[geo] WMO message to IPCC at 58th session

[olivier boucher]

Hello list, 

I don't think this was circulated to the list, my apologies if it was. 

Video message of WMO Secretary-General Prof. Petteri Taalas at opening of IPCC 
session on the Synthesis Report of the Sixth Assessment Report 
(that's the IPCC session that took place in March, not the one that is taking 
place this week in Nairobi) 

Text is available here [ 
https://www.ipcc.ch/site/assets/uploads/2023/03/IPCC-58-WMO-SG-Opening.pdf | 
https://www.ipcc.ch/site/assets/uploads/2023/03/IPCC-58-WMO-SG-Opening.pdf ] 

" ... And at least from our side there would be a need to have a report on 
geoengineering, which is one of the hot topics and which also carries many 
risks, and should be evaluated by the by the science community. ... " 

Olivier 

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[geo] Re: Zephalto - Low-carbon space travel

[olivier boucher]

sorry, I must correct myself. The French media quotes 27 kg CO2eq / passenger / 
flight. See 
https://gazette-du-midi.fr/au-sommaire/entreprises/zephalto-toucher-presque-les-etoiles
 

- Mail original -
De: "olivier boucher" 
À: "geoengineering" 
Cc: "Wake Smith" 
Envoyé: Mercredi 28 Décembre 2022 20:22:49
Objet: Zephalto - Low-carbon space travel

https://zephalto.com/en/

Zephalto is a start-up backed by the French spatial agency CNES that positions 
itself on low-carbon and safe "space" travel in the stratosphere at 25 km. I 
couldn't find what low carbon means on their web site, but I've read a French 
media quoting 27 t CO2eq per passenger for one trip up to 25 km (it doesn't 
sound that low ?!). Could this be a vehicle for delivering SO2 or some other 
aerosol precursor to the stratosphere? The payload must be fairly small and the 
cost pretty high. Smith and Wagner (2018, 
https://iopscience.iop.org/article/10.1088/1748-9326/aae98d) give a cost of 
40,000 $/ton for balloons. It's worth a comparison: Zephalto annouces a ticket 
price of 5000 € per passenger. Assuming a passenger weighs 80 kg, that's about 
60,000 $/ton but there is probably a huge potential for saving when scaling 
this up.  Worth considering if low carbon and reusable ?

Olivier

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[geo] Zephalto - Low-carbon space travel

[olivier boucher]

https://zephalto.com/en/

Zephalto is a start-up backed by the French spatial agency CNES that positions 
itself on low-carbon and safe "space" travel in the stratosphere at 25 km. I 
couldn't find what low carbon means on their web site, but I've read a French 
media quoting 27 t CO2eq per passenger for one trip up to 25 km (it doesn't 
sound that low ?!). Could this be a vehicle for delivering SO2 or some other 
aerosol precursor to the stratosphere? The payload must be fairly small and the 
cost pretty high. Smith and Wagner (2018, 
https://iopscience.iop.org/article/10.1088/1748-9326/aae98d) give a cost of 
40,000 $/ton for balloons. It's worth a comparison: Zephalto annouces a ticket 
price of 5000 € per passenger. Assuming a passenger weighs 80 kg, that's about 
60,000 $/ton but there is probably a huge potential for saving when scaling 
this up.  Worth considering if low carbon and reusable ?

Olivier  

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Re: [geo] Make sunsets - Calculating Cooling

[olivier boucher]

Thank you Andrew for pointing to this Make Sunset news which I had not seen. 

I find their calculations to be both optimistic and misleading. 

"The key number -.62 W/m2 radiative forcing created for a year by injecting 1 
Tg of sulfur" based on several studies 
- Ferrero et al 2012 did not inject aerosols but prescribed them in their 
model, they achieve -3.5 Wm-2 for a burden of 14.5 TgSO4, that's -0.7 Wm-2 / Tg 
S burden 
- Pope et al 2012 did not provide Wm-2 in their study 
- Kuebbeler et al 2012 provide an ERF (with cirrus adjustments) of -0.93 Wm-2 
for 5 Mt SO2/yr, that's -0.37 Wm-2 / (TgS/yr ) 
- Pitari et al 2014 : G4 experiment for 5 Mt SO2/yr shows -1.54, -0.73, -1.27 
and -1.31, that's -0.61, -0.29, -0.51, -0.52 Wm-2 / (TgS/yr) 
- Kleinschmitt et al 2018, table 7a : -0.35 Wm-2 / (TgS/yr) with a lower value 
from Niemeier and Timmreck (2015) on the same graph at -0.26 Wm-2 / (TgS/yr) 
- Dai et al. 2018 : equatorial 5 Mt-S/yr SO2 injection at 21–24.5 km results in 
0.72 Wm-2 / (TgS/yr), note that's a very high injection point 
So -0.6 Wm-2/(TgS/yr) is a clearly an upper (negative) bound of what the 
literature says. And it's unlikely to be achieved with an injection that is not 
controlled at all. 

"How long do these particles create cooling? 1-3 years. For our purposes, we'll 
go with 2.1 years" 
- Kleinschmitt et al 2017 point to a residence time of 0.8 year for their model 
and that of Niemeier and Timmreck, see Fig 7d. 
- Heckendorn et al 2012 has a residence time of at most 1 year for low 
injection rates, see their Fig 4a 
But more importantly there is no reason to mutiply by the residence time... all 
the above numbers are for continuous injections. Therefore they already account 
for the residence time of S ! 

"From the first table above, .7C per W/m2. So, we'll convert our radiative 
forcing per Tg SO2 to temperature change: -.31 W/m2 * .7C per W/m2 = -.217 C 
per Tg SO2/year" 
This value of the ECS is also for a constant-in-time RF and therefore a 
continuous injection rate. 
One cannot use a steady state calculation to infer what a pulse injection would 
do. 

There is a whole lot of literature on "climate metrics" on how to compare 
short-lived and long-lived species. This is a typical example here with SO2 (1 
yr) and CO2 (multi-century). There is no such thing as a best metric (it's 
partly a scientific, partly a policy choice) but it is important to avoid 
inconsistencies. Here Make Sunset uses something alike the GTPs (GTP for 
sustained emissions), see [ 
https://link.springer.com/article/10.1007/s10584-005-1146-9 | 
https://link.springer.com/article/10.1007/s10584-005-1146-9 ] , to draw an 
equivalence between the SO2 and the CO2 but then applies it to a pulse 
emission, which is why I say their approach is misleading. And there is this 
double counting with the residence time. In my calculation which I posted a 
couple of days ago, I implicitly chose a GWP1 (GWP with 1 yr time horizon) for 
my calculation, with the caveat that you have only offset the RF of the CO2 for 
one year. If one wants to go for a T calculation, I would suggest to use GTP20, 
GTP50 and GTP100 for pulse emissions to get a range of equivalences between g 
SO2 and CO2. 

Also in their Table : 
"RF efficacy decline of 1% for each additional TgS/yr" 
Although that's not part of the calculation, this is not supported by the above 
studies. The saturation effect is much more. 

Finally I did not see on their web site what 10 $ buys you. It seems 10 $ only 
buys you 10 $ of cooling. Could the "10 $ buys 1 gSO2" just be an extrapolation 
from MIT Tech Review? 

Best regards, 

Olivier 



De: "Govindasamy Bala"  
À: "Andrew Lockley"  
Cc: "geoengineering"  
Envoyé: Mercredi 28 Décembre 2022 07:42:32 
Objet: Re: [geo] Make sunsets - Calculating Cooling 

this is all good and well-known, but the cost of this commercial venture (as 
per the news) is way too high. 
For a 2deg offset, the calculations show ~4 TgSO2 of injection per year which 
translates to ~ 40 Trillion dollars per year at a rate of $10 per gram of SO2. 
Cost estimates have gone through the roof into the stratosphere from a few 
billion dollars to trillions of dollars. Well, looks this is what 
commercialization would do. At this rate, the cost of stratospheric aerosol 
geoengineering could be similar to the cost of mitigation 

Bala 

On Wed, Dec 28, 2022 at 5:07 AM Andrew Lockley < [ 
mailto:andrew.lock...@gmail.com | andrew.lock...@gmail.com ] > wrote: 



[ https://makesunsets.com/blogs/news/calculating-cooling | 
https://makesunsets.com/blogs/news/calculating-cooling ] 


DECEMBER 27, 2022 
Share 
Calculating Cooling 

How do we know how much cooling we're creating with our "clouds," and how does 
this compare to warming from carbon dioxide emissions? 
Fortunately, much smarter people have studied this for decades. Let's review 
some of their work and calculate our climate cooling impact. 

Radiative Forcing? 

Radiative forcing is the 

Re: [geo] A startup says it’s begun releasing particles into the atmosphere, in an effort to tweak the climate

[olivier boucher]

Hello, 

I didn't know about "Make sunsets". They claim on their web site: 

Specifically: we release a natural compound via reusable balloons to create 
reflective clouds in the stratosphere. They're * really* effective: 1 gram of 
our clouds offsets the warming that 1 ton of CO ₂ emissions creates for a year. 
After three years, our clouds compost and settle back to Earth. 

Assuming their inject sulphate or some similar aerosols, you may expect a 
radiative effect of -100 W g-1 that lasts for about a year or say a couple of 
years if you inject in the right place at the right time. In comparison, CO2 
exerts an absolute GWP of 2e-15 Wm-2.kg-1.yr after one year (and the absolute 
GWP keeps increasing with time for a long time), multiplied by the area of the 
Earth, one gets 2e-15 * 4 * pi * R^2 = 1 W.kg-1.yr so the aerosol offsets 100 
kg CO2 (and not a ton as claimed) for a year. And of course, you would have to 
repeat that every year for quite some time because of the CO2 lifetime in the 
atmosphere. 

Make sunsets must stand corrected ! 

Olivier 


De: "ayesha iqbal"  
À: "geoengineering"  
Envoyé: Dimanche 25 Décembre 2022 13:40:41 
Objet: [geo] A startup says it’s begun releasing particles into the atmosphere, 
in an effort to tweak the climate 



[ 
https://www.technologyreview.com/2022/12/24/1066041/a-startup-says-its-begun-releasing-particles-into-the-atmosphere-in-an-effort-to-tweak-the-climate/
 | 
https://www.technologyreview.com/2022/12/24/1066041/a-startup-says-its-begun-releasing-particles-into-the-atmosphere-in-an-effort-to-tweak-the-climate/
 ] 




Make Sunsets is already attempting to earn revenue for geoengineering, a move 
likely to provoke widespread criticism. 




By James Temple 




December 24, 2022 




A startup claims it has launched weather balloons that may have released 
reflective sulfur particles in the stratosphere, potentially crossing a 
controversial barrier in the field of solar geoengineering. 




That refers to deliberate efforts to manipulate the climate by reflecting more 
sunlight back into space, mimicking a natural process that occurs in the 
aftermath of large volcanic eruptions. In theory, spraying sulfur and similar 
particles in sufficient quantities could potentially ease global warming. 




It’s not technically difficult to release such compounds in the stratosphere. 
But scientists have mostly refrained from carrying out even small-scale outdoor 
experiments (though not entirely) [ 
https://www.technologyreview.com/2019/08/09/615/what-is-geoengineering-and-why-should-you-care-climate-change-harvard/
 | 
https://www.technologyreview.com/2019/08/09/615/what-is-geoengineering-and-why-should-you-care-climate-change-harvard/
 ] . And it’s not clear that any have yet injected materials into that specific 
layer of the atmosphere in the context of geoengineering-related research. 




That’s in part because it’s highly controversial, as little is known about the 
real-world effect of such deliberate interventions at large scales, including 
the potential for dangerous side-effects, uneven impacts across different 
regions and resulting geopolitical conflicts. 




Some researchers who have long studied the technology are deeply troubled that 
the company, Make Sunsets, appears to have moved forward with launches from a 
site in Mexico, without any public engagement or scientific scrutiny. It’s 
already attempting to sell “cooling credits” for future balloon flights that 
could carry larger payloads. 




Several researchers MIT Technology Review spoke with condemned the effort to 
commercialize geoengineering at this early stage. Some investors and potential 
customers who have reviewed the company’s proposals stress that it’s not a 
serious scientific effort or a credible business, arguing it’s more of an 
attention grab designed to stir up controversy in the field. 




Luke Iseman, the co-founder and CEO of Make Sunsets, acknowledges the effort is 
part entrepreneurial and part provocation, an act of geoengineering activism. 




He hopes that by moving ahead in the controversial space, the startup will help 
drive the public debate and push forward a scientific field that has faced 
great difficulty ( [ 
https://www.technologyreview.com/2021/03/31/1021479/harvard-geoengineering-balloon-experiment-sweden-suspended-climate-change/
 | 
https://www.technologyreview.com/2021/03/31/1021479/harvard-geoengineering-balloon-experiment-sweden-suspended-climate-change/
 ] ) moving ahead with small-scale field experiments amid criticism. 




“We joke slash not joke that this is partly a company and partly a cult,” he 
says. 




Iseman, previously a director of hardware at Y Combinator, says he expects to 
be pilloried by both geoengineering critics and researchers in the field for 
taking such a step, and recognizes that “making me look like the Bond villain 
is going to be helpful to certain groups.” But he says climate change is such a 
grave threat, and 

Re: [geo] Mark Twain was the first geoengineer

[olivier boucher]

Hi Alan, 
It would be a nice fit to our "le temps des écrivains" section of our 
three-monthly meteorological journal. 
See an example here: [ 
https://lameteorologie.fr/issues/2017/98/meteo_2017_98_52 | 
https://lameteorologie.fr/issues/2017/98/meteo_2017_98_52 ] The section 
reproduces selected writings on the weather. 
I checked and there is a French translation of the American Claimant, 
unfortunately the foreword and annex were not translated at the time. 
All the best, 
Olivier 


De: "Alan Robock"  
À: "geoengineering"  
Envoyé: Jeudi 5 Mai 2022 22:07:28 
Objet: [geo] Mark Twain was the first geoengineer 

Dear All, 

In these days with so much troubling news in the air, I thought some humor 
would help. 

It turns out that Mark Twain was the first geoengineer, as explained in his 
book American Claimant , written in 1891. After beginning the book with this 
hilarious explanation about weather, 

“No weather will be found in this book. This is an attempt to pull a book 
through without weather. It being the first attempt of the kind in fictitious 
literature, it may prove a failure, but it seemed worth the while of some 
dare-devil person to try it, and the author was in just the mood. Many a reader 
who wanted to read a tale through was not able to do it because of delays on 
account of the weather. Nothing breaks up an author’s progress like having to 
stop every few pages to fuss-up the weather. Thus it is plain that persistent 
intrusions of weather are bad for both reader and author. Of course weather is 
necessary to a narrative of human experience. That is conceded. But it ought to 
be put where it will not be in the way; where it will not interrupt the flow of 
the narrative. And it ought to be the ablest weather that can be had, not 
ignorant, poor-quality, amateur weather. Weather is a literary specialty, and 
no untrained hand can turn out a good article of it. The present author can do 
only a few trifling ordinary kinds of weather, and he cannot do those very 
good. So it has seemed wisest to borrow such weather as is necessary for the 
book from qualified and recognized experts—giving credit, of course. This 
weather will be found over in the back part of the book, out of the way. See 
Appendix. The reader is requested to turn over and help himself from time to 
time as he goes along.” 

he ends the book with geoengineering. Speaking is Colonel Sellers to his 
partner, describing his money-making scheme: 

“This grand new idea of mine—the sublimest I have ever conceived, will save me 
whole, I am sure. I am leaving for San Francisco this moment, to test it, by 
the help of the great Lick telescope. Like all of my more notable discoveries 
and inventions, it is based upon hard, practical scientific laws; all other 
bases are unsound and hence untrustworthy. In brief, then, I have conceived the 
stupendous idea of reorganizing the climates of the earth according to the 
desire of the populations interested. That is to say, I will furnish climates 
to order, for cash or negotiable paper, taking the old climates in part 
payment, of course, at a fair discount, where they are in condition to be 
repaired at small cost and let out for hire to poor and remote communities not 
able to afford a good climate and not caring for an expensive one for mere 
display. My studies have convinced me that the regulation of climates and the 
breeding of new varieties at will from the old stock is a feasible thing. 
Indeed I am convinced that it has been done before; done in prehistoric times 
by now forgotten and unrecorded civilizations. Everywhere I find hoary 
evidences of artificial manipulation of climates in bygone times. Take the 
glacial period. Was that produced by accident? Not at all; it was done for 
money. I have a thousand proofs of it, and will someday reveal them. 

“I will confide to you an outline of my idea. It is to utilize the spots on the 
sun—get control of them, you understand, and apply the stupendous energies 
which they wield to beneficent purposes in the reorganizing of our climates. At 
present they merely make trouble and do harm in the evoking of cyclones and 
other kinds of electric storms; but once under humane and intelligent control 
this will cease and they will become a boon to man. I have my plan all mapped 
out, whereby I hope and expect to acquire complete and perfect control of the 
sun-spots, also details of the method whereby I shall employ the same 
commercially; but I will not venture to go into particulars before the patents 
shall have been issued. I shall hope and expect to sell shop-rights to the 
minor countries at a reasonable figure and supply a good business article of 
climate to the great empires at special rates, together with fancy brands for 
coronations, battles and other great and particular occasions. There are 
billions of money in this enterprise, no expensive plant is required, and I 
shall begin to realize in a few days—in a few weeks at 

Re: [HCA-list] Re: [geo] Solar geoengineering: The case for an international non-use agreement

[olivier boucher]

Hello, 
a couple more papers on our side on regional SRM: 
- Quaas, J., Quaas, M.F., Boucher, O. and Rickels, W. (2016), Regional climate 
engineering by radiation management: Prerequisites and prospects. Earth's 
Future, 4: 618-625. [ https://doi.org/10.1002/2016EF000440 | 
https://doi.org/10.1002/2016EF000440 ] 
- Dipu, Sudhakar, Johannes Quaas, Martin Quaas, Wilfried Rickels, Johannes 
Mülmenstädt, and Olivier Boucher. 2021. "Substantial Climate Response outside 
the Target Area in an Idealized Experiment of Regional Radiation Management" 
Climate 9, no. 4: 66. [ https://doi.org/10.3390/cli9040066 | 
https://doi.org/10.3390/cli9040066 ] 
Maybe regional radiation management works better in some regions than in 
others. Where we tried, however, it wasn't so obvious that it would work. One 
has to hit the system quite hard to get a significant regional response. 
Best, 
Olivier 


De: "Mike MacCracken"  
À: rpbai...@gmail.com, "Clive Elsworth"  
Cc: "Daphne Wysham" , "H simmens" 
, "John Nissen" , "Robert Tulip" 
, "geoengineering" , 
"Planetary Restoration" , "Shaun 
Fitzgerald" , "Hugh.Hunt" , 
"healthy-planet-action-coalition" 
, "Andrew Lockley" 
 
Envoyé: Dimanche 30 Janvier 2022 16:45:18 
Objet: Re: [HCA-list] Re: [geo] Solar geoengineering: The case for an 
international non-use agreement 



And studies/analyses I've done a good bit back suggest the same thing. See 

MacCracken, M. C., H-J. Shin, K. Caldeira, and G. Ban-Weiss, 2013: Climate 
response to solar insolation reductions in high latitudes, Earth Systems 
Dynamics , 4 , 301-315, 2013; [ http://www.earth-syst-dynam.net/4/301/2013/ | 
www.earth-syst-dynam.net/4/301/2013/ ] ; doi:10.5194/esd-4-301-2013. 







MacCracken, M. C., 2016: The rationale for accelerating regionally focused 
climate intervention research, Earth’s Future 4 , 649-657, 
doi:10.1002/2016EF000450. 




Glad to hear of recent work in this area. 

Mike 



On 1/29/22 9:11 PM, Ron Baiman wrote: 



Follow Up to Clive's post: The folks at Cornell U. are apparently leaning in 
this direction: regional SAI for the Arctic where the Tropopause is lower, 
during the early summer or late spring - as I recall - months. Their climate 
models suggest that this is more efficient than uniform year around global SAI, 
and it could be less of a lift politically - though for balance this might have 
to be done at the south pole as well. Walker Lee discusses this in this podcast 
with Andrew Lockley: [ https://open.spotify.com/episode/2HVbDS3tp4sHruZ79kTfup 
| https://open.spotify.com/episode/2HVbDS3tp4sHruZ79kTfup ] 
Best, 
Ron 


On Sat, Jan 29, 2022 at 2:51 PM Clive Elsworth < [ 
mailto:cl...@endorphinsoftware.co.uk | cl...@endorphinsoftware.co.uk ] > wrote: 

BQ_BEGIN

Daphne 

My intention was not to associate ‘moral hazard versus moral imperative’ with 
stratospheric aerosol injection (SAI), but rather to highlight it as a usefully 
succinct way to describe a common dilemma. It could apply just as well to the 
dilemma faced by border forces. Should they save poor souls from perishing in 
the desert or drowning at sea, or leave them to die to dissuade others from 
making the same trip? (Note that I’m not trying to associate you with that 
either.) 

SAI is more complex because it involves physical hazard as well. The addition 
of solid particles into the ozone layer provides increased surface area for 
catalytic release of halogens that then go on to deplete ozone. 

That is why Franz and I hope that if it really must be done then it will be 
applied below the stratosphere in the Arctic during summer months only. The 
downward flow of air from Brewer Dobson circulation should bring the particles 
down to sea level with minimal amounts entering the stratosphere. 

Clive 

BQ_BEGIN

On 29/01/2022 02:24 Daphne Wysham < [ mailto:dap...@methaneaction.org | 
dap...@methaneaction.org ] > wrote: 


Greetings. 

I don't follow this list closely, but I do want to make sure that my quote, 
which was taken out of context, not be misconstrued as having anything to do 
with SRM, which I know very little about and am, frankly, quite uneasy about. 
In this quote which Clive shared from one of our methane group meetings, I was 
referring to methane removal, not SRM, when I said we have a moral obligation 
to act on rapidly rising methane levels in the atmosphere, while acknowledging 
that there is a moral hazard we also must admit to in including methane removal 
in the mix. 

My feeling is that the moral obligation to ensure methane removal is part of 
the mix, if acted on with good governance, social license, and integrity, would 
weaken the moral hazard critique. We must be mindful of and avoid all moral 
hazards, but the moral obligation to act on methane removal while there is 
still time is greater than the moral hazard in my mind. This is somethi

Re: [geo] Fwd: [CDR] CO2 shrinks the stratosphere

[Olivier Boucher]

Dear Oliver,

you may also refer to 
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2017GL074647 
(figures 2 & 3) though I have always felt our model overwarms the 
stratosphere in response to the stratospheric aerosols probably due to a 
RT model that is not sophisticated enough. The heating is due to both 
absorption by the aerosols but also by additional absorption by ozone 
due to the longer photon path in the aerosol plume. I've never seen a 
proper quantification of both effects.


All the best,

Olivier

Le 14/05/2021 à 22:33, Wingenter, Oliver a écrit :

Alan
Does the temperature of the tropopause change? What is the impact, if 
any, on the stratospheric exchange time? I am thinking about the 
effect on CFCs, CH4, and stratospheric chemistry.
Is there a paper on this? Does added sulfate from SO2 injection into 
the stratosphere warm the stratosphere significantly?


Regards
Oliver Wingenter

On Fri, May 14, 2021 at 12:44 AM Andrew Lockley 
mailto:andrew.lock...@gmail.com>> wrote:


I'm interested to understand the effect on SRM. Eg more technical
difficulties with lofting, earlier rain out, etc. I'd welcome
discussion.

Andrew

On Thu, 13 May 2021, 14:41 Alan Robock ☮,
mailto:rob...@envsci.rutgers.edu>> wrote:

This is certainly not unexpected.  We wrote a paper on this 25
years ago:

Vinnikov, Konstantin Ya., Alan Robock, Ronald J. Stouffer and
Syukuro Manabe, 1996: Vertical patterns of free and forced
climate variations. /Geophys. Res. Lett./, *23*, 1801-1804.
http://climate.envsci.rutgers.edu/pdf/VinnikovVertical96GL01736.pdf


And I don't think it is an important reason to do CDR. There
are other good reasons, but this does not affect us nearly as
much as other impacts of global warming.

Alan

Alan Robock, Distinguished Professor
  Chair-Elect, AGU College of Fellows
  Associate Editor, /Reviews of Geophysics/
Department of Environmental Sciences Phone:
+1-848-932-5751
Rutgers UniversityE-mail:
rob...@envsci.rutgers.edu 
14 College Farm Road http://people.envsci.rutgers.edu/robock

New Brunswick, NJ 08901-8551 ☮
https://twitter.com/AlanRobock 

"I've got a feeling 21 is going to be a good year" - The Who
from the album /Tommy/

Signature


On 5/13/2021 6:33 AM, Andrew Lockley wrote:


-- Forwarded message -
From: *Tom Goreau* mailto:gor...@globalcoral.org>>
Date: Thu, 13 May 2021, 11:03
Subject: [CDR] CO2 shrinks the stratosphere
To: 'Greg Rau' via Carbon Dioxide Removal
mailto:carbondioxideremo...@googlegroups.com>>


*Yet another unexpected reason why CDR is needed!*

**

*Stratospheric contraction caused by increasing greenhouse gases*

To cite this article before publication: Petr Pisoft et al
2021 Environ. Res. Lett. in press
https://doi.org/10.1088/1748-9326/abfe2b


P. Pisoft1 , P. Sacha1,2, L. M. Polvani3 , J. A. Añel4 , L.
de la Torre4 , R. Eichinger1,5,6, U. Foelsche7 , P. Huszar1 ,
C. Jacobi8 , J. Karlicky1,2, A. Kuchar1,8, J. Miksovsky1 , M.
Zak1 , H. E. Rieder2

_Abstract_ Rising emissions of anthropogenic greenhouse gases
(GHG) have led to tropospheric warming and stratospheric
cooling over recent decades. As a thermodynamic consequence,
the troposphere has expanded and the rise of the tropopause,
the boundary between the troposphere and stratosphere, has
been suggested as one of the most robust fingerprints of
anthropogenic climate change. Conversely, at altitudes above
~55 km (in the mesosphere and thermosphere) observational and
modeling evidence indicates a downward shift of the height of
pressure levels or decreasing density at fixed altitudes. The
layer in between, the stratosphere, has not been studied
extensively with respect to changes of its global structure.
Here we show that this atmospheric layer has contracted
substantially over the last decades, and that the main driver
for this are increasing concentrations of GHG. Using data
from coupled chemistry-climate models we show that this trend
will continue and the mean climatological thickness of the
stratosphere will decrease by 1.3 km following representative
concentration pathway 6.0 by 2080. We also demonstrate that
the stratospheric contraction is not only a response to
cooling, as changes in both tropopause 

Re: [geo] sulfate aerosol geoengineering modelled by solar dimming

[Olivier Boucher]

Hi Stephen,

you're correct and I'd think the negative SW RF is more offset by the 
positive LW RF in the tropics than in the high latitudes (alike the 
pattern of RF by WMGHG). But again, the pattern of a 
not-too-inhomogeneous forcing is only moderately important.


Regards

Olivier


Hi All

But you also have to consider outgoing long wave radiation especially 
in winter.


Stephen

Emeritus Professor of Engineering Design. School of Engineering, 
University of Edinburgh, Mayfield Road, Edinburgh EH9 3DW, Scotland 
s.sal...@ed.ac.uk, Tel +44 (0)131 662 1180 WWW.homepages.ed.ac.uk/shs, 
YouTube Jamie Taylor Power for Change

On 17/02/2020 08:35, Olivier Boucher wrote:


Dear Tamas,

there are typically 3 effects that govern RF by stratospheric 
aerosols as a function of latitude for a given aerosol burden. Let's 
think in terms of solar zenith angle (one has then to integrate over 
SZA which is a function of latitude and season)


1/ insolation decreases with SZA as cos(theta) where theta is the SZA

2/ air mass increases with  SZA as 1/cos(theta), of course the effect 
this has breaks down at some point because of multiple scattering


3/ upscattering function also increases with SZA (because more 
forward scattering contributes to upscattering).


You could assume 1/ and 2/ cancel each other at first approximation, 
so because of 3/ there is indeed more RF at larger SZA. In fact there 
is an optimum around SZA=60° but that depends on the AOD and how much 
multiple scattering there is.


Now life is a bit more complicated, as transport and aerosol size 
varies also.


In any case, the climate response is not a copy-paste of the spatial 
distribution of the RF. It matters but not too much. And it matters 
more for rapid adjustments than for feedbacks. See eg 
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2013JD021110


Regards,

Olivier



Dear All,

I would like to ask for some useful references about sulfate aerosol geoengineering. 
Assuming some uniform aerosol coverage around the globe, at some height, with a certain 
vertical layer thickness, i would imagine that at higher latitudes the radiative forcing 
exerted by the aerosols is larger due to the longer distance of travel of sun rays 
through the aerosol "cloud". As a consequence, the latitude-dependence of the 
downward-directed radiative forcing should have an even larger gradient than solar 
irradiance. Therefore, I’m wondering how big mistake it is to model such a geoengineering 
scenario by dimming the sun.

Any feedback or reference would be much appreciated.

Thank you,

Tamas


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Re: [geo] sulfate aerosol geoengineering modelled by solar dimming

[Olivier Boucher]

Dear Tamas,

there are typically 3 effects that govern RF by stratospheric aerosols 
as a function of latitude for a given aerosol burden. Let's think in 
terms of solar zenith angle (one has then to integrate over SZA which is 
a function of latitude and season)


1/ insolation decreases with SZA as cos(theta) where theta is the SZA

2/ air mass increases with  SZA as 1/cos(theta), of course the effect 
this has breaks down at some point because of multiple scattering


3/ upscattering function also increases with SZA (because more forward 
scattering contributes to upscattering).


You could assume 1/ and 2/ cancel each other at first approximation, so 
because of 3/ there is indeed more RF at larger SZA. In fact there is an 
optimum around SZA=60° but that depends on the AOD and how much multiple 
scattering there is.


Now life is a bit more complicated, as transport and aerosol size varies 
also.


In any case, the climate response is not a copy-paste of the spatial 
distribution of the RF. It matters but not too much. And it matters more 
for rapid adjustments than for feedbacks. See eg 
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2013JD021110


Regards,

Olivier



Dear All,

I would like to ask for some useful references about sulfate aerosol geoengineering. 
Assuming some uniform aerosol coverage around the globe, at some height, with a certain 
vertical layer thickness, i would imagine that at higher latitudes the radiative forcing 
exerted by the aerosols is larger due to the longer distance of travel of sun rays 
through the aerosol "cloud". As a consequence, the latitude-dependence of the 
downward-directed radiative forcing should have an even larger gradient than solar 
irradiance. Therefore, I’m wondering how big mistake it is to model such a geoengineering 
scenario by dimming the sun.

Any feedback or reference would be much appreciated.

Thank you,

Tamas


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Re: [geo] My CNN geoengineering question to Sen. Cory Booker

[Olivier Boucher]

Alan

I now decline such invitations because I consider them to be a trap. A 
symmetric one-to-one or four-to-four debate with skeptics does not work in the 
eyes of the public. It becomes a rhetoric thing. The public gets out that the 
scientists disagree, which is the primary objective of the organizer. This is a 
pity bceause beyond climate change there is a real debate to have on energy 
choices and so on.

Olivier (depuis / from smartphone)

> Le 6 sept. 2019 à 02:03, Alan Robock  a écrit :
> 
> Dear Colleagues,
> 
> Last night I attended CNN's Climate Town Hall, and asked my Senator Cory 
> Booker a question about solar geoengineering research.  You can see it 
> starting at 27:44 on 
> https://www.youtube.com/watch?v=WHIMD2E6DgE=PL29Rq0wvBhgOcY9ew5490FwzT5U5N6CqT=11=0s
>   He immediately called me "Sir," and said he did not know anything about it, 
> but would find out.  Today Rutgers got an email from his office asking for 
> more information and I will explain what it is and why we need more resources 
> for research.
> 
> I did not intend to embarrass him.  I submitted the same question to CNN to 
> be asked of all 10 candidates, and they decided to invite me and have me ask 
> it of my own Senator.  I spent 4 hours in the audience listening to Biden, 
> Sanders, Warren, Buttigieg, O'Rourke, and Booker, and was the last person to 
> ask a question.  It was a long time, but very interesting.  Mine was the only 
> geoengineering question.  Booker referenced one, and it must have been to one 
> of the four other candidates who appeared before my 4 hours.
> 
> The other interesting email I got today was the one below.  How do you 
> recommend I answer?   My plan is to say that appearing there would give 
> legitimacy to a "debate" about settled science.  I have not debated global 
> warming deniers for years now for this reason.
> Alan
> 
> Alan Robock, Distinguished Professor
>   Associate Editor, Reviews of Geophysics
> Department of Environmental Sciences Phone: +1-848-932-5751
> Rutgers UniversityE-mail: rob...@envsci.rutgers.edu
> 14 College Farm Roadhttp://people.envsci.rutgers.edu/robock
> New Brunswick, NJ 08901-8551  USA  ☮ http://twitter.com/AlanRobock
> 
> 
>  Forwarded Message 
> Subject:  INVITATION: Sept. 23 Debate on Global Climate Change and Need 
> for Action
> Date: Thu, 5 Sep 2019 13:11:59 +
> From: Jim Lakely 
> To:   rob...@envsci.rutgers.edu 
> 
> 
> Dr. Robock,
>  
> [NOTE: This letter is sent on behalf of Frank Lasée, president of The 
> Heartland Institute.]
>  
> In the wake of your excellent public performance on CNN last night, The 
> Heartland Institute would like to invite you to participate in an interactive 
> discussion and debate on climate change in New York City on September 23 in 
> conjunction with the United Nations Climate Action Summit. The goal of the 
> Heartland Institute event is to broaden public knowledge about the most 
> important and most discussed issues related to climate change.
>  
> The event will feature up to five climate experts and policymakers who warn 
> of an imminent climate crisis, and up to five climate experts and 
> policymakers who are skeptical of an asserted crisis. Each evenly matched 
> side will be given equal time to make their case in a live event streamed 
> globally on YouTube. Each participant will be given time to make an opening 
> statement as well as answer questions posed by a moderator. One participant 
> from each side will be allowed to present a final summary. 
>  
> We welcome suggested questions from each side. The moderator’s questions may 
> also include:
>  
> §  Does the world really have just 12 years left to radically transform our 
> lifestyles and energy sources to prevent unstoppable and catastrophic climate 
> change?
> §  Will melting glaciers release cataclysmic ancient diseases?
> §  How have United Nations climate models fared in their temperature 
> predictions?
> §  How much of the observed warming is caused by people and how much is 
> caused by nature?
> §  Is climate change making extreme weather events more frequent and severe?
> §  Is climate change causing a refugee crisis?
> §  Is observed climate change already harming food production?
> §  What observational evidence would induce you to change your current 
> position on the causes and consequences of climate change?
> §  Would action by the United States or Western democracies have much impact 
> without substantial reductions from China and other rapidly developing 
> nations?
> §  Is it possible for scientists with differing views to cooperate together 
> rather than form isolated camps?
>  
> The Heartland Institute will cover all of your travel expenses and will 
> contribute $1,000 to the charity of your choice in lieu of a personal 
> honorarium. We hope this event will provide a valuable public service by 
> increasing public knowledge on key climate change 

Re: [geo] Glacier methane

[Olivier Boucher]

Hello,

Thank you for the link. This is very nice stuff but I'm missing an 
indication as to whether this corresponds to say 0.5, 1 or 5% of current 
methane emissions when extrapolated to the globe. And how much of this 
is associated with the glacier melting that can be apportioned to global 
warming, versus how much can be considered natural.


Best regards

Olivier


Hi All

The site

https://www.nature.com/articles/s41586-018-0800-0

has a scary account of ice sheets currently being ignored in global
methane budgets but methane coming out from melting glaciers.

Stephen

--
Emeritus Professor of Engineering Design, School of Engineering,
Mayfield Road, University of Edinburgh EH9 3DW, Scotland
The University of Edinburgh is a charitable body, registered in Scotland, with 
registration number SC005336.


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COP24 : Le nouveau contexte scientifique des négociations climat 



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Re: [geo] Re: MCB/cirrus stripping with particle accelerators

[Olivier Boucher]

Dear Andrew,

as I stated before, I have some doubt about observed relationships 
between cosmic ray and cloudiness and if real, the physics is very 
unclear. However I do not understand your post. If there is such an 
effect, then why would you want to shot these particles downward from 
space rather than upward from the surface. The objective would be to 
increase low-level cloudiness, wouldn't it ?


Regards,
Olivier
There appears to be some confusion here in terms of the numbers to 
use. Most of the particles are atomic nuclei (overwhelmingly 
hydrogen). These are therefore charged, and thus are substantially 
attenuated by the earth's magnetic field. I've been unable to 
determine the extent, from a quick Google.


Furthermore, a proportion of scattering attenuation occurs in the high 
atmosphere, where it's too dry to produce clouds. It may therefore be 
more effective to use lower-flying aircraft, which are less lossy by 
this mechanism - although they may have very limited beam range. 
Nevertheless, Google's project Loon shows that mass production of 
non-high altitude balloons is at least worthy of consideration - 
numbers can potentially overwhelm range disadvantages.


Finally, there's the issue of energy distribution. I've been unable to 
find a source that links particle energy to cloud CCN. The number peak 
at 0.3GEv may not be representative of an efficacy peak. Certainly, 
highly energetic particles are disproportionately effective, but it's 
not clear whether their numerical rarity makes them irrelevant, 
overall. There are significant technical issues with producing 
high-energy particles in orbit. Individual particles are travelling at 
near light speed, and they experience significant relativistic 
effects. It therefore requires serious infrastructure to produce them. 
That's impractical for a satellite. However, intermediate energy 
accelerators could be mounted on 747-type platforms, and full sized 
accelerators could be land based. One problem with very high energy 
particles is that they're *individually* dangerous. The highest energy 
particles have the energy of a baseball travelling at nearly 100kmh. 
You can't go shooting those at airliners.


Further thoughts welcome.

Andrew

On Mon, 20 Aug 2018, 01:55 Russell Seitz, > wrote:


The  grid-to-beam efficiency of  greater than GEV particle
accelerators ranges from kess than 5 % for high current systems ,
to as little as  0.02% for superconducting colliders like the
LHC.  As the global cosmic ray flux is of the order of 5 GW,
matching it might therefore take anywhere from a hundred GW to
several tens of terawatts.

At the high end of that power range one runs into a serious
feedback-  the cloud nucleation cooling might be overwhelmed by
extra CO2  radiative forcing  from the thermal plants in the grid
powering the accelerators.

On Sunday, August 19, 2018 at 10:17:58 AM UTC-4, Andrew Lockley
wrote:

Cosmic rays cause cloud condensation nuclei. They are
therefore believed to affect cloudiness, and therefore
climate. If we made more cosmic rays, that would likely make
it more cloudy. Whether this was a warming or cooling effect
would depend on whether it was cirrus or cumulus clouds (NB,
sometimes making cirrus ultimately removes water, resulting in
less cirrus)

Cosmic rays are almost all protons, with an typical energy
peak distribution of 0.3GEv. (4.8×10^−11  J). No idea if
that's the right energy for CCN, but we can tweak that later.

Creating artificial cosmic rays is possible, using a linear
particle accelerator. This is similar to an ion thruster, as
used in space probes.

To affect climate, you'd probably have to get densities of the
order of 1/s/sqm (more on that, later).

360 million square kilometers of ocean is 360tn sqm or
3.6x10^14sqm. You don't really want to send particles into
people, and the cleaner air over the oceans makes them more
effective.

A kilo of hydrogen contains 6x10^26 protons.

That means 1kg of H2 gives you enough material for 1.6x10^12s
= roughly 50 years - so a satellite could easily carry enough
material to do the job.

Power is 3.6x10^14 x 4.8x10^-11J/s = 17kW - again, well within
what a satellite could muster (roughly 100sqm of solar panels,
at around 20% panel efficiency (conservative) and 50pc
conversion (made up) efficiency).

Cheap satellites are about $50m - well within the capabilities
of a rich philanthropist. Even if this is not cheap, it's
still only perhaps 500m

If I'm out by 5 orders (1 ray per sq cm, not per sq m each
second), then that's only 10,000 satellites. That's expensive,
but not outlandish. Superficially, that would be $500bn at the

Re: [geo] MCB/cirrus stripping with particle accelerators

[Olivier Boucher]

Dear Stephen,

Thank you for pointing this paper, I wasn't aware of it. The PDF is here:
http://orbit.dtu.dk/ws/files/126609957/Svensmark_et_al_2016_Journal_of_Geophysical_Research_Space_Physics.pdf
The paper is from 2016, so obviously couldn't be considered in the IPCC 
AR5. Let's see if AR6 has something else to say.


Svensmark had a similar paper in GRL (2009) which we cite in the AR5:  
"Svensmark et al. (2009) found large global reductions in the aerosol 
Ångström exponent, liquid water path, and cloud cover after large 
Forbush decreases, but these results were not corroborated by other 
studies that found no statistically significant links between the cosmic 
ray flux and clouds at the global scale (Čalogović et al., 2010; Laken 
and Čalogović, 2011). Although some studies found statistically 
significant correlations between the cosmic ray flux and cloudiness at 
the regional scale (Laken et al., 2010; Rohs et al., 2010), these 
correlations were generally weak, cloud changes were small, and the 
results were sensitive to how the Forbush events were selected and 
composited (Kristjánsson et al., 2008; Laken et al., 2009)."


Here I can see the signals are clearer, but still noisy. It would 
probably take an independent study to confirm the findings to convince 
the rest of the community. Also the physical mechanism behind it isn't 
clear. People have tried to increase aerosol nucleation manifold in 
their aerosol models and it doesn't change cloudiness because the system 
is very much buffered in terms of CCN. Pure speculation on my side, but 
I would like to be reassured to hear that there is no difference in how 
the electronics of the satellite instruments respond during Forbusch 
events as compared to the rest of the time.


Thank you again for pointing this, I'll try to discuss it with colleagues.

Best regards,
Olivier

Hi All

I cannot reconcile

https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1002/2016JA022689

with what Olivier says is the IPCC position without saying things 
which might annoy the IPCC.


Can anyone else?

Stephen

On 19-Aug-18 5:48 PM, Andrew Lockley wrote:
As discussed in my original post, a significant scaling of synthetic 
cosmic rays is possible, over background levels (3-5 orders) This may 
give a large climate signal, sufficient to analyse the effect with a 
view to using it for CE.


Does anyone have a view on the potential usefulness of high-volume, 
standard-energy cosmic rays?


A

On Sun, 19 Aug 2018, 16:35 Olivier Boucher, 
<mailto:olivier.bouc...@lmd.jussieu.fr>> wrote:



Hello Andrew,

see section 7.4.6 of IPCC AR5 :
http://www.ipcc.ch/pdf/assessment-report/ar5/wg1/WG1AR5_Chapter07_FINAL.pdf

The summary is

"Cosmic rays enhance new particle formation in the free
troposphere, but the effect on the concentration of cloud
condensation nuclei is too weak to have any detectable climatic
influence during a solar cycle or over the last century (medium
evidence, high agreement). No robust association between changes
in cosmic rays and cloudiness has been identified. In the event
that such an association existed, a mechanism other than cosmic
ray-induced nucleation of new aerosol particles would be needed
to explain it. {7.4.6}"

Best

Olivier



Cosmic rays cause cloud condensation nuclei. They are therefore
believed to affect cloudiness, and therefore climate. If we made
more cosmic rays, that would likely make it more cloudy. Whether
this was a warming or cooling effect would depend on whether it
was cirrus or cumulus clouds (NB, sometimes making cirrus
ultimately removes water, resulting in less cirrus)

Cosmic rays are almost all protons, with an typical energy peak
distribution of 0.3GEv. (4.8×10^−11  J). No idea if that's the
right energy for CCN, but we can tweak that later.

Creating artificial cosmic rays is possible, using a linear
particle accelerator. This is similar to an ion thruster, as
used in space probes.

To affect climate, you'd probably have to get densities of the
order of 1/s/sqm (more on that, later).

360 million square kilometers of ocean is 360tn sqm or
3.6x10^14sqm. You don't really want to send particles into
people, and the cleaner air over the oceans makes them more
effective.

A kilo of hydrogen contains 6x10^26 protons.

That means 1kg of H2 gives you enough material for 1.6x10^12s =
roughly 50 years - so a satellite could easily carry enough
material to do the job.

Power is 3.6x10^14 x 4.8x10^-11J/s = 17kW - again, well within
what a satellite could muster (roughly 100sqm of solar panels,
at around 20% panel efficiency (conservative) and 50pc
conversion (made up) efficiency).

Cheap satellites are about $50m - well within the capabilities
of a rich philanthropist. Even if this is not cheap, it's still
only perhaps 500m

Re: [geo] Re: MCB/cirrus stripping with particle accelerators

[Olivier Boucher]

You may want to look to 
https://www.geosci-model-dev.net/10/2247/2017/gmd-10-2247-2017.pdf
Sections 2.2.2 and 2.2.3.  There is an associated dataset in netcdf 
format available on the Earth System Federation grid (input4MIPS).
This is a little far from my field, but I trust this is a good source of 
data / information.


Best regards,
Olivier

Thanks, Russell. Do you have a citation for the power numbers for 
natural rays (although I've ignored the rarer, high-energy rays)? The 
numbers you've provided contradict my sources, which are many orders 
of magnitude lower.


For clarity, the comparator technology is an ion thruster, not a 
research particle accelerator. These have to be efficient, otherwise 
they'd impart a very large energy penalty on space probes.


A

On Mon, 20 Aug 2018, 01:55 Russell Seitz, > wrote:


The  grid-to-beam efficiency of  greater than GEV particle
accelerators ranges from kess than 5 % for high current systems ,
to as little as  0.02% for superconducting colliders like the
LHC.  As the global cosmic ray flux is of the order of 5 GW,
matching it might therefore take anywhere from a hundred GW to
several tens of terawatts.

At the high end of that power range one runs into a serious
feedback-  the cloud nucleation cooling might be overwhelmed by
extra CO2  radiative forcing  from the thermal plants in the grid
powering the accelerators.

On Sunday, August 19, 2018 at 10:17:58 AM UTC-4, Andrew Lockley
wrote:

Cosmic rays cause cloud condensation nuclei. They are
therefore believed to affect cloudiness, and therefore
climate. If we made more cosmic rays, that would likely make
it more cloudy. Whether this was a warming or cooling effect
would depend on whether it was cirrus or cumulus clouds (NB,
sometimes making cirrus ultimately removes water, resulting in
less cirrus)

Cosmic rays are almost all protons, with an typical energy
peak distribution of 0.3GEv. (4.8×10^−11  J). No idea if
that's the right energy for CCN, but we can tweak that later.

Creating artificial cosmic rays is possible, using a linear
particle accelerator. This is similar to an ion thruster, as
used in space probes.

To affect climate, you'd probably have to get densities of the
order of 1/s/sqm (more on that, later).

360 million square kilometers of ocean is 360tn sqm or
3.6x10^14sqm. You don't really want to send particles into
people, and the cleaner air over the oceans makes them more
effective.

A kilo of hydrogen contains 6x10^26 protons.

That means 1kg of H2 gives you enough material for 1.6x10^12s
= roughly 50 years - so a satellite could easily carry enough
material to do the job.

Power is 3.6x10^14 x 4.8x10^-11J/s = 17kW - again, well within
what a satellite could muster (roughly 100sqm of solar panels,
at around 20% panel efficiency (conservative) and 50pc
conversion (made up) efficiency).

Cheap satellites are about $50m - well within the capabilities
of a rich philanthropist. Even if this is not cheap, it's
still only perhaps 500m

If I'm out by 5 orders (1 ray per sq cm, not per sq m each
second), then that's only 10,000 satellites. That's expensive,
but not outlandish. Superficially, that would be $500bn at the
lower cost, but there is likely a 10x or 100x experience curve
cost reduction, meaning the whole programme would be about
$5-50bn max.

As an alternative, you could use aircraft or balloons, but
beam attenuation would be a serious issue. 40km balloons can
be launched, albeit with small payloads. They would fly at the
bottom of the mesosphere, over 99.9pc of the atmosphere. So
maybe beam attenuation would be tolerable, at that height. I
don't know how to calculate it, but I'm guessing it would be
cms to kms - so not really far enough to make a difference to
climate. You could perhaps have mountaintop accelerators with
very high powers, and a sweeping beam (like a lighthouse). If
the power requirement was GW-range, then maybe the beam range
would be a hundred km, or so. That might be enough to work,
but it would have some pretty significant effects on local
atmospheric chemistry - so probably not a good idea.

Any thoughts from anyone?

Andrew Lockley


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Re: [geo] MCB/cirrus stripping with particle accelerators

[Olivier Boucher]

Hello Andrew,

see section 7.4.6 of IPCC AR5 : 
http://www.ipcc.ch/pdf/assessment-report/ar5/wg1/WG1AR5_Chapter07_FINAL.pdf


The summary is

"Cosmic rays enhance new particle formation in the free troposphere, but 
the effect on the concentration of cloud condensation nuclei is too weak 
to have any detectable climatic influence during a solar cycle or over 
the last century (medium evidence, high agreement). No robust 
association between changes in cosmic rays and cloudiness has been 
identified. In the event that such an association existed, a mechanism 
other than cosmic ray-induced nucleation of new aerosol particles would 
be needed to explain it. {7.4.6}"


Best

Olivier


Cosmic rays cause cloud condensation nuclei. They are therefore 
believed to affect cloudiness, and therefore climate. If we made more 
cosmic rays, that would likely make it more cloudy. Whether this was a 
warming or cooling effect would depend on whether it was cirrus or 
cumulus clouds (NB, sometimes making cirrus ultimately removes water, 
resulting in less cirrus)


Cosmic rays are almost all protons, with an typical energy peak 
distribution of 0.3GEv. (4.8×10^−11  J). No idea if that's the right 
energy for CCN, but we can tweak that later.


Creating artificial cosmic rays is possible, using a linear particle 
accelerator. This is similar to an ion thruster, as used in space probes.


To affect climate, you'd probably have to get densities of the order 
of 1/s/sqm (more on that, later).


360 million square kilometers of ocean is 360tn sqm or 3.6x10^14sqm. 
You don't really want to send particles into people, and the cleaner 
air over the oceans makes them more effective.


A kilo of hydrogen contains 6x10^26 protons.

That means 1kg of H2 gives you enough material for 1.6x10^12s = 
roughly 50 years - so a satellite could easily carry enough material 
to do the job.


Power is 3.6x10^14 x 4.8x10^-11J/s = 17kW - again, well within what a 
satellite could muster (roughly 100sqm of solar panels, at around 20% 
panel efficiency (conservative) and 50pc conversion (made up) 
efficiency).


Cheap satellites are about $50m - well within the capabilities of a 
rich philanthropist. Even if this is not cheap, it's still only 
perhaps 500m


If I'm out by 5 orders (1 ray per sq cm, not per sq m each second), 
then that's only 10,000 satellites. That's expensive, but not 
outlandish. Superficially, that would be $500bn at the lower cost, but 
there is likely a 10x or 100x experience curve cost reduction, meaning 
the whole programme would be about $5-50bn max.


As an alternative, you could use aircraft or balloons, but beam 
attenuation would be a serious issue. 40km balloons can be launched, 
albeit with small payloads. They would fly at the bottom of the 
mesosphere, over 99.9pc of the atmosphere. So maybe beam attenuation 
would be tolerable, at that height. I don't know how to calculate it, 
but I'm guessing it would be cms to kms - so not really far enough to 
make a difference to climate. You could perhaps have mountaintop 
accelerators with very high powers, and a sweeping beam (like a 
lighthouse). If the power requirement was GW-range, then maybe the 
beam range would be a hundred km, or so. That might be enough to work, 
but it would have some pretty significant effects on local atmospheric 
chemistry - so probably not a good idea.


Any thoughts from anyone?

Andrew Lockley


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Re: [geo] Ramp down

[Olivier Boucher]

If you had SRM in mind, then you may start with this paper: 
https://cedmcenter.org/wp-content/uploads/2017/10/Tension-between-reducing-sea-level-rise-and-global-warming-through-solar-radiation-management.pdf


Olivier

For me, the key thing is to determine how fast we have to deploy 
geoengineering to save the cities. Sea level rise is largely 
irreversible, so if we're hoping to have NYC and London in 100-300y 
then we desperately need to know what we need to do with 
geoengineering deployment. I find it surprising so little attention 
has been paid to this


We could be facing a potentially brutal choice in a decade or two - 
either cut temperatures dangerously fast, or lose the cities. Far 
better to start earlier, and not have to decide between those two evils.


Andrew Lockley

A

On Sun, 15 Jul 2018, 15:10 Olivier Boucher, 
<mailto:olivier.bouc...@lmd.jussieu.fr>> wrote:


Dear Andrew,

we performed such an experiment with HadGEM2-ES a while back,
see http://iopscience.iop.org/article/10.1088/1748-9326/7/2/024013
We focused on various aspects of the C cycle (simplified as it is
in such a model).
We didn't look at sea level (too many terms involved that we do
not represent in the HadGEM model), but did show ocean heat
content in fig 2g. Basically there is an awful lot of intertia so
it takes a long long time before there is a change in sign during
the ramp down. We also cite a couple of studies which looked at
sea level rise in the introduction (last paragraph of section 1).
But the bottom line was that we could not find a lot of
irreversibility with our state-of-the-art ESM, mostly latency. It
doesn't mean there isn't irreversibility (ice sheet, permafrost,
...) but you would need more complex models to study these. The
little bit of irreversibility in ocean nutrient came as a surprised.

You may want to check who cited us

https://scholar.google.fr/scholar?cites=2691382164698590876_sdt=2005=0,5=en
to find more recent studies on the subject.

Also similar experiments are planned under CDRMIP so expect new
papers next year:
https://www.geosci-model-dev.net/11/1133/2018/

Best regards,
Olivier




Is anyone modelling various ramp down scenarios for bringing
temps down to pre industrial over eg 0, 5, 10, 20, 50, 100 years?
Would be interesting to see how biosphere and sea level responds

Andrew
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Re: [geo] Ramp down

[Olivier Boucher]

Dear Andrew,

we performed such an experiment with HadGEM2-ES a while back,
see http://iopscience.iop.org/article/10.1088/1748-9326/7/2/024013
We focused on various aspects of the C cycle (simplified as it is in 
such a model).
We didn't look at sea level (too many terms involved that we do not 
represent in the HadGEM model), but did show ocean heat content in fig 
2g. Basically there is an awful lot of intertia so it takes a long long 
time before there is a change in sign during the ramp down. We also cite 
a couple of studies which looked at sea level rise in the introduction 
(last paragraph of section 1).
But the bottom line was that we could not find a lot of irreversibility 
with our state-of-the-art ESM, mostly latency. It doesn't mean there 
isn't irreversibility (ice sheet, permafrost, ...) but you would need 
more complex models to study these. The little bit of irreversibility in 
ocean nutrient came as a surprised.


You may want to check who cited us
https://scholar.google.fr/scholar?cites=2691382164698590876_sdt=2005=0,5=en
to find more recent studies on the subject.

Also similar experiments are planned under CDRMIP so expect new papers 
next year:

https://www.geosci-model-dev.net/11/1133/2018/

Best regards,
Olivier




Is anyone modelling various ramp down scenarios for bringing temps 
down to pre industrial over eg 0, 5, 10, 20, 50, 100 years? Would be 
interesting to see how biosphere and sea level responds


Andrew
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Re: [geo] Soil carbon capture will not save us

[Olivier Boucher]

Dear Pete,

The 4 per thousand refers to a flux, the abstract of the papers also seem to 
imply that the fluxes can be sustained on the medium term. Doesn’t it saturate 
at some point? What’s your expert opinion on this ?

Olivier (depuis / from smartphone)

> Le 1 mars 2018 à 10:57, Smith, Professor Pete  a écrit 
> :
> 
> Dear Eric,
>  
> cc. geoengineering list
>  
> There are certainly barriers to implementation of soil carbon sequestration 
> and 4 parts per 1000 sequestration could not be met everywhere – but almost 
> all of the soil carbon sequestration value reported in this paper are above 4 
> parts per 1000!!
>  
> The authors conclude with the limitations – which are not actually the 
> subject of this study – no research is presented on any of these issues – so 
> it is a strange mixture of science showing that 4 per 1000 soil carbon 
> sequestration can be done on almost all of the experiments they examine, and 
> the author’s expert opinion (with no research on these issues presented in 
> the paper) that it will be difficult to implement.
>  
> It reads almost like the authors set out to show that 4 per 1000 was not 
> feasible – found that all of the data suggested it is – and wrote that they 
> didn’t think it is anyway.
>  
> Nice data and analysis – strangely disconnected conclusions.
>  
> Cheers,
>  
> Pete
>  
> ---
> 
> Prof. Pete Smith, FRS, FRSE, FNA, FRSB
> Professor of Soils & Global Change 
> (http://www.abdn.ac.uk/ibes/people/profiles/pete.smith),
> Science Director of Scotland's ClimateXChange (www.climatexchange.org.uk),
> Editor, Global Change Biology
> Editor, Global Change Biology Bioenergy
>  
> Institute of Biological and Environmental Sciences,
> School of Biological Sciences,
> University of Aberdeen,
> 23 St Machar Drive, Room G45
> Aberdeen,
> AB24 3UU, Scotland, UK
> 
> Tel: +44 (0)1224 272702
> Fax: +44 (0)1224 272703
> E-mail: pete.sm...@abdn.ac.uk
> 
> Highly Cited Researcher: http://hcr.stateofinnovation.com/
> Researcher ID: http://www.researcherid.com/rid/G-1041-2010
> Google Scholar: http://scholar.google.co.uk/citations?user=7P9W6pYJ=en
>  
> From: geoengineering@googlegroups.com 
> [mailto:geoengineering@googlegroups.com] On Behalf Of E Durbrow
> Sent: 28 February 2018 23:55
> To: geoengineering 
> Subject: [geo] Soil carbon capture will not save us
>  
> BECCS people response?
>  
> http://onlinelibrary.wiley.com/doi/10./gcb.14066/abstract;jsessionid=11D340C0D5B9914276D2EF84474A9A40.f04t01
>  
> Abstract
> We evaluated the “4 per 1000” initiative for increasing soil organic carbon 
> (SOC) by analysing rates of SOC increase in treatments in 16 long-term 
> experiments in southeast United Kingdom. The initiative sets a goal for SOC 
> stock to increase by 4‰ per year in the 0–40 cm soil depth, continued over 20 
> years. Our experiments, on three soil types, provided 114 treatment 
> comparisons over 7–157 years. Treatments included organic additions 
> (incorporated by inversion ploughing), N fertilizers, introducing pasture 
> leys into continuous arable systems, and converting arable land to woodland. 
> In 65% of cases, SOC increases occurred at >7‰ per year in the 0–23 cm depth, 
> approximately equivalent to 4‰ per year in the 0–40 cm depth. In the two 
> longest running experiments (>150 years), annual farmyard manure (FYM) 
> applications at 35 t fresh material per hectare (equivalent to approx. 3.2 t 
> organic C/ha/year) gave SOC increases of 18‰ and 43‰ per year in the 23 cm 
> depth during the first 20 years. Increases exceeding 7‰ per year continued 
> for 40–60 years. In other experiments, with FYM applied at lower rates or not 
> every year, there were increases of 3‰–8‰ per year over several decades. 
> Other treatments gave increases between zero and 19‰ per year over various 
> periods. We conclude that there are severe limitations to achieving the “4 
> per 1000” goal in practical agriculture over large areas. The reasons include 
> (1) farmers not having the necessary resources (e.g. insufficient manure); 
> (2) some, though not all, practices favouring SOC already widely adopted; (3) 
> practices uneconomic for farmers—potentially overcome by changes in 
> regulations or subsidies; (4) practices undesirable for global food security. 
> We suggest it is more realistic to promote practices for increasing SOC based 
> on improving soil quality and functioning as small increases can have 
> disproportionately large beneficial impacts, though not necessarily 
> translating into increased crop yield.
>  
> Press summary
> https://www.sciencedaily.com/releases/2018/02/180228134114.htm
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Re: [geo] Help: What do we know and what don't we know about solar geoengineering?

[Olivier Boucher]

Hello Ken,

my two pence, not repeating Klaus' input.

/1. What are the most important things we know about solar 
geoengineering?/
some techniques can cool the planet, rapidly and in a reversible way 
(although the impacts may not all be reversible)
there are side effects, eg on precipitation patterns, but these may well 
be in the noise for moderate amount
/2. What are the most important things we don't know about solar 
geoengineering?/

what is the upper bound of solar geoengineering?
how quickly can the technology be developed and at what cost?
what regional effects and what climate impacts on human and natural 
systems?

what impacts on the stratosphere for SAI?
can solar engineering be used for engineering the regional climate or 
extreme climate events?


See you on Sunday
Olivier

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Re: [geo] Zero emissions by 2040?

[Olivier Boucher]

Dear Stephen,

stabilizing emissions is not the same as stabilizing concentrations. For 
stable emissions, one still expects CO2 concentrations to increase for a 
while until a new equilibrium is found (this would take a long time, and 
an even longer time if "natural" emissions start increasing, eg from 
permafrost thawing). Only if emissions decrease drastically, can CO2 
concentration decrease. Figueres et al make it clear that emissions have 
to go to zero.


Best,
Olivier


Hi All

In their Nature paper

http://www.nature.com/news/three-years-to-safeguard-our-climate-1.22201

Figueres et al. write

"In the past three years, global emissions of carbon dioxide from the 
burning of fossil fuels have levelled after rising for decades."


But https://www.co2.earth/daily-co2

shows  atmospheric concentrations as

https://scripps.ucsd.edu/programs/keelingcurve/wp-content/plugins/sio-bluemoon/graphs/mlo_two_years.png

So either something else has emitted almost the same as the claimed 
reductions or the numbers for claimed emissions have been Volkswagened.


Stephen


Emeritus Professor of Engineering Design. School of Engineering, 
University of Edinburgh, Mayfield Road, Edinburgh EH9 3DW, Scotland 
s.sal...@ed.ac.uk, Tel +44 (0)131 650 5704, Cell 07795 203 195, 
WWW.homepages.ed.ac.uk/shs, YouTube Jamie Taylor Power for Change


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Re: [geo] RESEARCHERS INVESTIGATING LARGE SUNSHADES TO COMBAT GLOBAL WARMING

[Olivier Boucher]

Hello,

it's not the first time that I read such a thing:

The reflectors would be placed near L1 to ensure a stable orbit.
The L1 Lagrange point is *not* stable. They are quasi-periodic orbits 
around it, but it's not clear to me if they are suitable for 
geoengineering, if they are perfectly stable on long timescales needed 
for geoengineering or if they need a bit of controlling.


Regards,
Olivier

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Re: [geo] Negative Emissions: Arrows in the Quiver, Life Preserver, and/or Moral Hazard?

[Olivier Boucher]

Dear John,
there is no blunder here. This is an idealized scenario. If CO2 
emissions go to zero abruptly (red curve), then the committed warming 
(ie the warming in the pipeline because the ocean hasn't equilibrated 
yet) is approximately compensated by the decrease in CO2 emissions 
induced by zero emissions (because natural sinks to vegetation and ocean 
keep working).

Regards,
Olivier
*Blunder 2*. IPCC has ignored the warming effect of accumulated CO2.  
They say that global temperature rise will be halted when net CO2 
emissions have fallen to zero, ignoring the effect of accumulated CO2 
and other forcing agents in the atmosphere.


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Re: [geo] Aligning conceptions of geoengineering for a healthy climate conversation. Deich

[Olivier Boucher]

Hello,
this post is an opportunity to remind the list of our 2014 publication 
on "categorization of climate engineering techniques in the context of 
climate mitigation and adaptation",

see http://wires.wiley.com/WileyCDA/WiresArticle/wisId-WCC261.html
The paper is open access. Key sentence from the abstract:
We propose a new and more inclusive categorization into five different 
classes: anthropogenic emissions reductions (AER), territorial or 
domestic removal of atmospheric CO_2 and other greenhouse gases (D‐GGR), 
trans‐territorial removal of atmospheric CO_2 and other greenhouse gases 
(T‐GGR), regional to planetary targeted climate modification (TCM), and 
climate change adaptation measures (including local targeted climate and 
environmental modification, abbreviated CCAM).

All the best,
Olivier



http://dcgeoconsortium.org/2015/12/30/aligning-academic-and-popular-conceptions-of-geoengineering-an-imperative-for-a-healthy-climate-conversation-noah-deich/?utm_content=buffer53203_medium=social_source=twitter.com_campaign=buffer

Aligning conceptions of geoengineering for a healthy climate 
conversation – Noah Deich


December 30, 2015 /  dcgeoconsortium / Carbon Dioxide 
Removal, framing, CDR vs SRM


Today more than ever, it is critical that society has a conversation 
on geoengineering. We need to discuss if and how we want to research, 
develop, and/or deploy certain geoengineering techniques. However, a 
major obstacle is currently blocking the path towards effective 
conversation on geoengineering, namely that we cannot agree on what 
geoengineering actually is. In particular, the academic definition of 
geoengineering is quite different than the popular conception of the 
term. Unless this disconnect is addressed swiftly, the conversation on 
geoengineering is likely to stay muddled, and we are unlikely to reach 
agreement on the appropriate policy and regulatory path forward for a 
wide range of potential climate solutions.


Academic geoengineering: climate “remediation”

According to the IPCC: “Two categories of geoengineering are generally 
distinguished. Removal of GHGs, in particular carbon dioxide termed 
‘carbon dioxide removal’ or CDR, would reduce atmospheric GHG 
concentrations… ‘Solar radiation management’ or SRM technologies aim 
to increase the reflection of sunlight to cool the planet.”


The salient feature of this definition is remediation: any strategy 
that is “intentionally designed to counteract the climate effects 
of past greenhouse gas emissions to the atmosphere” (emphasis mine, 
source: Bipartisan Policy Center) falls under the academic definition 
of geoengineering. The risks, costs, and/or uncertainties surrounding 
those solutions arenot salient features of this definition, which is 
important because those characteristics dofeature prominently in the 
popular conception of geoengineering.


The popular conception of geoengineering: high-danger, high-risk, 
low-cost techno-fixes


From my experience talking with many non-academic climate 
practitioners about what they mean by geoengineering, I have found 
that only a small subset of the climate remediation solutions are 
viewed as examples of geoengineering in the mainstream conversation 
about climate change. The solutions I hear cited as geoengineering in 
non-academic circles include stratospheric aerosol injection, ocean 
iron fertilization, and even space mirrors. The salient features of 
the popular conception of geoengineering include:


High disaster potential—the negative unintended consequences of a 
given solution could prove catastrophic;High “Bond-villain” 
potential—a rogue actor could deploy a given solution unilaterally, at 
a relatively low cost; andMajor uncertainties surrounding direct and 
systems-level impacts of a given solution.


The problem

The core of this disconnect is that the academic definition of 
geoengineering blurs the line between geoengineering and mitigation. 
The IPCC notes that “the boundary between some mitigation and some CDR 
methods is not always clear,” and “some techniques that fall within 
the definition of CDR are also regarded as mitigation measures such as 
afforestation and BECCS.” All climate remediation solutions get 
included under the academic definition of geoengineering, whereas 
only some climate remediation solutions are seen as geoengineering 
among non-academic practitioners. For example, the academic definition 
of geoengineering includes many CDR approaches—like landscape 
restoration, soil carbon farming, and bioenergy with carbon capture 
and storage (BECCS)—that are seen exclusively as options for climate 
change mitigation in the mainstream climate conversation.


The mismatch between the academic and popular conception of 
geoengineering can muddle the conversation on whether/how we should be 
pursuing geoengineering solutions to climate change. If academics and 
non-academics think geoengineering is two different things, productive 

Re: [geo] The climate's apprentices-witches (ARTE TV)

[Olivier Boucher]

Hello,
the documentary was aired on ARTE in late November, right after another 
documentary on the Deep Decarbonization Pathways Project.

Best,
Olivier

One of our researchers spotted the French film that many of you appear 
in.


"The climate's apprentices-witches (ARTE TV)"
​ ​
- its up
​​
 on youtube
​ (here 
) 
​

, though my understanding is still has not aired on ARTE.

​On the channels website they've posted some graphics about CE techs 
(here 
) 
​



_​in the film_- ​
_
_
​​Nathan Myhrvold
David Keith
Matt Watson
Lee Lane
Clive Hamilton
Stewart Patrick
Dominique Bourg
Regis Briday
Mike MacCracken
Kristine C Harper
Ronald Doel
Ken Caldiera
Oliver Morton
Alan Robock
Yihui Ding
Kingsley Edney
Jiahua Pan
Paul Crutzen
Pablos Holman
Hugh Hunt
Anders Levermann
Michael Thompson
Katherine Houghton

*
Michael Thompson*
/Managing Director
Forum for Climate Engineering Assessment /
School of International Service, American University
www.ceassessment.org 
o - 202 885 2459
m- 202 556 3776


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Re: [geo] Tricky question - SRM / carbon credits

[Olivier Boucher]

Hello Maggie, Andrew,
from a purely earth science perspective, comparing SRM to CDR is 
essentially the same problem as extending GHG metrics to short-lived 
pollutants (eg black carbon, other aerosols, ozone). It is of course 
possible to compute equivalences for a given metric. There is a whole 
lot of literature on the subject, which basically says there is no 
unique answer, and the answer depends- a lot- on what climate goal 
you're pursuing. Then there are other things to be considered, and 
indeed I agree with Maggie that it may not be the right way of 
presenting things. I once read an estimate that painting xx square 
meters of roof in white was equivalent to mitigating yy tons of CO2, but 
I certainly disagree with such a simple equivalence.

Cheers,
Olivier



Hi Andrew,

Firstly, there is no sound answer to the question posed in terms of 
physics /earth science, exactly because SRM is not a true substitute 
of removing carbon, it does not confer the same effect in terms of 
duration of effect, and effect on many other aspects of the earth 
system other than the reduction of heat while the aerosol is in the 
air.  So it is scientifically flawed to ignore all of that, in order 
to render a carbon credit equivalent so as to be able to monitize SRM, 
just like everything else is driven to be monitized under the insane 
capitalist system.


Secondly, in a non-voluntary system that requires carbon credits in 
order to emit GHGs, SRM generated credits will simply add to the 
annual emissions cap, which is what I pointed out in my last email. 
 In a voluntary system where people/corporations simply purchase 
carbon credits to feel better or use as a PR tool, SRM generated 
credits allow them to justify their emissions which they otherwise 
would be under greater pressure to reduce, and for those emissions 
outside of their direct control, SRM generated credits won't help 
reduce anyway.  In fact they would feel even less responsible to 
change agricultural emissions (advocating for better agri practices, 
etc), or what their government is doing in their name.


It's amusing, if not also sad, that you considered what I discussed in 
the last email as from a political angle, i.e., not science 
proper.  I'd suggest that what I discussed there is simply science as 
applied to the physical reality of this earth, not some abstract 
concept that draws an artificial equivalence of SRM = C removal.

Peace.


Maggie Zhou, PhD
https://www.facebook.com/maggie.zhou.543




On Thursday, August 20, 2015 7:00 PM, Andrew Lockley 
andrew.lock...@gmail.com wrote:



Maggie (and list),
Thanks for your response. However, there are a couple of problems with 
the stance you take.
Firstly, I'm simply looking to answer a physics / earth science 
question. The answer will be true whether we want it to be, or not. 
The world deals with many other distasteful comparisons, such as how 
much is a life worth in cost-benefit analyses.
Secondly, even if we engage with the political angle you discuss, your 
logic doesn't necessarily bear scrutiny. People may choose to offset 
only the components of their emissions they have no control over, eg 
agriculture, government sector, etc. I'd suggest that those buying 
carbon credits are probably more prone to taking mitigation action 
than demographically matched controls.

I'd welcome further dialogue.
Thanks
Andrew Lockley
On 20 Aug 2015 23:49, Maggie Zhou mzhou...@yahoo.com 
mailto:mzhou...@yahoo.com wrote:


How many carbon credits is a tonne of SRM worth?

Seriously?  This is precisely what geoengineering proponents
promised that it won't be used for - as a substitute in any way,
shape or form to carbon emission mitigation.  To get acceptance
for the idea of even funding research into SRM or other
geoengineering schemes in response to global warming, the repeated
promise was that it is not meant to replace emission reductions,
only a backup to buy us some time...

Using SRM to generate carbon credits is EXACTLY to generate EXTRA
carbon emissions allowances - even though all SRM could do, at
best, is masking the true impact of the current GHG levels on
warming while the spraying is ongoing, without ever removing a
single atom of carbon from the atmosphere for which it's to claim
carbon credit.  In short, SRM will lead to even MORE emissions,
not less, and due to the masking and the lack of public awareness
that it's the masking that's keeping the temperatures from
shooting up even higher even quicker, it just helps keeping
business-as-usual longer, on top of ocean acidification, acid
rain, potential disruption of regional climate patterns, etc etc.


Maggie Zhou, PhD
https://www.facebook.com/maggie.zhou.543




On Thursday, August 20, 2015 4:15 AM, Andrew Lockley
andrew.lock...@gmail.com mailto:andrew.lock...@gmail.com wrote:


How many carbon credits is a tonne of SRM worth?
We could 

Re: [geo] Atmospheric CO2 to carbon fibers?

[Olivier Boucher]

Dear David,
I don't know the details of the technique, it is nice to see all the 
research done on this.
$1000 per ton C would correspond to $270 per ton CO2 extracted, in line 
with what other claims for direct capture, but these numbers should be 
taken with a pinch of salt. The fact that C nanofibers sell a high price 
is certainly interesting, but I guess the market is small. Do we really 
need 500 Gt of C nanofibers? I would think the only mass market for C 
captured from the air is fuel.

Regards,
Olivier


Stuart Licht at George Washington University apparently spoke at the 
American Chemical Society meeting today on a technique for extracting 
CO2 from the air and converting it into carbon nanofibers. Some 
highlights from the AAAS press release (linked below):


* Licht says, We calculate that with a physical area less than 10 
percent the size of the Sahara Desert, our process could remove enough 
CO2 to decrease atmospheric levels to those of the pre-industrial 
revolution within 10 years.
* Energy costs are estimated to be about $1,000 per ton of carbon 
nanofibers. Carbon nanofibers currently sell for much more than that.
* Because of its efficiency, this low-energy process can be run using 
only a few volts of electricity, sunlight and a whole lot of carbon 
dioxide. At its root, the system uses electrolytic syntheses to make 
the nanofibers. CO2 is broken down in a high-temperature electrolytic 
bath of molten carbonates at 1,380 degrees F (750 degrees C)To 
power the syntheses, heat and electricity are produced through a 
hybrid and extremely efficient concentrating solar-energy system. The 
system focuses the sun's rays on a photovoltaic solar cell to generate 
electricity and on a second system to generate heat and thermal 
energy, which raises the temperature of the electrolytic cell.


http://www.eurekalert.org/pub_releases/2015-08/acs-ft071615.php

Does anyone know more about this? It certainly sounds too good to be true.
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[geo] space elevator

[Olivier Boucher]

Hello,
this is relevant to SRM by stratospheric particles
http://www.independent.co.uk/news/science/a-canadian-company-is-planning-to-build-a-tower-thats-20km-high-and-could-making-flying-to-space-like-taking-a-passenger-jet-10459058.html
http://thothx.com/news-2/
although I don't know how realistic and advanced the plans are...
Regards,
Olivier

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[geo] Rethinking climate engineering categorization in the context of climate change mitigation and adaptation

[Olivier Boucher]

Dear members of the geoengineering newsgroup,

you may find our latest article published in WIREs climate change of 
interest to you. It can be found at 
http://wires.wiley.com/WileyCDA/WiresArticle/wisId-WCC261.html
Title: Rethinking climate engineering categorization in the context of 
climate change mitigation and adaptation 

Here is the abstract: 

The portfolio of approaches to respond to the challenges posed by 
anthropogenic climate change has broadened beyond mitigation and adaptation 
with the recent discussion of potential *climate engineering* options. How 
to define and categorize climate engineering options has been a recurring 
issue in both public and specialist discussions. We assert here that 
current definitions of mitigation, adaptation, and climate engineering are 
ambiguous, overlap with each other and thus contribute to confusing the 
discourse on how to tackle anthropogenic climate change. We propose a new 
and more inclusive categorization into five different classes: 
anthropogenic emissions reductions (AER), territorial or domestic removal 
of atmospheric CO2 and other greenhouse gases (D‐GGR), trans‐territorial 
removal of atmospheric CO2 and other greenhouse gases (T‐GGR), regional to 
planetary targeted climate modification (TCM), and climate change 
adaptation measures (including local targeted climate and environmental 
modification, abbreviated CCAM). Thus, we suggest that techniques for 
domestic greenhouse gas removal might better be thought of as forming a 
separate category alongside more traditional mitigation techniques that 
consist of emissions reductions. Local targeted climate modification can be 
seen as an adaptation measure as long as there are no detectable remote 
environmental effects. In both cases, the scale and intensity of action are 
essential attributes from the technological, climatic, and political 
viewpoints. While some of the boundaries in this revised classification 
depend on policy and judgement, it offers a foundation for debating on how 
to define and categorize climate engineering options and differentiate them 
from both mitigation and adaptation measures to climate change.

regards,

Olivier Boucher 

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