by Imran H. Khan
As Muslims across the world prepare for, typically, once in a lifetime travel to Mecca to fulfill their religious obligation, it is time to ponder upon its impact on our planet Earth. With the rapid growth in Muslim populations, the advent of aviation and relative prosperity, an increasing number of Muslims are performing Haj. Last year three million people performed it and the number of Hajis ( as they are called) are only going to increase with time as the facilities at Mecca are improved and the availability of aircraft like Airbus A380 and Boeing747.
A little bit of calculation results in 2.3 tonne of carbon dioxide emitted into the atmosphere per each Haji for performing Haj. This is based on 43.13 Passenger miles flown per gallon of jet fuel and on an estimate that on the average the Haji travels 4000 miles. Typically 23.88 pounds of carbon dioxide are produced per gallon of jet fuel use. In reality many Hajis travel a lot more than 4000 miles and the impact of air travel is not only carbon dioxide.
Aviation is different from other energy-using activities as the majority of emissions occur at altitude, and their influence on the atmosphere can be highly localised and short-lived. Emissions from aircraft are responsible for other atmospheric chemical processes that also have atmospheric warming consequences. Aviation emissions are therefore more significant contributors to climate change, than an equivalent amount of carbon dioxide emitted at ground level. Combustion of fuel in aeroplane engines results in emissions of carbon dioxide (CO2) and nitrogen oxides, (termed NOx), as well as water vapour and particulates. It is the emission of NOx, water vapor and particulates at altitude that account for the extra impacts of aviation emissions.
Carbon dioxide is a greenhouse gas and alters the balance of incoming and outgoing radiation from the earth’s surface and contributes to warming of the atmosphere. Aviation emissions of carbon dioxide have the same effect on climate as terrestrial emissions, from power stations, industry or transportsources. Carbon dioxide has an atmospheric lifetime of up to 200 years, so ends up well mixed in the lower atmosphere over this timeframe no matter where it is emitted.
Emissions of nitrogen oxides initiate a series of chemical reactions in the atmosphere. Nitrogen oxides form ozone (O3) in the presence of light, and light intensity is higher at altitude, so more ozone is formed at altitude than from terrestrial sources of NOx. Emissions of nitrogen oxides from sub-sonic aircraft accelerate local generation of ozone in the lower atmosphere where aircraft typically fly. The increase in ozone concentration will generally be proportional to the amount of nitrogen oxides emitted from aircraft. Ozone is a potent greenhouse gas whose concentration is highly variable and controlled by atmospheric chemistry and dynamics. The increase in radiative forcing from ozone is greater than carbon dioxide emissions. However, the ozone is responsible for the destruction of atmospheric methane (CH4). Methane is also a potent greenhouse gas, with an atmospheric lifetime of 14 years. The destruction of methane as a direct result of aviation therefore reduces the extent of warming caused by aviation emissions.
Water vapour is also an important greenhouse gas, but emissions of water vapour from aviation only have a minor direct warming effect. Water vapour has a short lifetime in the atmosphere and is controlled by the hydrological cycle. Emission of water vapour at high altitudes will produce contrails – the cloud-like trails behind aircraft that are visible from the ground. These contrails also trap heat in the atmosphere and their warming effect is believed to be equivalent to that of carbon dioxide alone . Contrails do not form at lower altitudes, so could be avoided by flying lower. In practice this is not done as the fuel burn, and therefore running cost, is greater when flying at lower altitudes where the atmosphere is denser. The contrails themselves are implicated in the formation of high altitude cirrus clouds, which are believed to have a strong warming effect on the atmosphere, although quantification remains poorly understood.
Recent MIT study on global warming estimates it to be much worse than previously estimated. The most comprehensive modeling yet carried out on the likelihood of how much hotter the Earth’s climate will get in this century shows that without rapid and massive action, the problem will be about twice as severe as previously estimated six years ago – and could be even worse than that.
The study uses the MIT Integrated Global Systems Model, a detailed computer simulation of global economic activity and climate processes that has been developed and refined by the Joint Program on the Science and Policy of Global Change since the early 1990s. The new research involved 400 runs of the model with each run using slight variations in input parameters, selected so that each run has about an equal probability of being correct based on present observations and knowledge. Other research groups have estimated the probabilities of various outcomes, based on variations in the physical response of the climate system itself. But the MIT model is the only one that interactively includes detailed treatment of possible changes in human activities as well – such as the degree of economic growth, with its associated energy use, in different countries.
In my previous post I had highlighted the emphasis on using rational thinking in Quran. I think it is time for Muslims as responsible denizens of this planet to reflect and reconsider their options on performing Haj in the coming years. There are provisions in Islam whereby rituals like prayer and fasting can be deferred or not done based on extenuating circumstances. I believe the health of the planet is one of such extenuating circumstance. Organization of Islamic Countries should formulate a responsible policy that balances the desires of Muslims with the impact on the ecology. Such a step might also lead to other responsible interpretations of Quran in response to the changes in technology and increases in population.Views: 1850Share