Should We Fly Less or Fly More Efficiently?

A conversation with ICCT’s Dan Rutherford on the pathway to reduced emissions in travel.

A commercial airplane
Abhishek Singh & illuminati visuals / Getty Images

Last month, I wrote a piece arguing that we’re thinking about flying all wrong. My premise – right or wrong – was that we spend too much time talking about the impact of aviation on each individual’s personal carbon footprint, and not enough time talking about how all of us can play a role in shrinking the societal-level footprint of the industry. Just as vegans can join forces with reducetarians, I posited that those who don’t fly can and should find common ground with folks who want to fly less, or who want to shift their company’s or institution’s travel policies.

My musings caught the attention of Dan Rutherford – Program Director for the International Council on Clean Transportation’s (ICCT) Shipping and Aviation initiatives. Following some insightful exchanges on Twitter, I suggested we connect via phone. Below are some of the highlights.

On Decarbonizing and SAFs

I started by asking him how we might go about decarbonizing such an energy-intensive industry:

There’s a lot that needs to be done to build pathways to zero, and opinions vary dramatically on what should be done first. The industry itself is focused on sustainable aviation fuels (SAF) – which currently tend to be waste-based biofuels but could be near zero emission electrofuels (synthetic kerosene) in the future. Meanwhile, a lot of my research to date has focused on improving the efficiency of the aircraft themselves, and the airlines’ operations. It’s only more recently that conversations around real carbon pricing, frequent flyer levies or other forms of demand reduction – whether it’s ‘no fly’ campaigns or opposing airport expansion – have really come to the fore. My opinion is that we’re going to require all of the above.”

Given the sheer amount of fuel it takes to keep a commercial aircraft flying, I was curious whether SAFs really could live up to the hype from airlines and investors. He replied:

“They are important and they will play a role. The problem is first and foremost a pricing problem. Fundamentally, fossil jet fuel is too cheap, untaxed internationally, and often domestically too. A number of European states even exempt aviation from Value Added Tax, while train travel is taxed. Meanwhile, waste-based biofuels are 2 to 5 times as expensive, and electrofuels will be 9-10 times as expensive. Saying, as the airlines have been doing, that we will all get SAFs yet we don’t want to pay more for fuel is pure folly.”

Rutherford added that the problem with waste-based biofuels, which many of the current airline initiatives appear to emphasize, is that supply is massively limited. The industry also has to compete with countless other societal uses for these products. Meanwhile, using renewable electricity to create synthetic kerosene (electrofuel) has more potential, but would require an astronomical build-out of renewable energy capacity – at a time when we are not yet decarbonizing the rest of our electricity demand hard or fast enough. Finally, battery-electric flight might – he suggested – have some potential for regional travel, but because batteries are expensive and heavy, would likely only account for up to some 30% of flights and 10% of aviation emissions.

The Activist Approach

As he explained the shortcomings of each potential pathway toward lower emissions aviation, it was increasingly clear that there’s no single drop-in replacement for fossil-fueled flights. Given that fact, and given the huge amount of investment required to scale up the alternatives, I wondered whether the "flygskam" (flight shaming) and "no fly" efforts of climate activists might be onto something.

Climate Activist Greta Thunberg Arrives In NYC After Sailing Across Atlantic
Greta Thunberg arrives to New York City after crossing the Atlantic in a sailboat on on August 28, 2019. Spencer Platt / Getty Images

Rutherford agreed, and suggested that the impact reaches well beyond the carbon reductions of each individual flight avoided:

“I started working on aviation emissions in 2008. It’s been a really long slog for most of the time we were doing this. The aviation industry would set out long-term aspirational goals, but if you looked at the nuts and bolts – the planes they buy, the fuel they burn, and the routes they operate – they really were not taking it seriously. Things changed abruptly in 2019 due to the so-called ‘Greta Effect.’ It was almost like a light being switched on overnight. Now we’re seeing increasing commitments to Net Zero, we’re seeing roadmaps with some more teeth to them, and we’re witnessing shorter-term actions as well. The fact that the ‘Greta Effect’ had such a big impact convinced me that consumer action can have a huge influence.”

While he joked that the Greta Effect had far outpaced the Rutherford Effect, I was curious how he felt about the idea that environmentalists shouldn’t fly at all. Describing himself as "a reluctant traveler," and noting that he had both family in Japan, and professional reasons to travel regularly to Montreal, he said he didn’t personally feel comfortable moralizing about flying in absolute terms. He did, however, agree that a broad movement of demand reduction – encompassing both hardcore non-flyers and folks willing to cut back – could be a powerful force for change.

The Role of Frequent Fliers

The ICCT, for example, has researched the distribution of flights per capita and confirmed – like many other researchers – that the vast majority of flights are taken by a small minority of people (see below). This suggests both an urgent issue of equity and a potentially powerful inflection point for change. Focusing on those frequent flyers first, either through frequent flyer levies, workplace interventions to reduce the need for flying, or even by recruiting them to put pressure on airlines, could have a huge influence on emissions trajectories.

chart showing airplane trips
Courtesy of Dan Rutherford / ICCT

Exactly what that engagement might look like would depend on the individual. Rutherford pointed out that the ICCT’s research, for example, has shown huge disparities between the carbon intensity of flights between the same two cities – 50% or more depending on the carrier, the plane, and the seating that’s being chosen (see below). If frequent flyers could be mobilized to demand that information upfront, and to make better choices if and when they did fly, the impact could be substantial:

“The single most important mobilization would be a mass mobilization of frequent flyers who vow to never take a fossil-fueled flight again, and who also demand to see the emissions data of their flight choices.”

Map showing emissions from flights between AFO and ZRH
Courtesy of Dan Rutherford / ICCT

He also noted that this is far from an abstract conversation for him and his colleagues. As an international organization with staff on many continents, working on international-level policy, the ICCT has been having conversations themselves about how and how much to fly. The goal, said Rutherford, was to try and find a way down from current highs, while not compromising either the impact of the organization or placing undue burden on younger co-workers whose careers may be more directly impacted by an inability to travel. Pointing to the recent grounding of flights due to the pandemic, however, he suggested that the conversations about what’s possible in terms of demand reduction had shifted dramatically in just the past year:

“There’s credible modeling out there suggesting that up to a third of business travel may never come back. Companies are finding that they can do a lot of what they do without the need to travel, and they can do it a lot cheaper. […] What I would hope for is that we are in a transition generation, where a number of us made career or personal choices that locked us into travel-intensive lives. Maybe the next generation won’t have to make the same choices. In an ideal world, we move away from frequent flying as a societal requirement. COVID shuffled the deck so it will be interesting to see where it goes.”

Better Efficiency + Reduced Demand

Asked what that may look like, Dan suggested that an increase in the rate of efficiency – combined with a very real reduction in demand growth – means that he can finally see a pathway to far less emissions-intensive travel.

“The pre-COVID baseline was that demand was growing by 5% per year, while fuel efficiency was improving by 2% per year. Post-COVID, we might be looking at something like 3% annual growth in traffic, and we believe that 2.5% efficiency improvements per year are achievable long-term. That almost gets you to flat emissions. How much could new planes, electrification, SAF, route improvements, demand reduction achieve when combined? A 50% reduction in absolute emissions by 2050 certainly doesn’t look as crazy as it once did.”

Of course, in a world of constrained personal carbon budgets and the challenges of a 1,5 degree lifestyle, even a 50% reduction in absolute emissions would be a far cry from the zero-emissions we really need to achieve. Pointing to a recent article by former World Bank economist Branco Milanovic, Rutherford suggested that we really do need to think about curtailing the high emissions lifestyles of the globally rich – and the pandemic has shown that this is eminently possible:

“If someone had told us we’d achieve a 60% reduction in flights, and a 50% reduction in emissions, in just one year, we would have thought it was absurd. And yet here we are. Airlines workers have certainly been impacted, and we shouldn’t ignore the short-term impacts of that economic dislocation. But it actually happened, and it is something we found we can accept. We’re going to have some conversations going forward about what comes back, and how.”

We closed our conversation together by musing on the potential to move beyond the "do or don’t fly" debate as a question of absolute, personal morality. Instead, Dan suggested, it should be viewed as a strategic lever that can motivate systems-level change. Using this lens, he argued, it’s possible to bring together those folks who really have been able to go "cold turkey" and wean themselves from flying entirely, but also recruit those who feel they can’t or won’t yet make that commitment.

If simultaneous pressure could be brought to bear on airlines to decarbonize, on legislators to legislate, and on society more broadly to rethink its reliance on aviation, then it’s just possible that sustainable alternatives – be they telepresence or sleeper trains or some as-yet-unimagined new vessel – could emerge. The goal, after all, is not for each of us to reach zero carbon lifestyles as individuals. Instead, it’s to play a meaningful role in getting us there together.

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  1. Milanovic, Branko, et al. "Climate Change, Covid and Global Inequality." Globalinequality, 2021.