Global air traffic is expected to double to 8.2 billion passengers in 2037, according to IATA, which predicts that aviation's 2019 emissions peak of around 900 million metric tons of CO2 will be exceeded within the next two to three years.At the same time, the window to cut the world's reliance on fossil fuels and avoid catastrophic changes to the climate is closing rapidly. The International Energy Agency forecasts that aviation's share of global carbon emissions will increase to 3.5% by 2030 from just over 2.5% in 2019 in the absence of efforts to further decarbonize.