Carbon footprint from air accounts for the biggest chunk of travel emissions. According to the German travel trade body VDR, air accounts for 40% of emissions, followed by accommodation at 21% and ground transport, food and restaurants soaking up the remainder.

Thankfully, when it comes to sustainability the aviation industry is ahead of the curve and is moving towards net zero emissions by 2050 to meet the terms of the Paris Agreement.

CORSIA, the carbon offsetting scheme for airlines, is helping airlines in a quick-fix/least expensive/phase 1 carbon reduction drive.

The long game is the costlier electrification of aircraft and the switch to sustainable aviation fuels (SAF). IATA reckons that by 2025, some 1 billion passengers should be travelling on flights powered by a mix of jet fuel and SAF.

IAG, for example, is investing US$400m over the next 20 years in the development of SAF. The impact of Covid should get the industry there faster.

Last year saw the largest ever decline in global emissions and it has forced many polluting aircraft to be retired. New aircraft, such as Airbus A350s and Boeing 787s, are up to 40% more fuel efficient, which should go some way to counteracting an expected doubling in passenger numbers to 8.2 billion by 2037.

Large capital investments will be more challenging, as Covid decimated revenues last year to the tune of US$252bn according to KPMG, but Delta’s Amelia DeLuca, MD of Sustainability, says “stakeholders are demanding an acceleration of the company’s sustainability efforts”.

The world’s major airlines are therefore continuing to trial biofuels to part or totally replace jet fuel, reducing weight, finding lighter materials for on-board items, and building factories to satisfy future demand for biofuel.

“When it comes to sustainability the aviation industry is ahead of the curve and is moving towards net zero emissions by 2050”

Airlines are also using slower cruising speeds, taxiing on one engine rather than two, towing between gates, using continuous descent approaches, optimising air routes and recycling retired planes.

Delta, which has a carbon neutral goal, offers a carbon offset calculator. Its sales team works closely with travel managers to evaluate a business’ carbon footprint and in February it partnered with Deloitte to reduce its carbon emissions by purchasing SAF.

“The market is so underdeveloped that all SAFs produced in 2020 would only power Delta’s fleet for one day pre-Covid,” says DeLuca. “This is why investments, guided by a strong long-term vision, are so critical.”

United launched a similar scheme in April, when a dozen global corporates, among them DHL, Nike, Siemens and Deloitte, under the Eco-Skies Alliance Program, are allowing individual customers to purchase SAF.

United will be the first airline to invest in game-changing atmospheric carbon capture technology known as Direct Air Capture, as well as in SAF, environmental compliance and waste, water and energy programmes.

“We want to be authentic in our intention. It is going to be a challenge to get there,” admits Lauren Riley, MD of Global Environmental Affairs & Sustainability.

“There is no silver bullet to decarbonise aviation. Sustainable aviation fuel is two to four times the cost because there is not enough supply so we’re investing in production plants to create capacity.”

United is also testing a system that will provide greater transparency.