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Aviation: Part 1 #34

The climate impact of air travel

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Pauliina Meskanen

April 14, 2022

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Hi Human,

Welcome to the next deep dive series at Survivaltech.club! The topic of this deep dive series is aviation.

Aviation is my personal pain point and a topic that I have been intensively working on for the past six weeks. I’m excited to get to share my learnings with all of you!

This deep dive series consists of two parts:

  • Part 1: The climate impact of air travel
  • Part 2: Solutions and startups for zero climate impact aviation

Let’s fly!🛫

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Air travel - my pain point

Traveling is one of the things that I am most thankful for my parents. They took me to countries like India, Oman, China, and Marocco from a young age onward. This has undoubtedly shaped my way of looking at the world.

The little Pauliina internalized that there are fellow humans who speak a different language as I do, who believe in other gods or believe in a god in the first place, and who look different from what I do. And that’s perfectly fine and an integral part of humanity.

I still love to travel and explore new cultures and ways of living. For example, last November, I spent three weeks in Kenya. What a wonderful experience!

But there’s a severe downside to flying.

Flying is one of the most energy-intense ways of consumption and produces tons of CO2 and other emissions into the atmosphere. I feel guilty every time I step on a plane, and so do many of my friends back in Finland. There is even the word “flygskam” for flight shame in Sweden!

However, I am confident that we can tackle aviation’s climate impact. Let’s start by understanding how exactly aviation warms the climate.

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Sources of aviation’s climate impact

Flying warms the planet in several ways. When we burn jet fuel, we emit CO2 emissions, nitrogen oxides (NOx), water vapor, and make contrails in the sky. Jet fuel is a mixture of hydrocarbons, also known as kerosene.

For simplicity, I’ve divided the sources of climate warming in aviation into two categories: 1) CO2 emissions and 2) Non-CO2 sources.

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1. CO2 emissions

Burning hydrocarbons produces CO2. Commercial aviation releases on average 1 Gt of CO2 into the atmosphere every year. That’s around 3% of the global CO2 emissions.

Around 20% of the CO2 emissions originate from short-haul flights (<1000km), while medium and long-haul flights account for the bulk, 80%.

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2. Non-CO2 sources

  • Nitrogen oxides (NOx)
  • Water vapor
  • Contrails

We also emit NOx and water vapor from the jet turbine when we fly. NOx emissions lead to more ozone, a greenhouse gas (GHG), in the atmosphere. Water vapor itself is a GHG, although weaker than CO2.

In addition, airplanes form contrails behind them. A contrail gets created when water vapor makes ice crystals around soot particles (carbon particles in the exhaust gas). Contrails are problematic when they form in low-temperature ice-supersaturated air. This makes the contrails last for a long time. These persistent contrails warm the climate as they prevent radiation from the Earth from escaping to space.  

If you want to learn more about contrails, check out this Youtube video by Coby Explanes.

I spotted some contrails above Mono Lake, California, while we were driving back from Red Rocks, Nevada, last week.

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In case you are keen on learning about aviation’s climate impact in more detail, I highly recommend reading Lee et al. (2021)’s article. Below, you may find their overview of aviation’s climate warming mechanisms.

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Climate forcings from global aviation emissions and cloudiness by Lee et al. (2021)

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The warming impact of CO2 vs. Non-CO2 sources

Now, you may wonder, what’s the relative impact of CO2 vs. non-CO2 sources. Get ready to be surprised.

CO2 emissions account for one-third (34%) of aviation’s climate impact. On the other hand, non-CO2 emissions are responsible for a staggering two-thirds! (Lee et al., 2021)

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Source: Lee et al. (2021). The contribution of global aviation to anthropogenic climate forcing for 200 to 2018. Atmospheric Environment, 244. https://doi.org/10.1016/j.atmosenv.2020.117834

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This piece of information was surprising to me. Six weeks ago, I wasn’t even aware of the impact of non-CO2 sources. However, they account for 66% of aviation’s climate impact!

A key takeaway from this is that when tackling aviation’s climate impact, we must take a holistic approach and take into account both CO2 and non-CO2 sources.

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The outlook

Air travel is expected to more than double by 2050 despite the COVID effects. (Before COVID, it was estimated that the demand for global air transport would triple between 2020 and 2050!)

We can expect to see the largest growth rates in India and China.

Furthermore, aviation is one of the hardest-to-decarbonize sectors in our global economy. Commercial aviation is highly regulated for a good reason, and the turnaround time of an airplane fleet is several decades.

If no further action is taken, aviation is expected to be responsible for a staggering 22% of the global CO2 emissions in 2050. We have to act now.

In Part 2 of this deep dive series, we will look at possible solutions and startups that are working to turn these solutions into a reality.  

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Pauliina’s greetings from SF and Red Rocks!

I spent last week rock climbing on Red Rocks, Nevada, and remote working. Red Rocks rock!

Observations:

  • People in the US have a hard time understanding that Finns don’t pay tuition in their universities in Finland and get money from the government to live while studying.
  • The car infrastructure in the US is annoyingly good. In Las Vegas, it was practically impossible to get anywhere without a car (except on Las Vegas Strip).

If you liked this article, please share it with your climate friends!💚🌍

Best, Pauliina

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Sources