Les émissions de GES du transport aérien ne cessent d’augmenter, mettant en péril les efforts de lutte contre les changements climatiques. Mais peu d’options s’offrent à nous.
The news these days is rife with stories about the impending electric vehicle (EV) revolution, and for the most part, it’s a good-news story: EVs are expected to take over the global automobile market in the next few decades, thereby helping to reduce the transport sector’s carbon footprint.
Meanwhile, we hear almost nothing in the media about the rising greenhouse gas (GHG) emissions from air travel, which seem poised to negate some of the gains made from EVs. Unfortunately, unlike the shift towards electrification of automobiles and the growth of renewables, there are no good policy options on the table for adequately reducing emissions from aviation.
It is shaping up to be quite a dilemma: By all measures, modern humans are addicted to air travel, and yet despite considerable efforts by the airline industry to make airplanes more efficient, there is no practical way to produce zero-emission aircraft. Sadly, the only genuine way to reduce our collective carbon footprint from long-distance transport – given available technologies – is to significantly cut down on passenger and cargo flights.
And that’s where things get very uncomfortable. Clearly, major society-wide reductions in air transport would spell disaster for a range of economic sectors, not least aviation, but tourism and the petroleum sector too. It would also dramatically alter the social relations to which we’ve become accustomed in a globalized world. Cut out air travel or continue contributing to the ongoing climate emergency faced by our home planet — this is the inconvenient juncture at which we have arrived.
In some ways we’re lucky these are not the same stark choices we face for local transportation. Switching out an old gas-guzzling car for an EV (or even better, a bicycle or transit pass) may dramatically improve one’s local carbon footprint, but no parallel solution presently exists for fast long-distance travel, even domestically. For instance, VIA Rail’s transcontinental train journey from Toronto to Vancouver takes four days and (despite conventional wisdom) is substantially more taxing on the environment than flying, thanks to the low occupancy ratios and VIA’s old diesel-powered locomotives.
Cut out air travel or continue contributing to the ongoing climate emergency faced by our home planet — this is the inconvenient juncture at which we have arrived.
Transportation accounts for 14 percent of global emissions, but in industrialized countries like Canada and the United States the sector is responsible for about a quarter of anthropogenic emissions. In Canada, transportation emissions have grown by 42 percent since 1990, driven mostly by growth in road transportation. In fact, emissions from domestic aviation have only grown marginally since 1990, thanks largely to improvements in fuel efficiency counterbalancing growth in air travel. However, Canadian-based GHG emissions for international aviation (which are not included in the domestic figures above) have actually grown by 85 percent since 1990.
Again, this emissions growth is despite major improvements in the fuel-efficiency of aircraft in recent years. Indeed, many airlines have been successful in reducing carrying weights (through innovations in lightweight equipment and those expensive baggage restrictions we all know so well) — all of which helps cut down on fuel use. They have also been fairly successful in incorporating biofuels into the fuel mix (which can theoretically reduce the carbon footprint of a flight). Canada’s leading airlines are betting big on second-generation biofuels (which use forestry residue and agricultural by-products as feedstock rather than diverting food crops) to help reduce emissions. Unfortunately, the development of second-generation biofuels has largely stalled thanks to the low price of oil, and biofuels are not expected to make up more than a fraction of the fuel mix used in aviation in the coming decade. Meanwhile, the first-generation biofuels currently in use raise a host of other social and environmental concerns.
In short, improvements in fuel efficiency will take us only so far. The jumbo plane in the room is, literally, the jumbo plane! The number of air travellers globally has more than doubled in the last two decades, and forecasts expect demand for air travel to double again in the next two decades. The same story is true of world air cargo – with base-scenario forecasts expecting global air cargo traffic to more than double over the next two decades as well.
Even in a scenario with moderate technological improvements and modest regulatory changes, emissions from aviation are expected to grow by upwards of 76 percent over the next two decades
Efficient planes or not, this growth trend is clearly working against the already troubled efforts to avoid catastrophic global warming. Airline emissions today account for 2.5 percent of annual anthropogenic GHG emissions worldwide (that’s more than all GHG emissions emitted by Brazil — the world’s seventh-largest carbon-emitting state). Even in a scenario with moderate technological improvements and modest regulatory changes, emissions from aviation are expected to grow by upwards of 76 percent over the next two decades, simply because of the increase in demand.
While it is in the interest of airlines to improve fuel efficiency (since fuel accounts for up to a third of operational costs), it is clearly not in the industry’s interest to curtail growing demand. This is why the industry’s proposed solution to the problem, backed by global institutions, is a new program called the Carbon Offset and Reduction Scheme for International Aviation (CORSIA). The plan largely relies on offsets – investments in various emissions reduction projects elsewhere to cancel out the emissions from aviation. Yet while CORSIA might sound ambitious on paper — calling for the industry to cap its GHG emissions to 2020 levels by 2027 — it is bound to fail as a carbon mitigation strategy. Offsets, much like biofuels, face substantial limitations and conceptual flaws. As Kevin Anderson, former director of the Tyndall Centre (the UK’s leading academic climate change research organization), has written in Nature: “Offsetting is worse than doing nothing. It is without scientific legitimacy, is dangerously misleading and almost certainly contributes to a net increase in the absolute rate of global emissions growth.”
Not only are global regulatory “solutions” like CORSIA a non-starter, but new technologies are also impractical or unlikely to work at the level of the jumbo plane. Prototypes for everything from hydrogen fuel-cell-powered airplanes, to atomic airplanes, to solar-panelled airplanes, to hybrid-electric airplanes whose batteries can be recharged while in flight, all presently exist. But the chances that any one of these technological solutions will be applied to large commercial aircraft in the next decade are slim to none — because the technologies are only possible on small aircraft, or are too dangerous, or would take multi-year, multi-billion-dollar investments in a cutthroat industry that typically spends many years developing new aircraft only if a return on investment is expected.
In the end, the only practical way to reduce our society’s emissions from long-distance air transport (while admittedly giving rise to social costs elsewhere) is to restrict the growth in demand for air transport. It’s going to take some political guts to try to shape or nudge the demand for passenger and cargo air transport, and there are a number of mechanisms through which that could be done, ranging from the unpopular levying of flight taxes, to the political suicide of imposing hard-cap restrictions on flight growth. Needless to say, neither of these policy options is likely to be attempted. Either way, the jumbo plane needs to be let out of the room: Relying on technological innovation, other market forces, and a global system of carbon offsets will not solve the serious problem of growing GHG emissions from aviation.
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