on social media, about two years after Swedish singer Staffan Lindberg started

the movement with his pledge to give up flying.

The idea?

Get people to reduce their air travel, lowering the carbon emissions released by planes.

The movement went global thanks in part to fellow Swede Greta Thunberg.

The young environmental activist was both praised and criticised for ditching the plane

and crossing the Atlantic by boat to attend a United Nations summit.

So should you really suppress your wanderlust?

Or can the aviation industry evolve quickly enough to provide environmentally-conscious

consumers with a greener option?

According to the International Energy Agency, aviation is likely to be the most difficult

transport sector to decarbonize, due to the cost and scale of the industry.

From airlines to aircraft manufacturers and airports, the aviation industry has made some

moves to implement environmentally sustainable practices to fight climate change.

In 2019, Etihad Airways powered a commercial flight using a mix

of jet and biofuel made from a plant called Salicornia,

which grows in the Abu Dhabi desert.

Sustainable aviation fuel can be produced from plants, algae,

used cooking oil and even municipal waste.

And it seems like the trend is taking off.

To date, more than 170,000 commercial flights have been powered by biofuel blends, including

flights by Qantas Airways, United Airlines and Virgin Atlantic.

But that's still a tiny fraction of the jet fuel being used.

Biofuel was only used in just 0.1% of U.S. jet fuel in 2018.

Carbon emissions from aviation accounted for about 2.5% of global emissions in 2018.

If that seems like a small ripple, consider this.

From 2013 to 2018, CO2 emissions from commercial flights increased by 32%.

That's expected to triple, as the global travel industry begins to grow.

In 2019, 4.5 billion passengers travelled by air, while international tourist arrivals

rose 4% to 1.5 billion.

The top countries with outbound travellers contributing the most to CO2 emissions are

the United States, China, the United Kingdom, Japan and Germany.

In total, the top 10 countries made up 60% of the CO2 emissions coming from aviation.

A return flight from London to New York City

generates over one ton of carbon dioxide per passenger.

That's nearly the same as what the average citizen in Paraguay emits in a year.

Already, a growing number of travellers in Europe and the U.S. are reducing their air

travel because of environmental concerns, which may put the brakes on passenger growth.

The aviation industry is also looking to improve fuel efficiency, which refers to the distance

an aircraft can travel on one gallon of fuel.

Airbus and Boeing, the two biggest names in the industry, are already producing more

efficient planes, such as the Airbus A350 XWB and Boeing 787 Dreamliner.

Beyond fuel-efficient planes, there are other interesting solutions too.

Electric aircraft have made inroads in the recent years too, whether it's hybrid-electric

aircraft, which means an aircraft propelled by both fuel and an electric battery,

or a fully electric aircraft.

Prototypes such as the Eviation Alice are expected to enter commercial service

in the next few decades.

However, one of the main challenges facing electric aircraft is the battery.

They remain relatively heavy for aviation.

At the same weight, jet fuel consists about 14 times more usable energy

than a brand-new lithium battery.

Airports are also doing their part.

Since 2015, Oslo Airport in Norway has been distributing sustainable aviation fuels

to all airlines on a regular basis.

The Los Angeles International Airport, Stockholm Arlanda Airport and Norway's Bergen Airport

followed suit.

Consumers play a part too.

Besides reducing air travel, they can consider how climate-friendly an airline

is before buying a ticket, sort of like checking out the carbon emissions on a new car.

One such report by German nonprofit Atmosfair ranked and compared the carbon efficiency

of the 200 largest airlines worldwide, across 33 million short haul, medium haul

and long-haul flights.

For all three categories, no airline achieved the highest ranking of A, which meant optimal

carbon efficiency has not been managed yet.

The top five most carbon efficient airlines include the United Kingdom's TUI Airways,

LATAM Airlines Brasil, China West Air, Germany's TUI fly and Transavia France.

These rankings were determined by efficiency of aircraft type, seating capacity

and load factor.

So a fuel-efficient plane with a lot of seats and a lot of people in them

will get a higher rating.

For example, TUI Airways, the top ranking, flies consistently at almost maximum occupancy,

with highly efficient aircraft.

In 2009, the International Air Transport Association put in place strategic targets for the aviation

industry, including carbon-neutral growth from 2020 and a reduction in net aviation

CO2 emissions of 50% by 2050, relative to 2005 levels.

In 2016, the Carbon Offsetting and Reduction Scheme for International Aviation, or CORSIA,

was also implemented.

The UN deal would make airlines in participating countries offset any increases to their carbon

footprint from 2020, essentially forcing them to invest in environmental projects ranging

from clean energy technologies to planting trees.

Participation is voluntary from 2021 and mandatory from 2027.

A total of 81 states, representing nearly 77% of international aviation activity have

pledged to participate in CORSIA as of July 2019, including the United States

and United Kingdom, two of the biggest carbon emitters.

However, critics say the scheme doesn't go far enough.

The list of participating states has some notable absences, including China, India

and Brazil.

And many climate activists say being carbon neutral is no longer enough, and that a carbon

negative economy is the way forward.

Combating climate change in the aviation industry is a work in progress.

One day, with technological advances, we may be able to have our cake and eat it too.

But as many environmentalists argue, one day may not be soon enough.

So have you ever had flight shame?

Tell us in the comments.

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