Aviation needs bolder approaches to climate change than carbon offsets and cleaner fuels

Aviation is a big polluter. Globally, the industry generates roughly one billion tonnes of co₂ per year - comparable to Japan, the world’s third largest economy. Apart from a pause during the COVID-19 pandemic, emissions from flights have risen by 2.5% each year for the past two decades. In the next three decades the industry’s total impact on global warming is on track to exceed that of its whole history, since the Wright Brothers’ first flights in the early 1900s. 

Cutting the sector’s impact on global warming is high on the agenda at the upcoming assembly of the International Civil Aviation Organization (ICAO) in Montreal, Canada, 27 September – 7 October. Ministers from 193 nations will try to negotiate an industry-wide target for cutting emissions that is in line with the goals of the Paris Agreement. There will be much talk about the need for action but, based on the preparations, most of the focus will be on familiar ideas, like cleaner forms of jet fuel and improving schemes to offset carbon emissions. 

In a commentary in the 22 September issue of Nature, Steffen Kallbekken and David G. Victor from University of California San Diego School of Global Policy and Strategy, argue for experimentation and a better understanding of how uncertainties in climate science and technology will affect aviation’s emission control strategies. 

They argue that it might be difficult to produce Sustainable Aviation Fuels at sufficient scales, that offsetting as a strategy for reaching net zero might be a dead end and that addressing climate impacts of aviation beyond co₂, such as contrail cirrus (the condensation trails), might require a radical redesign of aeroplanes and airports. 

The scientists, who are part of a research project focusing on how aviation can contribute to a low-carbon society (AVIATE), propose three steps that would lead the aviation industry towards the technological revolution the industry needs to stand up to its bold pronouncements and net zero commitments: 

First, the industry must become more self-aware of the risks associated with its current approach to the climate crisis, which reflects self-interest in preserving the status quo.  Sustainable Aviation Fuels might have a big role to play, but a lot more investment is needed into options that are far from viable today, such as electric or hydrogen aircraft, that could prove to be effective strategies for reducing contrail cirrus formation and eliminating emissions. 

Second, international coalitions of ‘first movers’ in aviation need to be established --- small groups of governments and firms that are willing to lead.  A more diverse experimental approach than what we have seen so far is needed – investing in varied response strategies, including hydrogen, electricity, and cleaner, more scalable variants of fuel. 

Third, research is essential, for example, to bring knowledge about contrail cirrus and chemical interactions in the atmosphere to a level where the aviation industry can be more confident about the route forward.