Can Flying Less Help Reduce Emissions?

Written By Teacher: Liz Ransom

As a High School Spanish teacher and student newspaper advisor, Liz has taught for over 20 years and has served as World Languages Department Chair and K-6 summer camp activities leader. She has worked in Ohio, Maine, New Jersey, Maryland, and Chile.

 Getting from point A to point B might seem like a simple calculation, but there’s no doubt that our choices can have an outsized impact on climate change. This topic is suitable for any age group. For example, elementary students can practice their graph interpretation skills while seeking green transportation solutions in this math lesson. Older students can analyze rhetorical devices and the carbon footprint of tourism in this ELA lesson, or explore this multilingual website to discover the connections between aviation and climate justice.

Written By: MIT Environmental Solutions Initiative

The MIT Climate Change Engagement Program, a part of MIT Climate HQ, provides the public with nonpartisan, easy-to-understand, and scientifically-grounded information on climate change and its solutions.

Aviation emissions are responsible for around 5% of climate warming, and this share is rising. In 2015, aircraft burned 240 million metric tons of fuel, releasing about 756 million metric tons of carbon dioxide (CO2). While the fuel economy of aviation is improving at around 1-2% per year, this is being outstripped by growth in travel demand of 4-5% per year. The overall forecast is for aviation emissions to at least double by 2050, in a time frame when the world needs to stop the rise in greenhouse gases in the atmosphere altogether.

A Unique Problem

Aviation is also a unique industry: it is the only major source of emissions high in the atmosphere. These emissions have a very different effect than similar emissions at ground level. When fuel is burned, it results not only in CO2 but also water vapor. This vapor can condense and freeze in the cold higher atmosphere to form artificial, line-shaped clouds behind aircraft called condensation trails, or “contrails”.

These contrails reflect sunlight, which has a cooling effect on the planet, but also trap outgoing heat, causing a warming effect. Since these clouds trap more heat than they reflect, the contrails from planes have a warming effect on the Earth—about as strong as from their CO2 emissions. Night flights cause the most warming since there is no sunlight at night to reflect back into space, so contrails only trap heat.