1 Introduction to Aviation & Climate Change Policy
International aviation's contribution to global CO2 emissions has come under scrutiny since the early 2000s. Prior to that, mitigation focused on the CO2 released within national borders, given the exclusion of international aviation from the Kyoto Protocol's national targets. Although a considerable body of research has since interrogated aviation's CO2 contribution, discussing cuts in the CO2 produced by flights remains controversial and unpopular for many reasons voiced by industrial stakeholders and the general public (Budd and Ryley, 2013). So, while there are arguments for treating aviation on a level playing field with other sectors and implementing stringent mitigation policies aimed at tackling CO2 (Bows, 2010; Budd and Ryley, 2013; Peeters, Williams, and, Haan, 2009), this is not a universal view.
Aviation's economic importance is regularly cited as a key reason to avoid stringent CO2 mitigation (Wood, Bows, and Anderson, 2012). Another argument can be attached to its role in connecting nations at different stages of development. The sector's growth rate, coupled with few options for reducing carbon emissions per passenger-km (gC/RPK), drives up aviation's CO2 emissions. Increasing mobility and high rates of economic growth in industrializing nations influence demand. These industrializing nations do not in general foresee CO2 targets for their other sectors before 2020, and therefore few direct drivers toward cutting emissions. Globalization supports arguments for treating international aviation and shipping differently to sectors that do not operate within international airspace or waters, with policies that can allow for high growth rates in some countries. While this may have some traction, it only holds within a climate change context if globally averaged growth rates do not jeopardize the international commitment to remain within the 2 °C global temperature target.
There has been widespread political consensus enshrined in various accords, agreements, and declarations that “2 °C” represents the threshold between acceptable and dangerous climate change. Controlling emissions of greenhouse gases across sectors is critical if the carbon budgets underpinning this commitment are not to be exceeded. Yet the sizable and growing emissions from international aviation (and shipping) were exempt from national targets enshrined in the Kyoto Protocol. Domestic aviation emissions were included, but as the United States, with its dominant share of the CO2 from all internal flights when the Protocol was adopted (63% in 1997, IEA, 2014), did not ratify it, the already weak constraints on aviation emissions were watered down still further.
In a bid to include international aviation's CO2 within global climate commitments, the Kyoto Protocol tasked the UN's specialist agency, the International Civil Aviation Organization (ICAO), with responsibility for mitigating CO2 from aviation. However, slow progress during the 1990s led the EU Commission, having voiced its frustration, to independently develop proposals for including aviation within its Emissions Trading Scheme (ETS) and impose a carbon price on the industry (Bows, 2010). So, by the Kyoto Protocol's final official year, the EU had included aviation within its ETS despite concerns coming from the industry regarding elevated costs and doubt surrounding the resulting impact on CO2 emissions.
Yet even before the policy began operating, the EU suspended the inclusion of non-EU nations' flights in response to progress by ICAO toward establishing a global trading scheme, and in light of strong opposition to the scheme from some countries including the United States (Bows-Larkin, 2014). This suspension remains in place until 2016, when the ICAO mechanism is scheduled to be agreed. Other policy mechanisms promoted through ICAO include a voluntary global annual 2% fleet fuel efficiency improvement up to 2050, with a 50% reduction in net emissions from 2005 levels, and an aim for “carbon neutral growth” from 2020 (ICAO, 2013a).
By October 2013, development of ICAO's global trading scheme was underway, with derived revenue hypothecated to alleviate the impact of aircraft engine emissions, and developing low-carbon alternative fuels. However, with no mechanism agreed before 2016, and then further time needed for implementation, emissions are expected to rise unabated at least until then. Meanwhile, there have been developments within the United States. In 2014, the US Supreme Court upheld the United States Environmental Protection Agency's (EPA) power to regulate CO2 under the Clean Air Act. Now, the EPA is considering if aviation has an impact on human health, releasing an information sheet with potential plans to impose a CO2 standard on aircraft.
With cuts of at least 80% from 2010 levels by 2050 necessary across all sectors for a reasonable chance of avoiding 2 °C (Bows-Larkin, 2014), the current mitigation strategy for international aviation assumes other sectors will proportionally cut CO2 by more than aviation. Bows (2010) assessed aviation's climate impact, comparing scenarios for future aviation CO2 with carbon budgets associated with 2 °C. The paper presented the mitigation challenges for aviation and highlighted the importance of understanding the broader climate change context when assessing aviation's climate impact. This chapter updates Bows (2010) by comparing updated aviation scenarios with more recently published 2 °C carbon budgets. It discusses insights in the context of emerging developments, to reassess if that paper's conclusion that “without a large reduction in growth rate or significant penetration of alternative fuel by 2050, avi...
