Ukraine war forces planes to take longer routes, raising CO2

Global aviation carbon dioxide emissions increased by 1% in 2023 because planes had to fly longer routes to avoid Russian airspace, according to a new study.

After Russia invaded Ukraine in February 2022, Western airlines were banned from flying over Russia. This forced them to take much longer routes between Europe or North America and East Asia, burning more fuel in the process.

Published today (Wednesday, 12 February) in Communications Earth & Environment, the study found that detours caused by the Ukraine war led to planes using 13% more fuel on average compared to their original routes. The impact was even greater for flights between Europe and Asia, which saw a 14.8% increase in fuel consumption. Flights between North America and Asia experienced a smaller but still significant 9.8% increase.

Professor Nicolas Bellouin, currently seconded to the Institut Pierre-Simon Laplace (Sorbonne University/École Polytechnique/UVSQ) co-authored the research from the University of Reading. He said: “After the invasion of Ukraine, there was a drop in flights between Western countries and East Asia as airlines adjusted their routes. Over time, flights resumed but had to take significant detours, either flying south of Russia or over the Arctic.

“The affected flights make up about 1,100 flights per day, but the extra distance they must fly has a notable impact on aviation's overall carbon footprint. These detours added 8.2 million tonnes of CO2 to global aviation emissions in 2023.”

The research team used flight tracking data and sophisticated computer models to calculate how much extra fuel planes use on their new routes. Their analysis took into account factors like wind patterns, which can significantly affect fuel consumption.

Airspace restrictions over Libya, Syria, and Yemen were also considered by the research team. They found conflicts in each country affect between 60 and 100 flights per day. Planes avoiding Libyan airspace used 2.7% more fuel on average, while those avoiding Syria saw a 2.9% increase. The detours around Yemen had a slightly bigger impact, with planes using 4.3% more fuel. However, because these restrictions affect relatively few flights and require shorter detours, their impact on global aviation emissions was less than 0.2%.