Do Plane Contrails Have an Effect on Global Warming?

The feathery, white trail that you often see airplanes leave as they fly across the sky is a sight to see, especially on a clear, sunny day. However, what people don’t know about is that these pretty trails of ice have a dark side. What do these contrails do to the environment? They accelerate global warming.

What are contrails?

Contrails, short for condensation trails, are line-shaped clouds produced by aircraft engine exhaust. They are primarily composed of water in the form of ice crystals. Contrails result from the reaction water vapor in aircraft engine exhaust, soot, and the low ambient temperatures in high cruising altitudes, usually above 8,000 m or 26,000 ft above sea level.

There have been many conspiracies regarding contrails. But what stands out the most is that they are chemicals sprayed in the sky by the government to combat global warming, known as chemtrails. It cannot be any more different from the truth, though. Contrails are only by-products of the aviation industry, and they promote global warming instead of battle it.

How do contrails accelerate global warming?

Contrails are human-made cirrus clouds. Bernd Kärcher, a professor from the Institute of Atmospheric Physics in Oberpfaffenhofen, claimed that contrail cirrus clouds cover up to 0.6% of the global skies at any given point in time. They can collectively cover as much as 38,000 square miles in areas with high amounts of air traffic. Contrail cirrus clouds can last for several hours to a few days, depending on the weather condition.

Contrail cirrus clouds have two balancing effects on the climate. Like regular clouds, they reflect incoming sunlight to space. However, they also prevent heat radiating from the Earth’s surface from escaping, warming the air below. The cooling effect of contrail cirrus clouds makes up some of the warmings they bring during the day. But at night, when there is no sunlight to reflect, only the warming effect takes place.

How can we reduce the effects of contrails?

Although contrails contribute a lot to the warming of the atmosphere, the good news is that simple solutions can easily mitigate it. Contrails are only clouds, and they do not linger in the sky for a very long time. If their cause is stopped, they will disappear completely without a trace.

A paper published in the journal Environmental Science and Technology stated that the contrails that pose a problem to the atmosphere are mostly coming from flights in the late afternoon and early evening. These contrails are the ones that stay during the night and have purely heating effects. It was also discovered that only 2.2% of total flights create 80% of contrail-related warming.

The good news is that the heating effects of contrails can be greatly reduced by a minor change in the planes’ flight altitude. As per the researchers’ calculations, adjusting the altitude of less than 2% of the flights by 2000 feet will result in a 59% reduction of contrails’ total climate impact. Mark Stettler, the lead author of the paper, said, “It’s a really, really quick way that the aviation industry could address its impact on the climate.”

However, it is unlikely that airline companies will be willing to adjust their flight altitudes since they are optimized for fuel-efficiency. Fuel consumption accounts for about ⅓ of an airline’s expenses, and they would want to keep them down. It may take some time before airlines take action. Katherine Estep, communications director for the industry trade group Airlines for America, said airlines are currently NASA and the FAA to address the contrail issue through various methods such as more efficient aircraft, air traffic management, and sustainable jet fuel.


The effects of contrails can be easily addressed through the help of airline companies. Contrails do not have a lasting impact on climate change. But contrails are only the tip of the iceberg. Carbon emissions remain to be the main culprit of climate change, and the aviation industry produces 2% of the global human-made emissions. We need to address this problem in the long run.