JetBlue Airways Corp. is walking away from the purchase of carbon offsets for its domestic flights in 2023, instead opting to step up its investment in and use of  sustainable aviation fuel (SAF).

The carrier disclosed the shift Tuesday as part of a wider commitment to reducing lifecycle greenhouse gas emissions from jet fuel by 50% per revenue ton kilometer by 2035 from 2019 levels, a reduction the carrier said is its most aggressive near-term target. JetBlue earlier pledged to reach net zero emissions by 2040, a decade ahead of a broader airline industry target.

The growing use of carbon credits is controversial, as critics argue that many of the investments don’t or can’t guarantee a reduction in emissions elsewhere. An October report from Carbon Market Watch found that Europe’s leading airlines mislead consumers with claims they can fly guilt-free by using offsets to neutralize the environmental impact of air travel, and United Airlines Holdings Inc. Chief Executive Officer Scott Kirby has been a vocal critic of companies that rely on the programs as their sole response to climate change.

With a growing supply of green fuel, “the time is now to maximize investment into the space and accelerate our uptake of SAF,” Sara Bogdan, JetBlue’s director of sustainability and environmental social governance, said in an email Thursday. The carrier describes carbon offsets as as a “powerful tool” that allowed it to immediately address emissions when devising a reduction plan in 2019, before it had regular access to SAF.JetBlue isn’t giving up on offsets entirely. The company will continue to purchase a “small quantity of voluntary high-integrity credits” for flying from 2024 and to compensate for emissions from expanding its international flights, Bogdan said. It will also work with experts to address concerns about offset programs and evaluate which bring the biggest benefit. “We do see an opportunity for greater transparency from the carbon credit market,” Bogdan said. 

The US carrier joins England’s EasyJet Plc, which said in September that it would stop purchasing carbon offsets as of 2023 to focus on SAF. In addition to SAF, airlines broadly are trying to cut emissions with more efficient aircraft and engines, as well as more direct flight routing. Airbus SE has also developed a system to reduce fuel burn as aircraft land

JetBlue first tapped the use of carbon offsets in 2008, when the carrier offered customers the ability to offset emissions generated by their flight through contributions to The money was used to support projects like wind power development, methane gas capture at landfills and reforestation. 

JetBlue has been been using SAF for some flights from Los Angeles and San Francisco since 2020 under supply agreements with Neste and World Energy, and has signed with three additional producers for future stores. The carrier plans to convert 10% of its fuel to SAF by 2030.