The white trails left behind by planes in the sky may look harmless, but some of them contribute to global warming. Microsoft founder Bill Gates has highlighted how these trails, known as condensation trails or contrails, trap heat in the atmosphere. Bill Gates recently posted on the website – Gates Notes where he said that preventing certain contrails could eliminate up to 2% of global warming. Gates also explained that while aircraft emissions from burning jet fuel are a major climate concern, they are not the only way planes contribute to rising temperatures. He said some contrails can remain in the sky for hours, spread out and turn into thin clouds that trap heat.Gates said avoiding these trails could be a relatively low-cost way to reduce aviation’s impact on the climate while cleaner aircraft technologies and fuels are still being developed.
How can changing flight paths help prevent warming contrails
Contrails form when water vapour from aircraft engines meets the right combination of cold temperatures and humidity. Water freezes around tiny particles released by the engines, creating ice crystals that form the white trails seen behind planes. Most contrails disappear quickly and have little effect on the climate. However, some persist for hours and spread into high-altitude clouds known as cirrus clouds.These clouds can reflect sunlight back into space, but they also absorb heat that would otherwise escape from Earth.Bill Gates said persistent contrails are responsible for about half of the temperature increase caused by aviation. One way to prevent them is to change flight paths slightly so planes avoid areas of the atmosphere where persistent contrails are likely to form. Bill Gates said airlines could make these adjustments when preparing flight plans, usually four to eight hours before departure.According to Bill Gates, changing the routes of about 5% of flights worldwide could help avoid most of the regions where warming contrails form. He also said the changes could increase fuel use by as little as 0.1% when averaged across all flights.Gates estimated that avoiding contrails could cost less than $10 per tonne of emissions avoided, and possibly around $1 to $2. He compared this with $130 or more per tonne for sustainable aviation fuel, which can reduce the lifecycle emissions associated with flying.
Bill Gates helped start non profit organisation to tackle the trail problem
Bill Gates said the next challenge is making contrail avoidance a standard part of airline operations. He helped start the nonprofit Contrails.org, which is researching the problem and developing free, open-source software to help airlines plan routes.Last year, Contrails.org worked with American Airlines and Google Research on more than 100 flights that used contrail avoidance. Gates also highlighted Operation Blue Skies, a UK government-backed study in which some flights passing through Shanwick airspace, west of the UK, will have their routes adjusted to avoid creating contrails.Gates acknowledged that he also flies on private planes. He said he takes responsibility for reducing the climate impact of his flights by using routes that avoid warming contrails, using sustainable aviation fuel and offsetting his family’s aviation emissions.
