Environmental impact of air transport

Climate-optimised flight routes
Air traffic management for the benefit of the environment and climate

Beyond the economically driven desire to minimise fuel consumption and hence carbon dioxide emissions, a further reduction in the climate effects of air transport can be achieved by adopting aircraft routes that avoid non-carbon-dioxide effects such as contrail formation or ozone production. However, the climate impact of these environmental aspects is not considered in current flight planning practices. Enhanced flight planning procedures that identify climate-optimised aircraft routes are not yet available. Such concepts are currently under development and will combine state-of-the-art climate science with today’s air traffic management systems and infrastructure. Air transport accounts for five percent of anthropogenic climate change. This includes non-carbon-dioxide effects, such as contrail formation and the impact of the emission of oxides of nitrogen on ozone and methane. These cause effects in the same order of magnitude as the emission of carbon dioxide. At present, flight routes are planned on the basis of minimising operating costs (typically based on fuel consumption, time, and overfly charges) while complying with Air traffic Management (ATM) and operational constraints.

The sensitivity of the atmosphere to air transport emissions exhibits strong spatial and temporal variations. These result in a potential for mitigating climate impacts by avoiding regions of the atmosphere which are in particular sensitive to air transport emissions. Introducing climate change functions as a measure of the climate effect of air transport in a specific region as a meteorological (MET) service would enable flight planning procedures to have information on the location of regions experiencing large climate effects available during the flight planning process. Identifying alternative routes that avoid these regions has the potential to reduce the total climate effect of aircraft operations. A direct link to numerical weather predictions by means of an algorithm has been suggested to efficiently integrate such a MET service.

With regard to air-transport-induced climate change, the impact of carbon dioxide emissions is directly linked to fuel consumption, while non-carbon-dioxide emission effects depend on regional and seasonal variations in meteorological conditions. Different spatial and temporal scales of individual impacts have to be considered. Hence, the contribution of air transport non-carbon-dioxide effects to climate change is more difficult to assess due to its inherent complexity and depends on flight performance, weather conditions and the timing of the emissions.

Together with partners from industry, research organisations and other DLR institutes, the DLR Institute of Atmospheric Physics is working on concepts to identify climate-optimised flight routes. These will offer the possibility of a robust and eco-efficient reduction of the climate footprint of air transport. In addition, situations with a high potential for reducing the climate impact at low or even no additional cost can be identified. There are also situations where the climate impact as well as the cost can be reduced. Finally, these strategies can be implemented in a meteorological service that gives ATM the possibility to understand these processes and integrate them into their planning procedures.

German Aerospace Center (DLR)
Institute of Atmospheric Physics
Sigrun Matthes · Email sigrun.matthes@dlr.de