Aviation and the Global Atmosphere

Aviation and the Global Atmosphere
Future scenarios predict fuel use and NO x emissions that vary over a wide range, depending on the economic growth scenario and model used for the calculations.
Although none of the scenarios are considered impossible as outcomes for 2050, some of the EDF high-growth scenarios are believed to be less plausible. The FESG
low-growth scenarios, though plausible in terms of achievability, use traffic estimates that are very likely to be exceeded given the present state of the industry and
planned developments.
The 3-D gridded outputs from all of the FESG 2050 scenarios and from the DTI 2050 scenario are suitable for use as input to chemical transport models and may also
be used to calculate the effect of aviation CO 2 emissions. The FESG scenarios project aviation fuel use in 2050 to be in the range of 471-488 Tg, with corresponding
NO x emissions of 7.2 and 5.5 Tg (as NO 2 ) for IS92a, depending on the technology scenario; 268-277 Tg fuel and NO x of 4.0 and 3.1 Tg for IS92c; and 744-772 Tg fuel
and NO x of 11.4 and 8.8 Tg for IS92e. (For all of the individual FESG IS92-based scenarios, higher fuel usage-thus CO 2 emissions-were a result of the more
aggressive NO x reduction technology assumed). The DTI scenario projects aviation fuel use in 2050 to be 633 Tg, with NO x emissions at 4.5 Tg.
As a result of higher projected fuel usage, EDF projections of CO 2 emissions are all higher than those of FESG by factors of approximately 2.4 to 4.3 for IS92a, 3.1 to
5.7 for IS92c, and 1.7 to 3.1 for IS92e. Results from EDF scenarios based on IS92a and IS92d are suitable for use in calculating the effect of CO 2 emissions as
sensitivity analyses; the latter scenario projects CO 2 emissions levels from aviation 2.2 times greater in 2050 than the highest of the FESG scenarios.
The effects of a fleet of high-speed civil transport (HSCT) aircraft on fuel burned and NO x emissions in the year 2050 were calculated using the FESG year 2050
subsonic inventories as a base. A fleet of 1,000 HSCTs operating with a program goal EI(NO x ) of 5 in 2050 was calculated to increase global fuel burned by 12-18%
and reduce global NO x by 1-2% (depending on the scenario chosen), assuming that low-NO x HSCTs displace traffic from the higher NO x subsonic fleet. A fleet of
1,000 HSCT aircraft was chosen to evaluate the effect of a large fleet; it does not constitute a forecast of the size of an HSCT fleet in 2050.
The simplifying assumptions used in calculating all of the historical and present-day 3-D inventories (1976 through 1992)-great circle routing, no winds, standard
temperatures, no cargo payload-cause a systematic underestimate of fuel burned (therefore emissions produced) by aviation on the order of 15%, so calculated values
were scaled up accordingly. By 2015, we assume that the introduction of advanced air traffic management systems will reduce this underestimate to approximately
5%. Full implementation of these systems by 2050 should reduce the error somewhat further, but given the wide range of year 2050 scenario projections, adjustments
to calculated fuel values in 2050 were not considered to be necessary.
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