Aviation Environmental Issues: Emissions, Noise & NextGen

Introduction

Many environmental problems are directly linked to the way certain industries operate. The air transport industry faces a number of specific environmental challenges in the 21st century. This paper examines those challenges — including greenhouse gas emissions, reliance on fossil fuels, local air quality, and noise pollution — and evaluates the technological and policy solutions that have been proposed to address them.

Greenhouse Gas Emissions and Climate Change

The problem of global warming has created environmental concern on a scale previously unseen. Industries around the world have been under pressure to alter their operations in order to address this challenge. In the air transport and aviation sector, one of the most prominent issues is the emission of greenhouse gases, which are widely believed to be a primary driver of global warming.

According to Zhang et al. (2010), "Climate change has become an issue that has aroused much public concern around the world in recent years. In 2006, the world transport sector emitted 6.5 gigatons of carbon dioxide (CO2), approximately 23% of total CO2 emissions. According to the Organization for Economic Cooperation and Development (2008), air transport could, based on a 'business as usual' scenario, grow from 14.8% in 2010 to 23.0% of transportation CO2 emissions in 2050. This is partially due to more readily available environmentally friendly energy in the future for ground-based transportation compared to air transport, as well as a faster growth rate of air transport compared to other modes" (Zhang et al., 2010).

As with other forms of transportation, the operation of aircraft generates significant greenhouse gases. The most prominent among these are carbon dioxide (CO2), oxides of nitrogen, and water vapor (H2O) (Zhang et al., 2010). Carbon dioxide is the most prevalent and widely discussed greenhouse gas in the context of aviation. The overall environmental impact of the air transport industry is measured using radiative forcing, defined as "an externally imposed perturbation in the radiative energy budget of the Earth's climate system," and is estimated to be around two to four times the effect of CO2 emissions alone (Zhang et al., 2010).

Zhang et al. (2010) further note that while the air transport industry accounts for approximately 1% of world GDP, it is responsible for 2–4% of global greenhouse gas emissions and an estimated 2% of current climate change. That share is projected to rise to 3% by 2050. Air travel has also increased by roughly 5% per year over the past two decades, and this growth is expected to continue. Although the average aircraft's fuel efficiency has improved over the same period, the sheer growth in passenger numbers means total greenhouse gas output continues to rise. In 2007, the Intergovernmental Panel on Climate Change reported that "technology developments might offer a 40–50% improvement in fuel efficiency by 2050 compared to 1997, but would still generate about a 2–3% increase in greenhouse gas emissions per year due to growth, assuming a business-as-usual scenario" (Zhang et al., 2010).

Public concern over aviation's role in climate change has placed considerable pressure on the industry to adopt new approaches to emissions control. In response, governmental agencies around the world have taken both unilateral and multilateral action. The Kyoto Protocol, ratified by 180 countries, is designed to reduce overall greenhouse gas emissions. It covers domestic aviation emissions but does not set binding standards for international flights. It does, however, encourage countries to pursue emissions-reduction policies for international aviation through the International Civil Aviation Organization (ICAO) (Zhang et al., 2010). The ICAO's mandate is to develop technologies and operational measures for managing greenhouse gas emissions, though its authority over market-based measures is significantly limited — in 2004, for example, it was decided that the organization would not pursue new global legal or market-based instruments.

International efforts to reduce aviation emissions have progressed slowly, but the European Union has been a notable exception. The EU has developed greenhouse gas emissions regulations covering all airline flights within the EU as well as flights to and from it (Zhang et al., 2010). These regulations are codified in the European Emissions Trading System (ETS), which was set to be implemented beginning in 2012. Under this system, permitted emissions by air transport are capped, and all airlines must hold permits corresponding to the CO2 pollution generated by their fleets. These permits are initially distributed free of charge and then traded among carriers. The initial cap is set at 97% of average 2004–2006 emission levels (Zhang et al., 2010).

Fossil Fuel Reliance and Local Air Quality

This approach is known as "cap and trade," and the United States has considered adopting a similar policy. In the United Kingdom, an "Air Passenger Duty" is levied on all airline tickets sold domestically. This government tax is intended to reduce CO2 emissions and raise funds to address global warming. Additionally, the UN Copenhagen Summit of December 2009 addressed the potential inclusion of international aviation within a new international framework for combating climate change. As Zhang et al. (2010) explain, regardless of whether emissions policies follow the EU's cap-and-trade model or the UK's carbon tax approach, both can be understood as policies that effectively raise the fuel price paid by airlines. The expectation is that higher operating costs would lead to increased airfares, thereby reducing demand and ultimately lowering emissions.

A related major issue is the aviation industry's dependence on fossil fuels to produce jet fuel. The environmental costs of fossil fuel extraction are significant and wide-ranging. The aviation sector's high demand for oil contributes to the broader pressures driving offshore and other forms of extraction, with potentially severe ecological consequences. Although the link between aviation and any single environmental incident may seem indirect, the systemic reliance on fossil fuels has contributed to global problems including resource conflicts and economic instability. Reducing this dependence is an urgent priority for the 21st century.

In relation to greenhouse gas emissions and global warming, aircraft emissions also degrade local air quality. According to the Centre for Air Transport and the Environment (CATE), aircraft operations can lead to poor air quality in communities located near commercial and private airports. CATE asserts that "the impact of aircraft emissions on local air quality is becoming a capacity constraint for many airports because of new legislative and regulatory requirements." A report published by the Partnership for Air Transportation Noise and Emissions Reduction (PARTNER) further explains that "aircraft landing and take-off (LTO) emissions include those produced during idle, taxi to and from terminal gates, take-off and climb-out, and approach to the airport. Aircraft LTO emissions contribute to ambient pollutant concentrations and are quantified in local and regional emissions inventories" (Ratliff et al., 2009). Local air quality has direct public health implications — for example, elevated pollution levels can exacerbate respiratory conditions such as asthma. Reducing such emissions must therefore be a high priority for the aviation industry.

Conclusion

The research indicates that there are several environmental issues that are currently prevalent in the air transport industry. These issues include greenhouse emissions, noise pollution, local air pollution, and dependence on fossil fuels. The literature demonstrates that all of these challenges have been thoroughly investigated and that a range of solutions has been proposed. The primary environmental concern in aviation remains the reduction of greenhouse gas emissions — and while meaningful efforts have been made, the continued growth in air travel demand makes this problem difficult to fully resolve. The evidence suggests that all of these issues must be addressed through 21st-century technology and coordinated policy action. Implementing comprehensive solutions will be challenging, and environmental concerns related to aviation will remain significant well into the future.