Airlines are finally admitting that contrails are a growing threat to the environment, and they are finally beginning to take action to limit their creation. But what are contrails and what danger do they present? Let’s dive in.

Contrails, a portmanteau of condensation trails, are thin, wispy clouds created when an airplane flies through a cold, humid area in the air. 

The exhaust created by jet engines contains various greenhouse gases like nitrogen oxides, carbon dioxide, carbon monoxide, and water vapor. When the hot, humid exhaust mixes with the cold, dry atmosphere, the water vapor freezes and condenses around the soot from the engine, forming small ice clouds high up in the air. 

These cirrus clouds form in a line that follows the path of the plane, and can last for long periods of time. If the area around the plane is dry, the contrails tend to disappear quickly, but if the climate is more humid, the clouds can last for up to a day. Additionally, in high-humidity areas known as Ice Super Saturated Regions (ISSRs), the contrails can spread and merge with other cirrus clouds, creating a massive blanket cloud that can cover thousands of square miles.

While these contrails can be beautiful to look at, they have a devastating impact on the environment, specifically at night. Contrails are virtually the same as regular cirrus clouds but artificially created, meaning that they also trap heat inside Earth’s atmosphere. However, due to the white color of the clouds, contrails also reflect sunlight back towards space, meaning that they actually have a net cooling effect during the day. 

Nevertheless, at night, there is no sunlight hitting the Earth, taking away those reflecting properties. This means that the contrails do nothing but trap heat when they are not faced with sunlight, giving them an extremely strong warming effect during the night. 

Now, over the past few years, researchers have begun to truly understand the impact of contrails on climate change, and they have quickly emerged as a silent but deadly environmental killer. 

According to recent studies, the aviation industry accounts for around 2.5% of global carbon dioxide emissions, but around 4% of global warming can be attributed to the sector. Out of this 4% share, two-thirds of it comes from non-CO₂ sources, with contrails as the largest contributor. Other studies have confirmed that the environmental impact of contrails is around two to three times as much as that of carbon dioxide, making it a major threat.

Furthermore, studies on aviation’s share of global warming have not taken non-CO₂ sources like contrails into account, suggesting that the industry’s net impact on the environment could be much larger than previously thought.

Despite these concerns, airlines have not acknowledged the dangers of contrails until now, and almost no action has been taken to stop them. However, there is a simple and easy solution, and airlines are already taking steps towards eliminating long-lasting contrails completely. 

Further research has proven that around 80% of all contrails can be traced back to between 2 and 10% of all flights, suggesting that the problem’s cause is smaller than expected. Experts have confirmed that redirecting those 10% of flights to change their altitude slightly or adjust their flight path can eliminate a large portion of the contrails produced during that time– avoiding ISSRs is key to the process.

Airlines have already begun this process, analyzing planes that are already in the air and locating exactly which areas are most prone to contrail formation. While a small change in the flight path could cause a small increase in CO₂ emissions, the contrail-induced warming impact that it avoids is much, much greater. Additionally, flights that create contrails in the morning or midday can continue with their regular flight paths, as those contrails can actually reflect sunlight back into space and reduce global warming. 

The Rocky Mountain Institute, a non-profit think tank dedicated to ensuring a smooth transition to clean energy, has already begun a huge project to tackle contrails, involving various major players. They have brought together a cross-sector task force involving Breakthrough Energy, a climate-focused venture capital fund backed by billionaires like Bill Gates, Jeff Bezos, and Michael Bloomberg; Alaska Airlines, American Airlines, Southwest Airlines, United Airlines, and Virgin Atlantic from the airline industry; Airbus and Boeing from the airplane manufacturing industry; Flightkeys, an Austria-based flight planning software company; Google Research, which is helping with analytics; and Imperial College London, who have done several studies on the global impacts of contrails. 

Google Research has also brought artificial intelligence (AI) into the picture, assisting in the analytics portion of the project. Google’s researchers have already begun amassing weather data, satellite data, and flight data to locate ISSRs and detect contrails, with the rest of their team working to feed that data into an AI that informs pilots of their likelihood of creating a contrail in real time. The pilots can then adjust their altitude or flight path accordingly, minimizing contrail formation. 

An initial round of the project was completed in collaboration with Breakthrough Energy and American Airlines in 2023, involving 70 test flights over six months– and they saw a contrail reduction of 54%. 

Nevertheless, airlines are still a long way from implementing this on a more widespread scale, and regulations will need to be adjusted to account for the change in air traffic as well. In addition, while it is one of the fastest, most efficient ways to reduce the aviation industry’s climate impact, the plan still costs money, which many airlines might not be willing to spend.

All things considered, contrails continue to pose a massive threat to the environment, making up a significant portion of aviation’s global warming impact, but airlines and other companies have already begun tackling the problem. If AI can be successfully utilized to limit contrail formation on a global scale, it could be another huge step towards preventing climate change– but only if sufficient action is taken to address the problem now.

Image credit to Britannica