Belfrey
Senior Member.
Sure there's some reason for concern, that's the main reason why scientists have been studying them and publishing papers about them for several decades.
Debunked: Belfort Group "Case Orange" conclusions & recommendations
- Thread starter Jay Reynolds
- Start date
Sure there's some reason for concern, that's the main reason why scientists have been studying them and publishing papers about them for several decades.
Classified
New Member
That is correct, the exhaust is always there. Also the contrails can transition into cirrus and uncinus clouds creating a temperature increase.
So if we are facing global warming, why aren't you against contrails being stopped Mick?External Quote:
Since the Intergovernmental Panel on Climate Change (IPCC) special report on Aviation and the Global Atmosphere (1999) it has been widely accepted that contrails, and the cirrus clouds they may form have a climate impact comparable to the CO2 from the combustion process. These additional clouds reduce the incoming solar radiation as well as the outgoing thermal radiation in a way that the mean net balance at top of the atmosphere is slightly positive—i.e. they add to the greenhouse effect (Meerkötter et al., 1999). 1
A note on how to avoid contrail cirrus
- Deutsches Zentrum für Luft- und Raumfahrt, Institut für Physik der Atmosphäre, Oberpfaffenhofen, 82230 Weßling, Germany
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I'm not against it. It's just not clear that it's a good use of resources, or if it can be done without additional pollution. See:
http://contrailscience.com/contrail-avoidance-and-mitigation-techniques/
I'd rather spend money on reducing carbon emissions.
Classified
New Member
If there is research suggesting that contrail cirrus effects are comparable to the Co2 output, shouldn't we be questioning why contrails are still being produced?
Does reducing carbon emissions change the fact that contrails heat the earth?
MikeC
Closed Account
the question why contrails are produced is easy to answer - because the alternative are to burn more fuel or restrict the amount of air traffic allowed - even to the point of doign away with it.
Airliners fly as high as they can - that saves a lot of fuel. By flying lower you can avoid contrails, but you burn a lot more fuel.
Airliners fly as high as they can - that saves a lot of fuel. By flying lower you can avoid contrails, but you burn a lot more fuel.
If contrails have an effect, then it could be stopped in a matter of hours.
Carbon on the other hand will have an effect that lasts for decades. So given that the radiative forcing effect of contrails is both uncertain and small, then I think the focus should be reducing carbon.
See "Linear Contrails" here:
This is something that IS being questioned, a lot, by lots of scientists, for many years.
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F4Jock
Senior Member.
Stop heating your house. It heats the earth. Stop driving. No matter what you drive it heats the earth. Stop doing laundry. It heats the earth. Turn off everything electric. It heats the earth. Go back to spears and loincloths with lots of lice and ....No wait. Stop breathing. It heats the earth! And almost everything we do emits carbon ......
Ok it's hyperbole but where do you propose we stop?
TWCobra
Senior Member.
In countries like the US, Australia and over Europe most flights try, dependent on the route length, to fly between FL 330 and FL410. They start lower and climb as fuel is burnt off.
When I fly transcontinental in Australia, we rarely fly below FL380 and usually finish the flight at FL 400 or FL 410.
Forcing flights like that to cruise say at FL 310 to avoid making a contrail increases the fuel burn by approx 20% in a A330. That's 20% percent more CO2 created. That 20% increase would be roughly identical for most current airliners.
So while the cost of fuel is a factor, the benefit of reducing contrails re: global warming may simply not be there.
When I fly transcontinental in Australia, we rarely fly below FL380 and usually finish the flight at FL 400 or FL 410.
Forcing flights like that to cruise say at FL 310 to avoid making a contrail increases the fuel burn by approx 20% in a A330. That's 20% percent more CO2 created. That 20% increase would be roughly identical for most current airliners.
So while the cost of fuel is a factor, the benefit of reducing contrails re: global warming may simply not be there.
Classified
New Member
If contrails have an effect, then it could be stopped in a matter of hours.
Carbon on the other hand will have an effect that lasts for decades. So given that the radiative forcing effect of contrails is both uncertain and small, then I think the focus should be reducing carbon.
See "Linear Contrails" here:
This is something that IS being questioned, a lot, by lots of scientists, for many years.
That is an interesting chart, however linear contrails do not include contrail cirrus or contrail uncinus, correct?
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Cairenn
Senior Member.
And in spite of your insistence that contrails are WARMING the planet, the study after 9/11 showed a very slight WARMING without contrails.
Another poster here mentioned that a cirrus cloud cover can reduce thermals needed for gliders.
Low clouds tend to have a warming effect on the surface.
Another poster here mentioned that a cirrus cloud cover can reduce thermals needed for gliders.
Low clouds tend to have a warming effect on the surface.
George B
Extinct but not forgotten Staff Member
I will go out on a limb without the appropriate cited authority but I believe clouds with higher optical density in the lower troposphere are thought to exert a net cooling effect and the lower optical density clouds in the upper troposphere like cirrus clouds have a net warming effect . . . whether it is night or day also plays a role . . . clouds at night can help to reflect long wave radiation back to ground level and trap heat especially in the winter . . .
lotek
Active Member
cairenn, wasnt that cited elsewhere here as having reason to think there was really zero net effect shown by the study or am i thinking of a different one? or atleast it was within the statistical range too close to consider valid? i cant remember who pointed it out but i swear there was a "oh by the way this whole thing is probably invalid because" moment pointed out by the researchers in the conclusion. may be a different subject tho.
Classified
New Member
"Although most investigators favor the finding that contrail cirrus produce atmospheric warming on regional scales in the United States and Europe, the impact on global warming is still in the noise. Should aircraft activity increase as projected, the global effects
would become significant by 2050."
http://journals.ametsoc.org/doi/pdf/10.1175/JAM2325.1
"These additional clouds reduce the incoming solar radiation as well as the outgoing thermal radiation in a way that the mean net balance at top of the atmosphere is slightly positive—i.e. they add to the greenhouse effect" (Meerkötter et al., 1999). 1
A note on how to avoid contrail cirrus
- Hermann Mannstein
, 
, - Peter Spichtinger,
- Klaus Gierens
Are you still claiming contrails have an overall cooling effect Cairenn? How much misinformation do you spread on this website?
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Met Watch
Moderator
"Although most investigators favor the finding that contrail cirrus produce atmospheric warming on regional scales in the United States and Europe, the impact on global warming is still in the noise. Should aircraft activity increase as projected, the global effects
would become significant by 2050."
http://journals.ametsoc.org/doi/pdf/10.1175/JAM2325.1
"These additional clouds reduce the incoming solar radiation as well as the outgoing thermal radiation in a way that the mean net balance at top of the atmosphere is slightly positive—i.e. they add to the greenhouse effect" (Meerkötter et al., 1999). 1
A note on how to avoid contrail cirrus
- Hermann Mannstein
- Peter Spichtinger,
- Klaus Gierens
Are you still claiming contrails have an overall cooling effect Cairenn? How much misinformation do you spread on this website?
I think she's showing that warming has occurred without any contrail activity at all, to the point that the cause warming can not be successfully directly tied to contrails. I didn't see any mention of cooling at all.
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Cairenn
Senior Member.
But as it was pointed out to you, that reducing the contrails would INCREASE the carbon emissions
Sorry, I NEVER claimed that. I pointed out that when there was an absence of them the temperature went up a tiny bit.
Another poster mentioned their effect on thermals.
Their presence seems to be have a micro effect, either way on LOCAL weather. The ocean is STILL far more important to overall weather patterns. So are greenhouse gases. In fact so are cows.
Sorry, I NEVER claimed that. I pointed out that when there was an absence of them the temperature went up a tiny bit.
Another poster mentioned their effect on thermals.
Their presence seems to be have a micro effect, either way on LOCAL weather. The ocean is STILL far more important to overall weather patterns. So are greenhouse gases. In fact so are cows.
Jazzy
Closed Account
Yes. Disappointing isn't it? It all happened while I slept. Good job, Mick.
F4Jock
Senior Member.
"Although most investigators favor the finding that contrail cirrus produce atmospheric warming on regional scales in the United States and Europe, the impact on global warming is still in the noise. Should aircraft activity increase as projected, the global effects
would become significant by 2050."
http://journals.ametsoc.org/doi/pdf/10.1175/JAM2325.1
"These additional clouds reduce the incoming solar radiation as well as the outgoing thermal radiation in a way that the mean net balance at top of the atmosphere is slightly positive—i.e. they add to the greenhouse effect" (Meerkötter et al., 1999). 1
A note on how to avoid contrail cirrus
- Hermann Mannstein
- Peter Spichtinger,
- Klaus Gierens
Are you still claiming contrails have an overall cooling effect Cairenn? How much misinformation do you spread on this website?
Have you not noticed the caveats in the language of your citations? "Most." "Should." "As projected." Seems that the science is not definitive at this point. As well, the unwritten assumption is that aircraft engine design will remain static in the ensuing 37 years......
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Jazzy
Closed Account
"increase as expected"
That would be exponentially, with a doubling time every 12 yrs. Meaning EIGHT TIMES MORE aviation by 2050. Ballpark figures.
"Significant"
That would be the statistical use of the word, meaning "possible to mathematically distinguish from no effect at all". For sure, so-to-speak.
Nobody in your quotes was considering the global atmospheric temperature rise attributable to the 700% increase in aviation-created carbon dioxide to the atmosphere that this prediction entails.
Nobody in the future is going to be able to spot much blue skies. They will be brief periods between storms.
In the meanwhile there are better things to consider other than ameliorating whiteouts. Let alone poisoning myths.
George B
Extinct but not forgotten Staff Member
Seems to me the large body of reaearch done over the years by the EPA, FAA, DoE, NOAA, NASA, and their European counterparts regarding persistent contrails raises a red flag IMO. . . if so insignificant way all the fuss and bother ?
Because it's unknown how significant it is. Most of the research is about trying to understand the atmosphere in more detail. Look at the ranges of uncertainty on the various charts of radiative forcing. The thin lines are the range of uncertainty. It's very important to make those lines shorter, so we know what's the best course of action.
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That does not sound right. Where did you get that from?
George B
Extinct but not forgotten Staff Member
1) Thanks for emphasizing uncertainty. . . I would also add . . . if significant potential for climatic alteration did not exist the "Uncertainty" would not generate inquiry. . .Because it's unknown how significant it is. Most of the research is about trying to understand the atmosphere in more detail. Look at the ranges of uncertainty on the various charts of radiative forcing. The thin lines are the range of uncertainty. It's very important to make those lines shorter, so we know what's the best course of action.
2) Is it possible that the threshold or tipping point is so narrow that something like increased albedo or net warming from a growing industry may be the straw that breaks the camels back. . . ?
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If you mean geoengineering, then I disagree. The uncertainty would still be an important factor even if our only option was to reduce carbon emissions.
Jazzy
Closed Account
The title of the paper was on the constituents of a contrail. Predictions made by such papers (this was a paragraph in the summary) are part of the scientific method, and could form the basis of future research, not just to verify whether the prediction was accurate, but also of cross-disciplinary nature, to confirm other research findings, or fill in gaps of understanding. This paper came with a page of prior research references.
People who spend their time in politics never make it to atmospheric scientist. Hanson has demonstrated the reverse to be true as well, unfortunately.
Let's not argue they conspire with the PTB to produce Marshall Institute claptrap, eh?
George B
Extinct but not forgotten Staff Member
I was not arguing geo-engineering . . .simply a growth industry. . . a fear for a razors edge between business as usual and potential crisis . . .
Jazzy
Closed Account
See:
http://legacy.icao.int/icao/en/env2010/Pubs/EnvReport2010/ICAO_EnvReport10-Outlook_en.pdf
Projects 4.8% per year through 2036, still higher than I thought. Doubling ever 15 years. (1.048^15 = 2.02)
That's passenger traffic, contrail cover increase might be less if there's more big jets in use.
Classified
New Member
Please dont try to change what you said now that you realize you were wrong. Your words were-
"And in spite of your insistence that contrails are WARMING the planet"
So now I insist again Cairenn. Contrails are warming the planet. [...]
Classified
New Member
So I am very curious Mick. If you are concerned only with truth and accuracy, why do you allow users like Cairenn to constantly spout misinformation without any recourse from you?
Why do you continue to claim contrails are just ice, yet heres an FAA study showing a young contrail to contain more than just ice.
So when does the actual debunking occur Mick? Why leave out so many facts?
Why do you continue to claim contrails are just ice, yet heres an FAA study showing a young contrail to contain more than just ice.
http://www.faa.gov/about/office_org...d_modeling/accri/media/ACCRI_SSWP_VI_PING.pdfExternal Quote:
So when does the actual debunking occur Mick? Why leave out so many facts?
Jay Reynolds
Senior Member.
An even younger contrail contains nearly no ice at all, mostly steam and ordinary exhaust products like cars and trains do . Contrails do have a range of composition depending on age. This is quite ordinary and is relevant as it pertains to the chemtrails hoax. That meme claims that contrails always behave the same, never grow, always dissipate quickly, etc..
There is no dispute that contrails accrete moisture from the air and grow by 4 orders magnitude from water vapor already in the air. That is why a young contrail will contain more soot etc than an aged contrail.
The problem is, 'Classified' is actually debunking people like Michael Murphy and Dane Wigington by bringing out some of the facts about known contrail characteristics.
And, of course the visible portion of all contrails is the ice. So, why haven't you shown us what the ordinary mineral dust contribution of barium in the atmosphere actually is?
I'm not actually sure what facts are being left out? And if they are left out, then why can't you just add them with references, like you just did.
Say contrails are "just ice" is a bit semantic. One could argue that the other stuff is just part of the jet exhaust, which is there anyway even if the contrail is not. But either way, nobody dispute the presence of CCN in contrails.
Jazzy
Closed Account
Contrails are NOT warming the planet. The solar energy they reflect during the day is somewhat greater than the thermal back radiation they trap during the night. One of the reasons is the difference in the number of flights between day and night, and the fact that the trails are always falling downwards into lower altitudes and temperatures where they can evaporate. It's a close run thing.
Cairenn is more correct about this than you are. Calls to Mick are only going to get you into trouble with many of us.
The contrails are warming the planet indirectly because to produce a trail (or even NO trail) is always to release a stream of CO2, and if you had any scientific judgment you would concentrate on this, because it is by far the greater effect, being SEMI-PERMANENT, whereas ALL TRAILS ARE TEMPORARY.
Try and be reasonable, will you?
As for the carbon and unburnt hydrocarbon content of any trail, this diagram may well suffice.
The figures are typical for about 15 years ago. I dare say there will be a further marginal reduction in soot and UHCs with the improvements there have been in compressor aerodynamics, injector nozzle design, and combustion chamber thermodynamics, but higher combustion temperatures may well involve a marginal increase in NOx.
The higher the combustion temperature, the more efficient such engines can be. They "run cooler" because the core combustion system is admixed with 300% compressed air which cools this exhaust temperature as it causes massive low-grade heat expansion, which is why such engines are so devastatingly efficient.
But we are going to get ourselves a much greater increase in NOx anyway, as anthropogenic warming speeds up all our thunderstorms.
George B
Extinct but not forgotten Staff Member
Hmmmm. . . seems persistent contrails are either blooming or they are not regardless of the CO2, NOx, Sulfur, H2O, etc. that they inject into the Troposphere and lower reaches of the Stratosphere (their amounts are a given and are background noise and cannot be reduced without ceasing or reducing flights) . . . the issue to me is whether there are blooms of cirrus clouds and cirrus cloud banks propagated . . . these beasties have the highest likelihood of causing an additional net warming effect (admittedly temporary but increasing in frequency and easy to mitigate and thereby manageable if desired) . . . an analogy is a full tub of water . . . the most important water is the last that goes into it . . . this last additional water goes over the rim and floods the bathroom . . .
The ICOA report I linked above goes into some details about projected future emission, accounting for improvements in engine tech.
http://legacy.icao.int/icao/en/env2010/Pubs/EnvReport2010/ICAO_EnvReport10-Outlook_en.pdf
Belfrey
Senior Member.
To be fair, the research does not seem to be settled on this question - I have seen a few research papers which conclude that the net radiative effect is small but positive, with the night heat trapping effect somewhat greater than the day reflection.
Jazzy
Closed Account
I agree it's much of a muchness. There are more daytime than night-time flights, which probably redresses the balance. I was really calling out Classified's wild pomposity as too much, which it was.
Jazzy
Closed Account
I love the (for me) new term of "aspirational goal". Thanks.
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