Aviation and the Global Atmosphere

Aviation and the Global Atmosphere
Aviation and the Global Atmosphere
Table of contents | Previous page | Next page
6.3.2. Radiative Forcing for CO 2
Other reports in this collection
Carbon dioxide has a long atmospheric residence time (on the order of many decades); hence, aircraft CO 2 becomes well mixed within the atmosphere and can be
treated together with other anthropogenic CO 2 emissions in conventional global warming simulations (e.g., Washington and Meehl, 1989; Cubasch et al., 1992;
Murphy and Mitchell, 1995). The aircraft influence depends on the temporal evolution of the amount of the CO 2 increase that can be attributed to aircraft emissions,
which is directly proportional to the amount of fuel burned. See Section 6.1.2 and Table 6-2 for the calculation of CO 2 increases attributed to aviation.
Over the period 1990 to 2050, under IS92a we expect an increase in atmospheric CO 2 of about 155 ppmv from burning of fossil fuels, cement production, and other
anthropogenic activities that release biospheric carbon. By 2050, F-type aviation scenarios produce a 5-7 ppmv increase, and the high-growth Edh scenario leads to a
13 ppmv increase. Thus, aviation in these scenarios would be responsible for 3-8% of the total anthropogenic increase in CO 2 from 1990 to 2050.
The RF for aviation CO 2 in 1992 is estimated to be +0.018 W m-2, with a likely range of ±30% that includes uncertainties in the carbon cycle and in radiative
calculations (see WMO, 1999). Uncertainties and confidence intervals discussed here do not include possible errors in predicting future scenarios. By 2050, the
different aviation scenarios have a range of +0.06 to +0.16 W m-2. The technology option 2 scenario (Fa2) leads to a 0.1 ppmv increase in CO 2 by 2050, with only a
small increase in CO 2 -RF.
The HSCT option, F1aH, has 18% greater fuel use but only 8% greater CO 2 concentrations by 2050, with a corresponding increase in CO 2 -RF from +0.074 to +0.080
W m-2. Because the HSCT fleet has just reached maturity in 2040, the extra fuel consumption of the HSCT aircraft is barely felt in terms of the accumulation of CO 2 .
Similarly, the CO 2 impact of new subsonic technologies that are introduced linearly between 2015 and 2050 is not fully effected by 2050. A fuller evaluation would have
to extend the assessment beyond 2050, when the cumulative effects of mature fleets would be felt (e.g., Sausen and Schumann, 1999).
http://www.ipcc.ch/ipccreports/sres/aviation/074.htm (1 von 2)08.05.2008 02:43:00