The issue of climate change has become prominent in recent scientific and policy debates and now represents one of the dominant global environmental issues (Adams 2009; Houghton 2009; IPCC 2007; Stern 2007). Popular and scientific concerns have been expressed about the effects and impacts of climate change, which are projected to become increasingly profound and widespread. As a result, concerted efforts at all levels are required to adapt to, and to mitigate, those impacts (IPCC 2007; Stern 2007). Air transport is currently a small but nonetheless significant contributor to climate change, mainly as a result of the various, interrelated effects of aircraft emissions (for an overview, see Chapter 2). However, given the projected sustained rapid growth of the air transport industry of around five per cent per year, aircraft emissions are expected to constitute a substantial proportion of global greenhouse gas emissions by 2050 (Bows et al. 2009). The task of reducing the impact of air transport on climate represents a major challenge. The fact that the industry is international in its scope, is technologically mature and is characterised by long lead-in times and long in-service times means that achieving emissions reductions will be extremely difficult (Gössling and Upham 2009; Lee 2004: Peeters et al. 2009). Besides the effects of aircraft emissions, other aviationrelated impacts on climate occur due to the operation of airports and their ancillary services, and the prospect of reducing the emissions generated by those activities may be greater. Despite the challenges involved, there exists a growing determination to reduce the overall impact of aviation on climate, as the G8 Gleneagles climate statement, signed on 8 July 2005, attests (Forster et al. 2006; Upham and Gössling 2009).