The aviation industry has been confronted with the rise of flygskam, or flight shaming movement, where some travelers are shunning air travel and becoming more aware of their environmental impact.

This has prompted airlines to take action, announcing programs to offset emissions of flights and also focusing on improving fuel efficiency.

During the International Air Transport Association's global media day conference in Geneva earlier this month, Alexandre de Juniac, the association's director general and CEO, stressed that "flying is not the enemy, it's carbon" and also highlighted the "serious climate action commitments" from the industry long before the flight shaming movement began.

According to the IATA, the global body representing some 290 airlines, carbon emissions per passenger have declined by more than 50 percent since 1990.

The association attributed the improvements to the industry achieving an annual fuel efficiency rate of 2.3 percent over the period since 2009, some 0.8 percentage points ahead of target.

"Cutting per passenger emissions in half is an amazing achievement of the technical expertise and innovation in the aviation industry," said de Juniac, adding that they have bigger ambitions such as capping net emissions from 2020. By 2050, IATA plans to cut emissions to half of 2005 levels.

Sustainable Fuels

"Accomplishing these targets means continued investment in new technology, sustainable fuels, and operational improvements," de Juniac said.

According to the Intergovernmental Panel on Climate Change, a UN body for assessing the science related to climate change, carbon emissions grew 2 percent and reached a record high of 37 billion metric tons of carbon dioxide in 2018.

Tim Johnson, director of Aviation Environment Federation, a London-based NGO campaigning on the environmental impacts of aviation and promoting a sustainable future for the sector, said: "The IATA statistic is correct when viewed on a per passenger kilometer basis. However, the number of passengers flying has increased significantly over the same period, so absolute levels of CO2 from the aviation sector have been, and continue to grow."

With passenger demand expected to rise at around 5 percent per year globally, Johnson said the "total CO2 emissions are forecast to keep growing even with efficiency improvements and some use of sustainable aviation fuels".

"What aviation needs to do now is set a long-term climate goal that's in line with reaching net zero greenhouse gas emissions by the second half of this century," the federation's director said. "IATA (via Air Transport Action Group) has pledged to reduce emissions by 50 percent below 2005 levels by 2050. We believe this is a minimum level of ambition and should be delivered without relying on offsets."

The IATA said the introduction of the Carbon Offsetting and Reduction Scheme for International Aviation will ensure carbon neutral growth on international flights from 2020 and raise around US$40 billion in climate finance.

It is estimated that CORSIA will reduce emissions by around 2.5 billion tons over the lifetime of the scheme.

Carbon Footprint Rising

"The carbon footprint of our flights overall still continues to rise as more of us fly year on year," Sharon George, course director for Environmental Sustainability and Green Technology at Keele University, United Kingdom, said.

We are unlikely to reduce the number of flights in the future and there are only a limited number of efficiencies we can make with our current designs and operations, so we need to innovate if we are going to continue to cut our flight emissions much further."

George suggested one way to do this is to rethink fuel use altogether.

"Biofuels offer a more sustainable fuel and Rolls-Royce has developed a battery powered aircraft, which offers the possibility of flights using batteries charged by totally green energy, from the wind or sun," she said.

But environmental groups said that CORSIA should only be seen as a short-term measure and drastic action is needed.

Johnson said: "The 7 million liters of biofuel used in aviation last year would power the global fleet for just ten minutes. This highlights the scale of change in investment and production necessary to make even a significant dent in the sector's emissions."

He said that "fully electric commercial aircraft for medium-and long-haul travel is unlikely before 2050".

"Given these obstacles, the journey toward net zero will mean we can't have an unquestioning attitude toward meeting demand. In the future we will need to think about how, and how often, we use air travel," Johnson added.