Dear Stephen: I hasten to point out that your analysis of cloud cooling of 23km3 from the top down applies equally to microbubble cooling SRM from the bottom up.
Last year, after meeting with UNEP coral conservtionist Tom Goreau I visiited several reef damage redmediation sites in the Grenadines, where though emphasis has been on replanting , widespread bleaching has also led to interest in sea surface cooling. As bothh ocean and lake models suggest the fresh water techniques we are developing to curb fresh water reservoir evaporation can realitstically achieve coolings of 5 K or more, and the energy cost per hectare is reckoned to be a kilowatt or less, a continouous multimegawatt reduction in solar load may be an afforable alterative to your admittedly better developed cloud nucleation work. It shoud be noted that many South China Sea reefs face thermal stresses approaching those of the GBR as well - in both cases ecologists should explore the addvantages and hazards of brightening the water instead of dimming the sun. Best regards Russsell Seitz Senior Fellow The Climate Institute On Saturday, April 22, 2017 at 6:18:33 AM UTC-4, Stephen Salter wrote: > > Hi All > > Ken says there might not be enough clouds to save the barrier reef. > > Below should be a map from Kari Alterskjaer from > doi:10.5194/acp-12-2795-2012 showing how good different regions are > through the seasons. > > The very best red ones of California, Peru and Namibia score 0.12 but the > much larger white areas are 0.085 show the best are only 40% better. > > Further more the life time of nuclei under clear skies will be longer so a > high cloud fraction is less important. We should not let the best become > the enemy of the quite good. > > > > I got some data about flow rates into the Barrier Reef region from a PhD > thesis by Severine Choukroun from > > https://researchonline.jcu.edu.au/24024/ > > The key number is 23 km3 per day. If anyone can give me other numbers > please do. If following Kohler you believe that the right size of > mono-disperse spray will give a high nucleation fraction and that some > other assumptions are reasonable then the calculations below will tell you > how many spray vessels would be needed to cool the Barrier Reef. > > However another paper from Norway > > DOI:10.1029/2010JD014015 > > suggests that my mono-disperse spray assumption does matter because spray > with the Aitken mode size distribution works in the wrong direction. > > Stephen > > > Emeritus Professor of Engineering Design. School of Engineering, > University of Edinburgh, Mayfield Road, Edinburgh EH9 3DW, Scotland > [email protected] <javascript:>, Tel +44 (0)131 650 5704, Cell 07795 203 > 195, WWW.homepages.ed.ac.uk/shs, YouTube Jamie Taylor Power for Change > On 22/04/2017 08:31, Andrew Lockley wrote: > > > > https://www.technologyreview.com/s/604211/scientists-consider-brighter-clouds-to-preserve-the-great-barrier-reef/ > > > - A scientist surveys bleaching damage on the Great Barrier Reef. > - TANE SINCLAIR-TAYLOR | ARC CENTRE OF EXCELLENCE CORAL REEF STUDIES > Sustainable Energy > <https://www.technologyreview.com/topic/sustainable-energy/> Scientists > Consider Brighter Clouds to Preserve the Great Barrier Reef > As bleaching devastates the critical ecosystem for a second year in a row, > marine scientists are getting desperate. > > - by James Temple > <https://www.technologyreview.com/profile/james-temple/> > - > - April 20, 2017 > > Agroup of Australian marine scientists believe that altering clouds might > offer one of the best hopes for saving the Great Barrier Reef. > > For the last six months, researchers at the Sydney Institute of Marine > Science and the University of Sydney School of Geosciences have been > meeting regularly to explore the possibility of making low-lying clouds off > the northeastern coast of Australia more reflective in order to cool the > waters surrounding the world’s biggest coral reef system. > > During the last two years, the Great Barrier Reef has been devastated by > wide-scale bleaching, which occurs as warm ocean waters cause corals to > discharge the algae that live in symbiosis with them. Last year, as El Niño > events cranked up ocean temperatures, at least 20 percent of the reef died > and more than 90 percent of it was damaged. > > The Australian researchers took a hard look at a number > <https://www.theguardian.com/environment/2017/apr/07/plan-cold-water-barrier-reef-stop-bleaching> > of potential ways > <http://www.newyorker.com/magazine/2016/04/18/a-radical-attempt-to-save-the-reefs-and-forests> > to > preserve the reefs. But at this point, making clouds more reflective looks > like the most feasible way to protect an ecosystem that stretches across > more than 130,000 square miles, says Daniel Harrison, a postdoctoral > research associate with the Ocean Technology Group at the University of > Sydney. “Cloud brightening is the only thing we’ve identified that’s > scalable, sensible, and relatively environmentally benign,” he says. > Bleached corals on the Great Barrier Reef. > ED ROBERTS/TETHYS IMAGES | ARC CENTRE OF EXCELLENCE CORAL REEF STUDIES > > They’re one of several research groups that have started to explore > whether cloud brightening, generally discussed as a potential tool to alter > the climate as a whole, could be applied in more targeted ways. All the > scientists involved stress that the research is in its infancy. No one has > tested a system for cloud brightening at all, much less in geographically > focused applications. > > British scientist John Latham first proposed the idea as a potential way of > controlling global warming > <http://www.nature.com/nature/journal/v347/n6291/abs/347339b0.html> in > *Nature* nearly 30 years ago. The theory is that fleets of ships could > spray tiny salt particles, generated from sea water, toward the low-lying > marine clouds that hug the coasts of several continents. That would provide > the nuclei needed to induce additional droplet formation, expanding the > total surface area of the clouds. The resulting dense, white clouds should > reflect more heat back into space. A 2012 study led by Latham at the > University of Manchester found that the approach could offset the heating > that would result if carbon dioxide doubled in > <http://rsta.royalsocietypublishing.org/content/370/1974/4217> the > atmosphere. > > The Marine Cloud Brightening Project, a collaboration between a group of > Silicon > Valley researchers > <http://www.sfgate.com/science/article/Looking-to-sky-to-fight-climate-change-4170475.php> > and > University of Washington climate scientists, has done the most advanced > work on the idea to date. The team in Sunnyvale, California, has spent the > last seven years developing a nozzle that they believe can spray salt > particles of just the right size and quantity to alter the clouds. They’re > attempting to raise several million dollars to build full-scale sprayers, > in hopes of eventually conducting small-scale field trials at some flat > point along the Pacific coastline—ideally a place with onshore winds, > low-lying clouds, and open-minded neighbors. > The Marine Cloud Brightening Project's nozzle sprays a fine mist of tiny > salt particles. > JAMES TEMPLE > > They’re among a handful of researchers looking to conduct limited outdoor > experiments to explore the feasibility and risks of such approaches (see “The > Growing Case for Geoengineering > <https://www.technologyreview.com/s/604081/the-growing-case-for-geoengineering/?set=604205>”). > > But while the prospect of using geoengineering to ease global warming on a > large scale poses intractable governance issues, using the technology to > address a more localized problem could be more feasible, at least > politically. > > Coral reefs are crucial parts of the ocean ecosystem, providing hunting > grounds and homes for thousands of species. They also generate nearly $200 > billion in economic value annually, through tourism, fisheries, and other > activity, according to one study > <https://www.eurekalert.org/pub_releases/2009-10/d-wac101509.php>. Reefs, > however, have been hard hit worldwide by ocean acidification, pollution, > overfishing, and other environmental stresses. The Great Barrier Reef has > shrunk dramatically during the last three decades > <http://www.bbc.com/news/science-environment-19800253>. > > That makes it increasingly urgent to seriously explore ways of preserving > the reefs, even “fairly out-there, grand schemes,” Harrison says. Next > month, he plans to start computer climate modeling to explore > <http://myerfoundation.org.au/news/2017-myer-innovation-fellows-announced/> > whether > cloud brightening could make a big enough temperature difference to help. > The group plans to collaborate on the research with the Marine Cloud > Brightening Project team. > > Should scientists try to save the Great Barrier Reef by brightening the > clouds? Tell us what you think. > <https://www.technologyreview.com/s/604211/scientists-consider-brighter-clouds-to-preserve-the-great-barrier-reef/#comments> > > Coral reefs aren’t the only ecosystem that some scientists believe might > need help from geoengineering. Researchers at the University of California, > the Carnegie Institution, Stanford University, and Oregon State University > have begun a larger project <http://www.fogsci.com/> exploring, among > other things, how climate change is affecting or will affect the last > remaining stands of coast redwoods. > > They're the world's tallest trees, and rely on coastal fog for around half > of their moisture. But Northern California fog levels have dropped more > than 30 percent <http://www.pnas.org/content/107/10/4533.full> since the > early 20th century, a decline linked to urbanization and climate change. > The impact has been limited to date, but fear is growing > that these old-growth stands could be wiped out if the trends accelerate. > > Elliott Campbell, an associate professor of environmental engineering at > UC Merced, says the group has held early talks with the Marine Cloud > Brightening Project about whether the technique could generate more > low-lying clouds to help feed moisture to the redwoods. “If we could > artificially produce fog on summer mornings, and that could help us buy the > redwoods more time as we shift to a less carbon-intensive economy, that’s > potentially a good thing,” Campbell says. > Aerial view of a bleached portion of the Great Barrier Reef. > ARC CENTRE OF EXCELLENCE CORAL REEF STUDIES > > Ken Caldeira <https://www.technologyreview.com/s/543916/stop-emissions/>, > a prominent climate scientist at the Carnegie Institution who has modeled > the potential of cloud brightening, says the idea of localized > geoengineering is worth exploring. But he’s not convinced that cloud > brightening could produce a substantial climate effect at such a limited > level. Below a certain geographic footprint, probably around 10,000 square > miles, it might be difficult to produce a big enough change in cloud > density to add up to much of a difference, he says. He’s specifically > skeptical that it would work at the Great Barrier Reef. > > “I just don’t think there are enough clouds of the right type there that > would be susceptible to marine cloud brightening,” he says. > > The University of Sydney’s Harrison is aware of the concerns Caldeira > raises and intends to look at these issues closely in his feasibility > research. But at a first pass, he believes there could be sufficient marine > clouds to help preserve the Great Barrier Reef. > > In any case, he hopes so, because nothing else looks particularly > promising. > > Tech Obsessive? > Become an Insider to get the story behind the story — and before anyone > else. > Subscribe today > <https://ssl.drgnetwork.com/ecom/MTR/app/live/subscriptions?org=MTR&publ=TR&key_code=PRSPRIS&type=S> > > - > - > - > - > - > - > - > - > > Tagged > > Ken Caldeira <https://www.technologyreview.com/g/ken-caldeira/>, > geoengineering <https://www.technologyreview.com/g/geoengineering/>, > clouds <https://www.technologyreview.com/g/clouds/>,Great Barrier Reef > <https://www.technologyreview.com/g/great-barrier-reef/>, Daniel Harrison > <https://www.technologyreview.com/g/daniel-harrison/>, Australia > <https://www.technologyreview.com/g/australia/> > [image: James Temple] > > James Temple <https://www.technologyreview.com/profile/james-temple/>Senior > Editor, Energy > > I am the senior editor for energy at *MIT Technology Review*. I’m focused > on renewable energy and the use of technology to combat climate change. > Previously, I was a senior director at the *Verge*, deputy managing > editor at *Recode*, and columnist at the *San Francisco Chronicle*. When > I’m not writing about energy and climate change, I’m often hiking with my > dog or shooting video of California landscapes. > -- > You received this message because you are subscribed to the Google Groups > "geoengineering" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected] <javascript:>. > To post to this group, send email to [email protected] > <javascript:>. > Visit this group at https://groups.google.com/group/geoengineering. > For more options, visit https://groups.google.com/d/optout. > > > -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. 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