How TUI understands the Climate Debate

Since the end of the 80s, climate protection has become established as a permanent part of international and national politics. Scientific and political discussions on climate change, the greenhouse effect and the development of a suitable climate protection policy have been held and coordinated at an international level by the United Nations. The UN's civil aviation organisation ICAO (International Civil Aviation Organisation) has therefore been involved with questions concerning aviation and climate change.

At the UN level, the Intergovernmental Panel on Climate Change (IPCC) is discussing and compiling scientific findings and questions on the subject of climate change and global warming and is making them available to the international community as a basis for political action.

On a political level, in the context of the climate convention and the resulting Kyoto Agreement, the international community has developed climate protection mechanisms that can be used to achieve a world-wide reduction in greenhouse gas emissions: Emissions Trading, the Clean Development Mechanism and Joint Implementation. The Kyoto Agreement defines six gases as greenhouse gases, including carbon dioxide, carbon monoxide and CFCs.

However this does not include all the aviation emissions to which climate-relevant properties are attributed, for example water vapour (condensation trails), nitrogen oxide (or ozone), sulphur oxide and aerosols. In some respects, the relevance of many emissions with regard to the climate still needs in-depth research, so no reliable quantification of the effect on the climate is possible yet.


Aerosols
Particles suspended in the air, which may be solid (e.g. soot) or fluid (e.g. droplets of sulphuric acid). Aerosols have two contrasting effects on the climate: on the one hand, aerosols reflect the sun's radiation and therefore have a cooling effect on the earth's surface. On the other, they provide a surface on which steam can condense and thus promote the formation of clouds and condensation trails. These cause the earth's surface to heat up. It is mainly soot and sulphate aerosols that are produced by the combustion of kerosene. While soot particles contribute towards the greenhouse effect, sulphate aerosols cause cooling. There is a local limit to the effect of sulphate aerosols. zurück


Clean Development Mechanism
One of the reduction mechanisms according to the Kyoto Agreement. This mechanism envisages that countries which, according to Kyoto, are obliged to reduce emissions (mostly industrial nations) may also purchase emission rights by investing in climate protection technologies in developing countries and thus contributing towards a global reduction of emissions. zurück


CFCs
Fully halogenated chlorofluorocarbons, which do not occur naturally; they are used, amongst other things, as the coolant in refrigerators and freezers and in air conditioning systems. CFCs are classed as extremely effective greenhouse gases. They are also considered to be the main cause of the decomposition of the ozone layer in the stratosphere that has been observed since 1980. zurück


Climate-relevant aviation emissions
IPCC calculates climate effect taking account of the following emissions: - carbon dioxide (CO2)
- nitrogen oxide (NOX) (favours the formation of ozone and the decomposition of methane)
- water vapour (condensation trails)
- cirrus clouds
- sulphate aerosols
- soot particles
Although not all emissions support a greenhouse effect – sulphate aerosols have a cooling effect and NOX emissions, amongst other things, contribute to the decomposition of the greenhouse gas methane. zurück


Emissions Trading
One of the reduction mechanisms according to the Kyoto Agreement. A maximum emission limit is set for greenhouse gases. Countries pass on emission entitlements (certificates) for these maximum amounts to emitters who can trade them amongst themselves. In the EU, emission trading started on 1st February 2005 for static installations. The legal basis for trading in greenhouse gases in Europe is the so-called Emissions Trading Directive 2003/87/EC. An emissions trading scheme is currently being discussed for international aviation as well. In addition to proposals to reduce emissions by improving infrastructure and flight management, the International Civil Aviation Organisation (ICAO) will, between now and 2007, work out proposals for an internationally binding trading system. zurück


ICAO
The International Civil Aviation Organisation (ICAO) was founded in 1954 as a United Nations' sub-organisation for civil aviation and is responsible for the planning of civil aviation. The main tasks of the ICAO are the regulation of international traffic laws, standardisation, production of recommendations and guidelines, safety, environmental protection and infrastructure development. An ICAO working group, the Committee on Aviation Environmental Protection (CAEP) is working out proposals on environment-related problems such as aviation emissions and flight noise. zurück


IPCC
Intergovernmental Panel on Climate Change, founded in 1988 by the World Meteorological Organisation (WMO) and the United Nations Environment Programme (UNEP). As a scientific expert committee, the IPCC has the task of evaluating scientific information on anthropogenically caused climate change and its possible effects. In 1999 a report was published on the effects of aviation on climate, with the title Aviation and the Global Atmosphere. zurück


Joint Implementation (JI)
One of the reduction mechanisms according to the Kyoto Agreement. It envisages that countries which, according to Kyoto, are obliged to reduce emissions (mostly industrial nations) fulfil part of their reduction obligations by performing projects in another country which, according to Kyoto, also has reduction obligations. zurück


Climate Change and Global Warming
The term climate change refers to the change in the climate on the earth over a the longer term, as has been taking place since the earth came into existence, sometimes to a significant extent. Research shows variations in the global mean temperature over the last million years of between 9°C and 16°C. The term global warming describes a world-wide climate phenomenon referring to the rise in the average global surface temperature. It is not the earth's climate history as a whole that is considered, but in particular the last 150 years. Since the start of industrialisation, from approx. 1860, a clear rise in the average annual temperature has been observed and, especially in the last few years, unusually high average temperatures have been measured. Both natural and man-made reasons have been taken into account in order to explain this phenomenon. The large majority of scientists (IPCC) now assume that the anthropogenic (man-made) greenhouse effect is the main cause of global warming. The rise in the concentration of greenhouse gases such as CO2 and methane in the atmosphere due to the combustion of fossil fuels (coal, oil, natural gas) play a crucial role in this. zurück


Carbon Dioxide (CO2)
A gas that occurs naturally in the atmosphere in a concentration of currently about 370 ppm and lasts for approximately 100 years. It occurs in the combustion or decomposition of biomass (plants, fossil fuels (oil, coal, natural gas, etc.)) and in the respiration of humans and animals. Since industrialisation began, the concentration of CO2 in the atmosphere has been increasing and scientists attribute this in particular to the combustion of fossil fuels by Man. CO2 contributes significantly to the natural greenhouse effect. The decomposition of atmospheric carbon dioxide takes place very slowly: the average time it remains in the atmosphere is in the order of 100 years. IPCC scientists also attribute some of the warming of the atmosphere, which goes beyond the natural greenhouse effect, to the CO2 emissions caused by Man. International aviation currently contributes 2 percent of these CO2 emissions. The total contribution to global warming, without taking account of steam emissions, is estimated at approx. 2.5 percent. zurück


Carbon Monoxide (CO)
A gas that is produced by the incomplete combustion of organic compounds. In air, it oxidises relatively quickly to carbon dioxide. In aviation, the emission of carbon monoxide depends upon the loading condition of the aircraft engine. When climbing and at cruising altitude the emissions are lower than when landing and idling (rolling). zurück


Condensation Trails
Under certain meteorological conditions, steam and particle emissions from aircraft engines can lead to the formation of condensation trails, which can occasionally last for several hours. Scientists (IPCC) assume that condensation trails influence the earth's radiation management by preventing heat being radiated back into space. The additional high clouds that are caused by linear steam trails make up 0.5 percent of clouds over west and central Europe and 1.3 percent of those over the USA. Projections from regional observations to a world-wide average give a value of approximately 0.07 percent. According to current calculations by the DLR, compared to the CO2 emissions from aviation, this has a less significant effect on climate. In model simulations, the DLR recently found that the influence that condensation trails have on radiation management is about 5 times smaller than that of the CO2 caused by aviation. The effect of the cirrus clouds that can result from condensation trails (contrail cirrus clouds) is the subject of current research activities. No figures have yet been published by the IPCC because the results of the research to date still have a lot of uncertainties. The reason for these uncertainties is that they concern effects that are extremely complex, in parts combined, often only short-lived and concentrated on a relatively small space, as well as being in areas that are quite different from the point of view of time and space (e.g. different ozone content and different effects at different altitudes). zurück


Kyoto Agreement
The Kyoto Agreement was adopted in 1992 in Kyoto, Japan, by the 3rd conference of states contracting to the climate convention and has to date been signed by 89 countries. It came into force on 16th February 2005. In the Kyoto Agreement, the industrialised countries agreed to a 5.2% world-wide reduction of greenhouse gas emissions compared to 1990. Europe has already declared that it is ready to reduce its greenhouse gas emissions by 8% (approx. 0.35 billion tons) compared to 1990. This target reduction objective is distributed differently between the individual Member States of the European Community (burden sharing). With approximately 75% of the European reduction goal, Germany is taking the main share and must reduce its greenhouse gas emissions by 21% compared to 1990. The Kyoto Agreement also describes the reduction mechanisms of emission trading, the clean development mechanism and joint implementation. International aviation and international shipping have not been taken into account in the reduction obligations in the Kyoto Agreement. zurück


Ozone
Ozone does not occur directly from the combustion of kerosene, but through the chemical reactions of nitrogen oxide emissions. At cruising altitude, ozone acts as a greenhouse gas (in the long-wave spectrum) and absorbs radiation in the solar (short-wave) spectrum. Scientists have estimated the increase in ozone concentration at cruising altitude due to aviation at 3-4%. zurück


Sulphur Dioxide (SO2)
Occurs in the combustion of fossil fuels from the sulphur contained in coal, oil and gas. In the atmosphere, SO2 is converted to sulphuric acid and sulphurous acid, from which sulphate aerosols result. Sulphate aerosols disperse solar radiation and therefore have a cooling effect. In the combustion of kerosene, approximately 0.5 kg of sulphur compounds per ton of fuel occur, assuming the maximum value for sulphur content in kerosene laid down in international standards. Thanks to improved fuel quality, the actual value should however be much lower. For example, for German refineries, the DLR assumes a sulphur content of 0.03 kg/ton or lower. zurück


Nitrogen Oxide (NOX)
NOX includes NO and NO2 as compounds of nitrogen and oxygen atoms. Nitrogen oxide is relevant to the climate, partly because it causes the oxidation of oxygen to ozone, a greenhouse gas, and partly because it contributes towards the decomposition of methane, also a greenhouse gas. The effect is limited to the area of the emission and is predominant in the central area of the northern hemisphere. Natural sources of nitrogen oxide are lightning and microbes in the earth. In combustion processes in aircraft engines, nitrogen oxides occur under high pressure and at high temperatures. In modern engines, however, both pressure and temperature during the combustion process have been reduced and so emissions of carbon monoxide and unburned hydrocarbons are noticeably lower. It has also been possible to reduce nitrogen oxide emissions by up to 85% thanks to new combustion chambers. Depending on the type of aircraft and how it is used, nitrogen oxide emissions vary between 6 and 20 grams per kilogram of kerosene burnt. In total, aviation is responsible for 2-3% of anthropogenic (man-made) nitrogen oxide emissions. zurück


Greenhouse Effect
Natural Greenhouse Effect
Steam and trace gases in the atmosphere such as carbon dioxide, dinitrogen monoxide, methane and ozone, allow the short-wave radiation from the sun to pass largely unhindered through the atmosphere to the earth, but absorb the longer-wave heat radiation given off by the earth. This causes the earth to warm up, as in a greenhouse, to an average global temperature of 15°C. Without this natural greenhouse effect, it would be approximately 33°C colder and the earth would be uninhabitable for most forms of live.
Anthropogenic Greenhouse Effect (caused by Man)
Human activities lead to a rise in the concentration of natural greenhouse gases in the atmosphere and also to the release of industrially produced gases that affect the climate and which accumulate in the atmosphere. In addition to the natural greenhouse effect, this causes an anthropogenically increased greenhouse effect. The global average temperature increases as a result. Aviation emissions occupy a particular position here: the proportion of emissions of CO2, CO, NOX, VOC and CO is low compared to total traffic – the main proportion of emissions however occurs at the cruising altitude of 8-12 km. At these altitudes, the time the gases remain in the atmosphere is much higher than near the surface of the earth. In addition, the temperatures are very low. This means that the emission of gases that absorb radiated heat cause a more pronounced greenhouse effect than comparable emissions close to the earth's surface. zurück


Water Vapour
Is the most significant greenhouse gas with a higher effect on the climate than carbon dioxide. Steam is responsible for two thirds of the natural greenhouse effect – without it, the temperature on the surface of the earth would be approximately 22°C cooler. Steam occurs, for example, in aircraft engines as a product of combustion (approximately 1.1 kg per litre of kerosene). Unlike carbon dioxide however, the steam emissions caused by Man are small compared to natural sources (evaporation). Every kilogram of kerosene generates 1.24 kilograms of steam. Fears that current aviation might increase the amount of steam in the stratosphere and thus change the climate have not stood up to scientific scrutiny. The German Centre for Air and Space Travel (Deutsche Zentrum für Luft- und Raumfahrt (DLR)) found that with current flight paths/heights, even 100 times the amount of steam released by aviation today would still not have any noticeable effect on the climate. zurück

Produced in collaboration between TUI and Lufthansa with assistance on content from Lufthansa AG, Environmental Concepts Department