Analysis of aircraft traffic data in Western Europe has revealed the dramatic reduction in carbon dioxide (CO2) emissions at the height of the Covid-19 travel restrictions. Looking at air traffic data powered by satellites, Spire Aviation has shown how a drop of more than 70 percent in carbon emissions resulted from a 43 percent decline in the number of aircraft in use.

On Jan. 5, 2020, Spire recorded 8,730 aircraft flying in Western Europe and calculated that they had emitted 700 million kg (1.5 billion pounds) of CO2. This was based on average fuel consumption for each aircraft type, average utilization of 10 flight hours per day, an average distance per flight of 1,000 nm, and around four separate flights for each aircraft. The study included all categories of aircraft, including airliners, private, government, and military.

For April 25, when most of Europe was under strict lockdown restrictions on travel, resulting in a widespread grounding of much of the region’s airline fleet, Spire counted only 4,980 aircraft and from these calculated a CO2 emissions total of 200 million kg. This represented a 500-million-kg cut in emissions. The same basis for emissions was used for this date, except that average utilization was reduced to five flight hours to account for reduced activity levels.

“This drop in aircraft carbon emissions alone was the equivalent of taking 43 million cars off the road, which is more than all the cars in France or the UK,” concluded Spire.

The impact of the Covid-19 pandemic on air transportation has sharpened the focus on the sector’s environmental impact. Though the industry is currently calculated to be responsible for only around 2 percent of global CO2 emissions, pre-Covid estimates of exponential growth in flight activity pointed to a trajectory in which this proportion would get significantly higher.

Last month, aviation consultancy Roland Berger estimated that even allowing for a temporary reduction in flight activity, current levels of CO2 levels from airline traffic alone are set to triple by 2050 from an annual level of around one billion tonnes. This trend has made the sector a higher priority for the vast majority of countries committed to achieving the overall goals set by the Paris Agreement on Climate Change.

Roland Berger recommended that the air transport industry take a four-step approach to reduce emissions, starting with the continued replacement of older, less fuel-efficient airliners and more efficient use of airspace in terms of route and altitude optimization. The company advocates efforts to introduce battery-based electric aircraft for flights of up to 1,500 km and hybrid-electric or hydrogen-fueled aircraft for longer sectors. It also proposes moves to switch to sustainable aviation fuel for longer-haul flights.

Next year, new carbon-offsetting requirements will begin under ICAO's Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA). Through 2026, these will apply to flights between the states that have volunteered to participate in the first phase of the program (mainly countries in North America, Europe, the Gulf states, and parts of the Asia-Pacific rim). From 2027, it will be expanded to include most international flights, with the exception of some of the least developed countries.

On July 1, in response to a request from the International Air Transport Association (IATA), ICAO agreed to use 2019 traffic levels as the basis for calculating CORSIA offsetting requirements. Originally, it had been intended to use a combination of 2019 and 2020 figures, but IATA argued that this year's traffic levels are abnormally low due to Covid travel restrictions.

As governments have made financial support available to struggling airlines, some, most notably the government of France, have made this contingent on taking steps to more aggressively reduce the carbon footprint of flight activity. Some countries have made specific pledges to achieve carbon-neutral aviation by specific dates, such as Norway, which is committed to having zero-emissions domestic flights by 2040.

IATA has indicated that it does not expect demand for airline flights to achieve a return to 2019 levels until 2023. Both Boeing and Airbus have sharply revised downward projections for new aircraft deliveries, suggesting that replacement of older aircraft, may now happen more slowly, at least in the short- to medium-term.

Spire Aviation is part of the Spire Global group, which is part of the San Francisco-headquartered Spacetech company. Based on its own satellite constellation, it identifies, tracks, and predicts the movement of multiple sets of resources and weather systems to support decisions by companies and governments.