Today, global aviation accounts for 2.4 percent of total carbon dioxide emissions and about 12 percent of greenhouse gases released by the transportation industry . While those percentages may seem low, they are expected to rapidly increase as demand for air travel skyrockets, especially in developing countries. This increased demand will lead to a drastically increased need for new aircraft.
The U.N. estimates that by 2028, the size of the global fleet will expand by 43 percent to more than 39,000 aircraft, and by 2050, aviation emissions will increase by more than 300 percent . However, a new study has found that global aviation emissions may be increasing more than 1.5 times as fast as this estimate . According to the study, airlines are becoming more fuel efficient, but increases in demand are rapidly outpacing increases in fuel efficiency .
There are many ways to combat this increase in expected emissions. A combination of sustainable fuels and optimized flight paths can help reduce emissions immediately while efforts are made to develop new engineering approaches that will have a larger impact . Electric planes are the most enticing long-term option as they can be truly carbon-free, but are likely decades away due to technological limitations . Similarly, hybrid aircraft reduce emissions by leveraging propulsion systems that are part combustion and part electric. In the short term, these could be used in the interim on the path to fully electric aircraft.
Global aviation emissions will continue to be a growing problem unless airline companies take massive efforts to increase fuel efficiency or remove fuel from the equation all-together. Airline companies need to take a step back and ignore growing demand and profit to understand the impact they are having on the environment. In this time where climate change is rapidly spiraling out of control, airliners need to take every possible stop to move towards truly sustainable aviation. Efforts need to be made now to increase sustainability today, in the near future, and in the long-term future.
 https://www.forbes.com/sites/oliverwyman/2019/09/03/why-tomorrows-aircraft-will-be-hybrids/#350ad5 ccc0fb
 https://www.theguardian.com/business/2019/sep/19/aviations-flight-towards-low-emissions-only-fuels-th e-crisis