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
This is why you should live in Australia. Virtually no contrails in the sky – sunny days stay sunny.
According to Gore, the US warmed up when Bush grounded all flights.
Al said so in his film.
So contrails cannot warm the Earth, they must shade it.
Tolja tolja tolja. Can I rest on my laurels now? (No — gets kicked)
I remembered a comment from George E. Smith in a thread last year
http://wattsupwiththat.com/2010/05/27/royal-society-to-review-climate-consensus-position/#comment-398653
that pretty much settled the feedback by height issue. Best was the IPCC-1-50-50 cloud for Intergovernmental Propaganda Concensus Cloud definition.
I live under a a busy air corridor in Pembrokeshire, UK. During the occasional warm and sunny day during summer I bring out my solar oven and attempt to cook my favourite dish, oxtail. It must be an absolutely clear blue sky overhead for successful cooking. If there is any indication of persistent contrails overhead I won’t attempt it as I know the temperature in the solar oven drops well below cooking level if that contrail moves between the sun and my oven.
On the basis of that experience I am inclined to consign the above article to the BS bin.
I understood that the temperature ‘shift’ that apparently took place in the US after 9/11 was the same in Canada that had no restrictions on flights. Can anyone confirm this?
Also, it seems to me that the transient nature of con trails means that comparison with CO2 it not realistic. I assume the photograph is either totally fake or taken in a way that doesn’t represent a true instant in time.
Les Francis wrote:
“During WWII there were hundreds of planes flying in formations leaving massive contrails. Is there any data showing any temperature anomalies at that time?”
Didn’t most aircraft then fly at lower altitudes than modern jets do? If that was so then the effect, if any, on temperatures might have been different.
This picture looks like a time lapse collection over several hours. For that number of trails to be so persistent for so long does not equate with my experience as RAF aircrew or actually looking at the sky.
Also that number of trails during the short time of one picture would indicate a more crowded sky that is probably permitted by US law from a flight safety point of view.
The IPCC is learning something new every day. Water vapour is much stronger than previously thought.
In the paper, Burkhardt and Kärcher themselves recognize how shaky their own finding are:
“Besides the uncertainty due to the treatment of contrail cirrus, our radiative-forcing estimates are also affected particularly by uncertainties related to the model’s representation of upper-tropospheric humidity and clouds. Clouds are influenced by small-scale processes that cannot be resolved by a large-scale climate model and which therefore need to be parametrized. The representation of clouds is a major source of uncertainty in climate simulations. The same problems also affect the representation of contrail cirrus.”
But of course none of this is picked up in the media – why bother with such nuances…?
Eric says:
March 31, 2011 at 12:50 pm
“I have often wondered after seeing this if the Clean Air Act was not itself a climate forcing that impacted some of the trends of US temperatures in the second half of the 20th century.”
You betcha! I’ve said that before. If we were burning fossil fuels the way God intended the cooling effect of the aerosol components would negate the warming effects of the GHG components. But noooooooooooo… the ecoloon inspired acid rain hysteria caused laws to be passed requiring that the aerosols be scrubbed from fossil fuel emissions. No wonder then that “global warming” accelerated not long after the passage of the passage of the Clean Air Act of 1963.
@Eric (con’t)
That’s not to say I don’t like the 1963 Clean Air Act. Global cooling is bad. Global warming is good. CO2 makes plants grow faster and use less water when doing it. The unintended consequence (global warming) of the CLA in this case was a highly beneficial consequence. This just goes to show that even a blind squirrel finds an occasional acorn.
Since contrails only appear under certain atmospheric conditions and altitudes the solution is easy. Don’t fly that high and don’t fly into those conditions. Problem solved.
This reminds me of the Star Trek episode of the warp drive causing a wrinkle in space along a corridor. It was a global warming episode.
Just a question… from the NASA page featuring the image “This enhanced infrared image from the Moderate Resolution Imaging Spectroradiometer (MODIS), aboard NASA’s Terra satellite, shows widespread contrails over the southeastern United States during the morning of January 29, 2004”
Infrared… taken FROM a satellite… ABOVE the clouds that reflected.
Umm… that warms the surface how?
if contrails heat and we are cooling, then free flights for everyone.
on the contrary if they cool and we are heating, free flights for everyone
win win situation, start choosing where do you want to go and your favorite cocktail
Piscosour for me on my way to Eastern island, please
http://en.wikipedia.org/wiki/Pisco_Sour
I call BS. The paleoclimate record clearly shows a relationship between cooling and increased cloud cover (determined by cosmic rays and the solar wind). Pretty much every previous study has shown this too.
Ridiculous. Obviously the contrails are nucleation points for cloud formation, increasing the earth albedo and reducing world temperature.
This is bad news, I suppose now environmentalists will be spray painting air travelers as they enter the airport and signs that say murderer you are killing the earth. Or maybe not.
Simple, just restrict altitude to 12,500 feet or below. Y’all be careful up there!
Joel Shore says:
March 31, 2011 at 4:34 pm
Roger Pielke Sr. says:
It is fairly widely known that RP Sr. believes that other agents such as land use changes are at least as important as GHG. His context is therefore broader than just contrails vs CO2 and his point is that here we find another chip being taken off CO2 as the only warming cause of any magnitude.
It is interesting that the heavy-handedness of CO2 crusaders has attracted considerable new development of climate science from the skeptical side and the result is that even the IPCC has revised the weight of the CO2 effect back significantly. Before all this, when the CO2-based CAGW clique had a free rein, the the feedback multiplier was much higher and it continues to be whittled down (was it 3 down to 1.2?). Contrails would appear to chip off another piece. It seems there is a trend in the decline of CO2’s importance over the past several years. I always ask the CO2 crusaders: “Is the temperature today higher, lower or the same as you projected it would be 15 years ago?” I know Hansen’s and the IPCC’s answer to that question.
Que?
The 9-11 study clearly showed that contrails were a moderating (insulating) influence on the weather/climate, just as you would suspect – cooling peak daytime temperatures and increasing minimum nightime temperatures. But since there are many more daytime flights than nightime flights, the end result of many contrails should be a net cooling, which is what the study found.
http://pdfcast.org/pdf/climate-change-during-9-11
Thus aircraft are beneficial, because they oppose AGW. Thus GreenPeace and PlaneCrazy should be promoting aviation, rather than opposing it.
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>>mkelly says: April 1, 2011 at 7:07 am
>>Since contrails only appear under certain atmospheric conditions and altitudes
>>the solution is easy. Don’t fly that high and don’t fly into those conditions.
But then you run out of fuel and end up in the Atlantic rather than Paris. Aircraft fuel fuel burns are highly altitude sensitive, and to stay out of the contrailing altitude band would necessitate leaving many of the passengers and baggage behind, or simply not having enough fuel capacity to reach a given destination.
Besides, the 9-11 study demonstrated that contrails were beneficial, in cooling any perceived warming of the weather/climate.
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I have noticed over the years that an obsession with contrails (and especially the infamous c**mtrails) is an almost universally reliable indicator of netkookery.
I would like to say thanks a lot for your work you have made in writing this blog post. I am hoping the same perfect work from you down the road also.
Interesting post. Persistent contrails started in 1998. The thing I notice is that they are no longer white, but have a brown hue. Whatever is going on I believe that we should go to minimum impact if possible. In this case we should study why contrails started to become persistent in 1998.