Environmental Engineering Reference
In-Depth Information
Chapter 5
The global atmospheric impacts of
aviation
David Lee and David Raper
I
NTRODUCTION
The effects of civil aviation emissions on the atmosphere have been under discussion
for some time and are certainly not a 'new' subject. Indeed, the easily observed dark
plumes from early turbojets gave rise to concern over local air quality, prompting the
US Environmental Protection Agency (USEPA) to legislate against aircraft emissions
during the 1970s. This early legislation, local to the US, later gave rise to the engine
emission certification requirements of the International Civil Aviation Organization
(ICAO) (ICAO, 1995) on unburned hydrocarbons (UHCs), nitrogen oxides (NO
x
,
the sum of NO+NO
2
) and carbon monoxide (CO).
Concern over the effects of aircraft emissions on the upper atmosphere devel-
oped a little later during the 1970s when a fleet of supersonic aircraft that would fly
in the stratosphere was proposed. Crutzen (1971) and Johnston (1971) postulated
significant stratospheric ozone (O
3
) depletion as a result of the potential NO
x
emis-
sions. In the event, only a limited fleet was developed by the UK and France in the
form of Concorde. The only other civil supersonic aircraft developed was the Tupu-
lov 144, which saw only one year's active civilian transport service after a chequered
history of two catastrophic crashes: one at the Paris air show in 1973 and another in
Russia in 1978.
Renewed interest in the potential effects of aircraft emissions ensued during the
late 1980s and early 1990s, this time on climate from subsonic aircraft emissions
(Schumann, 1990), rather than stratospheric O
3
depletion. Initially, the attention
was focused upon the potential effects of aircraft NO
x
emissions on the production
of tropospheric O
3
. Whereas O
3
in the mid to upper stratosphere (~15 to 50km) pro-
vides a protective 'shield' against harmful ultraviolet radiation (UV), O
3
in the upper
