From Dr. Roger Pielke Senior: (with apologies to Tattoo)
There is a news article on March 29 2011 from Rueters titled
The text begins with [highlight added]
“Aircraft condensation trails criss-crossing the sky may be warming the planet on a normal day more than the carbon dioxide emitted by all planes since the Wright Brothers’ first flight in 1903, a study said on Tuesday.”
Another excerpt reads
“The study, by experts at the DLR German Aerospace Center, estimated that the net warming effect for the Earth of contrails and related cirrus clouds at any one time was 31 milliwatts per square meter, more than the warming effect of accumulated CO2 from aviation of 28 milliwatts.”
If correct, this is a remarkable finding with respect to contrails as a climate forcing. It also shows that as we study the climate system, we find it is affected by a wider diversity of human climate forcings than concluded by the IPCC. The human effect on the climate system is not dominated by CO2 and a few other greenhouse gases.
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Just a firm reminder, any comment mentioning, referring to, or paraphrasing anything to do with “chemtrails” will be automatically sent to the bit bucket. – Anthony
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How is it possible to isolate the effect of contrails from all the other effects on climate? There are two opposite effects from contrails; first they can reflect some of the sun’s radiation away from the surface, and second they can prevent some radiation from leaving the Earth by reflecting it back down. But which is the greater? I would have thought it was impossible to find out practically, so I assume it was done using a computer programme, in which case it all depends on what data was fed into the programme in the first place.
Further to the comment above IIRC the documentary was called “Global Dimming” and was by the BBC’s Horizon.
No refection of sunlight back out to space then?
I meant reflection…sorry.
One of our grandsons calls them ‘Aeroplane Tails’!
Con-trail = Cloud
Albedo vs GH gas ?
Would the Earth totally covered with cloud be warmer than the Earth with no cloud at all ?
If they waited a few days, it would have been April1.
😉
Anthony – I seem to remember a paper (?) soon after 9/11 which attempted to calculate the effect of vapour trails from aircraft based on observation (taking advantage of the fact that for a couple of days the skies in the US were free of aircraft). I recall the conclusion was that vapour trails had the effect of cooling the atmosphere (by reflecting sunlight).
So that is where the “UnitRoot” has been hiding !!
homo sapiens says:
March 31, 2011 at 12:54 pm
You beat me to it – it is all models.
The same models that say that clouds are positive feedback …
As pointed out by others. This was covered post-9/11. Look up global dimming on wikipedia for a synopsis.
Self-flagellation masquerading as science.
Chemtrails?? I thought that is what came through a straw from a mirror??? Nothing to do with climate or aircraft really.
And here I thought clouds cooled the earth! (I notice a distinct cooling when a cloud drifts by on a hot day.) Are you sure these “researchers” haven’t got their mathematical sign backwards??
This has been busted, or at least there is a peer-reviewed paper that disputes this totally.
The Hong paper made mincemeat out of the whole argument around 9/11 and this paper is just that same issue, but recycled. I didn’t tackle the issue directly, but I do cite the original papers when I was discussing the climate response time.
http://theinconvenientskeptic.com/2011/02/how-quickly-does-the-climate-respond-to-change-part-1/
Have they taken the contrail densities from the USA and extrapolated that to the entire planet? The USA and Western Europe have the densist air corridors, and there are corridors connecting Europe, Asia and the USA. But I would imagine that covers only a few percent of the Earth’s surface. I bet under most of the globe, you would be lucky to catch sight of a single contrail all day.
Simple observations…
Usually, on a nice clear summer morning, the sky is all blue without a trace of vapour or whatever. You can feel the warmth of the sun and you can see your garden being all happy to grow. Then you can see one trail, then another, and another and before noon comes the sky is always covered with a white veil of condensed vapour. Then it gets cooler but more importantly, the amount of photons reaching the surface and exciting the chlorophyll of my tomato plants is significantly reduced. Should they make a study on the effect of contrails on crop yield instead? I bet there should be a significant reduction, much more than a few tenth a degree of warming.
Now, since contrails are mainly found above continents and that the sun can still warm up the oceans, how a somewhat permanent cloud cover above land only should affect the global temperature?
This will never work…
…at least until they figure out a way to tax it
Funny how RAF jets contrails are absolutely… fine.
I think it is disingenious to use merged photos/elapsed time photography to “illustrate” and thus “overstate” the potential impact of contrails that is suggested by yet again another model. And I am with several other commenters, even if this extremely thin layer within the thin layer of the atomosphere does have an effect, I think the albedo effect from a contrail is of greater importance that their ability to hold in heat.
Sorry R. Gates, I don’t see this report in any way being a “strong rebuttal” of my thinking on human impacts on the “earth” – which are at best regional and to which regional actions are perfectly sufficient to address. (Beijing needs to get its pollution under control for its own residents or China’s, and eventually it will, just as LA has/is doing)
Whether it has a warming or cooling effect, file this under HIVES (Human Influenced Variations of Ecological Systems)
[snip – links to a chemtrails website]
It’s worse than we thought! ( humans are having a wider impact on the climate than previously thought)
I have never ever ever been on any holiday or beach or both where any sort of cloud made it warmer. Ever. Whenever the sun comes out from behind any sort of cloud it has always felt warmer and perceivably more than temperatures like 0.92C
My first cross country attempt in a glider ended in a field very near Aldermaston in the UK. What ended it was a very high and thin layer of cloud that came between the sun and the bit of the Earth I was flying over. I was at about 4,000 ft and it took about 5 minutes for the last thermals to come up and then I couldn’t find any lift. The cloud cover was continuous and 6 other gliders landed out at the same time across 2 counties.
If contrails are such a strong positive forcing, and the world hasn’t been warming since 1998, and we also had a growing CO2 positive forcing, this means that without human activities we would be… in an ice age already?
Phew. So let’s book some cheap holiday flights; keep up the good work, fellow humans!
Clouds, including from aircraft, cool the climate. They dont warm it.
O but I forgot – cooling is the new warming, or “disruption”.
Aircraft harm the climate by angering the evil spirits that live in the upper troposphere, who are also responsible for malicious global warming unless offerings of money and human blood are made to appease them.