What Is the True Climate Impact of Aviation?

Aviation isn't having much of an impact on the climate with most of the planes grounded, but before it hit, the industry was growing at about 5% per year. Now a new study, "The contribution of global aviation to anthropogenic climate forcing for 2000 to 2018," tries to calculate the total impact of both the CO2 emissions and other non-carbon effects that contribute to climate change.

The common number used for the impact of flying is 2% of global climate emissions, but that doesn't take into account radiative forcing and "effective radiative forcing" (ERF) which is a "metric of climate change to enable comparisons between different greenhouse gases and other impacts that affect the climate system" – basically putting a number to non-CO2 factors such as nitrogen dioxide, cloudiness from contrail formation, water vapor, soot, and sulfates.

The lead author of the study, Professor David S. Lee of the Centre for Aviation, Transport and the Environment at Manchester Metropolitan University, did a summary for Carbon Brief that is a lot easier to unpack, and concludes that it is a lot more than 2%:

"We find that, when all its impacts are taken into account, aviation represents around 3.5% of the warming impact caused by humans in the present day." 

But the planes are only one part of the aviation industry. As The Economist notes, it employs a lot of people doing lots of related activities:

"The airline-industrial complex is vast. Last year 4.5bn passengers buckled up for take-off. Over 100,000 commercial flights a day filled the skies. These journeys supported 10m jobs directly, according to the Air Transport Action Group, a trade body: 6m at airports, including staff of shops and cafés, luggage handlers, cooks of in-flight meals and the like; 2.7m airline workers; and 1.2m people in planemaking." 

And that doesn't include all the cars and taxis driving to the airports, and the vast amounts of concrete and steel that goes into building them, discussed in our last look at this subject. In total, it's a lot more than 3.5%.

What Happens When Things Reopen?

The real question is where the industry goes after the pandemic in a world where we need to cut our emissions in half by 2030 and to almost zero by 2050 to keep the global temperature rise below 1.5°C. Notwithstanding the Airbus plan to have hydrogen planes in the air, or the use of electric planes for short-haul flights, most are still going to be running on jet fuel. According to another Carbon Brief post that projected the continuing growth of aviation, they estimate that it could eat up 27% of the entire carbon budget for 1.5°C, and that's without even counting the non-CO2 effects.

"This gives a new perspective to the oft-repeated claim that aviation is responsible for 2% of global emissions — a claim repeated in the ICAO report and one the sector has been stressing since the early 1990s. While it is true that aviation may be a small slice of a large pie at the moment, as other sectors seek to reduce their emissions in line with the carbon budgets, aviation will come to occupy an increasingly large share, if it continues to grow."

The problem with flying becomes even more obvious when you look at who is doing it, which in fact is a very small portion of the world's population. The graph is for the European Union, but according to OXFAM,

"This pattern seems to be common across regions: another recent study estimated that the top 10% richest households globally use around 45% of all the energy linked to land transport, and around 75% of all energy linked to aviation, compared with just 10% and 5% respectively for the poorest 50%."

In fact, according to the former CEO of Boeing, this was a great opportunity: “Less than 20 percent of the world’s population has ever taken a single flight, believe it or not. This year alone, 100 million people in Asia will fly for the first time.”

Put it all together and one can't escape the conclusion that if we don't do something about aviation, then a small number of rich people are going to be responsible for eating up a quarter of our carbon budget. Professor Lee concludes in Carbon Brief:

"The aviation sector itself is calling for more investment to recover and decarbonise. However, unless measures to limit fossil fuel usage are also introduced, the sector will remain incompatible with the Paris ambitions."