I just wished to stress that the full science of anthropogenic changes to the atmosphere was yet to be fully understood, and that the incompletely-understood part was that of the migration of combustion products to the poles and their effect on the “ozone hole”.

No problem I think I came into the middle of an in depth discussion with a general observation.

Moving the aircraft’s cruise height will hardly affect its efficiency at all.

You got some numbers to back that up?

I am certainly not arguing with you. I am making the same point you are.

I wasn’t sure you were, sorry.

I just wished to stress that the full science of anthropogenic changes to the atmosphere was yet to be fully understood, and that the incompletely-understood part was that of the migration of combustion products to the poles and their effect on the “ozone hole”.

‘First of all to say “chemtrail believers” is an massive oversimplification.
Could you imagine trying to make the same generalizations about groups of people,
like lets say “christian ‘believer’s”
or “UFO believers”…??? well? could you?

No, you cannot.
If you call me a “chemtrail believer” I’ve already make the case that a “CHEMTRAIL” is also by my definition
also a Persistent Contrail.
So I’ve basically dis-proven your assumption.’

Commonly people of faith as are referred to as ‘believers’. You continue to have ‘faith’ that there is something nefarious about persistent contrails despite all the readily available science that disproves your hypothesis.

I’m wondering why you appear to be arguing with me.

‘NO scientists anywhere have ever denied “the existence of persistent contrails”. They have been known by ALL ATMOSPHERIC SCIENTISTS to exist at least since 1943, when they adversely affected the US Army’s bombing campaign over Germany in WW2.

They are NOT worried about the “negative effects of contrail induced cirrus – mainly in relation to global warming”. They KNOW (because they have measured and calculated it) that the effect of aviation is a 3.5% contribution to global warming.’

I am certainly not arguing with you. I am making the same point you are.

For all intensive purposes I’m right.

Sorry, but “intensive purposes” is really funny.

Why isn’t this done already? Cost of extra fuel waste?

I don’t know. I suggest it is because the airlines have no external compulsion upon them to increase their flight crews’ work rate.

During daylight (at least), a rearward-facing videocam could provide an instant view of the trail being made. If it turned out to be heavy, the crew could ask ATC for a different height to fly at.

By comparing notes with all the aircraft on the panel, ATC could form a pretty good picture of supersaturated layers. It may even be possible to develop the software to put these on screen.

It’s tricky because it is the aircraft engines themselves which are the most sensitive detectors of supersaturation.

Moving the aircraft’s cruise height will hardly affect its efficiency at all.

Changing the internal design of modern turbofans to produce such a drastic reduction of efficiency (as suggested by the paper you quoted) would put the aircraft industry in a whole new world of hurt. In fact it’s laughably unlikely.

The 3.5% figure is the IPCC estimate for the TOTAL CLIMATE EFFECT from air traffic, not just “pollution”. See here, where the various effects are broken down.

http://www.grida.no/publications/other/ipcc_sr/?src=/climate/ipcc/aviation/064.htm

For the 1992 aviation scenario (NASA-1992*), radiative forcing of climate change from aircraft emissions (gases and aerosols) is estimated to be +0.05 W m-2, which is about 3.5% of total anthropogenic radiative forcing as measured against the pre-industrial atmosphere of +1.4 W m-2 for combined greenhouse gases and aerosols (and +2.7 W m-2 for greenhouse gases alone). The components of aircraft-induced radiative forcing are as follows:

CO2, +0.018 W m-2;
NOx, +0.023 W m-2 (via ozone changes) and -0.014 W m-2 (via methane changes);
contrails, +0.02 W m-2;
stratospheric H2O, +0.002 W m-2;
sulfate aerosol (direct effect), -0.003 W m-2;
black carbon aerosol (soot), +0.003 W m-2.

Changes in “natural” cirrus clouds caused by aircraft may result in negligible or potentially large radiative forcing; an estimate could fall between 0 and 0.04 W m-2. Uncertainty estimates, typically a factor of 2 or 3, have been made for individual components and are intended to represent consistent confidence intervals that the radiative forcing value is likely (2/3 of the time) to fall within the range shown. The uncertainty estimate for the total radiative forcing (without additional cirrus clouds) is calculated as the square root of the sums of the squares of the upper and lower ranges of the individual components.

Projection of subsonic fleet growth to 2015 (NASA-2015* scenario) results in a best estimate for total aircraft-induced radiative forcing of +0.11 W m-2 in 2015-about 5% of IS92a projected radiative forcing from all anthropogenic emissions that year.

Note there’s some uncertainty there, but still scientists are pretty sure it’s in the ballpark. Estimated to rise to 5% by 2015.

The Pan Evaporation Rate decline you mention is thought to come mostly from particulates in the atmosphere from pollution. Jet flight does not contribute much to this. It’s linked to “Global Dimming”, which has actually been DECREASING in the last ten years. So can hardly be related to any supposed increase in contrails.

The 9/11 observations have since been re-analysed, and are not as significant as once thought, based on the actual weather at the time (it was an unusually sunny day in the US, as I’m sure you remember). See:

http://www.flightglobal.com/blogs/future-proof/2009/05/exclusive-911-not-to-blame-for-climate-effect.html

According to US scientists who studied US skies after the September 11 terrorist attacks in 2001, the absence of artificial clouds caused by the grounding of all civil aircraft triggered variations in the earth’s temperature range by 1.1 degrees Celsius (2 degrees Fahrenheit) each day.

But follow-up work by a number of scientists working independently have shown that the observed change in the daily temperature range or DTR was likely a statistical quirk associated with the weather and that contrails by themselves are likely only to have a very minor effect on DTR.

my suggestion to arrange that aircraft are simply routed to AVOID offending layers – without any loss in operating efficiency.

why isnt this done already?
cost of extra fuel waste?

The issue in question for contrail cirrus isnt so much just the “pollution” but the special effects it has on the whole climate-system and cloud formation itself.
It’s been quantified, hasn’t it, at 3.5%?

Actually, from my understanding, the 3.5% figure is in regards to the POLLUTION, not the EFFECTS of
CONTRAIL CIRRUS.
Are we reading the same information differently?
The way ARTIFICIAL CLOUD COVER effects the climate/global environment is an altogether different issue than
the pollution from aerosols etc…
We’re talking weather patterns/ amount of sunlight/ evaporation rate.
Remember, this “breakthrough” only came AFTER 9/11.
It was in 2001 that the issue really made its biggest statement.
The calculations previous this downing of all us airplanes gave a UNIQUE new look into whats going on.
They didnt expect what they found.

At least thats the information that I’ve read. From NASA as well.

BY 2050 the West is going to be lean, mean and hungry, while the East is going to pollute like we once did. The West will no longer be in control.

Cheap air travel is going to fade into the past, and air travel as a whole is going to stabilize to not much more than the present level – but centred around the Pacific rather than the Atlantic.

The Earth will be more than two degrees warmer, the sea level will have risen six feet.

Some tipping points; tundra methane, clathrate methane, Arctic ice cover, Antarctic Ice Shelf motion, ocean acidity, could render my predictions wildly inaccurate.

Aviation AGW will no longer be ours to argue about. We’ll be proliferating nuclear power stations all over.

It’ll be a gas…