Carbon offsetting: How to reduce the impact of flying

Air travel has found itself at the centre of the debate on climate change.

There’s no denying that it’s carbon intensive: each passenger on a return flight from London to Singapore accounts for around three tonnes of CO₂. That’s the equivalent of heating a family home for a year.

Flying less isn’t something everyone is able or willing to do. This has given rise to carbon offsetting schemes, which promise to make flights carbon neutral.

What is carbon offsetting?

The idea is that we voluntarily calculate the CO₂ we’re responsible for, then fund a project that reduces emissions by the same amount. Popular schemes include tree planting, wind farms and the distribution of fuel-efficient stoves in developing countries.

There are plenty of carbon calculators that ask you to input your flight route or an amount of CO₂ in kg. They then calculate a suggested donation to offset the impact of your journey.

Around 2% of Which? members told us they always pay to offset their flights. That figure is actually higher than the national average of just 1%, according to the International Air Transport Association (IATA).

How to offset your flight

The easiest way would be to opt in when paying for your flights online. For example, Ryanair gives you the option to ‘fully offset’ your emissions or offer a partial contribution of €2. This money supports various environmental initiatives, including a methane capture project in Bulgaria and another providing improved cooking stoves in Nepal.   

Those who want to offset their carbon emissions can also go to non-profit Atmosfair. Not all airlines are included in its flight calculator, but it also gives you the average carbon estimate for your route. 

If you have been given a CO2 estimate elsewhere, you can type the value into Atmosfair's 'offset a desired amount of CO2' calculator and make a one off payment. Another reliable source is ICAO's calculator.  

What is Sustainable Aviation Fuel (SAF)?

Airlines such as British Airways also invite flyers to make a contribution towards the development and production of sustainable aviation fuel (SAF). SAFs emit as 

much carbon as fossil-based fuels in-flight. However, they’re considered more sustainable because they’re made from waste oils and fats, such as cooking oil and animal fats - essentially ‘recycling’ carbon already in circulation. 

The major challenge is that the availability of SAF remains very low: for 2025, SAF must make up at least 2% of all jet fuel for flights taking off from the UK. 

This will have to be scaled up rapidly for the aviation industry to achieve its net-zero carbon emissions target by 2050.

How to choose the right carbon offsetting project

To make sure you choose an effective scheme, look for internationally recognised certification. VCS (Verified Carbon Standard) and Gold Standard are two you can trust.

A verified project will:

• Have no negative impact on local communities – eg displacement to make way for a new wind farm or tree-planting project
• Be monitored to make sure carbon reductions are achieved
• Do more than simply switch one fossil fuel for another.

The problems with offsetting

There are many reasons why people aren’t buying into carbon offsetting schemes. Responsible Travel argues that to tackle climate change we must actively reduce our carbon footprint, rather than trying to ‘cancel out’ the damage afterwards.

Sarah Leugers of the Gold Standard told Which? Travel: ‘Offsetting isn't the solution or the only thing we should be considering, but most of us can’t reduce our footprint to zero. Taking accountability for the remaining pollution is absolutely the right thing to do.’

Six ways to reduce your carbon footprint

1. Use Skyscanner

Its search tool will highlight the greenest flight for your journey with a leaf motif, alongside the percentage of CO₂ saved. An investigation by Which? Travel found that passengers can make a significant carbon reduction by changing which airline they fly with.

2. Fly economy

Business and first class are responsible for up to four times more CO₂ per passenger. See which carriers came top in our survey of best airlines.

3. Choose greener aircraft

Look out for newer, more fuel-efficient models, such as the Boeing 787-9 Dreamliner and Airbus A350-900 and A320neo.

4. Fly direct

Choose direct where possible. Taking off uses more fuel than cruising.

5. Pack light

A heavier plane also guzzles more fuel.

6. Take the train

Consider taking the train for short-haul journeys. The Eurostar emits around 90% less carbon than the equivalent flight.