Who Has the Highest Carbon Footprint of Flying?

Hannah Richie and the Our World in Data team from Oxford University always have the most interesting numbers. Their latest ones answer the question "Where in the world do people have the highest CO2 emissions from flying?" Treehugger might disagree with their very first sentence, where they say "aviation accounts for around 2.5% of global carbon dioxide (CO2) emissions" – we have written that when you take radiative forcing and all the support infrastructure for aviation, it is probably double that. We have also noted that if you want to know who is doing all the flying and putting out all the CO₂, it's the rich. These data simply look at the CO2 per capita from aviation by country.

What is really interesting in this discussion is the way it is broken down by sector; by domestic, international, and international tourism. Because if we are going to have a hope of keeping the global temperature rise below 1.5°C, we have to keep below an average carbon footprint of 2500 kg of carbon per person per year (or 6.85 kg/day) by 2030, and flying makes that very hard.

Domestic aviation is relatively easy to demonstrate because it is calculated in every country's inventory of greenhouse gases. (You can get greater detail and play with the graphs and maps here.)

When you look at the top 10 countries for domestic emissions, some strange things pop out. That the United States is so high is no surprise; it is wealthy, it is big, and it has lousy train service. The same could be said for Canada and Australia, which probably don't have the population density to support high-speed trains. But France and Japan have great high-speed trains, and Iceland is tiny. And what's the story with Norway?

The problem with the domestic travel numbers is that they could be so much lower. In Europe, the domestic airlines are so cheap that it is less expensive to fly from Paris to Marseilles than it is to take the high-speed train. In Iceland, you can literally walk to the domestic airport from downtown, and people use planes like others use buses.

But the U.S. has much higher per capita emissions than anyone else, and has the population density that could support a high-speed rail network. It's just crazy that the average American eats up 56 days worth of their annual carbon budget on domestic flights.

International Flights

Figuring out the emissions from international flights is much harder, because they are not counted in the Paris Agreement. And the Our World in Data people ask: "How would we do it? Who do emissions from international flights belong to: the country that owns the airline; the country of departure; the country of arrival?" Here, they based it on the country of departure. It makes sense that Iceland is so high; flying is the only way to go anywhere, and Icelandair carries a lot of tourists so there are a lot of planes flying out of Keflavik.

They then do a pretty sophisticated adjustment for tourism, and the picture changes dramatically. Iceland's Keflavik airport is a base for many cheap tourist flights, so the CO2 per person for citizens drops by two thirds. The UK pops into the scene because of all those cheap flights to Spain. Finns love to travel and pop up into fourth position. Israelis are as much an island politically as Iceland is geographically, so they pop onto the list. Rich countries whose citizens fly a lot are up near the top.

It is the international emissions that are so difficult to deal with; Australians and Icelanders have to fly to get anywhere. But there is no reason that Germany, Britain, Sweden or Switzerland need to be so high, if flying was properly priced to reflect its real costs. Is it that all these northern countries want to fly south for the winter? Is that why Canada's international footprint is 363kg and the U.S. is only 198kg, 26th in the world?

All Aviation, Tourism Adjusted

Then they combine the domestic and international flights, adjusted for tourism, and we see the final picture. It again is a story of money and geography.

Rich countries are on top. Island countries have no choice if they want to go anywhere. Finns just love to travel. Northerners want to go south. And who knows what is going on in the UAE, which has 10 times the emissions per capita than its neighbor Saudi Arabia.

But one thing becomes clear when you look at these numbers is that we can't just have a blanket statement like "ban flying." Every country has a different geography and different circumstances and probably needs its own solutions.

When one forgets about the per capita emissions and looks at the total emissions, one gets a very different picture. The U.S. may be a fraction of Iceland per capita, but Iceland has half the population of Wyoming. In the total emissions picture, the U.S. is number one, and China is in second place, and rising fast.

All of these numbers are from 2018, before the industry was shut down, and nobody knows how quickly it will all come back. I also reiterate that these numbers are probably off by half. Since it is unlikely to the point of fantasy that flying could ever decarbonize, Aviation looks like it is going to become a bigger part of the carbon crisis every year.