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Aviation and the Global Atmosphere

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<strong>Aviation</strong> <strong>and</strong> <strong>the</strong> <strong>Global</strong> <strong>Atmosphere</strong><br />

<strong>Aviation</strong> <strong>and</strong> <strong>the</strong> <strong>Global</strong> <strong>Atmosphere</strong><br />

O<strong>the</strong>r reports in this collection<br />

Figure 2b: Estimates of <strong>the</strong> globally <strong>and</strong> annually averaged radiative forcing (Wm -2 ) (see Footnote 4)<br />

from subsonic aircraft emissions in 1992 (2a) <strong>and</strong> in 2050 for scenario Fa1 (2b). The scale in Figure<br />

2b is greater than <strong>the</strong> scale in 2a by about a factor of 4. The bars indicate <strong>the</strong> best estimate of forcing<br />

while <strong>the</strong> line associated with each bar is a two-thirds uncertainty range developed using <strong>the</strong> best<br />

knowledge <strong>and</strong> tools available at <strong>the</strong> present time. (The two-thirds uncertainty range means that <strong>the</strong>re<br />

is a 67% probability that <strong>the</strong> true value falls within this range.) The available information on cirrus<br />

clouds is insufficient to determine ei<strong>the</strong>r a best estimate or an uncertainty range; <strong>the</strong> dashed line<br />

indicates a range of possible best estimates. The estimate for total forcing does not include <strong>the</strong> effect<br />

http://www.ipcc.ch/ipccreports/sres/aviation/spm2b.htm (1 von 2)08.05.2008 02:44:51

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