Impact of Aviation

---

According to the UN Environment Programs emission gap report 2019 Global GHG emissions were 59.1 GtCO2e with fossil carbon being 38 GtCO2. Aviation's contribution to this was around just under 914 million tonnes of CO2 accounting for 2.4% of carbon emissions. Obviously the pandemic saw a large drop in the emissions of the aviation sector but emissions are expected to exceed pre pandemic levels in 2024 or 2025.

Current global emissions, 59 GtCO2e, need to more than half to 25 GtCO2e by 2030 to be in line with a below 1.5 degree warming scenario. ICAO's 2050 fuel burn estimates for the air transport industry, carried out pre coronavirus, ranged from 730 Mt to 1.434 Billion tonnes of fuel the equivalent of 2,3 - 4,5 Gt CO2 per year. Under the Paris agreement net zero targets the UNEP believes that without abatement the aviation and shipping sectors could account for between 60% & 220% of allowable emissions in 2050.   

UNEP - https://www.unep.org/interactive/emissions-gap-report/2020/

If current crude oil production levels are sustained, by 2050 the aviation sector could take up between 16% and 32% of all crude oil production. Currently around 6% of oil is converted to Jet Kerosene. such a change in the scale of production will require significant investment. 

Bio-fuels or sustainable aviation fuels (SAF) have savings on CO2 emissions produced compared to burning jet fuel, typically somewhere between around 80% depending on the feedstock (source of the bio material) process it goes through to be refined. Global bio-fuel production is increasing as alternatives to fossil fuels are sought but still represents significantly less than 1% of total Jet fuel production. 

However, SAF at present cannot replace all fuel use as jet fuel has essential lubricant and cooling properties, meaning they must be mixed with conventional jet fuel for safety. This problem may be overcome in the future with new technology, but at present it means when using SAF at least 50% of emissions still come directly from jet fuel.

Bio-fuels also have other non CO2 benefits. NASA carried out tests on Alternative Fuel

Effects on Contrails and Cruise Emissions which showed a significant decrease in particulate emissions when using SAF of up to 90% which has positive impacts on the non CO2 warming impacts of aviation. 

The UK Committee on Climate Change cautiously estimate SAF use at 10% by 2050. However, ICAO is heavily reliant on SAF to meet Carbon Neutral Growth (CNG) aspirations.