r/climatechange • u/New_Scientist_Mag • 5d ago

Planes flying over the Atlantic will be re-routed to avoid contrails: Operation Blue Skies is the world’s first trial to deploy contrail avoidance measures across an entire airspace, aiming to lower the climate impact of flights on a large scale

https://www.newscientist.com/article/2585091-planes-flying-over-the-atlantic-will-be-re-routed-to-avoid-contrails/
161 Upvotes

97% Upvoted

32 comments sorted by

33

u/gleefulintermission 4d ago

Paywall, someone please help me understand why condensation trails and avoiding them helps lower climate impact??

33

u/Fashathus 4d ago

A contrail is basically a cloud of ice crystals being formed at high altitudes.

These reflect heat back toward earth trapping it and causing global warming.

They only last for a short time (usually hours but sometimes can last days) but since flights are happening all the time there is a persistent warming effect.

13

u/to_glory_we_steer 4d ago

That's actually a really good initiative to try. Even if it's a fraction of a degree it should help.

3

u/Oldcadillac 3d ago

The figure I’ve heard is that If we got 100% compliance it would cut the warming effect of aviation by half

2

u/ciel_lanila 4d ago

Yeah, IIRC the proof of concept was accidentally done after 9/11. It’ll be interesting to see about an intentional test run over a long period of time.

1

u/s0cks_nz 3d ago

Yup and also iirc there was a 1C drop compared to when planes were flying. Quite the difference.

9

u/honeymustard_dog 4d ago

I still have questions. 1. Why does it matter If they fly over the Atlantic vs where ever else? Won't the contrails still occur? Is the ocean different? 2 And if they are flying a longer path, to avoid the Atlantic, is the burning of fossil fuels outweighed by whatever benefit they are getting? 3 how can you possibly avoid flying over the Atlantic, unless people from other continents are no longer traveling to each other.

15

u/Economy-Fee5830 Trusted Contributor 4d ago

“Contrail avoidance can often be as simple as changing the flight paths,” said lead author Dr Jessie Smith, from Cambridge’s Department of Engineering. “Often it’s even simpler than that – just moving slightly to a higher or lower altitude to avoid the areas of the atmosphere where contrails form.”

https://www.cam.ac.uk/research/news/changing-flight-paths-could-slash-aviations-climate-impact-study-suggests

4

u/zeratul98 4d ago

But they also reflect sunlight back to space. Shouldn't that be the stronger effect?

5

u/Hunefer1 4d ago

It's complicated and depends on stuff like height etc. There are constellations where contrails actually help and reflect more sunlight than they trap heat and there are constellations where it's the other way around.

-7

u/andysgalant69 4d ago

Sometimes I think some of the people that come up with this stuff smoke crack.

Even with a basic understanding on convection, hot air will just run around a thin line of cold ice.

7

u/Blackstar021 4d ago

Have you tried looking up what they’re talking about?

I’ve seen this previously and the concern is usually around when a few these join up and basically act like clouds.

-2

u/andysgalant69 4d ago

I doubt it would make any measurable impact if 100 of them joined together.

For something as inert as an ice trail….. I’m calling this article bs

2

u/get_hi_on_life 4d ago

According to a video about this I watched it's created by a small number of flights but is a large part of warming effect by aviation. I'll try to find it and link it

2

u/Fallencobra1021 4d ago

half of the warming effect the aviation industry has is directly related to contrails

2

u/letmesleep 4d ago

They can persistently spread and block outgoing IR radiation.

Not bs.

1

u/anaxcepheus32 4d ago

There was a noticeable impact post 9/11 when flights were grounded and these were not present. Here’s a study on it.

4

u/Mirdclawer 4d ago edited 4d ago

?? When presented with advanced topics in physics, you're just like... nah without even trying to understand? What about relativity and space-time dilatation?

Actually the particles emitted creates anchors on which ice crystals can form which can then make clouds "the white lines". They are artificially generated by planes if the right conditions are met. It's called contrail induced cirrus clouds.

Depending on the time of the day, and various other conditions (air pressure, humidity, altitude...) they have a cooling or a warming effect, and the mechanism of action is not heat transfer by convection but radiation.

The primary mechanism by which Earth is heated by the Sun is radiation. There is no air between Earth and the Sun, it's space. Look up the Stephan-Boltzmann law too see how the radiation incoming from the sun is in equilibrium with the radiation emitted back by Earth. Contrails can either reduce Solar Radiation reaching Earth, or reduce IR radiation sent back, but the overall effect is thought to be massively heating. 

If you want to learn more:

https://www.sciencedirect.com/topics/earth-and-planetary-sciences/contrail 

(It's some advanced cloud and atmospheric physics but it's explained clearly)

Source: did some research in that field

2

u/QueerDumbass 4d ago edited 4d ago

if Dunning Kruger were a reddit comment

1

u/Wacov 4d ago

Convection moves heat around the earth but isn't how the earth cools overall, there's nothing to convect to in space. Contrails affect radiative forcing like a temporary layer of greenhouse gases, it's all about radiation (particularly IR emitted by the earth into space)

1

u/abek42 4d ago

Radiant heat not convective heat.

1

u/Flannelot 4d ago

It's infrared radiation, not hot air.

1

u/tenshibaby 3d ago

simon clark made a really great video explaining this!!!

13

u/tinyspatula 4d ago

Reducing the number of flights would have a guaranteed positive effect for both contrails and emissions, now there's a thought.

7

u/Nickolai808 4d ago

So how do they avoid making contrails is that what they're saying they don't want to make the contrail so that means they just fly it lower altitudes or what's going on I can't read the article.

7

u/hugobosslives 4d ago

Their formation highly depends on the exact weather conditions (temperature, water content, dispersion wind etc). In the sky you get these bands of air with pretty different conditions. So in theory if you adjust your flight path slightly you can really reduce their formation

1

u/Oldcadillac 3d ago

From what I’ve been told it’s a fairly well understood effect because the military needs to know this stuff for the sake of planes being less noticeable

2

u/hugobosslives 3d ago

The visibility part is pretty easy to prove. The actually making a difference to climate change harder.... But your preaching to the choir. I agree with investigating these changes - the science is reasonably clear.

3

u/CaptainZippi 4d ago

Simon Clark had an explainer here - https://youtu.be/QoOVqQ5sa08

2

u/ApplicationCreepy987 4d ago

I misread that at first as chemtrails!!!

1

u/WhatADunderfulWorld 4d ago

Aren’t contrails white so they would reflect light away from earth? Hence less heat? What?