What can civil aviation do to save the planet?

One scheme which is not talked about much . . . it doesn't use Sulfur Compounds nor does it use injection into the stratosphere is the following . . . it uses a type of high tropospheric cloud seeding to reduce cirrus clouds and thus reduce the amount of heat retained or reflected back into

Modification of cirrus clouds to reduce global warming
David L Mitchell and William Finnegan
Desert Research Institute, Reno, NV 89512-1095, USA
E-mail: david.mitchell@dri.edu
Received 1 April 2009
Accepted 12 August 2009
Published 30 October 2009
Abstract.
Greenhouse gases and cirrus clouds regulate outgoing longwave radiation (OLR) and cirrus cloud coverage is predicted to be sensitive to the ice fall speed which depends on ice crystal size. The higher the cirrus, the greater their impact is on OLR. Thus by changing ice crystal size in the coldest cirrus, OLR and climate might be modified. Fortunately the coldest cirrus have the highest ice supersaturation due to the dominance of homogeneous freezing nucleation. Seeding such cirrus with very efficient heterogeneous ice nuclei should produce larger ice crystals due to vapor competition effects, thus increasing OLR and surface cooling. Preliminary estimates of this global net cloud forcing are more negative than–2.8 W m–2 and could neutralize the radiative forcing due to a CO2 doubling (3.7 W m–2). A potential delivery mechanism for the seeding material is already in place: the airline industry. Since seeding aerosol residence times in the troposphere are relatively short, the climate might return to its normal state within months after stopping the geoengineering experiment. The main known drawback to this approach is that it would not stop ocean acidification. It does not have many of the drawbacks that stratospheric
injection of sulfur species has.
http://iopscience.iop.org/1748-9326/4/4/045102/fulltext/

"Substances exist that nucleate ice crystals as effectively as silver iodide (AgI, the best ice nucleant known) at cirrus cloud temperatures, and some are relatively inexpensive and non-toxic (see section 2.1). If significantly larger, these artificially seeded ice crystals would fall faster, and their higher fall velocities may lead to reduced cirrus cloud coverage as predicted in GCM simulations (Mitchell et al 2008, Sanderson et al 2008). The lower cirrus cloud coverage would result in greater OLR and cooler surface temperatures, thus reducing the impact of global warming. It is important to note that the decrease in cirrus coverage would occur where the cirrus greenhouse effect is strongest (i.e. temperatures < –40 °C). This is a key principle for this geoengineering idea."
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You will notice form this same paper (quote above) that the targeted area to mitigate Cirrus Clouds is where Cirrus Clouds naturally form . . . which is the same areas where contrails form via air traffic. So the aircraft do not produce the Cirrus Clouds they only trigger their formation when conditions are ripe . . . The key to this paper is that one could use silver iodine or some other nucleating agent to dissipate Cirrus Clouds in the higher Troposphere not that it is now being done!!!
Seems a possible scenario could be to get permission for each long haul commercial jet to carry a canister of silver iodide (AgI) and when they transverse an area of projected cirrus cloud bank (persistent contrail) activity via a projection by NASA . . . a ground signal could release the contents of the canister . . . this would be a passive system . . . when a canister is expended it would be replaced at the next airport . . . [link to cloudsgate2.larc.nasa.gov]http://cloudsgate2.larc.nasa.gov/cgi-bin/site/showdoc?docid=33&cmd=latest
 
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I'm pretty sure I've seen this mentioned on a chemmie site somewhere as "proof" that geoengineering causes droughts by making the clouds go away....can't find it atm tho.
 
One scheme which is not talked about much . . . it doesn't use sulfur compounds nor does it use injection into the stratosphere is the following . . . it uses a type of high tropospheric cloud seeding to reduce cirrus clouds and thus reduce the amount of heat retained or reflected back
At the expense of additional heat gained greater than that prevented from being retained.

The higher the cirrus, the greater their impact
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The material falls to the mid-troposphere where it evaporates and is made available to support more cirrus.

the climate might return to its normal state within months
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Within hours - maybe minutes.

It does not have many of the drawbacks that stratospheric injection of sulfur species has
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You mean it isn't acid. But it increases the rate at which the globe warms, nevertheless. You are burning fuel to put the stuff there, the cost being ten times the benefit.

these artificially seeded ice crystals would fall faster
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Doesn't matter what speed they fall, George. The water they drag away will soon be back. You would pit Mankind against the earth's quasi-biennial oscillation - a very much larger version of spitting into the wind. :D

Back to the swamp, George, before some well-informed tree hugger takes a shot at you. Are you extinct?

If you wish to know what will actually really help:
  • Hydrogen-fueled aircraft (no carbon added to the atmosphere. However there'll always be NOX)
  • Larger aircraft (passenger/mile efficiency)
  • Desulfurized hydrocarbon fuels for aircraft (reduces the ozone hole, at least)
  • Salter salt-spray trimarans (which create clouds that reflect solar energy without retaining it - using wind energy to do so)
  • Central ocean fertilization and management (absorbs CO2)
  • Reforestry (absorbs CO2)
  • Permacultural farming practices (require little fuel or fertilizer)
  • Constant-contour canals (redistribute fresh water)
  • Systematized mass-transit systems and electric vehicles (more efficient and reduce pollution)
  • The abolition of mass-produced internal combustion engines (unless they're hydrogen-fuelled)
  • More use of ocean thermal power (it's a bottomless pit of energy wherever the ocean is deep)
The above strategies will work (with varying degrees of effectiveness), and I've told you about them before. Why are you so resistant? Or do you just forget?
 
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At the expense of additional heat gained greater than that prevented from being retained.

The higher the cirrus, the greater their impact
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The material falls to the mid-troposphere where it evaporates and is made available to support more cirrus.

the climate might return to its normal state within months
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Within hours - maybe minutes.

It does not have many of the drawbacks that stratospheric injection of sulfur species has
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You mean it isn't acid. But it increases the rate at which the globe warms, nevertheless. You are burning fuel to put the stuff there, the cost being ten times the benefit.

these artificially seeded ice crystals would fall faster
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Doesn't matter what speed they fall, George. The water they drag away will soon be back. You would pit Mankind against the earth's quasi-biennial oscillation - a very much larger version of spitting into the wind. :D

Back to the swamp, George, before some well-informed tree hugger takes a shot at you. Are you extinct?

If you wish to know what will actually really help:
  • Hydrogen-fueled aircraft
  • Larger aircraft
  • Desulfurized hydrocarbon fuels for aircraft
  • Salter salt-spray trimarans which create clouds that reflect solar energy without retaining it
  • Central ocean fertilization and management (absorbs CO2)
  • Reforestry (absorbs CO2)
  • Permacultural farming practices (require little fuel or fertilizer)
  • Constant-contour canals (redistribute fresh water)
  • Systematized mass-transit systems and Electric vehicles (more efficient and reduce pollution)
  • The abolition of mass-produced internal combustion engines
The above strategies will work (with varying degrees of effectiveness), and I've told you about them before. Why are you so resistant? Or do you just forget?
I have nothing vested in this strategy . . . it seemed better than Sulfur Injection if emergency measures were ever considered necessary. . . Thanks for your analysis . . . :)
 
I have nothing vested in this strategy . . . it seemed better than Sulfur Injection if emergency measures were ever considered necessary. . . Thanks for your analysis . . . :)
Well, my main point is that your strategy is no more "effective" than contrails are. They cool during the day and warm during the night*. But the CARBON DIOXIDE is the problem, and you aren't addressing it.

Not that we haven't both benefited from your raising of the topic. The list of things we should be doing, but aren't, is lengthening as we write.

* The Salter trimarans would work in the southern oceans, NOT creating clouds at night - out of sight of Man - and serve as research bases or rescue centers, manned or unmanned. 95% of our oceans and the species they contain are yet to be discovered...
 
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Well, my main point is that your strategy is no more "effective" than contrails are. They cool during the day and warm during the night*. But the CARBON DIOXIDE is the problem, and you aren't addressing it.

Not that we haven't both benefited from your raising of the topic. The list of things we should be doing, but aren't, is lengthening as we write.

* The Salter trimarans would work in the southern oceans, NOT creating clouds at night - out of
sight of Man - and serve as research bases or rescue centers, manned or unmanned. 95% of our oceans and the species they contain are yet to be discovered...
The idea is the removal of high altitude cirrus and contrails which theoretically results in cooling . . .
 
Apparently there is more research on Cirrus Cloud Seeding . . . and I have been told there are three more to be published. . . .


http://www.researchgate.net/publication/258787436_Cirrus_cloud_seeding_has_potential_to_cool_climate

Article
Cirrus cloud seeding has potential to cool climate
T. Storelvmo, J. E. Kristjansson, H. Muri, M. Pfeffer, D. Barahona, A. Nenes

Geophysical Research Letters (Impact Factor: 3.98). 01/2013; 40(1):178-182. DOI:10.1029/2012GL054201
ABSTRACT Cirrus clouds, thin ice clouds in the upper troposphere, have a net warming
effect on Earth's climate. Consequently, a reduction in cirrus cloud
amount or optical thickness would cool the climate. Recent research
indicates that by seeding cirrus clouds with particles that promote ice
nucleation, their lifetimes and coverage could be reduced. We have
tested this hypothesis in a global climate model with a state-of-the-art
representation of cirrus clouds and find that cirrus cloud seeding has
the potential to cancel the entire warming caused by human activity from
pre-industrial times to present day. However, the desired effect is only
obtained for seeding particle concentrations that lie within an optimal
range. With lower than optimal particle concentrations, a seeding
exercise would have no effect. Moreover, a higher than optimal
concentration results in an over-seeding that could have the deleterious
effect of prolonging cirrus lifetime and contributing to global warming.


J. E. Kristjánsson
University of Oslo
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The benefits of Cirrus Cloud Seeding as an emergency global warming mitigation are IMO the following . . .

a . There would be no need for dedicated flights into the desired areas for mitigation.
b. The mitigation of persistent contrails and aircraft induced cirrus clouds and cloud banks could result.
c. The removal of concerns regarding increased ocean acidification and acid rain from sulfur injection.
d. NASA would benefit from having an active role in reducing global warming and contrail mitigation.
e. Existing proven technology could possibly be used . . . cloud seeding canisters already used every day.
 
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