For the airline industry it was as “momentous decision”; for environment campaigners it was “essentially meaningless”. Earlier this month, the global airline trade body Iata passed a resolution, approved by almost 300 of the world’s biggest carriers, to achieve net zero carbon emissions by 2050. Like Santa Claus, millions of passengers wrestling the desire to fly with environmental guilt would love to believe in it. Willie Walsh, the Iata director general, is famously no Santa, but has pushed the policy, whose adoption perhaps met less acclaim than airlines hoped. Airlines first promised a 50% net reduction in emissions back in 2009, a target that after the 2015 Paris accords, “clearly wasn’t enough”, Walsh says. Some airlines – including the one Walsh was then running, British Airways owner IAG – have since committed to reach net zero by 2050. Nonetheless, he says the agreement at Iata’s AGM this October remains “a big deal”. “In Europe the appreciation of the need to address this is more advanced,” Walsh says. “The important thing was to translate a commitment from some airlines into one on behalf of the industry.” How it will be done is a bigger question. Iata has fleshed out a plan that depends action by government and other industry players, such as fuel suppliers and aircraft manufacturers, as much as airlines, and will have a cost – to be borne somewhere between carriers, governments or passengers – of about $2tn (£1.5bn). Speaking in the run-up to the opening on Sunday of the Cop26 climate summit in Glasgow, Walsh is unrepentant, comparing airlines to car drivers: “You’ve got to mandate the people who produce the planes, the engines, the fuels, operate the air traffic control systems. They’re all standing there staring at us, saying, ‘OK guys now, you do it.’ In the same way as the car industry was forced to deliver, they’ve got to be forced to deliver. It clearly requires proper government policy.” That starts with making enough sustainable aviation fuels (SAFs), Walsh says. A theoretical blend of jet fuel using 50% derived from sustainable sources, such as household waste, could be used: “The issue is that airlines can’t get the supply … The fuel companies have to be mandated to produce at scale.” The British government took a first step in its net zero strategy, which was published this month, saying it would mandate that 10% of jet fuel produced were SAFs by 2030. Estimates are the fuel will initially cost three to four times as much to produce, until economies of scale reduce the expense. “There will be a cost … but we’re capable of adjusting to a higher fuel price,” says Walsh, acknowledging fares will rise. Better air navigation and redesigned planes will play a part. But Iata’s 2050 plan relies hugely on SAFs to abate about 65% of the accumulated emissions it anticipates – and on carbon offsetting, which remains controversial and unproven at best, no matter how closely schemes are monitored now. Aviation figures such as the easyJet chief, Johan Lundgren, have been frank about the limitations of SAFs: still burning fuel and producing carbon emissions. “We’re not trying to mislead,” says Walsh. “You’re still burning fuel. But it’s recycling the carbon – you’re not adding more CO2. SAF is absolutely a credible way of doing it. We’re talking about net zero – we’re not talking about zero. We recognise that we’re continuing to emit.” While the likes of easyJet hope to benefit from electric planes for short-haul flights, no such technological shift looks likely to happen in long-haul for a long time. “Hydrogen is potentially an option – beyond 2050,” says Walsh. “But I don’t think we’d be credible if we said we’ll get to zero like that.” Credibility is a recurrent theme. While Boris Johnson last year talked of the UK developing a “zero-emission” transatlantic plane by 2050, Walsh will not play along. “I don’t think that’s credible, and it’s not helpful. It’s nice to have ambition, and maybe that’s why he’s doing it. But we don’t think you can get a commercial transatlantic aircraft in the time frame he’s talking about.” For sceptics of Iata’s plan, most alarming will be that it accounts for air passenger journeys to grow fivefold to about 10bn passenger journeys by 2050. That, Walsh says, will happen whether or not European traffic slows, and workers in the west move to Zoom, with growth coming in places like China and India. Nonetheless he is adamant, despite accepting the climate emergency, despite aviation’s special pleading to use offsets because of its reliance on liquid fuel, that a cap on flying is not an answer. “Should people limit their use of the internet? It’s 3.7% of global emissions. People will have to adapt and do things differently, It’s not just about aviation. It’s everything.” Regardless of passenger travel, Walsh says, dependence on air freight is huge. “Think what would have happened if air cargo hadn’t been available at the beginning of this pandemic. Governments were hugely reliant on aircraft for vaccines and PPE.” While groups such as Campaign for Better Transport have proposed a ban for short-haul flights where there is a train alternative, Walsh cites Eurocontrol research: “If you limited all of the flights in Europe under 500km, it would cut 3.8% of aviation emissions. Great – but it’s not the solution.” For the Irishman, the question of a future without aviation is personal, linked with his heritage and Irish emigration: “People left Ireland and went to America; they were never seen again because they couldn’t afford to travel. I’ve got cousins in Boston that left Ireland back in the 1970s, we grew up together, they headed off and that was it – never to be seen again. You used to get a postcard.” Walsh says he cannot envisage a future without flying: “We’ve experienced what it’s like through the lockdown and the early stages of this pandemic.” Pointing at the screen through which he is being interviewed, he adds: “I hate this stuff.”