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Project title:

TRADEOFF – Aircraft emissions: Contributions of various climate compounds to changes in composition and radiative forcing – tradeoff to reduce atmospheric impact

Principal investigators:

Prof. David S. Lee


European comission, Department for Transport


2001 – 2003


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TRADEOFF was a project that involved 10 partners across Europe and was coordinated by Professor Ivar Isaksen of the University of Oslo. MMU was not a partner but the DERA PI subsequently moved to MMU in 2003 and has been involved in much of the work, including the final stages and subsequent scientific papers.

The main thrust of this project was to determine the potential atmospheric ‘tradeoffs’ in aviation effects on climate and whether changes in flying could ameliorate the problem.

In this research, a sophisticated model of global aviation emissions was used to formulate ‘base case’ inventories and then perturbation scenarios, for example, flying the global fleet higher and lower by flight level increments as the basis for parametric studies. In parallel, other partners in the project undertook a comprehensive assessment of the performance of their global 3D chemistry transport models (CTMs) and chemistry-climate models (Brunner et al., 2003; Brunner et al., 2005).

Many publications resulted from the TRADEOFF work programme but as examples, the effects of altitude changes in flight and Nox emissions on tropospheric O3 were investigated by Gauss et al., (2006).

Fichter et al., (2005), looked at the effects of altitude on contrail formation and subsequent radiative forcing and found that both contrail coverage and its forcing were reduced by approximately 43% by flying 6,000 feet lower for a penalty of a 6% increase in fuel usage and therefore CO2 emissions on a global scale. This study was performed as a parametric: it is certainly not suggested that any flying regime like this should be implemented. However, it is a first vital step in quantifying ‘tradeoffs’.

Lastly, TRADEOFF performed some important new quantification of cirrus cloud changes (Zerefos et al., 2003) and radiative forcing arising from these changes by examining trends in global and regional cirrus clouds in relation to aviation (Stordal et al., 2005). Lastly, the study provided a landmark paper that made an updated assessment of overall radiative forcing from aviation in 2000 (Sausen et al., 2005).



Image used under Creative Commons from Andrew3000