Under pressure from frequent flyers alarmed over climate change, the airline industry says it is "hellbent" on reducing emissions - but the technology needed to drastically reduce its carbon footprint is still out of reach.

In recent months, climate activists have stepped up efforts to convince travelers to boycott air travel. "The sector is under considerable pressure," admitted Alexandre de Juniac, chief executive of the International Air Transport Association (IATA), whose members met last week in Seoul, South Korea.

The industry has been under fire over its carbon emissions which, at 285 grams of CO2 emitted per kilometer traveled by a passenger, far exceed all other modes of transport. Road transportation follows at 158 grams and rail travel is at 14, according to European Environment Agency figures.

De Juniac said the industry was "hellbent" on lowering emissions but the sector is also accused of underestimating its environmental impact, with the IATA chief lobbying heavily against a "green tax" on aviation backed by several countries including the Netherlands. 

"Often these taxes are absorbed in the budgets of states and are spent on whatever they want, except the environment," he said.

The International Civil Aviation Organization estimates that air transport is responsible for 2 percent of global CO2 emissions.

But aircraft also emit particles such as nitrogen oxides, which can trap heat at high altitude, meaning the industry is actually responsible for five percent of global warming, according to the Climate Action Network, an umbrella group of environmental NGOs.

The industry has committed to improving fuel efficiency by 1.5 percent per year from 2009 to 2020 and stabilizing its CO2 emissions in preparation for a 50 percent reduction by 2050 compared to 2005.

Companies are banking on a new generation of less polluting planes with updated engines, aerodynamic modifications and fittings that weigh less - among them tablets to replace heavy pilot manuals.

However Shukor Yusof, ­analyst with Malaysia-based Endau Analytics, told AFP the industry had made progress but "that all these technological advances to cut emissions are tough to implement quickly due to the nature of the industry hemmed by high costs and the fact that planes typically take decades before they are replaced."