The Plane Truth About Climate Change

Apart from a few diehard sceptics, most people now accept that anthropogenic or human induced climate change is a grim reality. The Earth seems on track to warm three to four degrees centigrade by the end of the century, well above the theoretical “tipping point” of two degrees where abrupt and irreversible climatic changes are likely. In the medium and long term, the predictions include extreme weather events such as severe storms and deadly heat waves, inundation of low-lying coastal areas as the polar icecaps melt and extinction of many species.

When the world entered the commercial jet age in May 1952, it knew little or nothing of the existence of such potential dangers. The accent of aircraft manufacturers and airlines alike was on speed and comfort as they rushed to replace the lumbering yet economical piston engine planes with fuel-guzzling jets. Any effort to improve fuel efficiency was only to cut operating costs and make the sleek jets fly ever faster and farther. But the contribution of aviation to climate change is now under the scanner as never before.

ESCALATING EMISSIONS

Aviation is essentially a fossil fuel industry and it impacts the environment because aircraft engines release heat, noise, particulates, as well as carbon dioxide (CO₂) and other Greenhouse gases (GHG) that contribute to climate change. Aircraft emit mainly CO₂ and burning jet fuel currently generates around 2.5 per cent of total carbon emissions globally. But other waste products such as nitric oxide and nitrogen dioxide (together called NOx) are particularly effective in forming ozone that has a significant warming effect at high altitudes where commercial jets operate most of the time. Water vapour from the exhaust is also a GHG. At high altitude, under certain atmospheric conditions, it forms condensation trails (contrails) and cirrus-like clouds, which may have a significant radiative forcing (RF) effect. RF is a measure of the effect of human activity on global warming. Therefore an “emissions weighting factor” (EWF) must be taken into account. It is the factor by which aviation emissions should be multiplied to get the CO₂-equivalent emissions for average conditions and lies in the range of 1.3 to 2.9, generally taken as 1.9.

Why does flying make the greens see red? Mainly because whilst most other sectors are reducing their emissions through greener alternatives such as electricity, solar or wind energy, aviation as a whole is one of the fastest growing sources of GHG emissions. For instance, carbon emissions from all activities in the United Kingdom other than aviation declined by nine per cent between 1990 and 2000, but those related to aviation doubled during the same period. No way has yet been found to power large aircraft except by burning copious amounts of aviation turbine fuel (ATF). A small number of battery-powered planes are flying, but they have very limited payload, range and endurance compared with those powered by jet engines. Besides, for electric powered aircraft, the weight of their batteries is a huge problem.

dom other than aviation declined by nine per cent between 1990 and 2000, but those related to aviation doubled during the same period. No way has yet been found to power large aircraft except by burning copious amounts of aviation turbine fuel (ATF). A small number of battery-powered planes are flying, but they have very limited payload, range and endurance compared with those powered by jet engines. Besides, for electric powered aircraft, the weight of their batteries is a huge problem.

MITIGATION METHODS

Various measures can be taken to reduce ATF consumption and emissions including infrastructure enhancements and improved operating procedures such as flying more direct routes, using a fuel-optimised flight profile and increasing the load factor of aircraft. Improving the Air Traffic Management system alone could help carriers in some regions reduce emissions by about 18 to 20 per cent.

Aircraft manufacturers have a vital role to play in reducing both CO₂ and NOx emissions. New generation jets such as the Boeing 787 Dreamliner, Airbus A350 and Bombardier CSeries are about 20 per cent more fuel efficient than the aircraft they are replacing. Even the Airbus A320neo and the Boeing 737 MAX are about 15 per cent more fuel efficient than the previous models. The trouble is that fuel-efficient jets will take several years, perhaps decades, to enter widespread service. However, turboprop aircraft with their frugal consumption, are making a comeback. They cruise at lower speeds and altitudes than jets, where they are less likely to produce contrails and compared with jet powered aircraft, they burn only about two thirds of the fuel per passenger. With the ubiquitous tube-andwing configuration now reaching its limits of improvement, manufacturers are also investigating advanced aerodynamics and exotic shapes that could drastically reduce fuel burn and emissions.

THE AVIATION INDUSTRY WOULD PREFER TO REDUCE EMISSIONS BY IMPROVING AIRCRAFT EFFICIENCY, INTRODUCING LOW-CARBON SUSTAINABLE FUELS AND PURCHASING CARBON CREDITS

Biofuels are often cited as one of the most promising avenues to mitigate aviation emissions. However, in the foreseeable future, these cannot possibly meet the industry’s needs. In the UK, just 2.5 per cent of flights at domestic airports are expected to use biofuels by 2050. Besides, a mad rush to cash in on the biofuels boom has led to rampant deforestation in the developing countries in favour of biofuel crops. As a result, the net environmental effect may be of increased emissions. Efforts are now being made to switch from crop-based biofuels to those derived from wastes that cannot be reused or recycled.

CARBON CREDITS AND CORSIA

A popular method to limit aviation’s climate change effects is through economic measures such as carbon offsetting. Offsetting involves purchasing carbon credits in a recognised global market such as the Clean Development Mechanism (CDM) of the United Nations Framework Convention on Climate Change (UNFCCC). For instance, if a certain flight emits one tonne of CO₂, the airline can purchase a credit that helps fund a scheme for greener electricity production in a developing country and prevents one tonne of CO₂ from being generated there.

At the International Civil Aviation Organisation (ICAO) Assembly held in October 2016, several world governments agreed to adopt the Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA). CORSIA aims to stabilise overall CO₂ emissions at 2020 levels by requiring airlines to offset the growth of their emissions after 2020. However, it is purely voluntary from 2021-2027 and will be mandatory only after 2027.

Environmentalists refer to such schemes as “Greenwash”. They have two basic objections. First, a European Commission study found that 85 per cent of the offset projects under the UN’s CDM have failed to actually reduce emissions. Second, CORSIA does nothing to dampen demand for air transport or genuinely reduce aviation emissions, but simply pays other sectors to reduce theirs.

PRUNE EMISSIONS OR PERISH

Air travel worldwide has doubled in the last 15 years and is growing at four to five per cent per annum. It is expected to double again in the next 15 years. AirAsia’s slogan is apt: “Now everyone can fly.” Although aircraft are indeed becoming more fuel efficient and operations are constantly refined to consume less fuel, this cannot offset the impact of the huge growth of aviation. ICAO’s “aspirational goal” of two per cent annual fuel efficiency gains until 2050, will not make much of a difference.

It is in everybody’s interest, including that of the global aviation industry to reduce emissions and avert at least the more serious consequences of climate change. The airlines will be directly impacted because global warming may increase atmospheric turbulence, storminess and snowfall which could mean more diversions and flight cancellations. Increasing surface temperatures would also affect the takeoff performance of aircraft and hence there would be the need to build longer runways.

The need of the hour is to find ways to balance social, economic and environmental considerations. Environmentalists claim that current rates of aviation growth are unsustainable if climate change is to be effectively tackled. They object to flying being kept artificially cheap and incentivising travellers to fly more through frequent-flier programmes. They say that a more simple and straightforward way to reduce emissions would be to impose a carbon tax on aviation. Although this would be unpopular, it would moderate demand and reduce the quantum of air travel. The money obtained from the tax could then be used to mitigate some of the cataclysmic consequences of climate change.

The aviation industry however opposes such measures and any curbs on its growth. It would prefer to reduce emissions by improving aircraft efficiency, introducing low-carbon sustainable fuels, and purchasing carbon credits.

Which approach is better? You decide, dear reader!