Alan
At midsummer we have a factor of 540/440 = 1.23 for the sunshine
times 0.9 /0.25 = 3.6 for the cloud cover times 2000/200 = 10 for the
boundary layer thickness.
This makes 44.
The air will be cleaner too but you can estimate that. I am arguing
that a week in midsummer may be worth nearly a year at lower latitudes.
But there is no reason why a fast spray vessel cannot migrate spending a
month north of Iceland, a month at the Falklands and the rest of the
time doing whatever seems best for el Nino and the monsoons. You can
see why I want a ruggedised version of Hydroptere and get upset when
people model steady spray between + and -30 degrees latitude. They are
not taking into account one of the very attractive advantages of marine
cloud brightening from fast wind driven vessels.
Please let me have your ideas for the ratios above.
Stephen
Emeritus Professor of Engineering Design. School of Engineering,
University of Edinburgh, Mayfield Road, Edinburgh EH9 3JL, Scotland
[email protected], Tel +44 (0)131 650 5704, Cell 07795 203 195,
WWW.homepages.ed.ac.uk/shs, YouTube Jamie Taylor Power for Change
On 29/05/2015 13:27, Alan Gadian wrote:
Stephen,
I agree with your suggested costs being < 1 billion dollars a year,
given the most expensive expectations. I do not know how the RS (2009)
figures were calculated for Marine Cloud Brightening.
A point though is that the cooling of the poles is very well achieved
by sub-tropical solar reflection. The meridional poleward heat transport
is a major way that the system affects the polar ice reduction. The
large sub tropical area of the reflective SC clouds means that the
solar energy into the system is vastly reduced. The role of the
atmosphere in the atmospheric heat engine is to transfer heat to the
poles, where the ice
melting is an important feature. Thus the MCB increased large direct
reflection near the equator, directly affects polar ice melt in a
significant manner. This is an extra critical factor c.f. the
stratospheric sulphur process.
However, I would also agree with you that the increase in albedo
near the poles in the summer would make a significant contribution in
the cooling of the poles ... I also agree this is very important; but
I would
like to emphasise that in spring, winter and autumn, a large cooling
could be achieved with sub tropical MCB.
Thanks
Alan
On Fri, 29 May 2015, Stephen Salter wrote:
Hi All
From http://en.wikipedia.org/wiki/Insolation the variation
of solar input with season and latitude should be
shown below.
[IMAGE]
At midsummer there is about 540 watts per square metre going in to
the North pole compared with 440 going in to the
equator. In addition, around the Arctic there is a very high
fraction of low cloud cover, 80 to 90 % compared with
around 25% and a much lower boundary layer, about 200 metres so that
much less air has to be treated with salt nuclei.
The only requirements for slowing ice melt are mobility of spray
vessels and movement of air or water in a northerly
direction.
I was a bit puzzled by Ken's mention of a few billion dollars a year
for marine cloud brightening and would like to
collect references on this. My own figures were based on index
linking of the cost of Flower class corvettes in WW II
which were build in similar numbers and suggest a few billion dollars
for a fleet which might last for 20 years or more.
Please can people send me any other cost estimates?
However we can agree that the costs are 'in the noise'.
Stephen
Emeritus Professor of Engineering Design. School of Engineering,
University of Edinburgh, Mayfield Road, Edinburgh EH9
3JL, Scotland [email protected], Tel +44 (0)131 650 5704, Cell 07795
203 195, WWW.homepages.ed.ac.uk/shs, YouTube Jamie
Taylor Power for Change
On 28/05/2015 22:38, Ronal W. Larson wrote:
List cc Ken, John Nissen, Stephen Salter
Ken’s message re cloud brightening seems to be important . Maybe
well known to those close to the field, but I
found much new - especially between about 6 and 18 minutes in Part 4
( https://www.youtube.com/watch?v=b3D6mx5SQo8 ) . Nice to see credit
give to Stephen.
Dr. Neukermans and a very few others have done a lot of impressive
work (as volunteers). His speaking style I
found convincing (including all of video #3 - none on cloud
brightening). I liked that some unpromising approaches
were also described. Only a little new (but obviously well
justified) money is now being sought.
One question I pose on behalf of John Nissen and others in AMEG is
why the Arctic’s lack of sunlight (mentioned at
about the 18 minute mark) is critical. On an annual basis I believe
the insolation is about the world wide average
(as the sun doesn’t set for quite a few months). Not knowing enough
on the whole topic, this technical advance
would seem to be very good news for John/AMEG - if this Arctic solar
issue can still be on the table.
There are quite a few publications on this work, with a few of the
most recent at
https://www.researchgate.net/publication/260755971_Sub-micrometer_salt_aerosol_production_intended_for_marine_cloud_brig
htening
http://www.economist.com/news/science-and-technology/21635983-scientific-studies-techniques-deliberately-modifying-clima
te-are
http://articles.latimes.com/2014/mar/04/nation/la-na-climate-engineering-20140305/2
Ron
On May 28, 2015, at 9:04 AM, Ken Caldeira
<[email protected]> wrote:
Five YouTube videos of the 12 May event are available here:
https://www.youtube.com/playlist?list=PL4E3D946BECCF7DE3
The event is described here:
http://www.sri.com/newsroom/events/cafe-scientifique-silicon-valley-sri-two-novel-approaches-mitigating-climate-change
Part 1: Ken on solar geo and strat aerosols:
https://www.youtube.com/watch?v=-Y6p-B-KbiQ
Part 2: Ken on solar geo and strat aerosols:
https://www.youtube.com/watch?v=wo5Y-SPrybE
Part 3: Armand on marine cloud brighening:
https://www.youtube.com/watch?v=ZbpYGwu4KNA
Part 4: Armand on marine cloud brighening:
https://www.youtube.com/watch?v=b3D6mx5SQo8
Part 5: Ken and Armand answer questions:
https://www.youtube.com/watch?v=9KS9Nbe3Wzs
Cafe Scientifique Silicon Valley @ SRI: Reflecting Sunlight to
Cool Earth's Climate: Emulating Volcanoes and
Brightening Marine
Clouds
May 12, 2015
SRI - Menlo Park, CA
This free Cafe event will feature presentations by two thought
leaders on climate change:
Caldeira and Neukermans
Ken Caldeira (l); Armand Neukermans (r)
Solar Geoengineering and Climate Change: Nearly everyone understands
that the most effective way to reduce
environmental risk associated with climate change is to deeply cut
greenhouse gas emissions as soon as
possible, yet emissions and atmospheric concentrations of greenhouse
gases continue to increase. If current
emissions trends continue, by the end of this century, nearly every
summer in the tropics will be hotter than
the hottest summer yet on record, raising the possibility of
widespread crop failures and famine. If climate
change does prove truly catastrophic, the only feasible way to cool
the Earth rapidly would be to use solar
geoengineering technologies, for example, by emulating the cooling
effects of volcanoes. While it is fairly
certain that Earth's climate can be cooled in this way, it is far
less certain whether such approaches could
ever really reduce overall risk and damage. Dr. Ken Caldeira, a
senior climate scientist at the Carnegie
Institution for Science, will present the science of solar
geoengineering and discuss what this science might
mean for society.
Marine Cloud Brightening: The National Academy of Sciences recently
called for research into
“geoengineering“. Dr. Armand Neukermans will describe the efforts of
a group of retired scientists and
engineers to develop a spray system that might enable a study of the
feasibility of marine cloud brightening
(MCB) for climate cloud studies, as well as possible climate
intervention. MCB aims to increase the
reflectivity of low-hanging ocean clouds, thereby reflecting more
sunlight and cooling the planet. This might
be done by increasing the droplet concentration in the clouds by
spraying seawater from oceangoing ships. The
proposed systems aims to create 1015 cloud nuclei from a glass of
seawater. MCB ( if ever needed) might
conceivably be used globally or locally (e.g., for arctic melt
shielding, hurricane cooling, reef
preservation, or fog belt restoration).
About the Speakers
Dr. Ken Caldeira is a climate scientist working for the Carnegie
Institution for Science, Department of
Global Ecology at Stanford University. He investigates issues related
to climate, carbon, and energy systems.
His primary tools are climate and the carbon cycle models, although
he does field work related to ocean
acidification. Dr. Caldeira co-authored a recent National
Academies report, Climate Intervention: Reflecting
Sunlight to Cool Earth. A free PDF version is available.
Dr. Armand Neukermans has held research and management positions at
KLA-Tencor, Hewlett-Packard, Xerox, and
General Electric, and founded Xros, an optical switch company. He is
the author of 40 publications and the
inventor of more than 75 patents in diverse fields. He was named
Silicon Valley “Inventor of the year” in
2001. Since his retirement, he has been involved in environmental
projects, such as the foundation of the Big
Sur Environmental Institute, and in fostering the causes of social
entrepreneurs. He holds EE and ME degrees
from Louvain University, and a Ph.D. in applied physics from Stanford
University.
- See more
at:http://www.sri.com/newsroom/events/cafe-scientifique-silicon-valley-sri-two-novel-approaches-mitigating-climate-change#s
thash.S562iCyX.dpuf
_______________
Ken Caldeira
Carnegie Institution for Science Dept of Global Ecology
260 Panama Street, Stanford, CA 94305 USA
+1 650 704 7212 [email protected]
website: http://dge.stanford.edu/labs/caldeiralab/
blog: http://kencaldeira.org
@KenCaldeira
My assistant is Dawn Ross <[email protected]>, with access to
incoming emails.
Postdoc
positions: https://jobs.carnegiescience.edu/jobs/postdoctoral-opportunity-global-climate-modeling/
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