Air Transport and the Environment

Ben Daley

• Publisher: Routledge
• Year: 2016
• ISBN:
  9781317183365
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Aviation
• Index: Technology & Engineering

Air Transport and the Environment provides an overview of the main issues relating to aviation environmental impacts. It explains the challenge facing policymakers in terms of sustainable development, focusing on the importance of balancing the industry's economic, social and environmental costs and benefits, both for people living now and for future generations. Individual chapters review the current scientific understanding of the main aviation environmental impacts: climate change, local air pollution and aircraft noise. Various responses to those issues are also considered, including a range of policy options based on regulatory, market-based and voluntary approaches. Key concepts such as environmental capacity, radiative forcing and carbon offsetting are explained. In addition, the book emphasises the main implications of aviation environmental issues for policymakers and for the management of the air transport industry. Debates about the environmental impacts of flying often generate strongly polarised reactions, yet this book adopts a constructive approach to the subject and attempts to present the environmental issues in a clear, straightforward manner. It aims to provide a policy-relevant synthesis of a wide range of perspectives rather than advocating one particular viewpoint. Yet the central purpose of this book is to bring the sustainable development challenge facing the air transport industry to the fore, and so to inform effective policy responses. Air transport plays a critical role in supporting economies and societies that are increasingly interconnected by globalisation; this book presents the view that the vital economic and social benefits of the air transport industry should not be lost - and in fact could be distributed far more widely and equitably - but that the environmental impacts of air transport nevertheless require urgent and effective management. Air Transport and the Environment has been written primarily for professionals in the air transport industry, policymakers and regulators. It is also intended for use by academic researchers, students and others who are interested in the complex relationship between air transport and the environment.

1 Introduction

A Critical Challenge

Air transport is associated with a wide variety of ideas, representations and meanings. Flying, perhaps more than any other means of transport, conjures diverse images of leisure, recreation, connectivity, business productivity, social contact and cultural exchange. No other mode of transport offers such ease of access to international tourism destinations, such rapid transfer between major cities at the continental or global scales, or such a wide range of opportunities for travellers to encounter and experience new places. Given the capacity of the industry to drive economic growth and to enhance mobility, air transport has become an important instrument of globalisation (defined broadly as the process of increasing integration of economic, political, social and cultural activities at the global scale) and a potent symbol of those new patterns of interconnection. Yet, to some people, air transport represents a destructive force that threatens the integrity of communities and environments. Despite the emergence of the so-called low-cost carriers (LCCs), flying is still regarded by many people as a luxury enjoyed by affluent travellers with lifestyles of unprecedented leisure. Many others do not enjoy the benefits of aviation but nonetheless suffer its impacts: noise, pollution, congestion and – sometimes – dislocation. To some people, air transport represents an industry that has enjoyed unfair subsidies and that has been regulated with an excessively light touch. Air transport therefore generates fierce controversy, as in debates about the construction of new airport infrastructure, about the social acceptability of night flying or about the supply of air-freighted organic food. Above all, aviation has become a powerful symbol of fossil fuel consumption, greenhouse gas emissions and climate change. Such diverse images illustrate the complexity and relevance of the relationship between air transport and the environment.

As with many other environmental issues, debates about the environmental impacts of air transport are often framed within wider discussions of sustainable development. Put crudely, sustainable development means balancing the economic, social and environmental benefits and costs of development, both for people living now and for future generations (Adams 2009; Baker 2006; Dresner 2008; Elliott 2006; WCED 1987). Air transport is frequently celebrated because it provides important economic and social benefits. The economic benefits of air transport have been well documented, at least at the national scale (Boon and Wit 2005; DfT 2003a; OEF 1999; 2002; 2006). Aviation makes a vital contribution to economic development with the result that the industry is frequently described as a major engine of economic growth. That economic contribution occurs primarily through the influence of aviation on the performance of other industries and by supporting their growth: air transport facilitates greater access to markets, specialisation, economies of scale and foreign direct investment (FDI). In addition, however, air transport makes a substantial contribution to local, regional and national economies in its own right: by adding to gross domestic product (GDP), by creating direct and indirect employment, by raising productivity, by exporting goods and services, by contributing taxes and through investment. Thus aviation is regarded as a key component of transport infrastructure on which many other parts of national economies depend, and ‘investments in that infrastructure boost productivity growth across the rest of the economy’ (OEF 1999, 5). Aviation allows markets to expand – potentially to the global scale – and stimulates technological improvements and innovation. Therefore air transport is both an important economic sector in its own right and a vital facilitator of growth in other sectors. In addition to its economic benefits, air transport provides many social benefits associated with employment, leisure, recreation, cultural exchange, educational opportunities and greater access to family and friends (Bishop and Grayling 2003; Caves 2003; Shaw and Thomas 2006).

Given the importance of air transport for economic and social development – and the broad popularity of air travel – the aviation industry has generally sustained high rates of growth (of around five per cent per year) over the last five decades. During that period, aviation growth rates have tended to exceed the rate of global economic growth (Bailey 2007; Humphreys 2003; IPCC 1999; Lee 2004; Lee et al. 2009). In particular, the sustained growth of demand for air transport has been reinforced by two important trends: globalisation and the growth of tourism (Debbage 1994; Goetz and Graham 2004; Janelle and Beuthe 1997; Mayor and Tol 2010; Pels 2008). Globalisation is now acknowledged to be a complex process that is responsible for profound economic, political, social, cultural and environmental transformations worldwide. Communications between many places are now almost instantaneous; intercontinental transportation is commonplace; the world economy has become increasingly integrated; the influence of multinational organisations has expanded; and the autonomy of most nation-states has diminished (Hettne 2008). Air transport has been important in facilitating the process of globalisation, although globalisation has in turn increased the demand for air travel (Goetz and Graham 2004; Janelle and Beuthe 1997; Young 1997). The growth of demand for air transport has also been closely linked to the rising demand for tourism, an industry that is highly dependent upon the availability of rapid, long-distance air services (Bieger and Wittmer 2006; Daley et al. 2008; Gössling and Peeters 2007; Graham et al. 2008; May 2002; Mayor and Tol 2010). At the global scale, tourism, like aviation, is an important economic driver and is projected to expand rapidly, at an average rate of around four per cent per year, until at least 2020. Projections by the United Nations World Tourism Organization (UNWTO) have indicated that international tourist arrivals (ITAs) will double between 2005 and 2020 and are expected to reach 1.6 billion by the latter year (UNWTO 2007). Mayor and Tol (2010) have argued that international tourism is projected to grow substantially over the decadal timescale, with increases in the number and length of trips, and with growth being driven largely by increasing demand by consumers in Asian countries. All of these factors combine to suggest that strong, sustained growth in demand for air transport is likely to continue beyond 2030 (Bieger et al. 2007; Bows et al. 2005; 2006; DfT 2003c; IPCC 1999; Lee et al. 2009). By 2050, air passenger traffic is expected to have increased five-fold from 1995 levels (IPCC 1999).

Yet in addition to its substantial economic and social benefits, air transport has a range of significant – and generally increasing – environmental impacts (Table 1.1). Some aviation environmental impacts are local to airports, whilst others are of global concern. Aircraft noise has long been a source of nuisance for individuals living in the vicinity of airports and beneath their arrival and departure routes. Aircraft and airports also generate air pollution, especially due to the emission of nitrogen oxides (NO_x) and particles. Airports also have other localised environmental impacts including habitat modification and destruction, land contamination, waste production, water consumption and water pollution. At the global scale, concerns about the environmental impacts of aviation now focus sharply on the issue of climate change. The impact of air transport on global climate is already significant and is growing (Lee 2004; Mayor and Tol 2010). Aircraft emit the important greenhouse gas, carbon dioxide (CO₂), thereby contributing to the radiative forcing of climate. Besides the direct effects of CO₂ emissions, however, aircraft have various indirect effects on climate. Aircraft emissions of NO_x in the lower stratosphere and upper troposphere – the levels at which civil aircraft generally cruise – are responsible for the catalytic production of ozone (O₃) which acts as a powerful greenhouse gas at those levels, but NO_x emissions also deplete another greenhouse gas, methane (CH₄). Aircraft also emit soot and sulphate particles, which have different radiative effects on climate. In addition, aircraft create contrails (condensation trails) and cirrus clouds, the climate effects of which are not yet fully understood (Lee 2004). Further concerns have been expressed about the potential environmental impacts of a growing fleet of business jets, and even of a proposed fleet of supersonic aircraft cruising at high altitudes (in the mid-stratosphere), which could contribute to the destruction of stratospheric O₃ as a consequence of their NO_x emissions. Hence air transport has many environmental effects. Those effects interact in complex ways; they are rapidly increasing; and they can no longer be ignored by policymakers.

The environmental impacts of air transport form the subject of this book; they are discussed in greater detail in subsequent chapters. Here, it is simply acknowledged that those environmental impacts are compounded by the sustained, rapid growth of the air transport industry. Whilst technological and operational improvements have been made (such as advances in fuel combustor technology, the introduction of low-sulphur content fuels, the development of more aerodynamically efficient airframes and the use of noise abatement procedures), the growth of the industry has outpaced those improvements (Åkerman 2005; IPCC 1999; RCEP 2002; Sustainable Aviation 2005). Consequently, although greater fuel efficiencies – and concomitant emissions reductions – have been achieved, the absolute environmental impacts of air transport are increasing (Mayor and Tol 2010). Even in scenarios containing optimistic assumptions about the rate of technological progress, air transport is projected to produce almost twice as much CO₂ in 2030 as in 2002; in some scenarios, CO₂ emissions from aviation are projected to more than treble over the same period (Horton 2006; Lee 2004). By 2050, based on existing (Kyoto Protocol) commitments to reduce greenhouse gas emissions, aviation CO₂ emissions could consume entire national carbon budgets unless mitigation measures are urgently taken (Bows et al. 2006; 2009). In addition, whilst concerns about climate change represent an important obstacle to the growth of air transport, local environmental constraints may also be acute; at some airports, infrastructure development is already precluded by air quality legislation and by local agreements to limit aircraft noise levels. Furthermore, environmental regulations are likely to become more stringent as public tolerance of environmental impacts decreases. For all of these reasons, the air transport industry faces severe constraints to its growth due to limited environmental capacity (Graham and Guyer 1999; Upham 2001; Upham et al. 2003; 2004).

Table 1.1 The main environmental impacts of air transport

Thus the air transport industry faces a dilemma: how to deliver vital economic and social benefits – benefits that are increasingly being demanded by consumers – whilst reducing its absolute environmental impacts. That dilemma represents a formidable challenge because of the projected rapid growth of demand for air travel and tourism, the strong links between air transport service provision and economic growth, the high abatement costs of the sector and the limited potential for radical technological solutions to be found over decadal timescales (DfT 2004; IPCC 1999). Some improvements in environmental performance are expected to be achieved by 2030 due to innovations in engine and airframe technologies, in aviation fuels and in operating systems and procedures (including more efficient air traffic management (ATM)). However, even cumulatively, those improvements are unlikely to offset the escalating impacts of a growing air transport sector. In the long term, radical technological solutions are required. Until such solutions are available, attempts to make air transport compatible with sustainable development must rely on the formulation and implementation of effective policy. Yet progress in developing policy for international air transport has been slow, partly because civil aviation is a highly competitive, cross-border activity that has been historically been regulated by myriad bilateral air service agreements (ASAs) between states as well as through broader international agreements (Pastowski 2003). The task of devising policy measures to reduce the environmental impacts of air transport involves negotiating sensitive issues of equity – both intragenerational and intergenerational – as well as balancing a wide range of economic, social and other environmental considerations. Such issues are now framed within the context of increasingly urgent calls to reduce the impacts of climate change. At the same time, the extent and sophistication of the scientific and technological knowledge required to inform critical decisions about climate change – and about other global issues – are becoming apparent. In all, the challenge facing policymakers is immense.

Responding to the Challenge

A central observation that informs this book is that, whilst air transport has a range of significant (and growing) environmental impacts, environmentalist concerns, in turn, are increasingly curtailing the growth of the air transport industry. Indeed, the expansion of some major airports is already tightly constrained for environmental reasons (Upham 2001; Upham et al. 2003; 2004). Therefore, the task of decoupling the growth of air transport from its environmental impacts is vital for both economic development and environmental protection. Such a decoupling relies both on the achievement of major technological and operational improvements in the environmental performance of aircraft and on the introduction of effective policy measures to reduce aviation environmental impacts. Technological responses include improvements in engine and airframe design and performance as well as the development of alternative fuels. However, given the high abatement costs that characterise the air transport sector, the long lead-in times associated with developing aviation infrastructure and the long in-service lifetimes of aircraft, there is, apparently, limited potential for radical technological progress to be made in the short to medium term – although those options may be more promising in the long term (DfT 2004; IPCC 1999). Operational responses involve different methods of loading, manoeuvring and maintaining aircraft in addition to the use of revised ATM systems and procedures. Operational measures, likewise, require substantial reforms – such as major revisions of airspace and of ATM systems and procedures – to be made if they are to drive substantial improvements in environmental performance, although modest improvements in efficiency may be achieved in the short to medium term. Policy responses, as in other areas of environmental governance, focus on the use of a wide range of policy instruments to align economic growth with the principles of sustainable development (Baker 2006). Such policy instruments include regulatory measures (standards), market-based measures (such as taxes, emissions charges, subsidies and tradable permits) and voluntary measures (such as carbon offsetting schemes). In principle, policy instruments can be devised and implemented relatively quickly, although progress in this respect has been slow to date (Pastowski 2003). In subsequent chapters of this book, the challenge of ensuring that aviation growth is compatible with sustainable development is considered in more detail, in terms of technological, operational and policy responses. A brief summary of those types of response is provided below.

In general, technological responses to the challenge of reducing the environmental impacts of air transport have focused on achieving improvements in engine and airframe design and performance, and on developing alternative aviation fuels (Thomas and Raper 2000). Efforts to achieve the former have centred on maximising the fuel efficiency of aircraft, both by reducing the weight and drag of airframes and by maximising the energy conversion efficiency of engines. Over a period of four decades, from around 1960, specific aircraft fuel efficiency (which is defined as fuel efficiency per passenger-kilometre) improved by around 70 per cent due to improvements in engine technologies and airframe design, and because of increased load factors (IPCC 1999). Further improvements in airframe performance are anticipated with ongoing improvements in aerodynamic efficiency, the use of advanced materials, innovation in control and handling systems and the development of radical aircraft designs (such as the blended-wing body). However, aircraft engine technologies are now relatively mature and the prospect of radical improvements in engine performance appears to be remote. Currently, the most fuel-efficient aircraft engines are high-bypass, high-pressure-ratio gas turbine engines, and the prospects for developing viable alternatives remain elusive (Lee 2004). One important consideration in this respect is that aircraft engine design may be optimised for fuel efficiency – and hence, as a side-effect, for minimising CO₂ emissions – or alternatively for reducing NO_x emissions, but not for both, meaning that a trade-off exists in the management of those emissions (IPCC 1999). Technological improvements in aviation fuels have resulted in the development of low sulphur fuels, leading to reduced emissions of sulphur oxides (SO_x), and recent research has investigated the potential for biofuels or hydrogen to supplement or replace kerosene. Overall, however, technological responses – both those relating to aircraft design and performance and to aviation fuels – require substantial investment and are likely to yield benefits only in the long term.

Operational responses are based on the principle of maximising fuel efficiency by a variety of means: reducing aircraft weight, increasing load factors, ensuring high levels of aircraft maintenance, minimising route distances, optimising cruising speeds and levels, and manoeuvring aircraft more efficiently (IPCC 1999). Loading aircraft efficiently involves a combination of (a) minimising the weight of the aircraft before its payload is stowed (for instance, by minimising the unusable fuel carried) and (b) maximising the payload. More frequent aircraft maintenance (especially engine maintenance) may help to ensure that fuel efficiency is maximised throughout the service lives of the airframe and engines. Environmental impacts may also be reduced through the use of revised ATM procedures: reduced cruising speeds; flight level optimisation for emissions reduction; arrival management (AMAN) and departure management (DMAN) systems; continuous descent approaches (CDAs) and ‘low-power, low-drag’ (LP/LD) approaches, which may reduce aircraft emissions and noise during descent; noise abatement departure procedures (NADPs) and noise preferential routes (NPRs), which are intended to reduce noise levels in the vicinity of airports; and expedited climb departure procedures, which could allow aircraft to climb rapidly to their optimal cruising levels (Dobbie and Eran-Tasker 2001; ICAO 2004). Environmental impacts may also be reduced by the use of hub-bypass route planning and by the use of fixed electrical ground power (FEGP) in preference to auxiliary power units (APUs) (Morrell and Lu 2006). However, despite the various ways in which operational procedures may be revised, their potential to reduce the environmental impacts of aircraft is relatively modest and ‘these kinds of operational measures will not offset the impact of the forecast growth in air travel’ (DTI 1996, 10).

Therefore, due to the high abatement costs of the aviation sector, and because of the limited potential for radical technological or operational solutions to be found in the short to medium term, success in meeting the challenge of reconciling aviation growth with environmental protection depends on the formulation and implementation of effective policy. Numerous instruments are available to policymakers, including regulatory, market-based and voluntary instruments; many of those have received scrutiny from a wide range of stakeholders. Thus proposals to cap aviation emissions, to impose taxes and emissions charges, to introduce or remove subsidies, to issue tradable permits for aviation emissions and to encourage the use of voluntary agreements, have been widely debated and contested (Bishop and Grayling 2003; IPCC 1999; Pastowski 2003). Such proposals have individual strengths but they are also problematic for reasons that are explained in more detail in subsequent chapters of this book. In general, however, regulatory approaches face the problem that air ...