Aviation and the Global Atmosphere

Aviation and the Global Atmosphere
are suitable for use in chemical transport models for modeling other emissions (see Chapters 2
and 4) and their effects on radiative forcing (see Chapter 6) because they provide gridded data
that include a consideration of the potential changes in the spatial distribution of emissions. Only
the EDF study provides scenarios for demand from the aviation sector and subsequent global
CO 2 and NO x emissions to 2100. The EDF study provided 10 scenarios based on five different
IPCC IS92 world scenarios for the long-term development of world economy and population and
two air traffic demand scenarios (base case and high case). The FESG study calculated three air
traffic demand scenarios based on the IPCC IS92a, IS92c, and IS92e world scenarios, which
were combined with two engine technology scenarios to produce six different emissions
inventories. The FESG scenarios of regional and global air traffic were based on a logistic
regression model of traffic demand since 1960 using global GDP as a predictor. The FESG
model used a combination of top-down and bottom-up approaches, in which global volumes of
civil aircraft flight kilometers were predicted using the regression model for different GDP
scenarios. All available information on regions, including regional variation in growth, was then
used to disaggregate these global values in a consistent way over 45 traffic flows within and
between the regions of the world by using a market share allocation model. Year 2050 values of
fuel burned and NO x emissions for military traffic were estimated separately.
The EDF scenarios also were based on the use of logistic growth curves to model air traffic
growth for business and personal travel (plus military and freight traffic). Model parameters were
chosen through observation of historical traffic trends in the United States. Regional population
was used as a predictor of personal passenger travel, and regional GNP was used as a predictor
of business passenger travel and freight demand. Both the FESG and EDF models incorporate
the underlying assumption that the chosen parameters are satisfactory predictors of aviation
demand and that aviation markets eventually mature.
Figure 9-28: Cumulative traffic demand (IS92a
scenario, Fa1,2).
Figure 9-29: Distribution of passenger demand (IS92a
scenario, Eab).
There are large differences between the EDF and FESG models with respect to the
development of emissions scenarios. The EDF model uses a constant capacity logistic to
describe fuel efficiency improvements, which extrapolates Greene's (1992) forecast to 2010 with varied rates for five geographic world regions and the military/freight
aviation sector. For the trend in fleet EI(NO x ) a single global logistic model extrapolates from the 1990 and 2015 values. The FESG scenarios are based on two engine
technology scenarios developed by ICCAIA for ICAO/FESG and IPCC (see Chapter 7). These scenarios represent an industry perspective on likely future
developments in fuel efficiency and NO x reduction technologies, as well as further potentials and limitations. The fuel efficiency technology element of the DTI scenario
was similar in this respect, but a NO x technology scenario appropriate to stricter emissions regulations was assumed, in which subsonic engine research programs
would deliver emissions levels similar to those targeted in the NASA HSCT program.
Additional assumptions are also important to the results of the scenario models. In the EDF model, assumptions about the dates of market expansion and maturity and
the ultimate capacity levels chosen for the economic regions strongly influence the outcomes. The EDF, FESG, and DTI models all use statistics of traffic/air traffic
from international organizations and OECD countries, as well as numerous other recently published sources, and adopt one or more of the IPCC IS92 scenarios to
describe the long-term development of worldwide economic growth and population. The FESG, EDF, and DTI models also use information from the NASA and ANCAT/
EC gridded inventories of traffic flows and related emissions. The FESG models used new, partly proprietary, information from industry as a base to project emissions
in the year 2050.
http://www.ipcc.ch/ipccreports/sres/aviation/143.htm (2 von 3)08.05.2008 02:44:32