An investigation conducted by Which? Travel reveals that flying with British Airways can increase CO2 emissions by up to 45% per passenger.
The website revealed that it compared carriers across six routes using a calculator by independent carbon analytics company Flyzen.
When doing the investigation, factors like the aircraft model, mileage, seat configuration and the efficiency of the engine were taken into consideration, according to MailOnline.
The investigation found that one passenger who flew from Heathrow to Miami with British Airways was allegedly responsible for 1.13 tonnes of carbon compared to other airlines on the same route.
The research found that there were also differences on short-haul journeys. For example, a British Airways flight from London Stansted to Palma de Mallorca emits almost 160kg CO2 per passenger, compared to Ryanair, Jet2 or Tui, which is around 109.3kg.