Higher or lower: Flying at different altitude 'could help aviation cut climate impact'

Flying planes consistently higher or lower than current altitudes could help the aviation industry reach net zero faster, a report has found.

The suggestion is among four goals the industry could adopt to help the sector – a major contributor to climate change – achieve net-zero emissions globally by 2050.

“Aviation stands at a pivotal moment, much like the automotive industry in the late 2000s,” said Prof Rob Miller, director of the Whittle Laboratory at the University of Cambridge. “Back then, discussions centred around biofuels as the replacement for petrol and diesel – until Tesla revolutionised the future with electric vehicles. Our five-year plan is designed to accelerate this decision point in aviation, setting it on a path to achieve net zero by 2050.”

The plan, drawn up alongside the Cambridge Institute for Sustainability Leadership, outlines four steps the researchers say must start immediately and be completed within five years for the sector to remain on track to achieve net zero by 2050.

Eliminating vapour trails – a combination of ice crystals and soot that can follow an aircraft’s path – is the first. About one in 30 flights produces a persistent contrail, which can trap heat and increase aviation’s climate impact.

“Persistent contrails can be avoided by adjusting an aircraft’s altitude in regions where contrails form, known as ice-supersaturated regions. These regions are pancake-shaped – wide but shallow – making altitude changes effective in preventing contrail formation,” the report said.

“Successfully implementing contrail avoidance could reduce the climate impact of aviation by roughly 40 per cent.”

Commercial planes typically fly at an altitude of 31,000 to 42,000 feet.

The second goal is to introduce new policies aimed at achieving efficiency across the existing aviation sector, such as reducing fuel burn by using new aircraft and engine technology.

“However, several bold efficiency measures exist, which are currently hard to access because they involve systems-wide change,” the report said. “If implemented, these measures could reduce fuel burn by up to 50 per cent by 2050.”

Under the third goal, governments would reform sustainable aviation fuel policies, moving beyond purely biomass-based methods to introduce more carbon-efficient synthetic production techniques.

The last of the four goals is to launch 'moon shot' technology demonstration programmes to assess the benefits of transformative technology.

The industry is primarily relying on sustainable aviation fuels to help it reach net zero. But other options should be studied, including long-haul hydrogen aircraft, which would be lighter and remove CO2 emissions from flight, the report said.

“If these goals are not immediately implemented and achieved by 2030, the window for transformation will close, leaving the world to face the escalating climate consequences of a rapidly expanding aviation industry, which is projected to at least double by 2050,” it added. “The urgency of this moment cannot be overstated.”