With the COP26 concluded a little over a week ago (November 13), here is something to ponder. Must we travel as much as we do on airplanes?
A flight from London to San Francisco releases approximately 5.5 tonnes of CO2 per person. By contrast, an entire year of driving a typical passenger car emits 4.6 metric tonnes. More than a whole year’s car emissions released in one 11-hour flight.
Aviation is estimated to account for approximately 2.5% of global CO2 emissions. While this number may not sound significant, if aviation were a country, it would be sixth in the world. Forecasts estimate that by 2050, approximately 43 metric gigatons of carbon dioxide will be generated by aviation worldwide. And when the damage from aircraft includes the discharge of other gases and vapor trails in addition to the CO2, the total jumps to 5% of global emissions.
Contrails, the white streaks we see in the sky, are produced when hot exhaust gases come into contact with low-pressure, cold air. They contain black carbon particles. Moisture condenses on these to form ice. Though some contrails only last a few minutes, some join with cirrus clouds and other contrails, and this larger mixture can remain for up to eighteen hours. This contrail cloud mixture causes an effect known as ‘radiative forcing’. The balance between heat emitted from the earth and that coming from the sun is altered. And this causes a change in climate. Thus, there is a double negative to aircraft – the CO2 emissions, and the radiative forcing effect from the contrails.
It turns out the damage from contrails can be mitigated by changing flight paths. Researchers at Imperial College London have found that flight altitude changes of just 2,000 feet could curb the effect. A study of Japan’s airspace found that changing just 1.7 percent of flights could cut contrail climate forcing by 59%.
Small changes in flight paths can significantly curb the impact of each flight, and at low cost. If these changes are implemented throughout the world, the effects could be significant.
Some airlines are leading the way towards environmental sustainability. Last winter, Air France KLM Martinair launched the world’s first sustainable aviation fuels (SAF) program to reduce CO2 emissions.
Then there are innovators devising environmentally friendly small aircraft to one day meet some passengers’ needs. As a start, the company Pipistrel received EU certification for its electric two-seater plane a little over a year ago. And Swiss flying school AlpinAirPlanes installed solar panels to recharge them (Engineering and Technology Magazine, Volume 16, Issue 7, August 2021).
For larger aircraft Rolls-Royce is in the process of developing hydrogen-fuelled engines that are likely to be available by 2035. They have three concept designs: a turboprop for 100 passengers, a turbofan for 200 passengers, and a futuristic blended-wing body design. Unfortunately there are many obstacles with hydrogen that lead some experts to believe that hydrogen aircraft are unlikely to be available until 2050 (Engineering and Technology Magazine, Volume 16, Issue 7, August 2021). Still, they do give us some hope for the future.
In the short term, Sustainable Aviation Fuel (SAF), has been introduced by Air France. It is a kerosene-like fuel but not derived from fossil sources. Such biofuels have difficulties of their own. It takes an enormous amount of crops to produce enough energy for aircraft, and the decision of the best use for those crops – food versus airlines — is certainly not a clear cut one. SAF is a very good idea but will be slow in transition, and during the next four decades when mitigating emissions is crucial, we must find alternatives.
Hydrogen or biofuels are the two likely choices for the future, and hydrogen as we know is a long process in development. In the meantime, while scientists work on improving flying options, what is the best way for us to reduce our carbon footprint, and still travel when we need to?
For domestic travel, high-speed rail proves a good alternative. The Brussels-London Eurostar launch caused aviation along that route to decrease by 55%. In other instances high-speed rail has been shown to reduce air transport by as much as 80%. The International Energy Agency has summarized the direct impact of launching high-speed lines on the corresponding flight paths in a telling chart. It notes that the Paris-Strasbourg train decreased air travel by over 80%. The Paris-London and the Seville-Madrid train routes decreased corresponding aviation travel by over 50%, and in China the Taipei-Kaohsiung train decreased flights by 80%.
Domestic flight travel emissions have increased 17% since 1990 and they continue to grow. But where high speed rail is present, this is being mitigated. Building more high-speed trains between common flight destinations could be part of the solution.
Thus connecting major cities like New York, San Francisco and Chicago through high-speed rail could significantly reduce carbon emissions. That, and allowing online meetings to be the modus operandi for the corporate world could together have a real impact. The pandemic has given us a window of opportunity – a chance to try virtual meetings and to see how they perform. And they work well.
There is no simple answer to the problem of carbon emissions; there are many changes that can have a cumulative positive effect. Here are a few ways to help reduce the climate impact of aircraft — this is by no means an exhaustive list, only a beginning:
1. Use the Cloud, Not the Conference Room
Simply reducing flights when meetings can be conducted online has a huge impact. The International Civil Aviation Organization has verified that global passenger traffic decreased a huge 60 percent over 2020. While the pandemic mindset exists, let’s keep the conference room online and make it a permanent fixture. The cloud is better for the planet, better for families to spend more time together, and better for our pets — no need to be left alone or boarded for that business trip.
2. Slightly Alter Flight Altitudes
Imperial College London has shown that at a low cost and with only minor flight altitude adjustments, we can reduce damaging radiative forcing that contributes to global warming.
3. Fund Environmentally Friendly SAF Programs
With airlines struggling as they are today, government funding for SAF research and airplane innovation could help, especially in the long-term.
4. High-Speed Rail
Our government should build high-speed trains, particularly between commonly used flight paths. And when we have the option of a high-speed train instead of a jet, we should use it. Fortunately, the research shows we do. So it is just a matter of putting some tracks down, starting to build, and fighting the airline lobby.
All of it will take time; some we can do now.
