How Bad Are Airline Emissions, Really?

In December, climate activists in Germany glued themselves to the runways of major airports in Munich in a direct action protest to call attention to the carbon emissions associated with air travel. Their protest followed a similar action at Berlin’s Brandenburg airport in late November. Despite the photo-ready nature of the sit-ins, they generated relatively minimal media reporting. Still, the protests fall in line with a longstanding climate critique of air travel, from Greta Thunberg’s high-profile decision to sail across the Atlantic Ocean rather than fly to the United States to attend the UN Climate Action Summit in 2019 to France’s recent move to ban three short domestic air travel routes with good rail travel alternatives.

Among climate activists, air travel certainly makes for an appealing target, with its considerable carbon footprint and association with luxury vacations. Nothing communicates conspicuous consumption more than celebrities like Taylor Swift or Elon Musk choosing to take private jet flights over distances shorter than some people’s daily commutes. And when airline operators operated nearly-empty planes and competed to offer cheap “flights to nowhere” in response to collapsing passenger bookings during the early COVID-19 pandemic, the level of corporate complicity in apparently wasteful travel became clear. example of corporate complicity in climate change. Even climate deniers have selectively invoked jet plane emissions to poke ridicule at international climate meetings and earth science conferences.

As the fight heats up in the skies, meanwhile, so has that underground. In the past weeks, as some activists tried to disrupt air travel, elsewhere in Germany a longtime battle over the fate of the historic town of Lützerath in Germany’s Ruhr Valley has dramatically escalated, with protesters now standing directly in the way of excavators to prevent the expansion of the Garzweiler II lignite coal mine. On January 17th, famed Swedish climate activist Greta Thunberg even joined protesters near the edge of the coal pit, before being briefly arrested by German police.

In many ways, coal is an even clearer target than air travel. The available low-carbon replacements for coal-fired electricity—solar, wind, nuclear, and more—are already fully developed commercially. Whereas technical solutions for aviation may not be implementable for years, governments can phase out coal energy today. The burning of lignite in coal plants emits chemical and particulate pollution that pose far greater immediate public health harms than jumbo jets. Similarly, coal mining poses significant environmental impacts while affecting nearby communities.

These issues may seem unrelated but what if there was a way to, in effect, mobilize on both at once? By prioritizing a different issue altogether, in fact, German environmental advocates could cut Germany’s yearly emissions by an amount equivalent to eliminating every passenger jet flight leaving the country, while simultaneously reducing demand for domestically mined coal.

In fact, keeping Germany’s last three nuclear reactors online would reduce Germany’s annual fossil fuel emissions by 27.9 Mt CO2eq/yr, assuming retirement of an equivalent amount of domestic coal generation. From preserving operation of just these three reactor units, the long-term carbon impact is on par with the average annual carbon footprint of all commercial flights leaving Germany over the 2013-2019 period: 27.04 Mt CO2 eq/yr. Meanwhile, assuming a net calorific value of 8.7 MJ/kg and an emissions factor of 113.1 tons of CO2/TJ for Rhineland lignite, saving the power plants would save the need for burning 28.5 million tons of Rhineland coal—almost the full annual production (30 million t/yr) of the entire Garzweiler mine.

There’s good reason to tackle the airline and coal issues this way. While both aviation and coal mining have significant environmental impact in terms of emissions, emissions from aviation are hard to reduce significantly. Certainly, governments should consider policies that dissuade airline companies from flying empty aircraft, that levy a progressive tax on frequent fliers, or that disincentivize private jet travel. But objectively speaking, the climate movement is perhaps too overly focused on marginally reducing jet fuel consumption in a sector where potential near-term emissions benefits are small. One recent research paper, for instance, finds that the emissions savings from banning all super short-distance flights across Europe would only reduce jet fuel consumption by around 5.9%, out of the estimated 3% sliver of total CO2 emissions that aviation is responsible for in Europe.

Beyond nibbling at the margins of air transportation, saving existing nuclear reactors brings other huge benefits. That climate activists even have this option is something of a stroke of fortune; had Russia not invaded Ukraine in early 2022, throwing Europe headlong into a continental energy crisis, the last three German reactorswould have retired in the very same month as the Berlin and Munich airport protests. Many political parties and advocacy groups that ostensibly prioritize climate goals, such as Greenpeace, are cheering that the reprieve on their retirement is only temporary, even while vocally opposing the Garzweiler II mine, whose product directly benefits from Berlin’s nuclear phaseout policy.

Certainly, extending operations at Germany’s last three nuclear plants may not directly lead to closure of the Neurath and Niederaussem coal plants or the Garzweiler mine. Even so, continued operation of the last German reactors accompanied by further buildout of diverse forms of new clean energy would signal a new start, and is unequivocally the fastest path to eventually eliminating the Garzweiler coal pit (or prevent it from spreading further).

Germany is not the only country that risks missing valuable climate opportunities by missing the forest for the trees.

We compiled a list of nuclear reactors scheduled to be shut down in or prior to 2030, and compared the emissions benefits of preserving these reactors (and retiring fossil fuel generation instead) against the annual emissions from flights departing selected countries and regions—a major target of climate activists the world over. We also considered the future emissions benefits already secured thanks to changes in policies, regulatory changes, and supportive activism that saved a separate set of reactors previously scheduled for closure. These changes benefited the Dresden NPP in Illinois, Pickering in Ontario and Diablo Canyon in California.

Our emissions estimates utilize regularly-published OECD data on flights originating in OECD countries. We compared the emissions generated by flights leaving OECD member states against the emissions potentially saved by preventing future shutdowns of nuclear power plants and retiring an equivalent amount of fossil generation capacity instead. This calculation adapts the methodology we previously used to demonstrate how the annual climate impact of premature nuclear plant shutdowns from 2011 to date exceeds the cumulative annual emissions of the 37 lowest-emitting countries in Africa.

We find that in several OECD countries, the climate benefit of extending operations at nuclear plants imminently scheduled to close and retiring fossil generation vastly exceeds the emissions footprint of all commercial flights leaving those countries. Continuing to operate Germany’s three remaining reactors; Units 1 and 2 at both the Tihange and Doel nuclear power plants plants in Belgium; Taiwan’s three last reactors; as well as Units 1 and 2 at both the Almaraz and Ascó plants in Spain—and retiring an appropriate amount of coal generation—would reduce annual CO2 emissions by nearly 110 million metric tons of CO2. Additionally, bringing back online both Chinshan reactors and completing the nearly finished Lungmen reactors in Taiwan would allow the retirement of 36.4 GWh of electricity from coal, or 33.6 million tons of CO2, or the equivalent of 12% of Taiwan’s total emissions. And by preventing early reactor shutdowns in Canada and the US we are preventing the emissions of extra 28.25 million tons of CO2 every year these reactors stay active past their previously scheduled closing dates.

Such a climate benefit would be larger than a policy banning every single departing jumbo jet flight from the entire continent of Europe in a year. These carbon savings equate to almost 80% of the annual emissions from flights originating in North America or about 65% of annual emissions from flights departing Asia, and well exceeds all annual emissions from flights originating in South America, Africa and Oceania combined. In other words, preserving only 14 nuclear reactors around the world would be enough to offset the yearly emissions from all flights from Europe, those from Oceania, Africa and South America combined, the majority of emissions from the flights in North America, or more than half of the emissions generated from flights in Asia, and it would come with none of the political and social consequences of implementing even a partial flight ban.

Recent decisions to extend the lifetimes of many existing nuclear power plants are already set to produce future climate benefits. For instance, the projected carbon emissions savings from successfully preventing the shutdowns of the Dresden and Diablo Canyon plants in the United States and the Pickering plant in Canada are larger than the aviation-related emissions of any single European country.

While German aviation-related emissions have fallen as a result of the Covid-19 pandemic, the avoidable emissions resulting from historic nuclear phaseout policies to date still exceed those generated by the pre-pandemic aviation industry:

This would hardly be the first time that environmentalists have become captivated by specific issues whose aesthetic appeal far outweighs the environmental benefits at stake, or are even counterproductive. Plastic straws, or indeed marine plastic pollution writ large, attract a disproportionate degree of attention at the expense of other serious marine conservation issues such as invasive species management and marine anoxia. Meanwhile, suspect sustainability-related marketing in the food sector has become synonymous with organic labeling, despite a wealth of consensus among researchers that organic-only farming actually inflicts higher aggregate impacts upon the environment.

To be fair, the environmental impact of airline travel is indeed far more real than the ill effects from plastic straws. But in setting their sights on jumbo jets, climate advocates have in practice targeted a very difficult-to-decarbonize sector. It will be politically complicated to achieve meaningful reductions in commercial aviation, and also technologically difficult to decouple flying and negative environmental impacts anytime soon. Given the importance of tourist activity for many economies, poor and rich alike, significant restrictions on flying would also risk potentially large economic and social impacts for millions of people.

Despite what some people believe, flying is not always a luxury. For millions of immigrants in an increasingly globalized world, flying is the only way to see relatives; for many remote and island countries flying is the only practical means of international travel. As such, flying bans and restrictions could disproportionately impact the lives of immigrants, citizens of archipelagic states, and more.

In the end, the reasons why people choose to fly are deeply personal, and depend a lot on values. Rather than scrutinizing each and every case to eke out tiny returns in terms of carbon savings, policymakers should first prioritize areas where significant emissions reductions are possible with minimal impacts upon the lives of citizens.

Indeed, it is possible to significantly reduce carbon emissions without requiring people to give up basic services and pleasures like travel that should be accessible to more people, not less. In practice, the vast majority of the emissions we produce result from activities that help us keep the lights on, staying warm and well fed, and maintain the essential movement of people and goods that keeps society functioning. Indeed, despite great reductions in economic activity and in the usage of all forms of transportation due to the COVID-19 imposed lockdowns, societal emissions barely fell.

The key to broadly solving environmental problems will be eliminating the environmental impacts associated with both the essential and enjoyable activities we participate in, not eliminating those activities themselves. Phasing out coal power and promoting nuclear energy and other sources of clean generation is a sensible policy that encapsulates this approach perfectly.

Air travel serves a useful societal purpose. In contrast, coal is an obvious target for elimination. Prematurely shutting down nuclear power plants is thus both unnecessary and counterproductive for the climate, with benefits only for the coal mining sector and for coal-fired power. Activists can exert a large impact in the fight against climate change if they focus on the right targets.

Saving the last three German reactors, deploying more clean energy, and retiring coal instead could destroy demand for lignite coal equivalent to eliminating the Garzweiler coal mine in one fell swoop.