Aviation's Climate Change Impact is Small
Aviation is responsible for:
- 2% of global carbon dioxide (CO2) emissions
- 12% of CO2 emissions from all transport sources, compared to 74% from road transport
- 3% of the total man-made contribution to climate change
By 2020, airlines are aiming for at least an additional 25% improvement in fuel efficiency and CO2 emissions, through technology and operational enhancements.
Scientific Uncertainties
Although the natural greenhouse effect is vital for human existence, many scientists believe that additional warming linked to human activity may cause our climate to change irreversibly. However scientists disagree over the amount, probability and nature of these changes.
There is also disagreement over aviation's contribution to climate change. There is a good understanding of CO2 emissions, which contribute directly to the greenhouse effect, along with water vapour. Nitrogen oxides (NOx) contribute indirectly by creating ozone in the lower atmosphere. But little is known about the effect of contrails, cirrus cloud formation and the methane-reducing capabilities of NOx.
The best estimate of aviation's climate change impact is about 3% of the total contribution by human activities. This may grow to 5% by 2050.
Responsibly Addressing Climate Change
In 2005, IATA adopted an industry-wide climate change strategy (pdf, 196kb). This focuses on accelerating technological developments as the primary means of reducing greenhouse gas emissions. Infrastructure improvements are also needed, which could reduce fuel burn by 12%.
Fuel efficiency improvements enable airlines to reduce costs as well as emissions. Since the start of the jet age, aviation has reduced fuel burn, CO2 and water vapour emissions by some 70% per passenger km. The IATA fleet fuel efficiency improved by nearly 5% in 2005-2006. IATA's fuel action campaign assists its member airlines in saving fuel.
Emissions Policy Measures
Various policy options are being considered by governments to address aviation's emissions. These include voluntary measures, fuel taxes and charges and emissions trading. IATA advocates that global solutions are required, through the International Civil Aviation Organization.
See also Environmental Review 2004, part 3, "Confronting climate change".