Air travel cannot continue expanding at the current rate, but it must – that is the dividing line between environmentalists and the industry, with the latter arguing the economic benefits outweigh aviation’s contribution to global warming.
Addressing a recent conference in London on Aviation in the Shadow of Climate Change, Professor David Lee, chair of atmospheric science at Manchester Metropolitan University’s centre for air transport and the environment, outlined the latest scientific view.
“Despite the mantra that the science is uncertain, it is not,” he said. “There is wide evidence of [man-made] climate change.”
Some environmental changes have accelerated even between a report of the Intergovernmental Panel on Climate Change in 2001 and that issued this year.
However, assessing aviation’s contribution is difficult because of the range of emissions from aircraft in addition to carbon dioxide and a feature at cruise altitudes, known as radiative forcing, that appears to magnify the warming effect. Lee warned: “We don’t know the full future impact.”
Sky-high expectations
Lee described an industry forecast of a 50% reduction in CO2 emissions per passenger by 2030 as “over-optimistic”, since: “It assumes all aircraft will have access to the latest technology.” Typically, aircraft remain in use for 20 years or more.
Lee concluded: “The effects of CO2 and nitrous oxide (NOX) emissions could be addressed. But current projections show even the most optimistic forecasts cannot offset the growth in emissions.”
Cranfield University professor of aerospace engineering Ian Poll criticised the tendency to multiply the impact of CO2 emissions to take account of radiative forcing. However, he said progress in one area can be detrimental elsewhere – for example, the more fuel-efficient an engine and the lower its CO2 emissions, the more NOX it produces.
“One benefit must usually be traded against another,” said Poll. “The Airbus A380 pays a penalty in CO2 emissions at cruising altitude to be sufficiently quiet at Heathrow.”
Poll also conceded that the use of biofuels – produced from plants as an alternative to oil – poses serious difficulties, despite hopes surrounding Virgin Atlantic’s involvement in a trial next year. “There are more problems than benefits at the moment. It will be a long time before we can be sure they are safe to use,” said Poll.
Mixed-mode move
He argued the industry forecast of a 50% reduction in CO2 emissions by 2030 is achievable by developing engine and air-frame technologies and operational improvements, while the greatest fuel efficiencies will still come from “packing the plane”.
But Poll said: “All conventional technology improvements will not fully offset the estimated growth [in air travel]. Beyond 2030 we will have to use technology now considered too high risk.” He added: “We are so close to the laws of physics – the [modern] engine is almost a miracle.”
Other industry speakers stressed the economic benefits of air travel – the 200,000 employed in the UK, the £11.4 billion a year contributed to gross domestic product, the 2.3 million tonnes of cargo.
British Airways general manager for airport policy Paul Ellis suggested a proposed move to mixed-mode runway operation at Heathrow – allowing take-offs and landings on a single runway – would cut CO2 emissions by 500,000 tonnes a year by reducing wasted fuel.
However, Ellis somewhat undermined this argument by suggesting the time savings would allow an increase in flights from Heathrow – meaning the projected emissions savings would be lost.
Heathrow is permitted a maximum of 480,000 flights a year and will operate at 98.5% of that capacity this year. Mixed-mode operation would increase the limit to 500,000 and possibly 540,000 flights by 2015.
‘Deep concern’
Civil Aviation Authority chairman Sir Roy McNulty pointed out UK air travel has increased fivefold in the past 30 years and is projected to double again by 2030. He said: “Aviation should meet the full environmental costs and only grow where overall benefits outweigh the costs.”
McNulty argued: “Today’s aircraft are at least 50% cleaner on NOX than those certified in 1980.” But he said tighter regulation, not market forces, had produced most of this reduction.
Lord Clive Soley, chairman of pro-expansion lobby group Future Heathrow, acknowledged: “There is deep concern that the industry has been very slow to respond to the threat of climate change. We can’t wait for technological advances. We have to drive down carbon emissions, while not talking about closing down industries.”
- Aviation Policy in the Shadow of Climate Change was organised by the Waterfront Conference Company