Aviation’s Climate Impact – Why Reducing Emissions Matters

Flight Carbon Footprint in a Global Context

If global air traffic were a country, it would be the seventh largest emitter of carbon dioxide worldwide. When the high-altitude effect is included – the impact of nitrogen oxides, water vapor, and particles emitted at cruising altitude – aviation’s true greenhouse gas emissions more than double. The figure mentioned above also does not account for other greenhouse gases such as methane and nitrous oxide, or upstream emissions linked to the fuel. Researchers estimate that the flight carbon footprint is between 3 and 5 percent of the world’s greenhouse gases.

Emissions Produced by International Flights

Most emissions produced come from international flights rather than domestic travel. Short international flights and long-haul round trips by plane generate the majority of the carbon footprint. Globally, an estimated 80 percent of the world’s population has never boarded a plane, meaning that the carbon emissions generated are highly uneven and concentrated in wealthy countries in Europe, North America, and Asia.

Swedes’ Carbon Footprint from Air Travel

For Swedes, air travel represents a particularly large share of greenhouse gas emissions. The carbon footprint per passenger from flights is five times larger than the global average. Before the pandemic, emissions produced by Swedes’ flight travel were equal to the greenhouse gas emissions from all passenger cars in Sweden.

During the pandemic, flying decreased sharply, cutting aviation emissions by about 20 percent. Although air travel has increased again, emissions are still below pre-pandemic levels. However, the upward trend means that unless action is taken, planes will soon return to generating emissions at unsustainable levels – undermining climate goals.

Why Aviation Fuel Has an Outsized Impact – The High-Altitude Effect

Planes burn aviation fuel that produces not only CO₂ but also other greenhouse gases and particles. At high altitude (8–12 km), these intensify climate change:

• Nitrogen oxides form ozone, a powerful greenhouse gas.
• Water vapor creates contrails that trap heat.
• Soot particles alter cloud formation.

Because of these effects, scientists use emission factors with an uplift of around 2-3 when they estimate carbon emissionsfrom aviation. This means the climate impact per passenger is more than double the CO₂ emissions from aviation fuel alone.

Measuring Aviation’s Climate Impact – Two Approaches

There are two main ways to calculate the aviation carbon footprint:

Territorial Emissions

These account for emissions produced by flights departing from a specific country or region. They are reported to international bodies such as the UNFCCC and form the basis of national climate inventories. However, they usually exclude high-altitude effects, which means the total climate impact is underestimated.

Consumption-Based Emissions

This approach allocates emissions to the passengers of a given country or population, regardless of where the flights take off or land. It also includes high-altitude effects, often by applying emission factors to account for contrails and nitrogen oxides. Research from institutions such as Chalmers University of Technology and the ICCT (International Council on Clean Transportation) shows that this method provides a more accurate estimate of aviation’s true contribution to the climate crisis.

Biofuels – Solution or Part of the Problem?

Switching from fossil fuels to biofuels is often proposed as a way to achieve carbon reduction in aviation. Biofuels can reduce the flight carbon footprint per passenger, but challenges remain:

• First-generation biofuels from food crops (corn, soy) compete with food supplies.
• Second-generation biofuels from waste and residues are more sustainable.

Today, 60 percent of EU biofuels are food-based. Oxfam’s Biofuel Blunders warns that this drives deforestation, food insecurity, and social conflicts. While advanced biofuels are emerging, the most responsible choice remains to fly less.

Responsible Actions to Reduce Flight Emissions

To reduce aviation’s climate impact, both individuals and companies can:

• Fly less and take trains within Europe.
• Avoid unnecessary round trips by using digital meetings.
• Choose efficient vehicles powered by electricity or sustainable biofuels.
• Offset emissions produced through high-quality climate finance.

Climate Finance and Carbon Credits

Because it will take years before aviation fuel becomes fossil-free, climate financing is essential. Companies (as well as individuals) can calculate their footprint using emission factors, then buy carbon credits that support projects preventing or removing greenhouse gas emissions elsewhere.

Examples include:

• Building wind and solar power to replace fossil fuel use.
• Protecting forests to prevent carbon emissions generated by deforestation.

To be effective, these projects must ensure:

• Additionality – they would not happen without outside funding.
• Certification – e.g., Gold Standard projects guarantee verified carbon reduction.

Carbon credits are not an excuse to pollute, but when used responsibly they help manage flight emissions during the transition away from fossil aviation fuel.

Find out more about how GoClimate works with Climate financing, here (link).

Conclusion – Planes Must Become Part of the Solution

Although aviation accounts for a relatively small share of the world’s carbon emissions, the flight carbon footprint is disproportionately high in wealthy countries like Sweden. Planes’ fuel consumption per passenger is particularly damaging on short international flights and long-haul round trips.

We face a choice: allow planes to undo the progress we’ve made in other sectors, or act responsibly to reduce their impact. By flying less, investing in renewable energy, applying robust emission factors to estimate carbon emissions accurately, and supporting high-quality carbon credits, we can ensure aviation contributes to solutions rather than problems.

The real question is not whether we can afford to reduce flight emissions – but whether we can afford not to.