Easyjet announced that from Tuesday it will offset carbon emissions from all its flights in a bid to become the world's first carbon-neutral airline.
The low-cost British carrier said the move will cost the company £25 million (€29.2 million) in the next financial year.
But Transport and Environment (T&E) warned carbon offsetting is unlikely to deliver the emissions reductions promised.
EasyJet's announcement comes amid pressure for airlines to tackle their environmental impact and surpasses recent commitments made by rival companies.
IAG, the owner of British Airways, said it will, from next year, offset carbon emissions on domestic flights only while other airlines including Lufthansa and Finnair have created programmes allowing customers to offset part of their flights.
Aviation is one of the fastest-growing sources of greenhouse gas emissions. According to the European Commission, direct emissions from aviation account for about 3% of the EU's total greenhouse gas emissions and more than 2% of global emissions. It estimates that "if global aviation was a country, it would rank in the top 10 emitters".
To achieve its target, EasyJet will invest in afforestation — the planting of new trees — as well as in the production of renewable energies.
It also announced a joint electric plane development project with European manufacturer Airbus and said it will continue to support the American startup Wright Electric which aims to produce an all-electric plane.
"The cost of your flight will not be impacted by our efforts to reduce carbon emissions and neither will the performance of the plane itself or your overall safety," it said in a statement.
However, the Brussels-based T&E research group, said that "stronger action by governments to tax the climate impact of flying and develop clean fuels" are needed to cut the sector's emissions.
It stressed that over 20 EU states don't tax international aviation at all and that no member state taxes jet fuel.
"Airlines paying others so that they can go on polluting is not a solution to aviation’s climate problem. Decades of airlines’ unchecked emissions growth shows governments need to step up and regulate aviation’s climate impact by ending the sector’s tax privileges and mandating clean fuels," Andrew Murphy, T&E's aviation manager, said in a statement.