Researchers at the University of Leeds have revealed that long-distance passenger travel has an impact on the climate. The study, which has been published in the journal Nature Energy, demonstrates that focusing on long-distance travel may be a more efficient strategy to reduce emissions than the present approaches, which emphasize local and commuter travel.
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Travels longer than 50 miles (one way) are responsible for 70% of all passenger travel-related carbon emissions, even though they make up less than 3% of all trips made by UK residents.
When only international travel is considered, the difference becomes even more pronounced: only 0.4% of all trips are made internationally, yet 55% of all emissions come from these travels.
The scale of the impact of long-distance travel is very large indeed.
Dr. Zia Wadud, Study Lead Researcher, Institute for Transport Studies, University of Leeds
Dr. Zia Wadud is also associated with the School of Chemical and Process Engineering.
Over the past 25 years, domestic long- and short-distance car travel has decreased somewhat, but international air travel has increased dramatically due to a rise in vacation and friend and family visits.
The scale of the impact of long-distance travel is very large indeed. That just less than 3% of our trips are responsible for around 60% of miles and 70% 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.
Dr. Zia Wadud, Study Lead Researcher, Institute for Transport Studies, University of Leeds
The research team has determined which travel scenarios could be altered to maximize a reduction in carbon emissions from passenger travel while affecting the fewest number of people or trips feasible. The team has developed a new metric they call emission reduction sensitivity.
Reducing Long-Distance Travel
According to the study, if all car trips under eight miles were replaced with walks or bicycle rides, carbon emissions would decrease by 9.3%. As most travel is done locally and in cars, about 55% of all journeys would need to be rerouted.
This change would result in the study's lowest emission reduction sensitivity, 0.17, calculated by dividing the percentage of altered journeys by the percentage of carbon reduction.
On the other hand, if all flights shorter than 1,000 miles were switched to rail, only 0.17% of trips would be impacted, and emissions would be reduced by 5.6%. This would result in a sensitivity value of 33.2.
Theoretically, restricting each person traveling to one return flight overseas annually would result in a value of 158.3, as very few journeys would be impacted.
The researchers emphasize that rather than offering specific policy recommendations, the possible changes are merely ideas designed to recognize and reevaluate the effects of long-distance travel.
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.
Dr. Muhammad Adeel, Study Co-Author, Centre for Transport and Society, University of the West of England
A Call to Rethink Travel’s Carbon Impact
The researchers also hope their findings will encourage policymakers to reconsider how effort is allocated to addressing the environmental impact of travel.
The information was gathered from the Department of Transportation's National Travel Survey and the Office for National Statistics' International Passenger Survey.
Public awareness of the potential effects of behavior modification is another benefit the research provides.
Dr. Wadud added: “The important thing both at the policy and personal level is that we prioritize the relatively fewer longer distance trips – especially flights – in order to realize the largest reductions.”
Journal Reference:
Wadud, Z., et al. (2024) Understanding the large role of long-distance travel in carbon emissions from passenger travel. Nature Energy. doi.org/10.1038/s41560-024-01561-3