Can the aviation industry ever be sustainable? Aviation may only be responsible for 2 percent of global CO2 output,1 but that’s 13 percent of the world’s transportation fuels each year,2 or 670 tonnes (metric tons) of CO2 annually.3 It would take roughly 23,680,000 trees planted per month to offset all the aviation carbon produced each year.4 The International Civil Aviation Organization (ICAO) predicts that aviation will continue to grow globally by 5.6 percent per year through 2024, but the urgency in finding a solution is even more apparent when we consider the Centre for Asia Pacific Aviation’s projections for passenger growth in India and China over the next 20 years. Less than 2 percent of Indians fly domestically each year. This is forecast to increase sevenfold in the next 20 years. China’s domestic air traffic is five times that of India’s, with a fivefold increase predicted in 20 years. Such figures are alarming, yet their contribution to greenhouse gas emissions comprises only a fraction of global output. To have any marked greenhouse gas reduction, developed nations must lead the way.

There are no simple answers for achieving the International Air Transportation Association’s (IATA) target of carbon-neutral growth by 2025, but the introduction of more fuel-efficient aircraft, the balanced implementation of a global emissions trading scheme, the development of alternative fuel sources, and the upgrading of air traffic control through more efficient air traffic management procedures could be major steps toward a more ecofriendly sky.

Improving Fuel Efficiency

David Carr of Wings magazine reports that, since the signing of the Kyoto agreement in 1992, the airline sector has moderated its annual CO2 output by more than 70 million tonnes. The economic recession of recent years combined with the fallout from September 11 clearly had a role to play, but the overall reduction in carbon output is largely attributable to fuel efficiency. As the director general of IATA, Giovanni Bisignani, put it, “our U.S.$186 billion fuel bill is the biggest economic incentive of any industry to improve environmental performance.”5

Engineers have achieved this by (1) increasing the efficiency of airplane engines, (2) increasing the aerodynamic efficiency of the aircraft, and (3) reducing the structural weight. Carbon-fiber composite materials, which are lighter and stronger than other materials, have been used in aircraft body parts. Commercial use of composites will feature extensively in both the upcoming Boeing 787 and Airbus A350. The major benefit of composite construction in environmental terms is that it results in a substantially lighter aircraft, meaning greatly reduced fuel consumption.

Emissions Tax and Trading Schemes


NAV CANADA estimates that 12.7 million metric tons of CO2 emissions will have been avoided by 2016 through system and equipment upgrades, changes to procedures, and developing routes in collaboration with operators.

One sure way of curbing carbon emissions would be putting a price on carbon in the form of a carbon tax, but this has been met with understandably loud objections from the industry.6 At the 2009 IATA annual general meeting in Kuala Lumpur, Bisignani said carriers were “absolutely against” another levy at a time when the industry is struggling to make ends meet. “We have seen so many taxes that we are fed up,” he said.7

Therefore, rather than a flat tax on the industry, policymakers and economists are leaning toward an emissions trading scheme, where each entity has a quota of emissions. It can meet this quota by either reducing activity, becoming more efficient, or buying credits from those below the quota. For the scheme to be effective, it should be global, open, and flexible. In this light, the European Union has recently included aviation in the European Union Emissions Trading Scheme, where emissions are traded in euros per metric ton of CO2. The economic cost of implementing an emissions trading scheme on a global scale will depend on the caps set by governments, which would have to be adjusted to ensure that companies can survive the cost of complying. By 2025, 90 million tonnes of CO2 will need to be offset by the aviation industry to achieve IATA’s target of carbon-neutral growth. At a cost of U.S.$7 billion per annum (based on a carbon price of $65 a tonne in 2020),8 Willie Walsh, chief executive of British Airways, has declared: “This will cost us. There’s no free lunch.”9 These fees will likely be absorbed by major carriers through ticket surcharges.

Use of Biofuels

Various stakeholders have been exploring the possibility of reducing carbon emissions by switching from fossil fuels to biofuels, with IATA setting a target of using 10 percent biofuels by 2017.8 Biofuels are typically produced from plant oils and, ideally, yield a lower carbon footprint. The main objection has been that cultivating crops to make fuel is not sustainable, as the processing of biofuels produces higher emissions than petrol. It also uses land suitable for food production; 100,000 square kilometers of land would need to be cultivated to generate 1 exajoule (EJ) of aviation fuel (1 EJ = 1018 J and 1 kWh = 3.6 × 106 J).

An alternative is biofuels not born of food crops, such as jatropha and algae. In 2008, flight tests in a Virgin Atlantic Boeing 747 powered by General Electric engines were run on a fuel derived from jatropha.2 An algae-based biofuel was tested in a Continental 737-800 with a CFM-56 engine. These flights showed that mixing biofuels burnt less regular gas and had no detrimental effects on the performance of modern commercial engines.

Algae is renewable, has a high oil yield per weight, and has a high crop yield per hectare. It can be adapted to grow in diverse climates, but currently the production cost is still about five times higher than petroleum-based fuel. The airline industry is conducting further research into production and refining methods to make it more cost effective, as well as investigating alternative environmentally friendly fuels such as cryogenic and synthetic fuels.

Improving Air Traffic Control Systems

In aviation’s utopia, all aircraft would adhere to the most direct and fuel-efficient flight profiles while a centralized flow-management system would ensure that aircraft were granted their most economical cruising altitudes and optimized profile descent. The main hurdle to achieving this is runway congestion. Apart from the construction of additional runways, the only way to reduce delays is via more efficient flow-management procedures. Yet, with tens of thousands of aircraft traversing the globe daily, the integration of such a volume and variety of flight plans could create a veritable Gordian knot exacerbated by broad discrepancies in the international application of aircraft separation standards and air traffic management protocols.


Continuous descent approaches facilitated by an advanced form of GPS navigation called Required Navigation Performance save fuel and will reduce the footprint of Calgary-based WestJet Airlines by 4,930 tonnes of CO2 in 2010.

Customarily, the jurisdictions of air navigation service (ANS) providers have corresponded with national borders. Alas, geopolitical precincts more often than not fail to correlate with commonly flown international city pairings. An aircraft operating between London and Paris, for example, will fall under the control of two separate ANS providers despite the short duration and heavy congestion of the route. In an effort to eliminate such redundancies, the Single European Sky initiative (also known as SESAR) was formed. Since 2004, participating European nations have been working to carve out a new airspace model that operates independently from national borders through the implementation of functional airspace blocks (FABs). SESAR is expected to save upward of 16 million tonnes of carbon emissions annually through the use of more streamlined air traffic management procedures5 and could serve as a model for broader international cooperation. If SESAR is able to facilitate carbon-neutral growth in Europe by cutting back airborne delays and facilitating more optimum routes, net CO2 emissions from European aviation would peak between now and 2020 and then would stabilise and decline, despite a forecast increase in traffic.

On the other hand, nations that boast vast expanses of domestic airspace may implement uniform adjustments to airspace structures unencumbered by political constraint. Over oceanic airspace and sparsely settled areas that lie beyond radar coverage, a satellite-based monitoring system known as automatic dependent surveillance-broadcast (ADS-B) can significantly reduce the required lateral spacing between aircraft, allowing airplanes to operate on more direct routes at their most efficient cruising altitudes.

While progressive airlines are pioneering navigational technologies that employ GPS to create precise and efficient arrival and departure routes, unprecedented cooperation in the aviation industry will be required—from aeronautical engineers, to governments, to ANS providers and users. The Single European Sky initiative and functional airspace blocks are steps in the right direction.

Looking Forward

Economist Paul Krugman addressed the economics of carbon emissions control in his New York Times column on April 7, 2010. Based on available estimates for the period 2010–50, if we take action with a strong climate policy, it would cost between 1 and 3 percent of global GDP. On the other hand, if we don’t act, a temperature rise of 9° Fahrenheit (5° Celsius) will result in an estimated 5 percent reduction in global GDP. Krugman sees “policies to reduce carbon emissions as a sort of public investment project: you pay a price now and derive benefits in the form of a less-damaged planet later.”

The aviation industry can be sustainable, but even as our climate crisis deepens, this will only happen when stakeholders come to accept that reducing greenhouse gas emissions makes sense not only for ecological reasons but for economical ones too.


James Marasa

James Marasa cofounded, an online Aviation English training program which helps aviation students and non-English-speaking pilots understand and communicate effectively in demanding air...

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