in 2001 (only to reverse that decision in 2009).

    The European Union went ahead with its regional emissions-trading system not just because it was an option accepted by the ICAO, but because it was the only option with international support.

    Bill Hemmings
    Transport & Environment

    * SIR – We’re told that the “main objection to the EU’s policy is that it applies to air-miles clocked up outside European airspace.” For some of us that’s a minor issue compared to the tortured logic used by the European Court of Justice to rationalise the scheme: that although each of the individual nations in the EU is an ICAO signatory, the EU itself is not, and that the EU is thus not bound by the Chicago Convention.

    So, how about American Airlines claiming exemption because Texas isn’t a signatory to ICAO?

    True, the hierarchical relationships are inverted, the United States and Texas versus the European Union and its member nations, but ex falso sequitur quodlibet should take care of any objections based on that.

    Citing America’s requirement for double-hull tankers as a precedent for the EU’s action is similarly flawed reasoning. Tanker operators are required to meet a set of equipment specifications, not to pay fees ad infinitum into a transfer program over which they have no control. If they can figure out how to buy and operate double-hulled vessels at no expense, then meeting the requirement costs them nothing. (And that ignores the benefits that may obtain from meeting the specification, such as lower insurance rates.)

    Karl Sutterfield

    * SIR – Your argument is disappointing and not in keeping with your free-trade orientation. The EU has no more right impose a tax on flights between Beijing and Shanghai than China has a right to impose a financial penalty on sales of the Dalai Lama’s book in Rome. The EU is attempting to impose a tax on activity that happens exclusively in other countries.

    Your article was clearly mistaken in asserting that American regulations requiring double-hull ships establish a precedent for such extraterritoriality. Ships must dock within the United States to be affected. Shipping companies are free to use single-hulled ships outside the US while concurrently operating double-hulled ships for US routes.

    It is surprising that a newspaper noted for its free trade advocacy would support a tariff that raises little revenue but has a high likelihood of inciting retaliation, especially when the tariff opens the pandora’s box of extraterritoriality.

    Andrew Sacher
    Fairfax, Virginia

  22. Planes and pollution
    Trouble in the air, double on the ground
    China objects to European efforts to curb its airlines’ emissions

    As an effort to make airlines pay for their pollution, the EU’s action is overdue. In global terms, their emissions are modest, about 3% of the total. Yet they are rising fast: between 2005 and 2010 they grew by 11.2%. Meanwhile the UN’s International Civil Aviation Organisation (ICAO), which was charged with taking steps to mitigate them, has done nothing of the sort. In 2004 it ruled out negotiating a global deal to curb the emissions of all airlines, and instead recommended that countries include their airlines in whatever national mitigation scheme they had in place. In 2010 it changed its mind, announcing that it would, after all, initiate a “framework”—whatever that might be—for a global deal to address airline emissions.

    The main objection to the EU’s policy is that it applies to air-miles clocked up outside European airspace. The EU argues that its approach is consistent with ICAO’s own guidelines and that it would be impossible to regulate otherwise. But the dissenters claim this infringes their sovereignty and breaks the terms of the Chicago Convention, which has regulated aviation since 1944. A group of American airlines therefore launched a legal challenge to the policy; but it was dismissed by the European Court of Justice in December. There was a precedent supporting the Europeans: American green laws insist that ships docking locally be double hulled, even though that forces ship owners to pay for unwanted double hulls on international waters en route to American ports.

  23. Fly and Be Damned: What Now for Aviation and Climate Change?

    by Peter McManners
    ZED BOOKS PRESS: 2012. 192 pp. £14.99

    In Fly and Be Damned, consultant and author Peter McManners explores the sustainability of the aviation industry and calls for a fundamental change in our travelling habits. McManners argues that aviation is stuck in a stalemate between misguided policy and a growing imperative to deal with its environmental impact, suggesting that there is now little possibility of a smooth transition into sustainable flying.

  24. “Planes don’t just release carbon dioxide, they also emit nitrogen oxides, sulfur oxides and black carbon, as well as water vapor that can form heat-trapping clouds… These emissions take place in the upper troposphere, where their effects are magnified. When this so-called radiative forcing effect is taken into account, aviation emissions produce about 2.7 times the warming effects of CO2 alone.”

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