Flying into the future
Civil aviation is one of the world's fastest growing industries. It has expanded at an average annual rate of 3.8\;% between 2001 and 2005 and currently is growing at 5.9\;% per year. The success of the aviation industry is poised to continue over the coming decades. Continuing rapid growth in aviation would provide economic benefits and allow greater mobility amongst the world's population. However, these benefits would come at a cost – most notably a significant increase in aviation greenhouse gas (GHG) emissions. Most projections are based on scenarios that try to imagine what the future would look like if air transport corporations continued to apply existing policies. Still, there are many projections for global aviation emissions and this makes it hard to establish one 'business as usual' case. Efforts to provide projections taking into account changes in technology as well as in society have been undertaken by the Consave 2050 project. For example, even though there have been significant improvements in fuel efficiency through technological innovation, this has been outweighed by the increase in air traffic. Consave 2050 project partners allowed for social, political and economic uncertainties by developing four possible scenarios for the growth of global (national and international) aviation emissions. Each of these scenarios is a more aggressive, or a less likely, departure from the current situation in terms of policy and technology. These scenarios range from the so-called 'Down to earth' requiring policy action and regulations to an 'Unlimited skies' scenario, which is comparable with an unconstrained demand situation. The latter also includes the assumption that fuel efficiency of the global aircraft fleet improves at an annual rate of 1.5\;%. In addition, it is contingent on improvements in air traffic management and airport operations. These assumptions are broadly consistent with those of scenarios developed during the 'Astera' project to support the mission of the Advisory Council for Aeronautics Research in Europe (ACARE). Without significant policy action at an international level, air transport corporations are more likely to be on a path resembling the Consave 'Unlimited skies' scenario. In this case, the global aviation emissions have been estimated to account for a significant proportion of the total allowed emissions in 2050. The Consave 2050 project partners argued that the four new scenarios can establish a baseline against which changes caused by new policies can be evaluated. Furthermore, they should provide incentives to reduce aviation emissions and thereby limit the risk of undesirable climate change.