New Delhi: With the aviation sector experiencing a phenomenal growth rate especially in Asia-Pacific region and more importantly in India and China, environmentalists point out that the industry is becoming the fastest growing contributor to global warming. Airline manufactures however refute the charge.

"Last year people took more than two billion journeys on scheduled airlines worldwide, up four percent over 2005, according to the International Civil Aviation Organisation. IATA, the International Air Transport Association, predicts another 500 million passengers will take to the skies by 2010. With jet aircraft emitting 23 kilograms of CO2 per 100 passenger kilometres, that's a lot of carbon dioxide being dumped into the atmosphere," says Eurorail group in a release.

Environmentalists argue that since the airplanes travel at very high altitudes, the impact on global warming is more. "The logic being that since the emission of CO2 in huge amounts and at such high altitude will have a direct impact on the green house effect leading to increase in global warming," says K Srinivas, Climate Campaigner, Greenpeace, an international NGO working against global warming.

Others NGOs also point out that boom in the aviation market is a major concern since global warming is on the increase. "The average plane releases close to one tonne of carbon dioxide for each passenger it carries from London to New York. Scientists say that high-altitude emissions are more damaging to the environment. Nitrogen dioxide from airline engines leads to formation of ozone and they are worried about the impact of cirrus clouds formed because of airline travel, which they believe in turn contribute to global warming," says Sunita Narain, Director, Centre for Science and Environment.