Air traffic is expected to double every fifteen years.

Economic and technological advancements will make air travel even more common as we move into the near future. Aircraft contribute to 2% of all carbon dioxide emitted into the atmosphere and 10% of all transport related emissions. This huge emission of greenhouse gases into the air has already contributed greatly to global warming.

The amount of irreplaceable fossil fuels consumed per passenger/flight needs to be reduced drastically to reduce the amount of greenhouses gases emitted into the atmosphere.

This can be actualised through various methods:

Modern aircraft design - Future aircraft design will have a clear emphasis on reduction of fuel-burn reduction and noise reduction.

Highly matured flow, load and noise-control technologies can be used not only to improve security but increase the aerodynamic efficiency of fuel consumption.
The design of fins and wings can be optimised to reduce friction drag and achieve a performance increase in cruise conditions.
Technologies that mitigate airframe noise during landing, which is generated on the flaps and undercarriage and through the mutual interaction of both, should be employed in design.
Vibrations in the undercarriage area that are caused by highly unsteady or in-homogeneous inflow can be considered to reduce noise pollution.
The ever evolving technologies rule leads to inevitability of more fuel efficient engines. More efficient engines will reduce the amount of greenhouse gases released to the environment.

Use of BioFuel - Biofuels are made of renewable resources and can be used to lower the level of emissions.

Biofuels can be engineered to remove aromatics or sulfur which can result in a substantial reduction in carbon monoxide and other hydrocarbon emissions. If surveys are to be believed, BioFuels can achieve an 80% reduction in emissions.
Interestingly, BioFuels can be grown/engineered with a higher calorific value than petroleum fuel - producing more 'bang' for the 'buck'!

Introduction of 'Electric' Aircraft – Electrical energy is both a clean and renewable source of energy. We have all recently witnessed the first round the world trip by the Solar Impulse (https://www.solarimpulse.com/adventure).

Rechargeable batteries can be used to replace fuel as a source of aircraft power. If the recharging of these batteries is combined with renewable sources such as solar or wind, the vast majority of emissions associated with powered flight can removed.
Maybe this technology can be borrowed from the dynamic development of electric cars. No doubt there are current limitation imposed by weight, longevity and durability however the technology is there to be developed.
Potentially, battery endurance can be improved in-transit and supplemented by including solar energy engineering in the airplane. Solar panels can be fitted on the plane and help recharge the batteries in the air (or on the ground in suitable climates).

As the population continues to grow, if the technology can support it, the future of transportation will may be through the air. ALready we see that the advancement in social, economic and political environments is heralding the highest level of air transport in history. Unless checked, this increase will continue to contribute to the increase in global warming.

The Greening of Air Transport will help to check the rise in harmful emissions into our atmosphere.