[geo] Re: Balancing the pros and cons of geoengineering

Regarding: Furthermore, existing observing systems for stratospheric aerosols are difficult to use. The SAGE satellites are no longer working. There is a spare SAGE III on the shelf at NASA, but there are no plans to launch it. Calipso lidar can make episodic measurements along very narrow

[geo] Re: Balancing the pros and cons of geoengineering

As you say, pinatubo etc. prove that stratospheric aeroslols would cool the world and it is therefore the disadvantages that we have to evaluate. Many of us see the greatest and most urgent dangers in the Arctic and Antarctic and think that localised stratospheric aerosols would probably avoid

[geo] Re: Balancing the pros and cons of geoengineering

Although I was initially worried by Denis's point that arctic aerosols will capture some rays that would otherwise just pass tangentially through the stratosphere, I have now done some geometry and believe that this will only apply to about 0.2% of the incident sunlight on the Arctic at

[geo] Re: Balancing the pros and cons of geoengineering

You'd have to calculate this across the whole globe, surely? If the whole atmos was affected, then this would mean the Earth turned from being a sharp round disc to a bigger, hazy one? But, the evidence from Pinatubo surely demonstrates that this doesn't cause a problem, it still cools down.

[geo] Re: Balancing the pros and cons of geoengineering

A couple of points: 1. On the angle issue, this is of course taken into consideration in calculating how much solar radiation reaches the Arctic at any given time‹and rays just passing tangentially through will not count much at all. That the actual incident light in high latitudes in summer,

[geo] Re: Balancing the pros and cons of geoengineering

I have to admit I hadnt thought of that aspect of aerosols in the arctic. To Gregory Benfold -What do you think ? John Gorman - Original Message - From: Bonnelle Denis To: gorm...@waitrose.com ; andrew.lock...@gmail.com ; John Nissen ; geoengineering@googlegroups.com Sent:

[geo] Re: Balancing the pros and cons of geoengineering

Andrew There is a list of packages at http://atol.ucsd.edu/scatlib/scatterlib.htm You can download a wonderful free computing package for liquid drops written by Philip Laven from http://www.philiplaven.com/mieplot.htm See also: http://www.philiplaven.com/index1.html

[geo] Re: Balancing the pros and cons of geoengineering

All: Bonnelle Denis is right that a detailed study of aerosol reflections needs doing. Someone may wish to use research time on it, but without any funding it's difficult to mount a determined attack on the many parameters that need varying. The issue of particle size demands some actual

[geo] Re: Balancing the pros and cons of geoengineering

First, of course, one would be working to do the reflection only during the sunlit months, so Sun is a bit higher in the sky. During peak summer, there is as much solar incident on Arctic latitudes over 24 hours as at the equator. Yes, at a lower sun angle, but still a lot of solar. And as to

[geo] Re: Balancing the pros and cons of geoengineering

John, No you may not assume any such thing. Far, far too low on both % and numbers for a max possible risk. A 2009/5/11 John Nissen j...@cloudworld.co.uk Hi all, In the absense of any figures from you for monsoon failure risk, may I suggest a maximum probability of 1% of severe failure,

[geo] Re: Balancing the pros and cons of geoengineering

Since nobody knows, estimates are pointless without better data, simulations etc Gregory -Original Message- From: Andrew Lockley andrew.lock...@gmail.com To: John Nissen j...@cloudworld.co.uk Cc: geoengineering geoengineering@googlegroups.com Sent: Mon, 11 May 2009 3:29 pm Subject:

[geo] Re: Balancing the pros and cons of geoengineering

John, This is really flimsy thinking. It springs from a WAG (wild-ass-guess) type analysis of risk--i.e. If it's not a lot, then it must be a little. For a humorous take on this, watch Jon Stewart's daily show last week on the LHC (Large Hadron Collider). I think it's about 19 minutes in.

[geo] Re: Balancing the pros and cons of geoengineering

It is all about risk reduction. You cannot say how much risk we would be willing to accept from a climate intervention without first characterizing the risk of not intervening in climate. If it is clear that a climate intervention would reduce risk (taking into account relevant distributional

[geo] Re: Balancing the pros and cons of geoengineering

Debate, analysis, and modeling of the status quo and thought experiments should be continuous. The more the better. -Original Message- From: Andrew Lockley Sent: May 11, 2009 6:29 PM To: John Nissen Cc: geoengineering

[geo] Re: Balancing the pros and cons of geoengineering - eating of the fruit of the tree of knowledge

Eugene good idea I think Biosphere Carbon Stock Management is a game plan but for reasons stated previously think it needs to be associated with an ocean surface cooling programme.** Any more ideas or modifications needed? I'm 73 and not very well Why don't you do it? Peter **And a lot of

[geo] Re: Balancing the pros and cons of geoengineering

Comments: 2) Stratospheric sulphur aerosols look fairly promising, and we can cheaply deploy them with balloons. They might wreck the hydrological cycle in general, and the monsoon in particular. Other aerosols are worth a look. Balloons are not optimal. Airplanes work fine at Arctic needed

[geo] Re: Balancing the pros and cons of geoengineering

Greg, I don't think the us-them dichotomy is helpful. As in all areas of controversy there is a spectrum ranging from those who indiscriminately deploy whatever argument crosses their radar screen if it fits their pre-conceived idea of the right answer to those who actually would like to see

[geo] Re: Balancing the pros and cons of geoengineering

Dave: Of course us/them is there--we have plenty of ferocious opponents--and without funding, we won't get to do the rigorous description of how to design field experiments that both have trivial risks and are capable of providing useful information to better characterize the risks of full

[geo] Re: Balancing the pros and cons of geoengineering

Dear Stephen, I would not put much faith in this highly idealized model, unless it could be shown to actually simulate past monsoon variations. It is a nice intellectual exercise, but ignores many of the important processes of the climate system. Alan Alan Robock, Professor II Director,

[geo] Re: Balancing the pros and cons of geoengineering

Good discussion. This is what geoengineering is all about. -Original Message- From: geoengineering@googlegroups.com [mailto:geoengineer...@googlegroups.com] On Behalf Of Alvia Gaskill Sent: Saturday, May 09, 2009 11:50 AM To: s.sal...@ed.ac.uk; rob...@envsci.rutgers.edu Cc:

[geo] Re: Balancing the pros and cons of geoengineering

A few comments on that:1) Droplet size shouldn't affect chemistry. Both surface area and the cross sectional area are proportional to the square of the radius. Volume affects residence time, and is proportional to the cube of the radius. Big droplets are shorter-lived, and hence more

[geo] Re: Balancing the pros and cons of geoengineering

Droplet size may affect chemistry because of surface tension. At sufficiently small scales, a high-curvature surface isn't the same chemically as a lower-curvature surface. My impression is that the Brewer Dobson circulation is the net circulation after east-west wind is canceled out, since the

[geo] Re: Balancing the pros and cons of geoengineering

John: You strike the nub of it: Alan claims that the aerosols would not be confined to the polar region. But doesn't this depend on: the timing range of the release of precursor, the height range in the stratosphere, and the latitude range? Suppose that the release is in spring such that

[geo] Re: Balancing the pros and cons of geoengineering

It's essential to consider the 'unmodified case'. Whatever 'damage' geoeng does has to be weighed against the damage that would occur from unfettered global warming to the Arctic region. The plight of the Polar bear is the poster child for global warming, which makes my point in a very clear

[geo] Re: Balancing the pros and cons of geoengineering

Dear Ken, I agree. We need several models to do the same experiment so we can see how robust the ModelE results are. That is why we have proposed to the IPCC modeling groups to all do the same experiments so we can compare results. Nevertheless, observations after large volcanic eruptions,

[geo] Re: Balancing the pros and cons of geoengineering

Hi all, I'm restricting this analysis to geoengineering with stratospheric aerosols to save the Arctic sea ice. I've not received any additions to the list of pros and cons I posted on 29th April. Some points have been discussed, mostly on 29th April also: S11. Cannot stop quickly William

[geo] Re: Balancing the pros and cons of geoengineering

This scare ,that stratospheric areosols would result in an even more global warming if stopped, has appeared in many articles. I therefore read the relevent papers fairly carefully and my reading is that temeratures would simply rise quickly to where they would have been without

[geo] Re: Balancing the pros and cons of geoengineering

Dear John: I did not see a principal advantage of SRM listed. That is that it is reversible, at least for sulfates in the stratosphere and for cloud whitening. Cheers, Bill On Apr 29, 2009, at 10:34 AM, John Nissen wrote: Hi all, Alan Robock has said: Whether we should use

[geo] Re: Balancing the pros and cons of geoengineering

Hi All A comment about John's item G2 'that we make such a hash of everything in the past that we are bound to make a hash of geo-engineering'. Everyone likes to believe this but the reality is that we magnify the hashes and ignore the many successes. I was certainly very bad to introduce

[geo] Re: Balancing the pros and cons of geoengineering

Shame on you. Were they white rabbits? I was certainly very bad to introduce rabbits to Australia. But horses to America? - Original Message - From: Stephen Salter s.sal...@ed.ac.uk To: j...@cloudworld.co.uk Cc: geoengineering geoengineering@googlegroups.com;

[geo] Re: Balancing the pros and cons of geoengineering

The Kasotchi eruption column only went up to 35,000 ft, the Lowermost Stratosphere, not the Lower Stratosphere, so no global or regional climatic impact would have been expected. Concept correct, example wrong. What one means by full scale has yet to be determined. A level that would

[geo] Re: Balancing the pros and cons of geoengineering

Dear Alvia, You can guess whatever you want, but I know of no examples of such low stratospheric loading that had a detectable climatic effect. And I have no idea what you mean by lowermost or lower stratosphere. The stratosphere begins at the tropopause, which is lower in the Arctic and

[geo] Re: Balancing the pros and cons of geoengineering

You seem to be ignoring the fact that smokestack emissions and tailpipe emissions of SO2 aerosols had a substantial cooling effect pre 1973 and were outlawed in the US and Europe thereafter, at which time the cooling immediately stopped and warming continued. That is documented in a NASA paper. I