An agreement was reached on Friday to try to achieve net-zero carbon emissions in air travel by 2050, the International Civil Aviation Organization said. The assembly, which brought together representatives from 193 nations at the ICAO’s Montreal headquarters, reached a “historic agreement on a collective long-term aspirational goal (LTAG) of net-zero carbon emissions by 2050!” the UN agency said in a Twitter message. A diplomatic source called the accord “an excellent result,” telling AFP that only four countries — including China, the main thrust of global growth in air travel — “had expressed reservations.” The air transportation industry has faced growing pressure to deal with its outsized role in the climate crisis. Currently responsible for 2.5 percent to three percent of global CO2 emissions, the sector’s switch to renewable fuels is proving difficult, even if the aeronautics industry and energy companies are seeking progress. According to airlines, it will require investments of $1.5 billion between 2021 and 2050 to decarbonize aviation.