An Honest Conversation About Aviation Carbon Emissions
In 2022 aviation carbon emissions accounted for 2% of global energy-related carbon footprint, having increased faster than other transportation methods such as rail, road, or shipping. This often-cited stat is misleading because the air travel plummeted due to the pandemic. We’ve seen a huge spike in demand for air travel, and the airline industry expects that it will be back to 2019 levels again by 2024 or 2025 at the latest. Aviation carbon emissions in 2022 alone reached about 80% of the pre-pandemic levels.
Therefore, the most relevant research shows that aviation contributes around 4% to human-induced carbon emissions, more than most countries. If we look at the aviation industry as a country, it would be the world’s sixth-biggest emitter globally, behind only China, the US, the EU, India, and Russia.
Moreover, the airline industry is slated to contribute roughly 0.1° Celsius (0.2° Fahrenheit) of warming by 2050 if aviation growth continues on its current trajectory.
The reason why there is a hyperfocus on the aviation sector is because airplane emissions will continue to increase as other sectors make significant gains in decarbonization. While industries like electricity, road transport, and heating have clear routes to adopting low-carbon alternatives, decarbonizing aviation poses distinct challenges.
How Do Airplane Carbon Emissions Affect the Climate?
When aircraft burn jet fuel, they generate not only carbon dioxide (CO2) but also other emissions such as nitrogen oxides, soot, water vapor, and sulfate aerosols. These emissions interact with the atmosphere in various ways and over different timeframes, influencing the climate.
Additionally, the water vapor trails, or contrails, produced by airplanes also contribute to this impact. However, studies have not definitively determined whether these contrails result in a net warming or cooling effect on the Earth’s climate. Depending on atmospheric conditions, contrails can persist and form cirrus clouds, which might further affect climate change dynamics. Some research indicates that these clouds may have differing effects, potentially cooling or warming the atmosphere, depending on factors like the time of day when flights occur.
Steps We Are Taking Toward Sustainable Aviation
Now that we’ve seen the extent to which aircraft emissions contribute negatively to the environment, let’s take a look at some of the most common solutions touted to reverse these trends.
Offsetting Air Transport Pollution
When it comes to reducing aviation carbon emissions, the industry begrudgingly accepts that completely eliminating emissions at the source is impossible. Instead, they plan to employ various offsetting mechanisms to mitigate the remaining impact. This involves compensating for emissions by investing in projects that reduce emissions elsewhere.
For instance, the Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) wants to cap airplane emissions at levels recorded in 2020. It achieves this by mandating airline carriers to offset their emissions generated after 2020.Airlines will offset their carbon emissions by investing in projects that cut down emissions in other industries, such as reforestation or renewable energy.
Based on the latest data, during the period 2021-2035, the scheme is projected to offset around 80% of the emissions above 2020 levels. This is because during the initial phases, states have the option to participate voluntarily, and there are exceptions for those with low aviation activity.
Reducing Aviation Carbon Emissions with Hydrogen and Electric-Powered Aircraft
Short-haul flights covering less than 600 miles contribute to over 17% of airline emissions. To tackle this, new technologies like electric and hydrogen-powered aircraft are in development. It’s believed that electrifying or using hydrogen power for flights under 2,500 miles, which account for over half of all CO2 emissions from aviation, could be the solution.
Airbus, a major player in aviation, is working on three models of zero-emission commercial aircraft fueled by hydrogen. These include a turboprop plane for up to 100 passengers with a range of over 1,000 nautical miles, a turbofan design for 120-200 passengers with a range of over 2,000 nautical miles, and a “blended-wing body” design for up to 200 passengers, also capable of flying over 2,000 nautical miles.
Rolls Royce builds state-of-the-art aircraft engines and has joined the good fight against aviation carbon emissions by setting up a hydrogen aircraft program. Hydrogen serves as both an electrical power source and a direct aircraft fuel.
The engine manufacturer suggests that hydrogen fuel cells could replace electric batteries in hybrid or all-electric small commuter aircraft, offering benefits like increased energy storage and quicker refueling. However, there are numerous technological challenges to address before these systems become commercially viable. Hydrogen fuel cells are likely to find their niche in medium to low-power applications where energy demands are less demanding.
However, even if hydrogen-powered air travel becomes a reality there’s another issue: for hydrogen to be a truly carbon-neutral aviation fuel, it must be produced sustainably. Many climate experts are underscoring the need to incentivize the use of green hydrogen, made using additional renewable energy, to achieve the deep decarbonization required in the aviation sector.
Focus on Sustainable Aviation Fuel
Sustainable aviation fuel (SAF) is an environmentally friendly alternative to traditional fossil-derived aviation fuels, produced from renewable resources such as biomass, waste materials, or synthetic processes powered by renewable energy. Another term used for SAF is biofuel.
SAF offers a significant reduction in carbon emissions compared to conventional jet fuels, contributing to efforts to mitigate the environmental impact of aviation.
Sustainable aviation fuels (SAF) are crafted from sources such as waste feedstocks, agricultural leftovers, forestry residues, and wet waste. When SAF is used, the carbon dioxide emitted is approximately equal to what was originally present in these waste materials. This sets it apart from fossil fuels, where carbon is stored in liquid form before combustion, potentially leading to higher carbon dioxide levels in the atmosphere.
What makes SAF particularly appealing is its full compatibility with existing aircraft and fueling infrastructure. However, due to high production costs and limited availability, its adoption has been relatively slow. Currently, SAF accounts for less than 1% of all jet fuel used globally.
Benefits of SAF
SAF’s capability to seamlessly replace conventional jet fuel in current aircraft offers a significant edge over emerging technologies such as electric and hydrogen planes. Unlike these alternatives, which would necessitate entirely new aircraft and infrastructure, SAF can slot right into existing setups without major overhaul.This makes SAF a more immediately attractive option for a reduction in aviation carbon emissions.
Based on IATA’s findings, hitting the aviation industry’s net zero target by 2050 would mean sustainable aviation fuels (SAF) could slash carbon emissions by a whopping 65%.
Implementing SAF is Promising but Complicated
Leading airplane makers are putting their efforts into ensuring that their fleets can run entirely on sustainable aviation fuels (SAF) down the line.
However, transitioning to SAF isn’t as straightforward as we’d like it to be. SAF faces steep hurdles like having to mix with traditional fuels and its limited availability on the market. Subject-matter experts maintain that there’s a shortage of resources to produce the necessary fuel and suggest that the land could be used more effectively for other purposes.
Simply put, using land specifically for bioenergy production means we’re not using it for growing food, animal feed, or storing carbon.
What’s more, traditional farming methods release a lot of carbon and cause a range of environmental problems like deforestation, pesticide runoff, and soil damage. So, we need to carefully study how biofuels are grown or made and their impact on nature to figure out if they’re truly “carbon neutral.”
Emission Cleaning Solutions
Carbon-neutral fuels don’t tackle problems like nitrogen oxides or soot emissions. So, another idea is to clean up the exhaust as it exits the airplane engine, using post-emissions controls similar to what you find in cars with catalytic converters. This requires rethinking how we design airplanes.
Since it’s not feasible to upgrade older planes, new ones would have to be manufactured with these cleaning systems already installed. Governments might have to step in with rules or incentives to encourage airlines to opt for more efficient planes.
Bottom Line on Aviation and Climate Change
While other industries are making strides towards low-carbon practices, the aviation sector has been lagging behind. As global demand for air travel continues to grow alongside economic expansion, the future of aviation emissions hinges on its capacity to enhance energy efficiency and embrace low-carbon fuels.
However, aviation remains a major source of global carbon emissions. Examining the industry’s emission profile reveals that addressing these challenges requires a multifaceted approach due to their complexities and scale.
From our current vantage point, it looks like effectively scaling down emissions requires a wide range of tools, including building more efficient planes, burning a mix of sustainable fuels, and electrifying short-range flights with renewable energy sources. Until this happens, the aviation sector will continue to contribute a massive share of emissions worldwide.
While these solutions will certainly curtail the impact of aviation carbon emissions, the best thing that we as individuals can do in the short-term lower the carbon footprint of air travel is to simply fly less.