Environmental Engineering Reference
In-Depth Information
Aviation growth
Much of aviation environmental policy-making begins with the premise that the
proportional and absolute environmental impact of aviation on climate change (also
on local air pollution, noise and human health) is likely to increase in line with the
growth in demand for aviation. Thus, the key assumption driving policy develop-
ment is that if the environmental impact of aviation is to be limited, aviation should
not grow as before.
This perception arises from the fact that, historically, aviation has experienced
the highest demand rates of all modes of transport, expanding as the world economy
has grown, thereby making aviation one of the fastest growing global industries.
Between 1970 and 1995 there was a 360 per cent growth in revenue passenger kilo-
metres worldwide - from 551 billion to 2537 billion (IPCC, 1999). Passenger traf-
fic grew at an average of 9 per cent per year (in revenue passenger kilometres) until
the mid 1990s, stabilizing at an average 5 per cent a year thereafter, as the industry
matured. Freight traffic (80 per cent of which is carried by passenger aircraft) grew
at an average annual rate of 11 per cent over the same period (IPCC, 1999).
Looking ahead to 2050, the Intergovernmental Panel on Climate Change (IPCC)
assessed the potential climate and ozone changes due to aircraft under different sce-
narios representing the plausible growth for aviation. These include a high-range
scenario that projects annual growth of 4.7 per cent on average between 1990 and
2050, a mid-range scenario that projects annual growth of 3.1 per cent on average,
and a low-range scenario that projects annual growth of 2.1 per cent on average (IPCC,
1999). For the range of scenarios, the range of an increase in carbon dioxide (CO
2
)
emissions from aviation to 2050 would be 1.6 to 10 times the value in 1992, reflect-
ing a growth in CO
2
emissions of 4-15 per cent (most probably 5-6 per cent) by
2050 (IPCC, 1999). The IPCC also observed that the effect of CO
2
emissions from
aviation is indistinguishable from that of other sources, and is difficult if not impos-
sible to identify.
More recent research has confirmed that there is considerable uncertainty with
regard to future levels of emissions and climate response, and that continuing research
will be needed in order to provide guidance for policy decisions. Scientific uncer-
tainties are largest for the complex impact of oxides of nitrogen (NO
x
) and methane
(CH
4
), for contrails and, especially, for the indirect effects of aviation on cirrus cloud
cover and changes in cirrus properties (European Commission, 2001).
The IPCC scenarios are not predictions of the future and are inherently uncer-
tain because they are based upon different assumptions about the future. Each
scenario reflects unconstrained growth. The factors acting to constrain growth
include those relating to limits in the supply of aviation infrastructure, including
airspace, aircraft and airport availability; in fossil fuel; and the maturity of the avia-
tion market. The factors most likely to sustain growth relate largely to the fact that
traditional patterns of supply and demand are giving way to global supply chains and
a trend towards more liberalized and deregulated economic activity, especially in
transitional economies.
