Aviation and the Global Atmosphere

Aviation and the Global Atmosphere
Aviation and the Global Atmosphere
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6.1.2. Aircraft-Induced Climate Change
Aircraft emissions are expected to modify the Earth's radiative budget and climate as a result of
several processes (see also Figure 6-1): emission of radiatively active substances (e.g., CO 2 or
H2O); emission of chemical species that produce or destroy radiatively active substances (such
as NOx, which modifies O3 concentration, or SO2, which oxidizes to sulfate aerosols); and
emission of substances (e.g., H2O, soot) that trigger the generation of additional clouds (e.g.,
contrails).
The task of detecting climate change is already difficult; the task of detecting the aircraft
contribution to the overall change is more difficult because aircraft forcing is a small fraction of
anthropogenic forcing as a whole. However, aircraft perturb the atmosphere in a specific way
because their emissions occur in the free troposphere and lower stratosphere, and they trigger
contrails, so the aircraft contribution to overall climate change may have a particular signature.
At a minimum, the aircraft-induced climate change pattern would have to be significantly different
from the overall climate change pattern in order to be detected.
The climatic impact of aircraft emissions is considered on the background of other anthropogenic
perturbations of climate. The present assessment is based on the IS92 scenarios used to
represent alternative futures in the Second Assessment Report (IPCC, 1996); it does not
incorporate recent observed trends in methane (Dlugokencky et al., 1998), nor any implications
from the Kyoto Protocol. The scenarios for aircraft flight patterns, fuel burn, and emissions are
described in Chapter 9. Atmospheric perturbations are taken from detailed atmospheric models
(Chapters 2, 3, and 4), except for CO 2 accumulation (which is discussed in this chapter).
http://www.ipcc.ch/ipccreports/sres/aviation/067.htm (1 von 4)08.05.2008 02:42:51
Figure 6-3: CO 2 concentration over the past 1000
years from ice core records (D47, D57, Siple, and
South Pole) and (since 1958) from Mauna Loa,
Hawaii, measurement site.
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