The chief executives of major U.S. airlines are set to meet virtually with two key White House advisers on Friday about efforts to reduce carbon emissions and use renewable fuels, five people briefed on the matter told Reuters. The CEOs of American Airlines, United Airlines, Delta Air Lines and Southwest Airlines are among those who have been invited to meet with White House National Climate Adviser Gina McCarthy and economic adviser Brian Deese to discuss environmental issues related to air travel, including using greener fuels to power air travel. The White House and a spokeswoman for a group representing the airlines declined to comment. McCarthy told Reuters earlier this month she had started discussions with the utility and automobile sectors about reducing greenhouse gas emissions. She said the talks were part of a broad effort by the Biden administration to engage every federal agency to decarbonize the U.S. power sector by 2035 and the whole economy by 2050. Last week Reuters reported U.S airlines and renewable energy companies are lobbying the Biden administration to back a big increase in subsidies for lower-carbon aviation fuel. They say new incentives are needed to help fight climate change. Air travel contributes around 2% of global greenhouse gas emissions, the Air Transport Action Group said. That percentage is expected to rise rapidly in coming decades if airlines do not quickly switch to “sustainable aviation fuel.” Such fuel is made from biologically sourced wastes like old cooking oil, animal fat and plant oils. It is much more expensive than traditional jet fuel. Speaking at an Axios event on the future of green travel, United Airlines Chief Executive Scott Kirby said the R&D investments needed to get the whole economy to net-zero emissions will require government support. United has committed to a multimillion-dollar investment in carbon capture, a technology designed to suck carbon dioxide from the atmosphere, as part of a plan to be 100% green by 2050. Industry trade group Airlines for America told Reuters previously it has also been in contact with the Biden administration’s climate change officials to discuss expanding the sustainable aviation fuel market. Currently, A4A members use only about 1.5 million gallons of green plane fuel in the United States a year, out of a total commercial jet fuel market that exceeds 620 million barrels annually. (One barrel of jet fuel contains 42 gallons.) Several other countries have already proposed sustainable aviation fuel mandates or are exploring them as a means of addressing increasing carbon output from air travel. A mandate in Norway came into force in January 2020, while the Netherlands is set to have one in place by 2023. European requirements are expected to be addressed at the White House meeting. Globally, more than 250,000 flights have run on sustainable aviation fuel since 2016, while an estimated 10.6 million gallons were produced in 2020, the International Air Transport Association said. Chicago-based Boeing Co has committed to fly with 100% sustainable aviation fuels by 2030, it said in January.