Eliminate warming contrails to reduce aviation’s climate impact.
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What’s the issue with contrails?
There is a simple solution to immediately reduce a significant portion of the climate impact from airplanes – eliminate persistent contrails. Contrails, the white streaks left by airplanes in the sky, make up a significant portion of aviation’s warming impact.
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If just 2% of planes are rerouted...
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80% of contrails could be avoided...
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eliminating 35% of aviation's impact...
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which could elimate 2% of all global warming.
In The News
Reports
Researchers from Breakthrough Energy, Flightkeys, and Imperial College London demonstrate that navigational contrail avoidance requires minimal cost and fuel burn penalties to yield notable reductions in contrail climate impact.
Researchers from Imperial College of London and DLR analyzed Japanese airspace and showed that only 2 to 2.5% of flights contribute to 80% of warming from contrails.
Researchers put together a blueprint to end warming contrails. “This paper…provides a stepping stone for policymakers, industry leaders, and other stakeholders with an interest in reducing aviation’s total climate impact, to understand how a large-scale warming-contrail-minimizing trial could work.”
Blog
Contrail Controller Series: Meet RMI Contrail Impact Task Force – Researching to Reach Results
Contrail management is a major challenge. As such, teamwork is needed across the industry to share information and develop strategies to address...
Eyes on the Skies with the Contrail Observer App
It may seem like the work surrounding contrails is very academic, reserved for scientists and aviation experts. It’s one thing to be a concerned...
Pilots’-Eye View of Contrails
The contrail collaboration thus far has been a thing of beauty. Efforts to share research and advance the technology through open discussions and...
Contrails 101
What Are Contrails?
According to the EPA, “contrails are line-shaped clouds or ‘condensation trails’, composed of ice particles, that are visible behind jet aircraft engines”.
Think of contrails as man-made clouds.
How Are Contrails Formed?
According to the EPA, “[a]ircraft engines emit water vapor, carbon dioxide (CO2), small amounts of nitrogen oxides (NOx), hydrocarbons, carbon monoxide, sulfur gases, and soot and metal particles formed by the high-temperature combustion of jet fuel during flight.”
Contrails are formed when particles emitted from an airplane’s engine exhaust interact with water vapor in the air. The particles provide water vapor with a place to attach and form ice nuclei.
The result? Long white streaks in the sky commonly known as contrails.
Because of their location high in the troposphere and net effect on our climate, scientists classify contrails as cirrus clouds.
What Are Cirrus Clouds?
Cirrus clouds are high, wispy clouds made up of tiny ice particles that are formed in the highest, coldest region of the troposphere. The troposphere is the lowest layer of earth’s atmosphere and is where most of our weather occurs and where commercial aircraft fly.
Cirrus clouds are unique from other clouds because they form by deposition, water vapor attaches to a particle (ice nuclei) and freezes into an ice particle.
Cirrus clouds have a net effect of warming the earth.
How Do Clouds Impact Our Climate?
Clouds play a central role in our climate by naturally regulating our earth’s energy balance.
Clouds control how much of the sun’s heat reaches the earth’s surface and how much of that heat is radiated back into space. Some clouds trap heat, warming the climate. Other clouds reflect heat, cooling the climate.
A cloud’s impact depends on its altitude (how high it is in the atmosphere), structure, composition (whether it is made of ice or water), and the terrain below (deserts and ice patches are more reflective of solar radiation).
What Are Persistent Contrails?
While cirrus clouds naturally heat the earth, man-made contrails artificially heat the earth.
A contrail’s lifetime depends on the surrounding atmospheric humidity. Low humidity will cause the contrails ice particles to evaporate quickly causing the contrail to disappear quickly and only leave a short trail behind the aircraft.
On the other hand, if the humidity is high, the contrail will be persistent and even expand as the ice particles take on water from the surrounding atmosphere and grow in size.
According to the EPA, persistent contrails can last for hours, grow several kilometers wide, and 200 to 400 meters high.
How Are Persistent Contrails Contributing to Climate Change?
Because clouds play an important role in controlling the earth’s temperature, changes to the earth’s cloudiness may be contributing to long-term changes to our climate.
Persistent contrails, or “aviation induced cloudiness” are increasing the cloudiness of our atmosphere. Aircraft are creating man-made clouds that would not have occurred without the passage of an aircraft. Further, persistent contrails are spreading into naturally existing cirrus clouds making it almost impossible to distinguish man-made from naturally occurring cloudiness.
This is not new science. The EPA has recognized that persistent contrails are impacting the cloudiness and temperature of earth’s atmosphere since at least 2000.
How Can I Help?
Check out the Take Action page to see how you can help end aviation’s climate impact.