This is something the military, e.g. fighter jets worry about. The altitudes (in a given airspace) that form contrails are briefed as part of "tactical weather". You try to avoid them if able, because no matter how stealthy you are, you are lit up for all to see if you fly at those altitudes.
Avoiding con-trail creation has been a factor for military aviation since at least WWII; bomber pilots then were briefed on what altitudes to fly at to avoid them as well, but not because they were especially stealthy.
I hate to break it to you, but the individual chem-trails that you can only see with my patented tin foil glasses are more dangerous than the visible ones. If you knew about the people trying to control you, you would know all about this.
Real chemtrails are already invisible. When you see a contrail it's because the jet engines have been poorly maintained to cut costs and increase quarterly returns to the shareholders.
Likewise. In fact, I was under the opposite impression because of the benefit that sulfur enriched shipping exhaust had for our climate [0]. It looks like these clouds are thinner and don't have the same impact as that, though. While I felt that the featured article linked to their favorite site aggressively (four links to contrails.org), it looks like the google site is legitimate [1]. I couldn't find a recent [2] paper on NoAA about contrails, but presumably others have studied it.
Given that the warming impacts of contrails are short-lived (roughly a day), I think it is a good idea to do research now on the weather forecasting needed to avoid producing contrails. But I don't really see a reason to actually start avoiding them now, with the associated costs in terms of fuel, CO2 emissions, and time. We can start avoiding them in a few decades when it might have become urgent to have cooling.
Aren't the impacts perpetual if we're creating new contrails every single day?
Taken from another comment, this seems pretty clear:
> Contrail cirrus may be air traffic's largest radiative forcing component, larger than all CO2 accumulated from aviation, and could triple from a 2006 baseline to 160–180 mW/m2 by 2050 without intervention.
Not sure how you haven't noticed, but climate change is already affecting precipitation and drought patterns, it exacerbates heatwaves, cold snaps, and flooding, it affects harvests, disrupts ecosystems etc. etc. Reducing warming is an urgent matter.
There was a really good section of the article that went into great detail of the math and how it would easily outweigh the CO2. How it would only require something like diverting 2% of all flights as it is only that percentage of flights that make the majority of the contrails and that the diversion of the average flight would be something small like an extra 2 minutes flight time for shorter flights and like 6 minutes on a longer flight which the article states is not much increase in fuel consumption as well as not such a time increase to dissatisfy customers. So if the article is accurate in their math then the associated costs in all three fuel, CO2, and time are not an issue.
The article mentions that some flights produce a net cooling effect. I wonder if it could be cost effective to divert flights toward contrail formation when it's predicted that they'll produce cooling (I also wonder what the actual circumstances are when they produce cooling--low surface temperatures, maybe?).
N2O (laughing gas) is not combustible, but autodecomposes into a mixture composed of 1 part oxygen gas and 2 parts nitrogen gas, which happens to be the approximate composition of the atmosphere.
In theory we could design and use N2O engines and airplanes etc, and their exhaust could be a gas that is nearly equivalent to atmospheric composition.
One important issue is making sure all the N2O has decomposed because it is a very potent GHG.
Would N2 and O2 create contrails? in what sense is it distinct from atmosphere?
Someone can break out their chemistry references, but I think N₂O is probably not workable as a fuel (or at best, not very good). It forms naturally in internal combustion engines, from air, at the temperature and pressures found in engines, given O₂ and N₂. If something has the habit of forming in an engine, I don’t think you could use it as fuel, but my thermodynamics is a bit too rusty to do any kind of ELI5 and I could just be wrong here. At the very least, it would be difficult to use or inefficient.
It decomposes into N₂ and O₂ at normal atmospheric temperatures and pressures, outside an engine.
I'm so confused. This article is explaining that eliminating contrails would have a significant effect on warming.
But contrails are just the tiniest, tiniest fraction of the sky somewhere and only last over a given area for a few minutes generally. Like, sure, if you live next to a busy airport maybe you see them more often, but that's balanced out by the 99.9% of sky not next to a busy airport. Plus the many days that they just don't show up at all, because they depend on certain weather conditions.
I mean, this just doesn't pass the smell test.
But Wikipedia has an entire section [1] full of citations. But then... it sounds like maybe a lot of them aren't credible or suggest that it's not a problem? E.g.:
> However, follow-up studies found that a natural change in cloud cover can more than explain these findings. The authors of a 2008 study wrote, "The variations in high cloud cover, including contrails and contrail-induced cirrus clouds, contribute weakly to the changes in the diurnal temperature range, which is governed primarily by lower altitude clouds, winds, and humidity."
> Then, the global response to the 2020 coronavirus pandemic led to a reduction in global air traffic of nearly 70% relative to 2019. Thus, it provided an extended opportunity to study the impact of contrails on regional and global temperature. Multiple studies found "no significant response of diurnal surface air temperature range" as the result of contrail changes, and either "no net significant global ERF" (effective radiative forcing) or a very small warming effect.
So it sounds like this theoretical contrail warming problem possibly doesn't exist? I find it strange the article doesn't even acknowledge any discussion over whether it's actually a problem in the first place.
> But contrails are just the tiniest
> tiniest fraction of the sky somewhere
Initially yes, but as a contrail diffuses it acts like a seed for wider cirrus cloud formation.
During COVID lockdown, researchers at Universität Leipzig found that the reduction of air travel correspondingly reduced cirrus formation by 9% in the area studied.
Check out satellite images and look at the clouds closely. Or, better still, try and predict rain just from the images. Chances are that you will be predicting a lot more rain or 'overcast days' than what you will get.
I am based in the UK and there are clear flight paths, for example, the big airport is west of London (Heathrow) and a lot of planes fly west to the 'New World'. A typical route will be over the Bristol Channel, which is over water rather than land. If you look at the satellite imagery in the different wavelengths then you will see the whole Bristol Channel 'clouded' with what can only be contrails.
If you are old enough then you might be able to remember 9/11 and the skies in the aftermath, when no planes were flying for quite a few days. The pandemic gave us a glimpse of this too, however, we were shutting down a lot else then.
To summarise, we are pissing in the pool big time with this aviation lark. I appreciate that you can't see it, but I don't think anyone that is heavily car dependent actually will. It is a 'wood for the trees' thing, and, if you are always around cars, trucks and planes, you are in the pool of piss and just not seeing it or smelling it.
You can see this filth if you get out of town, climb a hill and look back. If it is a clear day with a big sky and no wind, then you should be able to see the filthy air above the town, and that isn't from people riding bicycles.
What we have done with cars is to make them more efficient. Nobody is rolling coal any more, well, maybe in South Carolina, but everything was 'rolling coal' with added lead until relatively recent times. There might not be clumps of soot the size of snowflakes in the air, what happens now is that the car dependent person has a vehicle that burns the same amount of fuel as before, but the particle sizes that come out the back are extremely small, so small that you can't see them. But you can see them if you happen to be using a satellite to do so, or if you do get ten miles out of town on a clear day, and look at it properly.
I live in Scotland where we have had an interesting history with air quality. We have a network of paths that are made from former railway lines and canals that take you a long way from cars. There are stretches where you are riding through nothing but flowers for mile after mile. You can also unlock extra adventure levels to find networks of roads that don't exist on Google Maps that are closed to cars but definitely open to bicycles. However, eventually, some big road will need to be crossed or there will be a road running parallel to the trail. Then the magic ends.
What amazes me is how you can get used to the wonderful smells of the truly clean air to then be utterly appalled at how toxic the air is anywhere within a mile of a car. But, inside a car,the air always smells good, right? It is not as if you get tired from carbon monoxide poisoning on longer journeys, is it?
So, does any of this matter? Not if you are young with no health problems. Just suck in the air wherever there is an abundance of vehicles. You will never know what good air is or why it matters. Besides, we all need cars and trucks to get food on our tables, so there is no escaping and it would be hypocritical to do so.
Or you can opt out, to never fly and never drive. I chose this as a challenge and, so far, no regrets. I haven't been on a plane for three decades yet I seem to know more about the world than most frequent fliers. As for not getting into a car, there are occasions such as funerals where I will get a lift, and yes, I do get the occasional item delivered to my door, but everything else? Bicycle, or electric train, powered by wind farms. It seems to me that you can only really assess the problem if you aren't part of it.
Regarding contrails, they have been a conspiracy theorist talking point for as long as the internet has been around. What is pernicious about conspiracy stories is that there is always a small grain of truth in there. All of these hydrocarbons we burn - all of them - are toxic to life and cancer causing. Conspiracy theorists have egged the pudding on this, but who wins from this? Well, it means that anyone with a preference for genuinely clean air, buzzing with bees and wonderful smells from plants, can be branded a crazy person because they must be, right?
> The proposed detours typically result in a 1% shift (and again, this is only for a small percentage of flights). That means increasing fuel use and flight time by around 1%. So if your flight is three hours long, it’s only adding an extra two minutes. For a 10-hour flight, six minutes. This seems socially acceptable to me; most people would barely notice.
Somehow telling airlines to fly what might
be quite a bit longer, in order to avoid
all the different contrail potenial spot,
that will use even more fuel
migth nto be a popoular sell?
Due to the current war airplanes from Northern Europe to Asia are already re-routed, increasing travel time from Helsinki to Japan, for example, from previously some 9.5 hours to up to 13.5 hours.
But there's no physics which can remove heat from a thermal engine, other than shifting the heat to the outside.
(Science fiction books would use "heat sinks" in their war space ships to try to hide the heat for a short while, but would eventually have to dump the heat somewhere. As heat sinks are basically just a huge mass.. not an option for airplanes.)
As someone who lives near a flight path and has clear skies constantly ruined by contrails this would be fantastic from a purely aesthetic perspective.
There are a lot of comments here mocking “chemtrail” believers, but I think the confusion is understandable. There seems to be a mix-up between three terms: contrails, chemtrails, and cloud seeding.
Contrails are just condensation trails caused by jet exhaust and air pressure differences at high altitude.
Cloud seeding, on the other hand, is a real weather-modification technique that uses aircraft to disperse substances like silver iodide to encourage rainfall [1]
I completely empathize with people confused by this. They aren't all just a bunch of conspiracy nuts, many just don’t know how to identify what they’re seeing or how these technologies actually work. I don’t mock them, I try to educate.
The chemtrails conspiracy nuts aren't confused about cloud seeding. They believe contrails are visible evidence that airplanes are used to disperse mind control drugs over the populations below.
Greenhouse gases only interact with specific wavelengths of light. A lot of sunlight comes in as visible or ultraviolet light, mostly passing through those gases. It hits the surface of the Earth and is absorbed and then re-emitted as infrared light, and a lot of that is just the right wavelength for greenhouse gases to interfere. Here's a good article about the physics of this: https://www.quantamagazine.org/the-quantum-mechanics-of-gree...
Basic greenhouse effect: Visible light (and ultraviolet light) comes in relatively unhindered. Gets absorbed by the earth and heats it up. The heat is emitted as infrared radiation. This gets absorbed by CO2 (and equivalents) and reemitted in a random direction. Takes a long time to reach space by chance, so the energy stays in the atmosphere for a while.
The radiation on the way in has a different frequency than on the way out. For example, there is UV included in sunlight. But black body heat at Earth's temperature radiates in infrared. Clouds are very opaque to infrared, and more (though not completely) transparent to UV.
Single particles of radiation coming from the sun have higher energy than single particles radiating from the earth. Even though the total energy entering and leaving earth is at a near equilibrium.
My mental model is that a bullet leaving the barrel of a gun has much more penetrative power than that same bullet once it has ricocheted off a concrete wall.
Because it comes in at a different frequency versus when it goes out. Light, including UV and visible light, hits the ground, then the ground gets warm and radiates in the IR, which can be blocked by clouds.
"Why aren’t we doing more to eliminate contrails?"
I'm just having a hard time groking that contrails are really that impacting. TFA just quotes a bunch of numbers, but does not actually discuss how the numbers were derived. Maybe I've just been around too many people into Chemtrails, but this just reads to me as an offshoot of that type of thinking.
> It is considered that the largest contribution of aviation to climate change comes from contrails. In general, aircraft contrails trap outgoing longwave radiation emitted by the Earth and atmosphere more than they reflect incoming solar radiation, resulting in a net increase in radiative forcing. In 1992, this warming effect was estimated between 3.5 mW/m2 and 17 mW/m2. In 2009, its 2005 value was estimated at 12 mW/m2, based on the reanalysis data, climate models, and radiative transfer codes; with an uncertainty range of 5 to 26 mW/m2, and with a low level of scientific understanding. [...] Contrail cirrus may be air traffic's largest radiative forcing component, larger than all CO2 accumulated from aviation, and could triple from a 2006 baseline to 160–180 mW/m2 by 2050 without intervention.
What I can say is that even in a place with moderate air traffic, you get to see lots of contrails crisscrossing the sky on some days; in places near busy airports I hear that a sizable fraction of all cloud cover is due to lingering contrails.
Contrails observably suppress the Diurnal Temperature Range (i.e. they make it cooler during the day).
How could this be observed you might ask? It turns out there was a study done immediately after the grounding of airplanes during the September 11th, 2001 events to take advantage of this unique incidence of effectively halting all air transportation for a few days [0]
I understand why you're reminded of chemtrails, but it is not crazy or conspiratorial to look at these giant lines in the sky and think "those things must be doing something". You can't then make the leap to "it's intentional and it's a biological weapon to control my mind and I don't need any evidence to believe this", but you can take the next step of looking into decades of research on the topic and deciding if the conclusions make sense to you.
The claims they are making seem slightly at odds with the (I thought well-established) claims that jet emissions cause measurable global “dimming”: that is, that the pollutants reflect enough sunlight that it is accidentally retarding global warming, supporting the concern that necessarily cleaning up our air will briefly accelerate global warming itself. Are they? Or is it also a double whammy?
This was seen to be evident in global pan evaporation measurements after the essentially global flight travel bans in the few days after 9/11; I have often wondered whether the equivalent restrictions in the early days of the pandemic show it as clearly because the impacts on pollution were very striking.
So hard to get done though. Needs global cooperation. The overlap with chemtrails and climate change means Trump might hate it on vibes and ban this correction for US airlines.
Airlines are on wafer thin margins and for the longer turnaround times affecting schedules wont love it. The fact that it is a small % is worse: if you get hit you become less competitive!
Pilots workload is increased too.
Its a great technical idea but not sure how you'd get it off the ground.
In an alternative timeline with a carbon price it may work. You get x$ carbon credits for a detour. Let the planes decide if they want it.
Did I miss the part of the article stating what percentage of all effects this would have? Like if it moves the needle 0.000001% is it worth the effort? Not to play whatabouttism, but the top 8 countries after China (US through Germany) together emit about the same amount of CO2 as China alone. Not saying we shouldn't improve where we can, as the sum of many small efforts helps the whole.
> How, then, do contrails stack up in terms of total warming? They contribute roughly 2% to the world’s effective radiative forcing; tackling them would reduce that by a similar amount.
This is the terrible argument that leads so many countries to do nothing to reduce their emissions. Each country is a small portion of the total so they all do nothing.
The article claims that the warming effect from bouncing heat back down is overall larger than the cooling effect from bouncing heat back up. If you disagree with this assertion, you'll need to say why, not just call someone a liar.
The article does agree that 9% of contrails have an overall cooling effect, and perhaps that could be magnified by a larger or more persistent contrail.
Ah, yes, the solution is to pay someone to do something . An extra 3.50 euro pet flight/passenger to avoid extra contrails, genius money making machine.
the__alchemist|4 months ago
aerostable_slug|4 months ago
https://tridsys.com/our-divisions/optical-precision-sensors/
nickff|4 months ago
aeternum|4 months ago
citizenpaul|4 months ago
anigbrowl|4 months ago
api|4 months ago
You can’t reason (or evidence) someone out of a position that isn’t based on reason.
blipvert|4 months ago
LargoLasskhyfv|4 months ago
Furthermore https://duckduckgo.com/q=toxicologic+assessment+of+jet+fuel
and https://en.wikipedia.org/wiki/Fume_event
Are the fumes less bad, when they don't leak into the cabin by bleed air, just blown away backwards?
The solution to pollution is dilution (in the atmosphere)? With the current amount of global air traffic, no matter if civilian, or military?
anon291|4 months ago
PunchyHamster|4 months ago
nntwozz|4 months ago
lupusreal|4 months ago
apercu|4 months ago
[deleted]
bregma|4 months ago
pavel_lishin|4 months ago
Nzen|4 months ago
[0] https://cpo.noaa.gov/the-unintended-consequences-of-reducing...
[1] https://sites.research.google/gr/contrails/
[2] https://csl.noaa.gov/news/2011/101_0714.html
xnx|4 months ago
https://news.ycombinator.com/item?id=37060347
DominikPeters|4 months ago
evnp|4 months ago
Taken from another comment, this seems pretty clear:
> Contrail cirrus may be air traffic's largest radiative forcing component, larger than all CO2 accumulated from aviation, and could triple from a 2006 baseline to 160–180 mW/m2 by 2050 without intervention.
[1] https://en.wikipedia.org/wiki/Contrail#Impacts_on_climate
The original article describes associated costs in time and fuel usage in the realm of 1% increase.
SupremumLimit|4 months ago
14|4 months ago
wasabi991011|4 months ago
stevage|4 months ago
SyzygyRhythm|4 months ago
stevage|4 months ago
DoctorOetker|4 months ago
In theory we could design and use N2O engines and airplanes etc, and their exhaust could be a gas that is nearly equivalent to atmospheric composition.
One important issue is making sure all the N2O has decomposed because it is a very potent GHG.
Would N2 and O2 create contrails? in what sense is it distinct from atmosphere?
cyberax|4 months ago
It doesn't sound so bad, but when translated into grams, it's 1.86kJ/g for N2O and 13.3kJ/g for water.
In other words, when burning a gram of hydrogen, you get about 120kJ of energy. When decomposing a gram of N2O, you barely get 2kJ.
klodolph|4 months ago
It decomposes into N₂ and O₂ at normal atmospheric temperatures and pressures, outside an engine.
LargoLasskhyfv|4 months ago
crazygringo|4 months ago
But contrails are just the tiniest, tiniest fraction of the sky somewhere and only last over a given area for a few minutes generally. Like, sure, if you live next to a busy airport maybe you see them more often, but that's balanced out by the 99.9% of sky not next to a busy airport. Plus the many days that they just don't show up at all, because they depend on certain weather conditions.
I mean, this just doesn't pass the smell test.
But Wikipedia has an entire section [1] full of citations. But then... it sounds like maybe a lot of them aren't credible or suggest that it's not a problem? E.g.:
> However, follow-up studies found that a natural change in cloud cover can more than explain these findings. The authors of a 2008 study wrote, "The variations in high cloud cover, including contrails and contrail-induced cirrus clouds, contribute weakly to the changes in the diurnal temperature range, which is governed primarily by lower altitude clouds, winds, and humidity."
> Then, the global response to the 2020 coronavirus pandemic led to a reduction in global air traffic of nearly 70% relative to 2019. Thus, it provided an extended opportunity to study the impact of contrails on regional and global temperature. Multiple studies found "no significant response of diurnal surface air temperature range" as the result of contrail changes, and either "no net significant global ERF" (effective radiative forcing) or a very small warming effect.
So it sounds like this theoretical contrail warming problem possibly doesn't exist? I find it strange the article doesn't even acknowledge any discussion over whether it's actually a problem in the first place.
[1] https://en.wikipedia.org/wiki/Contrail#Impacts_on_climate
dingaling|4 months ago
Initially yes, but as a contrail diffuses it acts like a seed for wider cirrus cloud formation.
During COVID lockdown, researchers at Universität Leipzig found that the reduction of air travel correspondingly reduced cirrus formation by 9% in the area studied.
Theodores|4 months ago
I am based in the UK and there are clear flight paths, for example, the big airport is west of London (Heathrow) and a lot of planes fly west to the 'New World'. A typical route will be over the Bristol Channel, which is over water rather than land. If you look at the satellite imagery in the different wavelengths then you will see the whole Bristol Channel 'clouded' with what can only be contrails.
If you are old enough then you might be able to remember 9/11 and the skies in the aftermath, when no planes were flying for quite a few days. The pandemic gave us a glimpse of this too, however, we were shutting down a lot else then.
To summarise, we are pissing in the pool big time with this aviation lark. I appreciate that you can't see it, but I don't think anyone that is heavily car dependent actually will. It is a 'wood for the trees' thing, and, if you are always around cars, trucks and planes, you are in the pool of piss and just not seeing it or smelling it.
You can see this filth if you get out of town, climb a hill and look back. If it is a clear day with a big sky and no wind, then you should be able to see the filthy air above the town, and that isn't from people riding bicycles.
What we have done with cars is to make them more efficient. Nobody is rolling coal any more, well, maybe in South Carolina, but everything was 'rolling coal' with added lead until relatively recent times. There might not be clumps of soot the size of snowflakes in the air, what happens now is that the car dependent person has a vehicle that burns the same amount of fuel as before, but the particle sizes that come out the back are extremely small, so small that you can't see them. But you can see them if you happen to be using a satellite to do so, or if you do get ten miles out of town on a clear day, and look at it properly.
I live in Scotland where we have had an interesting history with air quality. We have a network of paths that are made from former railway lines and canals that take you a long way from cars. There are stretches where you are riding through nothing but flowers for mile after mile. You can also unlock extra adventure levels to find networks of roads that don't exist on Google Maps that are closed to cars but definitely open to bicycles. However, eventually, some big road will need to be crossed or there will be a road running parallel to the trail. Then the magic ends.
What amazes me is how you can get used to the wonderful smells of the truly clean air to then be utterly appalled at how toxic the air is anywhere within a mile of a car. But, inside a car,the air always smells good, right? It is not as if you get tired from carbon monoxide poisoning on longer journeys, is it?
So, does any of this matter? Not if you are young with no health problems. Just suck in the air wherever there is an abundance of vehicles. You will never know what good air is or why it matters. Besides, we all need cars and trucks to get food on our tables, so there is no escaping and it would be hypocritical to do so.
Or you can opt out, to never fly and never drive. I chose this as a challenge and, so far, no regrets. I haven't been on a plane for three decades yet I seem to know more about the world than most frequent fliers. As for not getting into a car, there are occasions such as funerals where I will get a lift, and yes, I do get the occasional item delivered to my door, but everything else? Bicycle, or electric train, powered by wind farms. It seems to me that you can only really assess the problem if you aren't part of it.
Regarding contrails, they have been a conspiracy theorist talking point for as long as the internet has been around. What is pernicious about conspiracy stories is that there is always a small grain of truth in there. All of these hydrocarbons we burn - all of them - are toxic to life and cancer causing. Conspiracy theorists have egged the pudding on this, but who wins from this? Well, it means that anyone with a preference for genuinely clean air, buzzing with bees and wonderful smells from plants, can be branded a crazy person because they must be, right?
ZeroGravitas|4 months ago
I wonder if factoring in the contrail reduction of this tilts them towards financial breakeven.
edit: Googled it and an Airbus test last year suggested a 25% decrease in contrail formation:
https://www.airbus.com/en/newsroom/press-releases/2024-06-wo...
rafa___|4 months ago
gcanyon|4 months ago
jagged-chisel|4 months ago
steanne|4 months ago
unknown|4 months ago
[deleted]
stevage|4 months ago
ThinkBeat|4 months ago
Tor3|4 months ago
fragmede|4 months ago
unknown|4 months ago
[deleted]
alberth|4 months ago
Then learned it’s just about rerouting a flight to climate zones that will less likely form a vapor trail.
Tor3|4 months ago
(Science fiction books would use "heat sinks" in their war space ships to try to hide the heat for a short while, but would eventually have to dump the heat somewhere. As heat sinks are basically just a huge mass.. not an option for airplanes.)
padjo|4 months ago
dustfinger|4 months ago
Contrails are just condensation trails caused by jet exhaust and air pressure differences at high altitude.
Cloud seeding, on the other hand, is a real weather-modification technique that uses aircraft to disperse substances like silver iodide to encourage rainfall [1]
I completely empathize with people confused by this. They aren't all just a bunch of conspiracy nuts, many just don’t know how to identify what they’re seeing or how these technologies actually work. I don’t mock them, I try to educate.
[1]: https://en.wikipedia.org/wiki/Cloud_seeding
greekrich92|4 months ago
imgabe|4 months ago
burkaman|4 months ago
continuational|4 months ago
cvoss|4 months ago
justonceokay|4 months ago
My mental model is that a bullet leaving the barrel of a gun has much more penetrative power than that same bullet once it has ricocheted off a concrete wall.
tejtm|4 months ago
More directly,radiation (light,photons) is absorbed and re-emmited by matter but the re-emitted energy is always at a lower frequency.
This absorbed & re-emitted longer wavelength radiation is what can become trapped.
vamin|4 months ago
dylan604|4 months ago
I'm just having a hard time groking that contrails are really that impacting. TFA just quotes a bunch of numbers, but does not actually discuss how the numbers were derived. Maybe I've just been around too many people into Chemtrails, but this just reads to me as an offshoot of that type of thinking.
DemocracyFTW2|4 months ago
> It is considered that the largest contribution of aviation to climate change comes from contrails. In general, aircraft contrails trap outgoing longwave radiation emitted by the Earth and atmosphere more than they reflect incoming solar radiation, resulting in a net increase in radiative forcing. In 1992, this warming effect was estimated between 3.5 mW/m2 and 17 mW/m2. In 2009, its 2005 value was estimated at 12 mW/m2, based on the reanalysis data, climate models, and radiative transfer codes; with an uncertainty range of 5 to 26 mW/m2, and with a low level of scientific understanding. [...] Contrail cirrus may be air traffic's largest radiative forcing component, larger than all CO2 accumulated from aviation, and could triple from a 2006 baseline to 160–180 mW/m2 by 2050 without intervention.
What I can say is that even in a place with moderate air traffic, you get to see lots of contrails crisscrossing the sky on some days; in places near busy airports I hear that a sizable fraction of all cloud cover is due to lingering contrails.
[1] https://en.wikipedia.org/wiki/Contrail#Impacts_on_climate
roadside_picnic|4 months ago
How could this be observed you might ask? It turns out there was a study done immediately after the grounding of airplanes during the September 11th, 2001 events to take advantage of this unique incidence of effectively halting all air transportation for a few days [0]
0. https://journals.ametsoc.org/view/journals/clim/17/5/1520-04...
readthenotes1|4 months ago
https://globalnews.ca/news/2934513/empty-skies-after-911-set...
jvanderbot|4 months ago
unknown|4 months ago
[deleted]
burkaman|4 months ago
And also this paper which is a very in-depth technical explanation: https://www.sciencedirect.com/science/article/pii/S135223102...
I understand why you're reminded of chemtrails, but it is not crazy or conspiratorial to look at these giant lines in the sky and think "those things must be doing something". You can't then make the leap to "it's intentional and it's a biological weapon to control my mind and I don't need any evidence to believe this", but you can take the next step of looking into decades of research on the topic and deciding if the conclusions make sense to you.
exasperaited|4 months ago
This was seen to be evident in global pan evaporation measurements after the essentially global flight travel bans in the few days after 9/11; I have often wondered whether the equivalent restrictions in the early days of the pandemic show it as clearly because the impacts on pollution were very striking.
hshdhdhehd|4 months ago
Airlines are on wafer thin margins and for the longer turnaround times affecting schedules wont love it. The fact that it is a small % is worse: if you get hit you become less competitive!
Pilots workload is increased too.
Its a great technical idea but not sure how you'd get it off the ground.
In an alternative timeline with a carbon price it may work. You get x$ carbon credits for a detour. Let the planes decide if they want it.
exabrial|4 months ago
maltyr|4 months ago
unknown|4 months ago
[deleted]
Oarch|4 months ago
If it was even 1% we'd surely be up in arms about how awful it looked.
squokko|4 months ago
unknown|4 months ago
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infradig|4 months ago
stevage|4 months ago
smakt|4 months ago
unknown|4 months ago
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huflungdung|4 months ago
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huvarda|4 months ago
phoehne|4 months ago
pfannkuchen|4 months ago
NedF|4 months ago
sfink|4 months ago
The article does agree that 9% of contrails have an overall cooling effect, and perhaps that could be magnified by a larger or more persistent contrail.
stevage|4 months ago
bitwize|4 months ago
cosmin800|4 months ago