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Product, Service & Design Innovation
As Travel Resumes, So Does Focus on Decarbonization of Aviation

After a lengthy pause, tourism stands on the precipice of restarting again. But even as many travelers prepare to take to the open skies, aviation continues to grapple with its oversized carbon footprint compared with the rest of the industry.

On May 13, the US Centers for Disease Control and Prevention announced that fully vaccinated people no longer have to wear their masks in most circumstances. Less than a week later, the United Kingdom reopened international travel under its new traffic light system. After a lengthy pause, the tourism industry stands on the precipice of restarting again. But even as many travelers prepare to take to the open skies, aviation continues to grapple with its oversized carbon footprint compared with the rest of the industry.

Global aviation, including domestic and international passenger and freight flights accounts for 1.9 percent of greenhouse gas emissions, 2.5 percent of carbon dioxide emissions, and 3.5 percent of effective radiative forcing. The industry has made strides since the 1950s due to improved design, technology, and passenger load factors. Yet, as Harold Goodwin pointed out for WTM, as other sectors decarbonize — and as the tourism industry itself decarbonizes through rewilding partnerships, lower-carbon tour options and other climate actions — aviation will become a larger proportion of emissions.

Recognizing the need to drastically cut carbon emissions, several solutions have surfaced within the sector, especially since the beginning of the year.

“We’ve committed to being 100 percent green by reducing our carbon emissions 100 percent by 2050 and have invested in ground-breaking technology to make our goal a reality. But there’s still a long way to go,” wrote United Airlines CEO Scott Kirby, in an email to MileagePlus members on April 13. United’s response to the crisis is the Eco-Skies Alliance — a program for companies to partner with the airline in its investment of approximately 3.4 million gallons of sustainable aviation fuel (SAF) this year. Individuals can also make non-tax-deductible donations toward the program.

United is not the only airline leaning into SAFs. In April, Alaska Airlines committed to reaching net-zero emissions by 2040 through a five-pronged approach — upgrading its fleet, improving flight efficiency, exploring electrification technology, investing in carbon-offsetting technologies (a controversial solution that may not be viable), and expanding the market for SAF. Japan Airlines recently operated its first commercial flight using SAF, as well.

Experts question the feasibility and integrity of these commitments, however — especially given their focus on future technological developments and sustainability.

“Alternative fuels and propulsion systems may well help with climate mitigation but it will probably be a long time before they are deployed at a scale that makes a difference,” said Dr. Giulio Mattioli, faculty of spatial planning in the Department of Transport Planning at TU Dortmund. “The aviation industry has a long history of exaggerating how soon new clean technologies will be available, and how much they will help in reducing emissions, in order to deny the fact that travel-demand management measures will also be necessary.”

This points to one of the key challenges of decarbonization within the aviation industry: Even though carbon dioxide emissions per passenger flight have fallen more than 50 percent since 1990, the volume of air traffic has increased by at least a fifth over the past five years. An estimated 10 billion passengers a year are expected to take to the air by 2050.

“The consensus in the sustainable transport research community is that it will be necessary to curb air travel levels, with travel-demand management measures,” Mattioli said. “However, to date, the industry and policy makers have been extremely reluctant to accept this, as they continue to cater to and encourage increasing travel activity — through, for example, airport expansions.”

Looking beyond technological solutions, some airlines are taking a more grounded approach to their decarbonization efforts. Deutsche Bahn and the German Aviation Association have stated an interest in working together over the next decade to expand rail service and decrease short-haul flights in Germany. These plans could move approximately 4.3 million flight passengers to rail lines every year.

Research also indicates that replacing flights between Sydney and Melbourne with high-speed train service could reduce carbon emissions over three decades. Additionally, data from Finland indicates that if all national short-haul flights were replaced by rail journeys, carbon emissions from these trips could be reduced by 95 percent. In April, the French National Assembly voted to ban domestic flights on routes where the journey could be completed by train in less than two-and-a-half hours. Only five routes were impacted and connecting flights won’t be affected.

“Short-haul flights are easier to ban because there are viable rail alternatives, but they account for a very small share of aviation emissions,” Mattioli said. He also noted there is a danger of “perverse effects” from cutting short-haul flights in that it would free up slots at airports that could be replaced with long-haul routes. “The net outcome of this would paradoxically be higher emissions,” he said.

Nonetheless, experts point out this shift in strategy from funding fuel alternatives to creating a culture shift is fundamental to decarbonizing aviation.

“It marks one of the first times that politicians in a wealthy country have endorsed something that most, if not all, have been reluctant to consider,” wrote Enrica Papa and Luis Delgado in a recent article for The Conversation about France’s cutback on domestic flights. “That high-carbon conveniences aren’t always necessary, or even desirable — and that curbs on the most polluting aspects of consumption are necessary to tackle climate change.”