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CNN - Changing cruise altitudes could cut climate impact in half

Posted: Fri Feb 14, 2020 2:43 pm
by AC333
https://www.cnn.com/travel/article/airp ... index.html

This seems dubious to me - What do you think?

Re: CNN - Changing cruise altitudes could cut climate impact in half

Posted: Fri Feb 14, 2020 3:23 pm
by LDRA
Probably in extreme cases, going from 30kft to 43kft

Re: CNN - Changing cruise altitudes could cut climate impact in half

Posted: Fri Feb 14, 2020 3:24 pm
by atcsundevil
Please stick to aviation discussion here. Discussion about climate change should occur in the Non Aviation Forum.

✈️ atcsundevil

Re: CNN - Changing cruise altitudes could cut climate impact in half

Posted: Fri Feb 14, 2020 3:40 pm
by Francoflier
Interesting. I originally thought that the reflective effect of contrails tended to counteract their tendency to accentuate the greenhouse effect.
I guess not.

I seem to recall a study made during the 2010 Iceland volcano eruption that a net (small) temperature increase was recorded over Europe as a result of the lack of contrails.

Either way, their effect is visibly much greater than we thought.

Re: CNN - Changing cruise altitudes could cut climate impact in half

Posted: Fri Feb 14, 2020 3:43 pm
by flyingturtle
LDRA wrote:
Probably in extreme cases, going from 30kft to 43kft


Nope. The altitude changes required would lead to a minuscule amount of additional fuel burn.

The crux is giving ATC (or the crews) the tools to detect layers of low humidity, so they can avoid contrail-forming conditions, or at least fly at an altitude where contrails would dissipate faster.

Re: CNN - Changing cruise altitudes could cut climate impact in half

Posted: Fri Feb 14, 2020 3:59 pm
by kalvado
Francoflier wrote:
Interesting. I originally thought that the reflective effect of contrails tended to counteract their tendency to accentuate the greenhouse effect.
I guess not.

I seem to recall a study made during the 2010 Iceland volcano eruption that a net (small) temperature increase was recorded over Europe as a result of the lack of contrails.

Either way, their effect is visibly much greater than we thought.

It is also said that in 3 days after 9/11, when no commercial flights over US, daytime vs nighttime temperature difference increased: contrails = extra high altitude clouds; that makes days colder and nights warmer.
Idea is brought up again and again, not sure how big total effect actually is

Re: CNN - Changing cruise altitudes could cut climate impact in half

Posted: Fri Feb 14, 2020 4:01 pm
by YYZYYT
hmmm. seems plausible to me.

My first thought was that they were talking about reducing emissions, but that's not it at all: contrails have the effect of creating a temporary "thermal blanket", which has an unduly large effect on climate, in fact than the effect of the actual emissions. I've attached a link to a paper form Yale which explains it well.

https://e360.yale.edu/features/how-airp ... net-warmer

And it looks like a solution is simple - fly at an altitude where humidity does not promote the formation of contrails. But that is also not so simple, since that altitude is not constant... the suggestion is that aircraft could be fitted with sensors which report data to ATC, so that flight levels are assigned to avoid certain conditions. Possible, although it would adds a layer of complexity to ATC.

One thing that the article did not deal with is the implications for the secret government agency (agencies?) using those contrails to spray mind-control chemicals. Suppressed by the government, no doubt :eek:

Re: CNN - Changing cruise altitudes could cut climate impact in half

Posted: Fri Feb 14, 2020 4:02 pm
by codc10
It would need to be part of a fairly complex algorithm; for instance, cruise altitudes are chosen due to airspace restrictions, fuel economy, aircraft performance, winds aloft, weather, ride comfort, etc. Selecting altitudes based on relative humidity would just be one component of that analysis, which could throw off another factor (like fuel burn), negating an advantage conferred by the reduction of contrails. It also suggests that the top-end "climate damage" savings (59%... of what?) would probably be mitigated as that seems to be derived from optimizing contrail-free cruise altitude to the exclusion of other factors.

It would be an interesting, and compelling layer to add to a futuristic model of an airspace/navigation paradigm, though.

Re: CNN - Changing cruise altitudes could cut climate impact in half

Posted: Fri Feb 14, 2020 4:08 pm
by Blerg
If they want to reduce emissions then maybe the way forward is to remove regional jets from high density routes and to have larger planes fly with fewer frequencies.

Re: CNN - Changing cruise altitudes could cut climate impact in half

Posted: Fri Feb 14, 2020 4:10 pm
by kalvado
YYZYYT wrote:
And it looks like a solution is simple - fly at an altitude where humidity does not promote the formation of contrails. But that is also not so simple, since that altitude is not constant... the suggestion is that aircraft could be fitted with sensors which report data to ATC, so that flight levels are assigned to avoid certain conditions. Possible, although it would adds a layer of complexity to ATC.

On the same token - as far as I know, there is a program when certain aircraft (some WN planes, I believe) carry, effectively, weather stations which collect data for NOAA/ weather service as plane flies. It is said that there is a lot of interesting information - and much more of that than collected by weather balloons (more total time airborne, if nothing else).
So extra instrument suit on board of the aircraft is pretty feasible after all.

Re: CNN - Changing cruise altitudes could cut climate impact in half

Posted: Fri Feb 14, 2020 4:40 pm
by amstone17
atcsundevil wrote:
Please stick to aviation discussion here. Discussion about climate change should occur in the Non Aviation Forum.

✈️ atcsundevil


Odd statement to make, this is an aviation story that happens to have a climate change factor. It belongs here just fine. People want to discuss a proposal to change cruising altitudes for airliners. How is that NOT related to aviation?

Re: CNN - Changing cruise altitudes could cut climate impact in half

Posted: Fri Feb 14, 2020 5:11 pm
by SuseJ772
I find this to be the oddest thing yet out of Climate Change studies. I know I am going to get slammed for this one, but this research is awful and it's conclusion is worse. The idea that changing altitudes to prevent contrails will have any impact on Climate Change is absurd.

Even if we agree with the premise of the research findings (that contrails have a negative impact), the shear amount of contrails in the sky is so infinitesimally small at a square mileage ratio of contrail to total atmosphere (let alone it's cubic mileage ratio), that this would have no overall impact on anything in our ecosystem.

I am not arguing for or against climate change in this. What I am saying is that this research is awful. Also, airlines fly at the most optimized altitudes they can for winds. They have a huge vested interest in using as little fuel as possible. To say that we are going to fly at different altitudes to counteract something that takes up such unbelievably low amount of space (whether square or cubic) at the cost of less optimized winds and more fuel burn is asinine to me. We have all lost it.

Re: CNN - Changing cruise altitudes could cut climate impact in half

Posted: Fri Feb 14, 2020 6:51 pm
by atcsundevil
amstone17 wrote:
atcsundevil wrote:
Please stick to aviation discussion here. Discussion about climate change should occur in the Non Aviation Forum.

✈️ atcsundevil


Odd statement to make, this is an aviation story that happens to have a climate change factor. It belongs here just fine. People want to discuss a proposal to change cruising altitudes for airliners. How is that NOT related to aviation?

I was referring to politically motivated statements about climate change. Several users posted their views on climate change without addressing anything aviation related. Not an odd statement, just reminding users of the rules.

Re: CNN - Changing cruise altitudes could cut climate impact in half

Posted: Fri Feb 14, 2020 8:21 pm
by VirginFlyer
SuseJ772 wrote:
I find this to be the oddest thing yet out of Climate Change studies. I know I am going to get slammed for this one, but this research is awful and it's conclusion is worse. The idea that changing altitudes to prevent contrails will have any impact on Climate Change is absurd.

Even if we agree with the premise of the research findings (that contrails have a negative impact), the shear amount of contrails in the sky is so infinitesimally small at a square mileage ratio of contrail to total atmosphere (let alone it's cubic mileage ratio), that this would have no overall impact on anything in our ecosystem.

I am not arguing for or against climate change in this. What I am saying is that this research is awful. Also, airlines fly at the most optimized altitudes they can for winds. They have a huge vested interest in using as little fuel as possible. To say that we are going to fly at different altitudes to counteract something that takes up such unbelievably low amount of space (whether square or cubic) at the cost of less optimized winds and more fuel burn is asinine to me. We have all lost it.

To borrow another poster’s signature, there is probably a lot more nuance here than has been made out. The study carried out by Travis et al from the University of Wisconsin - Whitewater looming at temperature variations in the days after 11 September 2001 when air traffic was grounded over the USA suggested that contrails reduced the daily temperature range (ie higher lows and lower highs). A number of subsequent studies (I’ve found 4 different papers in a quick Google search) conclude this analysis was not properly controlled for weather conditions and that there was not a causal link demonstrated between the lack of contrails and increased daily temperature variations. I’ve then come across some other papers which continue to posit that contrails can be demonstrated to have an impact.

I would chalk this one up to insufficient data - the only data point being measured was three September days in 2001. It would be necessary to have a longer term lack of contrails to be able to better measure their impact or lack thereof.

V/F

Re: CNN - Changing cruise altitudes could cut climate impact in half

Posted: Fri Feb 14, 2020 8:35 pm
by squakin1200
flyingturtle wrote:
LDRA wrote:
Probably in extreme cases, going from 30kft to 43kft


Nope. The altitude changes required would lead to a minuscule amount of additional fuel burn.

The crux is giving ATC (or the crews) the tools to detect layers of low humidity, so they can avoid contrail-forming conditions, or at least fly at an altitude where contrails would dissipate faster.


Quite the contrary my friend. The contrail altitude thickness can be as much as 10,000 feet. Imagine the contrail altitude on a cold winter day that starts at 28,000 and continues to 38,000. This would mean an airplane originally flying at a fuel burn corresponding to say, 35000 feet would now be flying at 28,000 and below. There is a substantial change in fuel burn at FL280 compares to FL350. For example a 737 flight from LAX-HNL might not make it to the island if it were restricted below FL280. Also, the ground delays associated with restricting all traffic below FL280 for example would be disastrous as many jets would not be able to climb up to the top of the contrail level above 38,000. This idea is good but just not practical.