As part of the CAEP/11 (2019) update to the ICAO Global Environmental Trends, a range of scenarios were developed for the assessment of future LAQ NOx and PM emission trends.
Scenario 1 for NOx and Scenario 1 for PM (CAEP/11 Baseline) assume no further aircraft technology or operational improvements after 2015. Scenarios 2 and 3 (moderate and advanced technology) for NOx assume aircraft NOx improvement based upon achieving 50 % and 100% respectively of the reduction from current NOx Emission levels to the NOx Emissions levels by CAEP/7 NOx Independent Expert (IE) goals review (-60 percent +/- 5 percent of current CAEP/6 NOx Standard) for 2036, with no further improvement thereafter. Scenario 2 for PM assumes only CAEP/9 IE Operational Improvement case.
Figure 1 shows results for NOx emissions within the LTO cycle, that is, below 3,000 feet above ground level from international aviation. In 2015, LTO NOx emissions were approximately 0.18 Mt. In 2045, they are projected to range from 0.44 to 0.80 Mt depending on the technology and ATM scenario, which represents a growth of between 2.4 and 4.4 times over the period and can be compared with the forecasted 3.3 times growth in international air traffic.
The long-term LTO NOx projections are lower by about 2%, compared with the prior trends projections, due to a combination of aircraft with lower NOx engines, a reduction in the forecasted long-term traffic demand, as well as a refinement to the method used for computing LTO NOx.
Figure 1 – NOx Emissions below 3,000 feet from International Aviation, 2010 to 2050.
Figure 2 provides results for total particulate matter (PM, both volatile and non-volatile) emissions below 3,000 feet from international aviation. In 2015, LTO PM emissions were approximately 1,243 tonnes. In 2045, they are projected to increase to 3,572 tonnes (operational improvements could provide reductions of up to 1,160 tonnes by 2050). This represents a growth up to 2.9 times over the period compared with 3.3 times growth in international air traffic.
Figure 2 – PM Emissions below 3,000 ft from International Aviation, 2010 to 2050.