Passenger air traffic in the world has doubled over the last 15 years. Over the last few years, European air traffic movements have increased by between 4% and 6% per annum and current forecasts indicate that European air traffic movements are likely to double by 2015 compared with 1998 figures. Most of the aviation fuel is consumed in the cruising phase, which for the majority of flights takes place at around 10 km altitude. Hence most pollutants emitted are released in this part of the atmosphere. The contribution of gaseous and particulate emissions by aviation is small in comparison to other global sources. However, as these emissions occur directly in the upper troposphere or lower stratosphere, those processes which would otherwise remove the gases and particles from the environment are largely ineffective. This means that the residence time of pollutants in the upper atmosphere is much greater than that of pollutants emitted near the ground. The main contribution of commercial air traffic to changes in the atmosphere’s composition takes place at altitudes between 9 and 13 kilometres. These changes may have impacts on the climate.
The objective was to evaluate, for the benefit of policy-makers, which measures could contribute to minimizing the effects of emissions from aviation in the Nordic region. This was to be done by studying and modeling the response of the atmospheric system to a range of air traffic scenarios. The environmental impacts resulting from each scenario were evaluated through interdisciplinary cooperation, by integrating the results of three models. The EIATNE project also aimed to develop a methodology for assessing environmental impacts which could be used to help formulate environmental policy.
The environmental impacts were studied for a number of different scenarios, involving inter alia:
- a doubling of air traffic within the next 30 years;
- increased air traffic over the Arctic region;
- a new cargo hub in Northern Europe and;
- lowering of the flight altitude.
A system of numerical models supported by the latest knowledge on emissions, atmospheric chemistry, and pollutant transport and deposition was used to evaluate the potential impacts of the different scenarios. The emphasis was placed on potential impacts of air traffic emissions on climate change, human health and vegetation damage.
- One of the findings was that today’s air traffic volume does not seem to pose a major threat to the relatively clean surface air and sensitive environment of the Northern European region. However, air traffic does contribute somewhat to acidification, eutrophication and ground level ozone.
- Flights in clean areas (such as Scandinavia) are more efficient in generating ozone than flights in more polluted regions (such as the continent and the North Atlantic corridor).
- Although recent studies have indicated that greenhouse gas generation could be minimised by lowering flight altitude in some regions, EAITNE’s calculations do not indicate that this is the case for the Arctic region.
- Relocation of some air traffic routes to the Arctic region, is therefore not expected to have severe environmental consequences. A potential air traffic hub in the Northern European region would only have limited impacts on ground level ozone and on nitrogen oxide (NOx) deposition.
- Emissions of NOx are important for ozone production not only near the ground (for surface ozone production) but also at cruising altitudes where they increase background ozone concentrations. As ozone acts as a greenhouse gas throughout the whole troposphere and in the long run has a negative effect on health and on vegetation, minimising NOx emissions at all levels is therefore essential.