cloud seeding

[Andrew Lockley]

I note the use of cloud seeding by the Chinese, and its unexpected effect in causing huge snowfalls in Beijing.  It seems that there may be two useful geoengineering approaches with this technique, and I'd be interested in hearing comments.

1) Rebuild ice - by inducing snowfalls over Greenland, Antarctica and the Arctic, it would perhaps be possible to maintain ice.  In Greenland, where the height of the ice cap is critical, this would seem a particularly appealing prospect.

2) Albedo modification - Fresh snow is whiter than old snow, especially in polluted areas.  Is the albedo change worth pursuing?  My guess is not.  HOWEVER, I suspect that triggering significant autumn and spring snowfalls in permafrost regions, we could potentially significantly modify albedo.

I invite comments.

A

[Brennan Jorgensen]

The Arctic and Antarctic are classified as deserts with limited or
variable cloud cover available for cloud seeding (correct me if I am
wrong)? To my knowledge, cloud seeding is costly and would also
involve the combustion of jet fuel that is, unfortunately, a
limitation apparent in today's conventional technologies. In addition,
if we just focus on cooling the Arctic would this not just increase
the kinetic-heat-conveyor belt of the Gulf Stream transporting heat
from the subtropics to the Arctic?

I would like to suggest that the highest climatic risk may involve
the possibility of a methane release. Covering the permafrost with an
environmentally friendly, biodegradable (maybe a 500+ year life) white
plastic sheeting (derived from algae) may provide a less variable and
more fail safe approach to hasten the albedo effect over critical
zones. The white membrane with some innovative material science could
also temporarily slow a or even partially absorb a potential methane
out gassing. A risk assessment/GIS map could be devised for the
permafrost with a corresponding deployment schedule. In this case the
Central Siberian permafrost would most likey be considered the first
critical zone for deployment.

Regards,

Brennan

[David]

RE: CH4

Would it be economically viable to capture the methane and burn it for
energy? Each CH4 -> CO2 + 2(H2O).

CO2 is less effective as a GHG as I understand it. Condensation of H2O
in the atmosphere would release heat to space.

I suspect it actually isn't. But I could be missing something.

An idea I like is cloud seeding tropical depressions and tropical
storms. These storms are heat driven engines that draw their power
from the warm surface water of the oceans. Ultimately heat is pumped
into space. This would be heat that is not pumped to the poles. The
extra cloud cover would provide albedo where it really helps, at low
incident angles.

Also, why not use ground / sea launched rockets to carry the seeding
aerosols? I'm sure there are propellents that are less harmful than
jet fuel. The propellents could produce the seeding material directly.
The rockets can be made out of inexpensive biodegradable materials.
Did anyone play with Estes model rockets as a kid? This is stuff that
can be scaled up cheaply I think.

Another possible carrier would be hydrogen filled balloons.

A good launch point for the Atlantic is West Africa. Just ride the
same trade winds that push the storms along.

On Dec 15, 8:58 am, Brennan Jorgensen <sunhydrosyst...@gmail.com>
wrote:

[Neil Farbstein]

I suggested the same cloud seeding strategy a month ago. Somebody
authoritative said that the biggest snowfall recorded over the
alaskan arctic caused the biggest melt water recorded during the
spring. That's anecdotal evidence but I dropped the idea of working on
that anyway.

There wont be a melt water problem if clouds are seeded over large
parts of the gulfstream to cool it and the winds that blow off it.

On Dec 15, 5:47 am, Andrew Lockley <andrew.lock...@gmail.com> wrote:

[Andrew Lockley]

For clarity, the main reason my for suggesting cloud seeding is that it can be used to build up greenland to a height where the air temperature is low enough to sustain the ice sheet.  The could potentially reverse the catastrophic Greenland tipping point - which will unleash several metres of sea level rise over a few hundred years.  Game over for London, Venice, Florida, New York, etc. if that happens.   Worth a bit of jet fuel or a few rockets to prevent that, I'd argue.

A

2009/12/15 Neil Farbstein <pro...@att.net>

--

You received this message because you are subscribed to the Google Groups "geoengineering" group.
To post to this group, send email to geoengi...@googlegroups.com.
To unsubscribe from this group, send email to geoengineerin...@googlegroups.com.
For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en.

[Neil Farbstein]

I'm glad we agree. Small cloud seeding experiments over Greenland
should be practical. We should give this some thought and modeling.
Can you do that at your lab? Google satellite pictures and weather
satellites can locate clouds that are likely targets to seed; The
bigger clouds in the places that are most strategic.
An international organization or groups of industrialized nations can
pay the local residents or the greenland government subsidies for
participating in the cloud seeding program.

> > geoengineerin...@googlegroups.com<geoengineering%2Bunsubscribe@go­oglegroups.com>
> > .

> > For more options, visit this group at

> >http://groups.google.com/group/geoengineering?hl=en.- Hide quoted text -
>
> - Show quoted text -

[Neil Farbstein]

Methane clathrates are "mined" by vacuuming them up from the ocean
bottom with underwater pipes that extend top the bottom of the ocean
bed from ships anchored above. The equipment currently developed works
but controversy and economics have kept the clathrates unmined. I
guess they can be vacuumed up in a year or two if the funds are
provided. As the world warms, ever bigger swaths of the ocean bed will
bubble up methane. If we vacuum up the clathrates with sufficient
numbers of mining ships we might be able keep up with the growth of
methane out gassings! There are about 250 known undersea out gassing
locations that have been found. I don't know what size they or what
amount of equipment has to be built. But a crash program could catch a
lot of the clathrates. I think it'll be alot more practical and easier
to flare them.

> > > A- Hide quoted text -

[John Latham]

Hello Neil, Andrew et al.

Cloud seeding (principally to make rain) has had a long and highly chequered history in the 60 years since Vonnegut, Schaefer & Langmuir did their pioneering work. Many studies since then were contaminated by commercial interests. There is no essentially no consensus as to whether and under what circumstances it will work. This is especially true for clouds that contain ice. Whether seeding will enhance, reduce or have negligible effect on such clouds depends on: atmospheric stability, cloud-base temperature, updraught speed, presence or absence of conditions in which natural secondary can function, level and location etc etc. I think there is good reason to feel sceptical of studies reporting quantitative estimates of changes induced by seeding. My view is that - as with several geoengineering schemes - what is urgently required is well-controlled , comprehensive field experiments. Only then will it be possible to establish whether cloud seeding might, on a regional scale, be important vis-a-vis climate change.

Cheers,   John.

                                                                ********************************

> geoengineerin...@googlegroups.com.

> For more options, visit this group at
> http://groups.google.com/group/geoengineering?hl=en.
>
>
>

--
John Latham

lat...@ucar.edu   &    john.l...@manchester.ac.uk

Tel. 303-444-2429 (H)    &  303-497-8182 (W)

[John Latham]

Quoting John Latham <john.l...@manchester.ac.uk>:

> Hello Neil, Andrew et al.
>
> Cloud seeding (principally to make rain) has had a long and highly
> chequered history in the 60 years since Vonnegut, Schaefer & Langmuir
> did their pioneering work. Many studies since then were contaminated
> by commercial interests. There is no essentially no consensus as to
> whether and under what circumstances it will work. This is especially
> true for clouds that contain ice. Whether seeding will enhance,
> reduce or have negligible effect on such clouds depends on:
> atmospheric stability, cloud-base temperature, updraught speed,

> presence or absence of conditions in which natural secondary ice formation process can

[Andrew Lockley]

Flaring of methane is a last resort, as the CO2 generated still ends up in the atmos.  Far better to capture the methane, use the energy, and capture the carbon.

Not all methane starts out as clathrates - in some cases it's directly vented from organic-rich mud and sediments in anoxic and low-oxygen waters.  You need to be clear on the source before you try to control it.

I will be working on my methane remediation paper over Xmas, and anyone interested in the subject is welcome to join as a co-author.  I'd appreciate all the available assistance as I'm a lowly mech-eng grad with not a paper or a science degree to my name.

A

2009/12/16 Neil Farbstein <pro...@att.net>

--

[Mike MacCracken]

With one exception, I agree with John. The exception is that I think it has been demonstrated that one can clear an ice fog with seeding, and this has been done to open airports, etc.--not to generate precipitation (in any form).

I would add that the water vapor content of air and clouds above Greenland is likely so low that one could not be likely to get a significant buildup of snow. Whether one could seed storms or change sea surface temperatures in surrounding areas in a way that would lead to greater likelihood of storms depositing snow on Greenland (or Antarctica, etc.) has not, to my knowledge, been looked at at all.

Mike

[John Latham]

Hello Mike et al,

I agree entirely with you Mike that seeding can cause ice fogs to disperse. Also electrostatic droplet seeding could help dissipate warm fogs. I should have more carefully indicated that I was focusing on seeding of  clouds containing ice, and particularly mixed-phase clouds.

Cheers,      John.

[John Nissen]

Hi John,

I saw some research somewhere that said that global cloud cover had decreased over the past decades, contributing slightly to global warming.  But I can't find it now.  Do you know about it?  Could it be due to black carbon?  Here's an extract from a Hansen essay:

'Black carbon aerosols cause a positive climate forcing that is very uncertain in magnitude, but we estimate that it is probably of the order of 0.5 to 1 Watt per square meter on global average. It causes warming in several ways: by absorbing sunlight, by warming the lower layer of the atmosphere and thus reducing cloud cover, by making clouds slightly "dirty", and by darkening snow and sea ice surfaces when it is deposited there.'

(http://www.giss.nasa.gov/research/features/200111_altscenario/discussion.html)

Perhaps more importantly, do we know what is happening in the Arctic?  I believe it was expected that cloud cover would increase significantly over coming decades - which would reduce the effectiveness of any stratospheric aerosol geoengineering.  (I'm copying this to Jeff Ridley who might know the answer.)

Whilst cloud cover has a cooling effect in Arctic summer, I assume it would have a heating effect in winter.  How do these effects balance out?  Has anybody done the calculations?

Cheers,

John

---

[Neil Farbstein]

What is electrostatic drop seeding. Can it be scaled up?

On Dec 16, 12:02 pm, John Latham <john.latha...@manchester.ac.uk>
wrote:

> Hello Mike et al,
>
> I agree entirely with you Mike that seeding can cause ice fogs to disperse. Also electrostatic droplet seeding could help dissipate warm fogs. I should have more carefully indicated that I was focusing on seeding of  clouds containing ice, and particularly mixed-phase clouds.
>
> Cheers,      John.
>

> Quoting Mike MacCracken <mmacc...@comcast.net>:
>
>
>
>
>
> > With one exception, I agree with John. The exception is that I think it has
> > been demonstrated that one can clear an ice fog with seeding, and this has
> > been done to open airports, etc.--not to generate precipitation (in any
> > form).
>
> > I would add that the water vapor content of air and clouds above Greenland
> > is likely so low that one could not be likely to get a significant buildup
> > of snow. Whether one could seed storms or change sea surface temperatures in
> > surrounding areas in a way that would lead to greater likelihood of storms
> > depositing snow on Greenland (or Antarctica, etc.) has not, to my knowledge,
> > been looked at at all.
>
> > Mike
>

> lat...@ucar.edu   &    john.latha...@manchester.ac.uk
>
> Tel. 303-444-2429 (H)    &  303-497-8182 (W)- Hide quoted text -

[Neil Farbstein]

Jeff's post about clouds over the arctic is interesting. If low
altitude clouds are beneficial in the summer and detrimental in the
other seasons, they can be seeded during the non-summer months to
prevent them from heating the land. They can be seeded in strategic
places also. Over the ocean to prevent rainfall over the land that
will melt ice and snow until winter when snow will fall, which will
increase ice formation. The main idea is to reinforce the effects we
want by timing them and placing them strategically.

> > - Show quoted text -- Hide quoted text -

[John Nissen]

Thanks, Jeff.

I'm copying your answer to the geoengineering group, because it has enormous implications for the effectiveness of SRM, and on  the positive feedback effects which need to be overcome.  SRM may have a better chance than I thought, if the albedo flip effect is less than I'd thought.  However there may be other feedback effects that now take more prominence.   The water-air interface could be key, if the summer sea ice retreat leads to more cloud cover in winter.  I've not heard of that positive feedback being discussed - do you know of any papers?  Somebody in the group has suggested the winter clouds are seeded to clear the skies - would that be practicable?

Cheers,

John

---

Ridley, Jeff wrote:

Hi John,

 

My albedo flip of 0.23 was based on the mean summer albedo of sea ice. It is not covered with snow for 2 of the 3 months of summer, even in preindustrial times (from the climate models - this is because colder winters actually mean less water transport and less snow. Even through summer temperatures are colder, less snow needs to be melted before the ice is bare).Clearly albedo only matters in the summer. We have just done some experiments with black carbon on snow and found that this increases global temperatures by about 0.5C through earlier melt of snow cover (similar experiments have been done by NCAR in the US)..

 

Cheers

 

Jeff

---

From: John Nissen [mailto:j...@cloudworld.co.uk]
Sent: Thursday, December 17, 2009 12:36 PM
To: Ridley, Jeff
Subject: Re: [geo] Re: cloud seeding - need for research - ja

Thanks, Jeff.  That's most helpful.

I expect there will be some follow up questions, and I'd be grateful if you could respond to them.

BTW, in one of my emails I gave estimates of the contribution to global warming from albedo flip, from pre-industrial to complete sea ice disappearance, as between 0.2 and 0.8 Watts per square metre.  Your estimate had come out 0.25, and mine 0.75.  The main difference arose because of uncertainty in the degree of albedo change: you had taken 0.23 and I'd taken 0.70, if I remember correctly.  The context of the calculation was over requirements for solar radiation management (SRM) to halt sea ice retreat. Added uncertainty in the calculation arose from the clouds, but if they reduce the albedo flip  (so requiring less SRM to counter), they also reduce the effectiveness of SRM correspondingly .  I wonder whether black carbon was crucial for our calculations - because if there is a significant amount, it reduces the albedo flip.  Is this why you took 0.23 for the albedo change?  I was assuming pristine snow pre-industrial!

Cheers,

John

---

Ridley, Jeff wrote:

Hi John,

 

Global cloud cover is expected to decrease with increase in CO2. The decrease is in the tropics. This occurs because increasing CO2 leads to a warming of the middle troposphere, where the greenhouse gases absorb the outgoing radiation, and this stabilises the atmosphere against convection. Thus, although the surface temperatures are warming, a tendency to increase convection, the tropospheric warming is countering it and less clouds form. Low cloud such as that in the polar regions is expected to increase (as confirmed by observations in the Arctic).

 

As you point out, increased cloud in the Arctic reduces summer melt but leads to a warming in all other seasons. In models it is this winter warming that is responsible for the long term decline in sea ice volume. With more downward long wave the ice does not thicken so much in winter, preconditioning it for an earlier melt in summer.

 

Regards

 

Jeff

---

From: John Nissen [mailto:j...@cloudworld.co.uk]
Sent: Wednesday, December 16, 2009 7:13 PM
To: john.l...@manchester.ac.uk
Cc: Mike MacCracken; Neil Farbstein; Andrew Lockley; Geoengineering; Ridley, Jeff
Subject: Re: [geo] Re: cloud seeding - need for research - ja