This review paper examines the greenhouse gas (GHG) emission reduction targets postulated by a range of organizations seeking to reduce the consequences of global climate change and how, or if, the global tourism sector can achieve its share of those targets. It takes both existing estimates of current tourism GHG emissions and emissions projected in a business-as-usual scenario through to 2035 and contrasts them with the "aspirational" emission reduction targets proclaimed by the sector. Analysis reveals that with current high-growth emission trends in tourism, the sector could become a major global source of GHGs in the future if other economic sectors achieve significant emission reductions. Success in achieving emission reductions in tourism is found to be largely dependent on major policy and practice changes in air travel, and stated tourism emission reduction targets do not appear feasible without volumetric changes considering the limited technical emission reduction potential currently projected for the aviation sector. The opportunities and challenges associated with a shift towards a low-carbon global economy are anticipated to transform tourism globally and in all respects. Much greater consideration and dissemination of these issues is required to inform future tourism development and travel decisions.