Aviation and the Global Atmosphere

Aviation and the Global Atmosphere
Aviation and the Global Atmosphere
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1.4. Emissions Scenarios
Other reports in this collection
Calculations of projected future changes in atmospheric composition rely on a number of additional factors. For example, atmospheric models require forecasts of
future emissions if realistic predictions of the future atmosphere are to be made. However, accurate forecasts of future demand are not possible. In this report, the
future is explored on the basis of scenarios. Scenarios should not be interpreted as forecasts but as tools to explore a range of future outcomes.
To assess the possible future impact of aviation, plausible scenarios for other changes in the future composition of the atmosphere are required-in particular for
background CO 2 , NO x , SO 2 , CO, and hydrocarbon emissions. The IS92 scenarios used here were originally described in IPCC (1992). Six scenarios of future
greenhouse gas and aerosol precursor emissions (IS92a-f) were developed, based on assumptions concerning population and economic growth, land use,
technological changes, energy availability, and fuel mix during the period 1990 to 2100. Through an understanding of the global carbon cycle and atmospheric
chemistry, these emissions can be used to project atmospheric concentrations of greenhouse gases and aerosols. In addition, scenarios for future atmospheric
chlorine and bromine abundances have been calculated by assuming that the Montreal Protocol and its Amendments and Adjustments will be followed and effective.
The IS92 scenarios are recognized to be imperfect (for instance, they assume that no regulatory interventions will be made, so they have been outdated by the
UNFCCC process). The underlying assumptions, strengths, and weaknesses were assessed in IPCC (1995). The IS92a scenario is a mid-range emissions scenario
and is used to describe future non-aviation emissions in the calculations presented in this report.
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