Environment - Flying in the face of climate change

Billed as humanity’s last chance to save the planet, the achievements of the COP 15 or the Copenhagen Conference of the UN Framework Convention on Climate Change (UNFCC) held in December are questionable. The accord, struck on the last day of the summit, neither mentioned specific emission reductions nor was it legally binding. The only ray of hope now being that a legally binding treaty may emerge, possibly by the end of 2010. Meanwhile, the vast majority of experts are convinced that anthropogenic or human-induced climate change is a grim reality. Many believe that global warming is accelerating; that abrupt and irreversible climatic changes are likely and it may be too late to avoid runaway climate change. A few, in despair, have given up trying to convince world leaders to act, preferring instead to study ways to mitigate the cataclysmic consequences.

But in the sphere of climate change very little is what it seems. For instance, according to recent analysis by the Global Carbon Project, global emissions surged 29 per cent between 2000 and 2008, and practically all of that growth came in emerging economies led by China. Reason enough to demand that these countries reduce their emissions drastically? Not really. Fully a quarter of the increase came from production of goods for consumption in industrialised nations. In effect, the developed world has ‘exported’ to developing countries the emissions needed to fund its insatiable consumption.

Soaring Emissions

Climate change is perfectly normal—the average temperature of the planet has fluctuated markedly through the ages. What is unique this time around is that human activity is adding to and ntensifying natural processes. Since the dawn of the industrial era, the world has been heavily dependent on fossil fuels like coal, oil and natural gas, which, when combusted release Carbon Dioxide (CO2), a significant heat-trapping Greenhouse Gas (GHG). CO2 persists for a century or more, so its presence in the atmosphere has already increased by 35 per cent over pre-industrial levels. Levels of CO2 today are higher than revealed in 650,000 years of ice-core records. Consequently, in the last 100 years, the global mean temperature has risen by about 0.75°C. This may not seem nearly enough to lose sleep over but scientists believe that a rise of just 2°C is all it might take to reach the ‘tipping point’ that leads to irreversible climate change.

As concern mounts, aviation is increasingly coming under the scanner. International aviation and shipping were excluded from the targets agreed under the 1997 Kyoto Protocol, the only binding international climate change agreement. The reason is that commercial aviation and shipping operate across international borders, making it difficult to pinpoint responsibility for emissions. Although Sulphur Dioxide emissions from shipping are an international health hazard, these actually help mitigate global warming which lets shipping off the hook for the time being leaving the aviation industry to handle the blame.

Aviation indisputably impacts climate change, but by how much? In 1999, the UN Intergovernmental Panel on Climate Change (IPCC) held aviation responsible for two per cent of global CO2 emissions and 3.5 per cent of Radiative Forcing (RF). RF is a measure of the effect of human activity on global warming. ‘Two per cent’ is the figure commonly quoted by the aviation industry to claim that the impact of aviation on climate change is too insignificant to bother about. However, the figure was based on 1992 air traffic statistics, so it is akin to planning civic services for Delhi in 2009 based on population recorded in the 1991 census.

Aviation also has short term effects from water vapour, particles and Nitrogen Oxides (NOx) as well as contrails and resultant cirrus cloud formation. Significant doubts remain about such non-carbon emissions, but aviation’s total climate impact including NOx emissions, contrails and cirrus clouds, is estimated to be two to five times greater than that of CO2 alone.

The general perception, that since the bulk of aircraft emissions (80-90 per cent) occur at higher altitudes, aviation has a greater impact on climate change, is not strictly true. It makes little difference whether CO2 is added to the atmosphere at the surface or in the stratosphere. However NOx, a GHG, when emitted in the upper troposphere or lower stratosphere (9-12 km) results in the formation of ozone, another GHG. Ozone, in turn, has a stronger RF effect at higher altitudes than on the ground. Aviation has a helpful side as well because, above an altitude of 20 km, aircraft NOx emissions destroy a small fraction of ambient methane, which itself is a powerful GHG and one of the important molecules leading to ozone formation.

The general perception, that since the bulk of aircraft emissions (80-90 per cent) occur at higher altitudes, aviation has a greater impact on climate change, is not strictly true. It makes little difference whether CO2 is added to the atmosphere at the surface or in the stratosphere. However NOx, a GHG, when emitted in the upper troposphere or lower stratosphere (9-12 km) results in the formation of ozone, another GHG. Ozone, in turn, has a stronger RF effect at higher altitudes than on the ground. Aviation has a helpful side as well because, above an altitude of 20 km, aircraft NOx emissions destroy a small fraction of ambient methane, which itself is a powerful GHG and one of the important molecules leading to ozone formation.

Taking the world economy as a whole, the share of various sources of emission is also changing. While emissions on account of transport and industry have skyrocketed over the past two decades, those from land use change have remained practically the same. Consequently, the proportion of global emissions attributable to deforestation has fallen—just 12 per cent now compared with around 20 per cent in 1990.

Why is commercial aviation to a green activist like a red rag to a bull? Because aviation is one of the fastest growing sources of global CO2 emissions. Over the last decade or so, air traffic growth has outstripped the ability of manufacturers to reduce emissions. While global CO2 emissions in 2008 were nearly 40 per cent higher than in 1990—the base year of the Kyoto Protocol—emissions from international aviation grew 83 per cent over the same period. In a carbon-constrained world (that is, with all sectors of the global economy striving to achieve deep cuts in their carbon emissions) aviation’s share as a proportion of total emissions is bound to rise. In September, the UK government’s Committee on Climate Change warned that if aviation growth was left unchecked, global aviation emissions could reach 15 to 20 per cent of all CO2 generated in 2050.