The latest scientific framing of climate change emphasizes the importance of limiting cumulative emissions and the need to urgently cut CO2. International agreements on avoiding a 2 °C global temperature rise make clear the scale of CO2 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. While difficulties in decarbonizing aviation are recognized by industry and policymakers alike, the gap between what's necessary to avoid 2 °C and aviation's CO2 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.