Comparing train and plane options on 10 UK routes, consumer organisation Which? found that flights emit twice the CO2 on average (118% more) when compared to travel by rail which tends to be around 35% more expensive.

The group found that just three out of 10 routes were cheaper by train.

On the Edinburgh to Bournemouth route, the cheapest rail fare cost £127, while a return flight cost £38. However, a flight emits an average of 218kg of CO2 per person, 131% more than travelling by train.

London to Edinburgh was 75% more expensive by train for the 8th and 15th April, coming in at £90 compared to £51 for a flight. However, CO2 emissions stood at 190kg per person by plane, compared to 90.9kg per person by train.

The largest difference in pollution when comparing rail with air was for journeys between Newcastle and Southampton. Carbon emissions on this route average 64.5kg by train, and 242kg per person by plane – 275% more.

However, this route was one of just three which is cheaper to complete by train, with a return ticket priced at £107 when using split tickets, compared with £175 to travel by air. However, the return rail journey would take over 11 hours, more than four times the duration by plane.

The only other two journeys found to be cheaper by rail were on the Edinburgh to Newquay route, and the Bristol to Aberdeen route. The former costs 13% less at £250 for a return fare, but would take more than seven times as long to complete – over 22 hours.

The Bristol to Aberdeen route costs just over a fifth less by rail (21%) but takes 18 and a half hours for a return trip, more than six times as long as by plane.

Air Passenger Duty cut and difficult price vs planet trade-off

From tomorrow, Saturday 1 April, a cut to Air Passenger Duty (APD) for domestic flights will see airlines’ tax bills halved from £13 to £6.50 per passenger, with airlines incentivised to introduce more domestic routes as a result.

Which? said it believes this may further widen the price gap between rail and air travel, particularly as rail fares have recently been hiked by 6%. As a result, we could soon see an uptick in pollution generated by inter-UK journeys, as fewer passengers opt to travel by rail, it said.

Rory Boland, Which? Travel editor, said: “As travellers become increasingly concerned about the environmental impact of their journeys, many face a difficult trade-off between the price of their ticket and the cost to the planet, with just three out of ten journeys we looked at working out cheaper by rail.

“For those who prefer to travel by train, there are steps you can take to cut costs. Take the time to compare dates and times to see if cheaper fares are available, and look into what railcards you might be eligible for, as these can save you up to a third of the ticket price. You may be able to make further savings by checking if split-ticketing is an option on your chosen route.”