Hi Thanks for the +ve reception to my comments.
@Mike: Sometimes numeric analysis is the best way to investigate, and sometimes it's not. I don't think that the relatively simplistic numerical analysis you suggest gets us much further. Let me propose a 'thought experiment' instead. Imagine you live by a highway in a hot dry desert (think Arizona or Nevada). You, and the critters around you, are used to it being hot and sunny pretty much the whole time. Visibility is very good, and you can see a long way. You can drive, and the critters can hunt. Now let's imagine Russell's idea works well. The trucks on the highway start emitting fog. Over the next few weeks, this builds up to a light mist which fills your entire environment. You notice it, but you can still drive OK, and the critters can still get about and look for food, albeit with perhaps a little more difficulty. Things are basically tolerable, albeit a little cooler and foggier - imagine perhaps the visibility of an LA smog (but without the toxicity). But, let's imagine the same scenario when things don't work as well. The mist is less persistent, and it doesn't hang around in your valley. To get the same albedo change, the trucks that pass you have to put out a whole load more fog to compensate. Up in the hills, the view is still virtually clear, but down near the road where you are, it's like a London pea-soup fog. You can't drive to work, the critters can't hunt. It's also really cold. Not only that, but the surface chemistry of the fog is such that it picks up all the dust in the air, and your lungs can't cope with it (just like in the London smogs). Eventually, the whole situation becomes too much, and you and the critters around you die and rot. Now, I can't be sure that this will or won't happen - but I don't think anyone else can, either. So let's bear in mind this thought experiment when doing the calculations, to see if we're doing the right ones. @Ron: The idea of focusing on the arctic is a good one. The ecosystem there is already adapted to high albedo, and will not suffer as much from the use of brightwater as would 'virgin' ecosystems. Furthermore, the performance of this technique is likely to be better than sea ice in some situations, because it allows LW radiation to escape unimpeded, but inhibits incoming SW. The lack of extant shipping lanes in the arctic is a challenge. I suggest that ships won't we the best way of distributing the bubbles. Much of the arctic is shallow (ESS), and anchored buoys with wind or tidal turbines on them would probably work better. This would be particularly useful in cooling the local waters which overlie vulnerable clathrate deposits. However, I don't agree that very small area tests would be particularly helpful, as dealing with lifetimes and mixing are the key issues here - which need km2 areas, at least (even if bubbling happened in a smaller area). A On 17 April 2011 06:32, <[email protected]> wrote: > Mike, Andrew (cc List) > > 1. Thanks for continuing this dialog. The part I find most encouraging > in the last several messages (below) is Andrew's statement in his last > paragraph re "Bright Water":* > "..... *It's the most exciting new geoeng idea for a > long time......". > The next most encouraging thing is that every one seems to agree that > a lot more exploratory R&D is needed. No-one is urging immediate > deployment. I don't see much discussion on the costs and the urgency. > > 2. I have just started reading some of the many dozens of the technical > references that Russell has provided. Besides being impressed by that > number, I am impressed by the depth of past work on bubbles and especially > ocean bubbles. This is a field with a substantial, credible and continuing > literature - both theoretical and experimental- albeit not for albedo > modification. We will not be starting at ground zero to answer the good > questions being raised about "Bright Water". > > 3. Three other so far unstated aspects of starting R&D soon: > First, almost everyone reading this could find a place to do something > useful at moderate cost on this technology. A square meter is probably mot > enough, but no-one needs a hectare. > Second, we don't need to cover the whole globe to have a sizeable > effect in the location most urgently needing attention - the Arctic. A > "Bright Water" covering in the Arctic will have a profoundly different > impact than the same covered area near the equator. > Lastly, if we concentrate on the Arctic (being the most likely place > to see a tipping point soon), we only need to cover the open-water (which > is not much at this time of the year), and we need only be concerned for the > summer months. As Dr. McCracken points out , this perhaps can be coupled > with summertime cloud formation in the Arctic - not worldwide (providing > further analysis deems that a worthy gamble in the Arctic). If it works > out, the next logical location is probably the Antarctic. > > 4. If we were in a proper "war-time" mood, any developed country could > probably get an answer in a year about proceeding to a first full scale > effort. Maybe at worse, two years. But we are not in such a mood. The > only hope I can see is that one of the few countries with a significant > annual budget surplus (China?. Brazil? Norway?) can jump in. I have zero > hope for the USA doing anything in the next few years. However, one > enlightened billionaire might hear about how small the dollar need is right > now - for the only SRM approach I see that can give us the needed (Arctic) > breathing room. > I am not saying "Bright Water" is a sure bet. Only that I agree with > Andrew: ".. It's the most exciting new geoeng idea for a long > time......". > > Thanks to Andrew and Mike for keeping this important dialog alive. If the > Arctic ice loss solution is not "Bright Water", what is? > > Ron > > > Begin forwarded message: > > *From:* Mike MacCracken <[email protected]> > *Date:* April 16, 2011 8:37:24 PM MDT > *To:* Geoengineering <[email protected]> > *Cc:* "Russell Seitz (2)" <[email protected]> > *Subject:* *Re: [geo] Re: for Geoe E group Bright Water the movie* > *Reply-To:* <[email protected]>[email protected] > > Hi Andrew—On your objection about the biology of bright water, I’d like to > better understand your concern. How do you think the effect of the bubbles > on a clear day would compare to the effects of a thick cloud cover? > Countering a pretty significant increase in CO2 warming would require, if it > could be done, only a several percent increase in cloud cover [our roughly > 50% cloud cover contributes to reflection of 25% of solar radiation; if what > we need to do is get a 1.8% reduction in the solar constant where we have a > 30% albedo, which is the same as reducing absorbed radiation by about 4 > W/m2, then what we need is the equivalent of an increase in cloud cover from > 50% to a bit less than 53%, or something like that]. Are you suggesting that > an increase in cloud cover from 50 to 53% would have a devastating effect on > marine ecosystems? > > Let me try the calculation another rough, idealized way: If the 50% of > clear sky is responsible for increasing the global albedo from 25% to 30%, > then, allowing for say 10% atmospheric absorption of solar radiation going > each way (forget compounding effect), and two-thirds of this takes place > over the 1/3 of area that is land and ice (so average albedo of land is 4 > times that of ocean), then average ocean albedo is 6%. To then increase the > global average outgoing solar radiation, I calculate that the average ocean > albedo has to go from about 6% to a bit over 10%, which would reduce the > available radiation in the water from 94% to 90% of incoming solar radiation > (accounting only for the effect in clear sky region). > > While I realize that BrightWater envisions making the albedo a good bit > higher, this would mean that I would need to do less elsewhere. Given there > are large areas of the ocean where there is little biological activity due > to low nutrient levels, perhaps I could concentrate the water brightening in > those areas. So, let’s hypothesize that I aim to raise the ocean albedo from > 6% to 15% over the half of the ocean area with the lowest biological > activity (and I think the low biological activity areas are larger than the > marine stratus areas so the pattern of flux change would be less sharp than > for the Salter-Latham approach that can get a global counter-balancing. With > bubble lives limited, unlikely it would be a problem of bubbles drifting > into biologically active areas. > > Now, let’s think about combining the BrightWater and the Salter-Latham > approaches, giving us more even coverage—with the boats shooting up sea salt > sprays when below marine stratus and injecting bubbles when in clear skies, > so maybe half of the albedo effect proposed is needed by each approach. So, > maybe the amount of solar reaching the ocean goes down a couple of percent. > Are you really suggesting that this would devastate marine ecosystems—and > indeed be worse than reflecting a similar amount of radiation using a global > stratospheric aerosol layer? It is true that the combined approaches would > be concentrating their influence over the oceans as opposed to the global > stratospheric layer that spreads the effect over the globe, but the sulfate > aerosols are such inefficient backscatterers that one ends up with a quite > high proportion of forward scattered radiation. > > I am not saying there will not be effects—we’ll need a good bit of research > to get a sense of things—but, assuming that I have things properly estimated > (and I do agree accounting for Sun angle might well require another > adjustment), I do not see how one can rule out the Brightwater approach (on > its own or coupled with Salter-Latham) thinking that the impact on marine > ecosystems would be large and could not be minimized by choosing carefully > where one used the approach. > > Best, Mike MacCracken > > ******* > > > > So, given these > > > On 4/16/11 9:41 PM, "Andrew Lockley" < <http://[email protected]> > [email protected]> wrote: > > Russell, > > My comments below relate to your 'brightwater' proposal. Out of courtesy, > I've removed the thread - so I'm not re-posting your comments without > consent. > > If bubble residency times are high, induced densities can be low. If > residency times are low, you'll have to greatly increase local > concentrations to cause a globally significant, persistent effect. I quote: > "Seitz admitted that scaling it to cover an entire ocean would be > technically difficult, not because of the energy > <<http://www.physorg.com/news189059955.html> > http://www.physorg.com/news189059955.html> requirement, which he said > would be equivalent to about 1000 windmills, but because of the fact that > the bubbles may not last long enough to effectively spread over large areas." > The risk is, therefore, that very much greater local effects may be induced > than is desirable, in order to create the necessary global cover. Not only > might this affect primary productivity, but also more subtle biological > events such as migration, navigation, feeding and breeding. Bioluminescence > is likely to be a notable casualty. 'Hot spots' (or should that be cold > spots) of concentrated treatment are therefore likely best avoided. The > hot-spot effect is not unlike covering a forest in a dense blanket of fog, > when the local weather never naturally causes such an effect. I would > expect the ecosystem impacts to be very significant, or even catastrophic, > especially if the treatment were persistent. > > Your video and images show the bubble plumes spreading laterally and > vertically, rather like slicks. They also show a high optical density, far > higher than I would regard as desirable in open ecosystems. Were the > bubbles' residence time longer, the local concentrations could be relatively > reduced, thus reducing the localised optical impact. Churning the bubbled > water into untreated volumes would be desirable, and a towed streamer design > with many small bubblers would be beneficial in this regard. Oil survey > vessels use such a system, which I understand relies on hydrodynamic forces > to distribute hydrophones over a wide track. > > The behaviour of microbubbles in high concentrations may be entirely > different to that in lower concentrations - not least because of the > limitations of locally available substances to dwell on the bubble surfaces. > I think it would be extremely brave to make detailed predictions when such a > large range of complex factors can affect the behaviour of the bubbles (to > such an extent that the idea could easily be rendered impractical). Not > only are optical effects a consideration, but you also need to consider the > ecosystem impact of the surface physics and chemistry. If the microbubbles > affect the movement or cycling of detritus and microorganisms, the ecosystem > impact could be severe. > > I've also briefly looked over the maths you're proposing, and I'm not fully > reassured by the calculations. I haven't checked the detail of the model > you're using, but I'm concerned by the assertion that "The backscattering > coefficient (bb) of hydrosols of micron-sized bubbles depends on the > fraction of incident light that is intercepted and returned between 90º and > 180º." - as, at high densities, there's a significant chance of > rescattering of once-reflected light. I can't see how this has been > accounted for in your model. > > Of further serious concern is your proposal to create 'icecaps' in the > tropics. Such a localised cooling has the potential to strongly affect > ocean overturning circulation, and could possibly induce an anoxic event. I > don't think your modelling is robust enough to eliminate this possibility. > > Furthermore, by concentrating cooling in waterbodies, an intuitive analysis > suggests that a reduction in evaporation will result. This has potentially > major implications for terrestrial ecosystems and agriculture. Specific > research in this regard is merited. > > I'm sure many of my criticisms have already been considered and discounted, > so perhaps you can fill me in? > > > > Please don't get me wrong - I like your idea, and I want it to work. It's > the most exciting new geoeng idea for a long time. But we need to be honest > about the practical limitations of our predictive powers here, and the range > of factors which need further study before we can start to hang our hats on > these proposals. We also need to make sure that we don't unwittingly > advocate a technique which could possibly cause a local or global > environmental disaster. > > A > > -- > 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. > > -- 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.
