Aviation and the Global Atmosphere

Aviation and the Global Atmosphere
NO x
SO x O and H 2 SO 4
Soot
Troposphere
O 3 formation in upper troposphere
radiative forcing warming
reduced UV-B
Decrease in CH 4 less radiative forcing cooling
Stratosphere
O 3 formation below 18-20 km reduced UV-B
O 3 formation above 18-20 km enhanced UV-B
Enhanced PSC formation O 3 depletion enhanced UV-B
Troposphere
Enhanced sulfate aerosol concentrations
Direct radiative forcing cooling
Contrail formation radiative forcing warming
Increased cirrus cloud cover radiative forcing warming
Modifies O 3 chemistry
Stratosphere
Modifies O 3 chemistry
Troposphere
Direct radiative forcing warming
Contrail formation radiative forcing warming
Increased cirrus cloud cover radiative forcing warming
Modifies O 3 chemistry
Stratosphere
Modifies O 3 chemistry
Notes:
1) Positive radiative forcing will tend to warm the Earth's surface; negative forcing will tend to cool the Earth's surface.
2) Any warming at the Earth's surface caused by increases in atmospheric CO 2 will be accompanied by a cooling of the stratosphere.
3) Any decrease in ozone, whether in the troposphere or stratosphere, will tend to enhance UV-B radiation and cool the Earth's surface. Conversely,
any increase in ozone will tend to reduce UV-B and heat the Earth's surface. This dual effect is shown in this table only for tropospheric ozone.
4) Chemi-ions and metal particles are also emitted from aircraft. They may play an important role in contrail and enhanced cirrus formation (see
Chapter 3), in which case their emission would lead to a tendency to warm the Earth's surface.
5) Hydrocarbons and CO are also emitted and contribute in a minor way to tropospheric ozone formation.
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