Aviation and Climate Change – the continuing challenge Alice Bows-Larkin*, Sarah L. Mander, Michael B. Traut, Kevin L. Anderson, and F. Ruth Wood Tyndall Centre for Climate Change Research, School of Mechanical Aerospace and Civil Engineering, University of Manchester, Manchester, UK. M13 9PL. *Corresponding Author. Tel: 0161 306 3737; alice.bows-larkin@manchester.ac.uk Keywords: aviation; climate change; scenarios; mitigation; demand-management; carbon dioxide emissions; fuel efficiency; alternative fuels Abstract The latest scientific framing of climate change emphasises the importance of limiting cumulative emissions and the need to urgently cut CO 2 . International agreements on avoiding a 2°C global temperature rise make clear the scale of CO 2 reductions required across all sectors. Set against a context of urgent mitigation, the outlook for aviation’s emissions is one of continued growth. Limited opportunities to further improve fuel efficiency, slow uptake of new innovations, coupled with anticipated rises in demand across continents collectively present a huge challenge to aviation in cutting emissions. Whilst difficulties in decarbonising aviation are recognised by industry and policymakers alike, the gap between what’s necessary to avoid 2°C and aviation’s CO 2 projections has profound implications. Biofuel is one of the few innovations that could play a significant role in closing the gap, but with low anticipated penetration before 2020 its contribution would have little impact over the desired timeframe. If the aviation sector does not urgently address rising emissions, there is an increasing risk that investment in new aircraft and infrastructure could lead to stranded assets. This leaves it facing an uncomfortable reality. Either the sector acts urgently on climate change and curtails rising demand, or it will be failing to take responsibility for a considerable and growing portion of climate change impacts. 1. INTRODUCTION TO AVIATION & CLIMATE CHANGE POLICY International aviation’s contribution to global CO 2 emissions has come under scrutiny since the early 2000s. Prior to that, mitigation focused on the CO 2 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 CO 2 contribution, discussing cuts in the CO 2 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 CO 2 (Bows 2010; Budd and Ryley 2013; Peeters Williams and Haan 2009) this is not a universal view.