Hello All,
Some good points, Alvia, exposing lack of precision in my note, which
I'll now try to rectify.
There exists solid experimental field evidence from a significant
variety of sources - see our 2 Phil Trans Roy Soc papers, cited below
- to show that:-
1. there is a general positive correlation between marine
stratocumulus cloud albedo and cloud droplet number concentration.
2. a significant fraction of aerosol particles released at or just
above the ocean surface beneath such clouds make their way via
turbulence into the clouds.
3. such particles can act as cloud condensation nuclei CCN to produce
additional cloud droplets, thus enhancing cloud albedo. The roughly
1um seawater droplets which we advocate disseminating would certainly
act as CCN and produce new droplets.
So we know already that the major components of our proposed scheme
are already supported qualitatively by appreciable evidence.
What we don't know, however, is:-
4. Is the scheme QUANTITATIVELY adequate to be of importance in global
temperature stabilisation? (Recent GCM results from 2 independent
groups suggest that it is, but this conclusion is subject to one or
two caveats - questions which must be resolved before we have clarity).
5. Can we produce and disseminate suitable aerosol of the required
size and narrow size-range. (Stephen's work is very encouraging in
this regard, but we don't have hard evidence at this stage).
6. Can we disseminate these particles on the massive geographical
scale required? (Again, Stephen's work is very encouraging in this
regard, but we don't have hard evidence at this stage).
At some stage, perhaps 2 or 3 years away, if the idea hasn’t been
shown to be unworkable (or irrelevant, if some superior idea will
clearly work) we will need to perform a comprehensive field study –
along the lines described in my earlier note - to try to establish the
quantitative validity of the scheme. We are certainly not ready yet.
My statement “we need to get it right first time”, which Alvia quite
rightly picked me up on, was unclear and perhaps too sweeping. What I
have in mind is a 6-8 week study (rather like VOCALS, but on a
significantly smaller scale) in which we do indeed, as Alvia suggests,
test the idea under as wide a range of conditions as possible. I
didn’t mean to imply that we’d have a definitive answer at the end of
Day1. And if course, if the results from this project were
inconclusive we’d try again – but I feel sure that we wouldn’t find it
easy to procure funding for a second shot. So we must prepare
meticulously for the first attempt.
I agree with Alvia’s final sentence – that had the Discovery
experiment produced cloud brightening (had there been a cloud to
brighten), we might be encouraged, but nothing more. But I see no
point in trying to reproduce their experiment. The conditions in their
demonstration were so far removed from those that would prevail if our
system was ever to be deployed that no valid extrapolation would have
been possible. Their experiment provided no new relevant information.
Steve and I told them in advance that the experiment wouldn’t work,
but they went ahead anyway. They were of course right, in the one
sense only – but the paramount one, from the point of view of a TV
company – that the conflagration produced by igniting the flares
produced spectacular television. Had Steve and I (or any of our
colleagues on the boat) been roasted in the pursuit of scientific
truth – and I felt perilously close to that at one stage – I think the
documentary would have been deluged with awards. (Actually, they were
a great bunch of people and working with them was fun).
Oliver, in his message today, makes the very important point that it’s
crucial to examine, fully and quantitatively, all ramifications of the
possible adoption of our scheme. This aspect of our work, conducted by
Phil Rasch and Jack Chen at NCAR, using a fully coupled
ocean/atmosphere model, has already commenced. I’m not competent,
Oliver, to assess your chemical points, but I hope to be so in due
course.
Cheers, John. [EMAIL PROTECTED] 29 November 2008
182. J. Latham, P.J. Rasch, C.C.Chen, L. Kettles, A. Gadian, A.
Gettelman, H. Morrison, K. Bower, T.W.Choularton.,
Global Temperature Stabilization via Controlled Albedo
Enhancement of Low-level Maritime Clouds. 2008. Phil. Trans. Roy.
Soc. A, 366, 3969–3987, doi:10.1098/rsta.2008.0137
183. Salter, S, G. Sortino & J. Latham, (2008). Sea-going hardware for
the cloud albedo method of reversing global warming,
2008. Phil. Trans. Roy. Soc. A, 366, 3989–4006,
doi:10.1098/rsta.2008.0136
********************************
Quoting "Alvia Gaskill" <[EMAIL PROTECTED]>:
> Before such field tests are conducted, shouldn't you first repeat the
> experiment from the Discovery Channel Project Earth program using salt
> flares? Had the clouds been present, that would have proven that water
> vapor redistribution within clouds can be be accomplished manually. It
> would also set an upper bound on what can be achieved as the actual
> field system wouldn't produce nearly as many salt particles. As for
> "getting it right first-time," I would think that regardless of the
> outcome, the experiment has to be repeated numerous times under varying
> conditions to determine general efficacy. For example, had the
> Discovery Channel experiment succeeded with clouds present, I would say
> that the results were encouraging, but not yet conclusive.
>
>
> **************************
----- Original Message ----- From: "John Latham"
> <[EMAIL PROTECTED]>
> To: "John Nissen" <[EMAIL PROTECTED]>
> Cc: <[EMAIL PROTECTED]>; <[email protected]>;
> <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>;
> <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>;
> "GeorgeMonbiot" <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>
> Sent: Friday, November 28, 2008 3:49 PM
> Subject: Re: [geo] Climate restoration and ecosystem recovery - newproposal
>
>
> Hello All,
>
> Two points:-
>
> 1. I think the plan that John et al are developing is definitely a
> worthwhile venture. I am inclined towards Ken's version of it.
>
> 2. Re the cloud-albedo-enhancement scheme, I think that Stephen's
> photographic technique, which he describes as part of a field
> experiment designed to test the idea, is very ingenious. Other parts
> of the experiment which are crucial include: ground-based measurements
> (radar and/or lidar), airborne microphysical, meteorological and
> radiative measurements (some above, below, and within the clouds) and
> satellite observations.The cost of the experiment would probably be in
> the 10M-20M range, so it's vital to get it right first-time: which
> requires meticulous preparation, and some seasoned, world-class
> scientists (like the ones recently involved in the international
> marine stratocumulus experiment VOCALS, off Peru, just completed). We
> have reason to believe that such people would want to be involved in
> testing our hypothesis & system.
>
> Cheers, John.
>
*******************
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"geoengineering" group.
To post to this group, send email to [email protected]
To unsubscribe from this group, send email to [EMAIL PROTECTED]
For more options, visit this group at
http://groups.google.com/group/geoengineering?hl=en
-~----------~----~----~----~------~----~------~--~---
