Leeds study reveals carbon impact of long distance travel

Journeys over 50 miles are responsible for 70 per cent of all UK passenger-related carbon emissions, despite making up just three per cent of all trips. According to the research, published in Nature Energy, international travel is by far the biggest contributor. Despite accounting for 0.3 per cent of all travel, international journeys make up 55 per cent of all UK passenger emissions.

“The scale of the impact of long-distance travel is very large indeed,” said research lead Dr Zia Wadud, from Leeds University’s Institute for Transport Studies and School of Chemical and Process Engineering.

“That just less than three per cent of our trips are responsible for around 60 per cent of miles and 70 per cent of emissions shows how important long-distance travel is in the fight to combat climate change. Worryingly, long distance trips, especially flights, have been growing; however, they offer opportunities too.”

In order to inform strategies to maximise reductions in passenger-related emissions, the researchers devised a new metric called emission reduction sensitivity, calculated by dividing the carbon reduction percentage by the percentage of journeys altered. They found that if all car journeys under eight miles were shifted to walking or cycling, there would be a 9.3 per cent reduction in carbon emissions. However, around 55 per cent of all journeys would need to be shifted to achieve this, meaning the emission reduction sensitivity for this change would be just 0.17.

At the other end of the spectrum, if everyone who currently flies now was limited to one return overseas flight per year, that would have an emission reduction sensitivity value of 158.3, as so few individual trips would be affected. The research team also pointed out that aviation emissions are invariably left out of national statistics, despite being by far the largest source of passenger-related carbon emissions.

“Whilst efforts to move local journeys to more sustainable modes of transport are really positive, by omitting aviation emissions from national statistics – as is the case at the moment in nearly all countries – we are not getting a holistic picture and ignoring a large part of the problem,” said Dr Muhammad Adeel, a co-author currently working at the Centre for Transport and Society at the University of the West of England.

The data used in the study was collected from the Department for Transport’s National Travel Survey, and the International Passenger Survey, which is organised by the Office for National Statistics.