Aviation emissions – Measures to decrease emissions in line with the 1.5 degree climate target

Aviation causes carbon dioxide emissions and other climate forcers like water vapour, nitrogen and sulphur oxides, volatile organic compounds and particulate matters. Globally aviation accounts 2 to 3 percent of carbon dioxide and 4 percent of total greenhouse gas emissions originating from human activity. However, the share of aviation is likely increasing as the number of air passengers is growing annually. This review study maps existing and known measures to tackle aviation emissions. In addition to global perspective, air travel in the Nordic countries is viewed as an example of wealthy societies where many people afford to travel. When calculating emissions, air traffic is divided into domestic and international travel, based on the amount of aviation fuel sold. The statistics do not provide clear picture of the air passengers’ nationalities: Flights taken by foreign travellers in one country affect the level of its domestic air traffic emissions, while flights taken by that country’s citizens between two foreign countries or from a foreign country to home country have no impact on the aviation emissions on that specific country. While number of flights per person varies a lot, even a single flight can have significant contribution on one’s carbon footprint. A single passenger can reduce own air traffic emissions through personal choices, for example by changing travel mode or destination. However, in work related travel the employers are in a key position to determine the travel policies and practices. Greenhouse gas emissions per passenger kilometre have been reduced by improved aircraft technologies and design, together with air traffic management and operational efficiency such as continuous descent approach. The efficiency of aviation has increased, but the growth of air travelling has outweighed the emission savings, thus the total emissions are increasing. Expectations with technological improvements are in the development of electric aircrafts and fuel related solutions: Replacing fossil fuels with alternative and sustainably manufactured low emission fuels plays a vital role in reducing emissions. The high cost and limited volume of sustainably available raw materials and capacity of manufacturing are the greatest hinders for a wider adoption of alternative fuels. Flights within the European Economic Area have been part of the emission trading scheme since 2012. Globally, the sector is measuring its net emissions during years 2019 and 2020 and the growth of net emissions from 2020 onwards are going to be compensated through the Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) of International Civil Aviation Organization (ICAO). If the aviation is not successful in reducing its emissions, the aviation could use alone roughly half of the annual carbon budget left in 2050 to remain under 1.5 degree target. In such a case, the other economic sectors should be highly successful in reducing their emissions close to zero by 2050. Reforming regulations, taxation and other measures to increase the use of alternative fuels are probably important steering measures in the future. Global or at least continental regulation enables more uniform and equal competition between airlines, airports and other transport means.