Pro SRM research article in today’s Guardian

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H simmens

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Jan 6, 2026, 11:51:55 AMJan 6
to healthy-planet-action-coalition, Planetary Restoration

Danielle Visioni of Cornell and Dakota Bruening, Reflexive CEO (who is on the HPAC list) have a very important opinion piece outlining a phased SAI testing program that begins to approach the mission driven model that needs to be adopted by governments and the SRM research community. 

Not surprisingly they still leave open the question of whether safe and effective SRM should be deployed.  

Hat’s off to the Guardian for publishing a piece like this. 

Herb


Herb Simmens
Author of A Climate Vocabulary of the Future
“A SciencePoem and an Inspiration.” Kim Stanley Robinson
@herbsimmens
HerbSimmens.com

rob...@rtulip.net

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Jan 7, 2026, 7:54:37 AMJan 7
to H simmens, healthy-planet-action-coalition, Planetary Restoration

Hi Herb,

This Guardian piece is an excellent milestone in the legitimisation of SRM advocacy. The Guardian deserves credit for hosting this kind of evidence-based discussion while most mainstream media still ignore it completely.

However, I find two of their framing moves problematic. The line “The world may never need to reflect sunlight” concedes far too much to the bullying and stigma directed at SRM. I understand why they pitch it this cautiously in order to get published at all, but the underlying reality is stark: eight billion people on a planet with collapsing albedo have no feasible path to long-term stability and prosperity without organised, industrial-scale sunlight reflection. The benefits overwhelmingly outweigh the risks. While it is logically possible that field research could prove otherwise, the probability of that outcome is extremely low – and, if it did occur, it would amount to a sentence of unmanaged collapse. The challenge is to make SRM safe, effective and well-governed, not to imply that it may be unnecessary.  I can well imagine some readers reacting that if even the advocates have such doubts it must not be a priority.

Similarly, the line “Outdoor research is not a slippery slope to deployment” may be technically correct, but again gives comfort to unreasoned opposition by suggesting that a sustainable future without sunlight reflection remains a realistic option. In practice, I am certain that sunlight reflection will become a major global industry this century, ramping up far faster than most experts currently expect, with strong private-sector leadership. Academic caution of the sort expressed in this article may be tactically useful for now, but it is likely to open the door to a more focused practical advocacy very soon – not “whether” to deploy, but “how fast can we deploy safely and fairly”.

Daniele Visioni has a consistent history of criticising work that falls outside tightly controlled academic channels, most recently in his comments on Stardust in this paywalled article and in his contribution to the SRM360 collection. I endorse his instinct that commercial work needs robust public governance, but his approach in practice lines up with the tone of this Guardian piece – too wary of entrepreneurial initiative when we urgently need it. To make progress at the speed the physics demands, we will need both strong public governance and a vigorous, innovative private sector.

 

Regards

 

Robert Tulip

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robert...@gmail.com

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Jan 7, 2026, 8:15:07 AMJan 7
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Hi RobertT

I almost entirely agree with your comments about this Guardian piece.  Where I diverge is in the final paragraph.  The innovation you refer to is vital and much of that will come from the private sector but the process will not advance at the pace necessary unless it is driven by government intervention.  This does not need to be global, but it does need to involve a multi-faceted international coalition.  I think of this like defence spending  The private sector delivers most of the weaponry used by governments for their military.  But the specification of the requirement (in terms of hardware, capacity and scale) and the financing come from government not from the private sector.  Ultimately, SRM is a public good and this makes it an unattractive market for the private sector without support from the public purse.   The entrepreneurial initiative will come into play as companies bid to fulfil government SRM contracts.  How governments managed the procurement process will be key but if they don't lead, there'll be no market for the the private sector to engage with.

Regards

RobertC


H simmens

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Jan 7, 2026, 8:42:11 AMJan 7
to rob...@rtulip.net, H simmens, healthy-planet-action-coalition, Planetary Restoration
Hi Robert,

I wholeheartedly agree with you. 

As I have previously pointed out the SRM research community studiously avoids from what I can tell any effort to describe under what conditions direct climate cooling should be employed. 

Doing so would not compromise what many would believe is their role of not advocating for or against deployment. 

They rarely as far as I have seen address the consequences of deploying later rather than sooner - either the amount of time it would take to actually deploy and have an appreciable difference on the climate, and the additional suffering, death, collapse of Ecosystems, tipping point irreversible activations and derailment risks of deploying later rather than sooner. 

At the Cambridge Arctic repair confidence this past June a representative from Ocean Visions started her presentation by pointing out that they are not in favor of deployment. 

During the Q&A I asked her (and everyone else sitting in the auditorium ) at what point in the progression of the climate crisis would Ocean Visions be prepared to advocate for deployment. 

Her response was to avoid a direct response to my question.  Not once during the three days did I hear any speaker or any member of the audience raise much less attempt to answer the central question of “At what point”. 

This gaping reticence to provide the public and policy makers with rigorous analysis to help guide the world community to be in a position to make well informed decisions borders on the irresponsible. 

You are exactly correct that “ The challenge is to make SRM safe, effective and well-governed.”

This is essentially what the HPAC Mission statement - which was reaffirmed during the strategic planning process last year - articulates. 

We advocate the world community urgently come together to carry out an equitable science based plan of action that includes what HPAC calls the Climate Triad:

- Directly cooling the climate through sunshine reflection ecosystem restoration and other safe and effective means


- Accelerating emission reductions


- Deploying large scale removal of atmospheric carbon dioxide and other greenhouse gases. 


The goal of these actions along with enhanced and transformative adaptation and regeneration measures is to reduce the average global temperature increase to well below 1° C in the coming decades.


 Doing so will sharply reduce weather extremes, slow or stop the collapse of key ecosystems and help ensure a livable planet for humanity and the natural world.”


Herb

Herb Simmens
Author of A Climate Vocabulary of the Future
“A SciencePoem and an Inspiration.” Kim Stanley Robinson
@herbsimmens
HerbSimmens.com



Herb Simmens
Author of A Climate Vocabulary of the Future
“A SciencePoem and an Inspiration.” Kim Stanley Robinson
@herbsimmens
HerbSimmens.com

Alan Kerstein

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Jan 7, 2026, 10:07:51 AMJan 7
to H simmens, Robert Tulip, healthy-planet-action-coalition, Planetary Restoration
Herb,

'Safe and effective' could be too high a bar because SRM might fall short of either or both criteria, depending on how they are framed (in itself a minefield) yet still be hugely preferable relative to solely ER and CDR. Hence, anything but the risk versus risk rubric is fraught.

Robert C,

Companies like Anduril are showing that designing, building, and marketing for/to the public sector, in this case specifically the defense sector, is a winning strategy. Private venture capital is quite willing to fund this once they recognize that there is a durable demand on the public sector side. The advantage of this strategy is that it avoids getting the public sector involved in the minutiae of setting detailed requirements. SpaceX is another example.

Alan

oswald....@hispeed.ch

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Jan 7, 2026, 10:52:21 AMJan 7
to Alan Kerstein, H simmens, Robert Tulip, healthy-planet-action-coalition, Planetary Restoration

Alan, Herb,

 

private companies have the edge over public organizations because they are more flexible, more innovative and more risk-oriented. Public organizations have the advantage to be legitimized by democratic mandates but tend to be risk-averse and bureaucratic. Together both can create the necessary infrastructure, where private investors lead and public organizations follow. That’s all fine and not new.

 

However nowadays, int the days of tech monopolies and winner takes all capitalism, we should beware not to get into a situation where a private investor (E.g. E. Musk) can hold the global community at ransom. Any private or public entity in the field of climate cooling should be held responsible for their influencing the global climate. This requirement is more important here than in say the production of some private consumer good.

 

A useful approach would be to e.g. separate the suppliers of material from the operators of the planes and split up the job between a number of companies which specialize in certain areas. This is the case in defence, where armies are the operators and private sector companies supply the weapons and ammunitions. A similar distribution of tasks might help to defuse the situation in GeoEngineering, which is bound to be a highly politicized market.

 

I am however sceptical that a global body for solar geoengineering will form within the next 20 years. Developments of this magnitude do not happen overnight, in the contrary, they take many years form the brain-storming phase (now) to the drawing board, then to field testing and from there to some technical buildup and realization. Solar geoengineering requires global governmental regulation. There exists no adequate organization, at this stage, which would be willing and able to take over the enormous responsibility of the task.

 

All in all I do not think it is likely we will see SAI/SRM happen in our lifetime.

 

Oswald Petersen

Author of „GeoRestoration – Cool the Climate with Natural Technology“

Atmospheric Methane Removal AG

Lärchenstr. 5

CH-8280 Kreuzlingen

Tel: +41-71-6887514

Mob: +49-177-2734245

https://amr.earth

https://georestoration.earth

https://cool-planet.earth

robert...@gmail.com

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Jan 7, 2026, 11:11:30 AMJan 7
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Hi Alan

Exactly - once they recognize that there is a durable demand on the public sector side!  The whole point about supplying a public good, is that there's only ever one customer, the public.  The public may be represented by a range of agencies but theae are rarely competing with each, rather than are fulfilling different missions in different parts of the public realm.  The competition that fuels the innovation comes from the procurement process, or not, as the case may be.

Your comment on 'safe and effective' echoes mine.

Regards

Robert


Alan Kerstein

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Jan 7, 2026, 11:28:58 AMJan 7
to Robert Chris, healthy-planet-action-coalition
Agreed Robert, with one caveat. You might recall the thread about SRM being inevitable regardless of what public or elite opinion might indicate now. Forward-looking investors and entrepreneurs might therefore take action ahead of overt demand.

Alan


Robert Chris

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Jan 7, 2026, 1:24:24 PMJan 7
to Alan Kerstein, healthy-planet-action-coalition

Hi Alan

I don't believe that withstands scrutiny.  There is every possibility that other entrepreneurs will follow in the footsteps of Making Sunsets, even at much greater scale.  But there is zero possibility, without explicit support from at least one and probably many governments, of any sustained climatically significant programme of SRM, of whatever technology, being undertaken by private enterprise.

Regards

Robert


Alan Kerstein

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Jan 7, 2026, 2:27:44 PMJan 7
to Robert Chris, healthy-planet-action-coalition
I have in mind the Anduril model Robert, namely take it to the prototype stage and then market it to governments. It's not an exact analogy, but few believed that this business model could be successful until Anduril showed that it could be done. It is implicit in the presumed inevitability of SRM that governments will be orchestrating and funding deployment. The more that the private sector can do before the government gets seriously involved, the faster and better the outcome will be.

Alan 

Paul Gambill

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Jan 7, 2026, 3:15:14 PMJan 7
to Alan Kerstein, Robert Chris, healthy-planet-action-coalition

Hi all,

I thought I might offer a few thoughts on this, because this has been my exact area of focus for the last 6 months.

First, I agree with Herb and Robert T on two counts:

  1. Fantastic that the Guardian published this. In fact, I'm told that there might be more coming soon.
  2. The need for sunlight reflection is already apparent. If it were possible to do so with risks mitigated and governance sorted (obviously these are gigantic 'ifs') I would think it wise to implement reflection as soon as possible.

But I do want to offer some nuance on the rest of the conversation. I'm actually going to publish an article on this very topic next week called "You Can't Focus Group Your Way to Permission." The core argument is that we're treating a permission problem as if it were a messaging problem, and those require different approaches. Here's a bit of a preview.

It's not surprising to me that Dakota and Daniele hedged on whether SRM is necessary. Reflective states it very clearly in their organization's principles: "Objectivity: If it is determined that sunlight reflection is a bad idea in terms of outcomes on people or the planet, getting to that clarity is a victory and we will CELEBRATE that outcome."

Why do they say that? For one, we don't actually know with a high degree of confidence yet whether SAI will result in "good outcomes on people or planet". But I think there's also an institutional reality at play here. There are only a handful of philanthropic foundations and individuals willing to put money into SRM research and activity today. If you want to start a new org working on SRM and want to find funding, the big foundations don't want to touch this because it remains politically unpalatable. The Overton window for this is at best open to neutrality (i.e. "research, but not advocate for deployment") while there is a large and well-funded opposition. So if you are trying to raise money for continued research, you have to stay within the window of what funders will grant money to. I think the institutional constraints shape what people in these positions can say publicly, regardless of what conclusions the evidence might support.

I have also spoken with scientists like Daniele about this. Universally, they will say "we know with great confidence that SAI will cool the global temperature. What we don't know yet is whether the potential tradeoff consequences of that in terms of regional effects and other even unknown consequences are worth it." And that is a pretty reasonable interpretation of the science. The fact that we don't have enough information reflects both a) this op-ed itself, calling for reasonable field experimentation, and b) the fact that scientists will always want to conduct more research. For more perspective on this dynamic, I highly suggest reading Simon Sharpe's book Five Times Faster (or at least the first third of it). About the only prominent researcher you will find coming anywhere close to advocating for the need to deploy SAI is David Keith, but he sits in rarified air and has a particular amount of leeway to say that sort of thing. That is not typical.

I admire both Dakota and Daniele greatly, and think they are very courageous for their leadership in this space going back many years.

I would also posit that if you want to bring the public along (which is necessary to some degree, though what that degree is is very debatable) then you need to meet them where they are. Meeting people where they are doesn't mean being timid about the stakes. It means being honest without being apocalyptic, and pairing the problem with a clear articulation of what we're proposing to do about it. Suggesting "things are getting really hot, it turns out we might have a way to deal with this while we continue decarbonizing" lands very differently from "things are getting really hot, we need to implement this untested and very risky atmospheric change, and by the way just ignore all the vociferous opposition to this while we get underway." In a world with growing amounts of populism and distrust of elites and institutions, my opinion is that you cannot try to force this issue and expect to get much agreement.

Now onto the entrepreneurial side of things. I am an engineer and entrepreneur myself, I have raised lots of venture capital money before, and I empathize greatly with the engineering instinct to build a better widget. But I also find myself more reticent to support the approaches that Make Sunsets and Stardust are taking, though these two companies are quite different and deserve distinct assessments. Make Sunsets is deliberately provocative in ways that create problems for people working through policy channels. Stardust is trying to build legitimate technology but has raised venture capital, which creates incentive structures around IP and returns that I think are misaligned with something that affects everyone on Earth.

I've always believed that if governments decide to deploy SRM, it will be private companies building the hardware and technology to do so—that's how we build things at scale. But I also believe strongly that this needs to be treated as a public good, with public governance and public accountability. The defense industry analogy is apt: private contractors build the equipment, but governments set the requirements and maintain control. Given that SRM is our last best hope for averting catastrophic outcomes, I think it warrants a great deal of prudence when considering what the private sector does outside of that kind of framework. Actions taken now and in the next few years are going to determine outcomes for the next several centuries. That is a huge amount of risk and responsibility.

All this said, I think we should not be too hard on the people making the case in public. This is politics, like it or not, and politics is a challenging business. I also think that direct advocacy for the necessity of cooling interventions is very clearly a gap in the ecosystem, and it's this gap that I am concentrating my attention on. The case needs to be made in a way that can be heard by the people who need to hear it, and sometimes institutional constraints prevent the people we would want to make that case from being able to make it.

Paul Gambill

https://www.inevitableandobvious.com/




Robert Chris

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Jan 7, 2026, 5:49:09 PMJan 7
to Paul Gambill, Alan Kerstein, healthy-planet-action-coalition

Hi Paul

Looking forward to tomorrow's MEER talk.  This post couldn't be more timely.

You quote from Reflective '"Objectivity: If it is determined that sunlight reflection is a bad idea in terms of outcomes on people or the planet, getting to that clarity is a victory and we will CELEBRATE that outcome."  Do you not think this is an incoherent and unhelpful contribution?

First, it's set up as a binary, it is either determined to be a bad idea or it isn't.  That's obviously not how the real world works.  Is it set up as a Pareto optimal objective - it's a good idea if some are better off and no one is worse off?  And conversely, it's a bad idea if anyone is worse off irrespective of how many are better off?  That's an invitation to throw the baby out with the bathwater.

Who are 'the people' they're so concerned about?  Those alive today, future generations, and if them, how far into the future?  What obligations do we even have to future generations?  And before answering that question take a look at Parfit's Non Identity Problem.

It talks about clarity.  The only way to determine what the outcomes on people are, is to do it.  But this statement is saying that we won't do it unless it is determined that there won't be any bad outcomes.  That's obviously a logical contradiction.  One supposes that the so-called 'determination' will be made on the basis of projections and forecasts.  But all such forecasts and projections are inescapably riven with uncertainties.  Who's to say which uncertainties are acceptable and which not?

These are fine words emanating from a thoroughbred Cartesian reductionist scientific mind.  When you try to map this aspiration onto the realities of policymaking, they are just that, fine words, and little more.

The emerging truth now is that it is almost certain that a dependence on decarbonisation alone will lead to COCAWKI (Collapse Of Civilisation As We Know It).  We can argue about the details, but the direction and rate of travel are now more or less set in stone.  How can you be honest without being apocalyptic?  That's another contradiction in terms.

COCAWKI seems to me to fulfil the definition of 'a bad idea in terms of outcomes'.  Maybe I'm in a minority on that!  But how about defining 'a good idea' simply as one that's not as bad as that bad idea?  We accept collateral damage in almost every sphere of public policy, why not here as well?

But I couldn't agree more, these are difficult ideas to discuss in a public setting.

Looking forward to learning more about the distinction between permission and messaging problems.

Finally, I really appreciate your remark about not being too hard on those involved climate policymaking.  They are on a hiding to nothing.  They are rarely trained scientists and almost never climate scientists..  They depend on a close-knit community of scientific advisors that in many instances is riddled with egregious Groupthink.  We always have to remember that climate change is just one of the issues they have to deal with and the others can't just be ignored because climate is in some senses a higher priority.  We need to support people, not demonise them.

Regards

RobertC


oswald....@hispeed.ch

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Jan 8, 2026, 5:46:19 AMJan 8
to Paul Gambill, Alan Kerstein, Robert Chris, healthy-planet-action-coalition

Hello Paul,

 

this your comment is by far the best I have read regarding the matter of public support for SRM and possible infrastructure for delivering it. I would want to add that it is a good idea to separate operators and material suppliers, make them different entities, which adhere to different principles. Operators of the planes should be public agencies or private non-profit companies which are under tight control of the public. Suppliers of material and equipment can be normal private co’s. E.g. there is no reason why Boeing could not be a supplier of planes doing SRM, however it would be a non-starter to make Boeing, a US defence company, cool planet earth. Keep those two things apart and you might be winning.

 

Operators of the flights could be regional entities, which are, naturally, bound to an airport. It is very important, in a global exercise, that all major powers, at least all members of the UN security council, are involved and operate at least one starting point for planes. Otherwise they will certainly veto it down. But I agree to you, that at this stage there is no real chance to win the political battle.

 

The whole approach is much more palatable with ferric chloride dispersion, which is far less expensive and requires much less sophisticated flying equipment. Also the amounts of material needed for global cooling are around 3% of what is needed for SAI, as far as I have read the numbers which call for 10 million tonnes of SO2 / year versus 300.000 tonnes of FeCl3 for ferric chloride dispersion.

 

But still, both approaches have many similarities, and therefore we should cooperate in the realm of infrastructure and politics.

 

Regards

 

Oswald Petersen

Author of „GeoRestoration – Cool the Climate with Natural Technology“

Atmospheric Methane Removal AG

Lärchenstr. 5

CH-8280 Kreuzlingen

Tel: +41-71-6887514

Mob: +49-177-2734245

https://amr.earth

https://georestoration.earth

https://cool-planet.earth

 

Ron Baiman

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Jan 11, 2026, 5:51:24 PMJan 11
to H simmens, healthy-planet-action-coalition, Planetary Restoration, Michael MacCracken
Good catch Herb!  Thanks for sharing. Interestingly this is precisely the discussion that was carried on at the AGU2025 Geoengineering sessions where Daniele, MacMartin, Keith, Waker, Tilmes, Smith, and many others were attending. It appears very close to what Doug MacMartin was proposing that I heartily endorsed at the session and specifically noted the that issue of how long it takes the aerosols to form from gaseous SO2 - referencing an old paper that Mike had mentioned - suggests that  it might take months (so that adequate testing would need to be carried out over a long period of time). Doug replied that this is a key issue for which testing is needed. 

This 1984 paper may be the one that Mike recollected: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/JD089iD03p04873  It suggests (if my understanding is correct), using El Chicon volcano data, that forming sulfates from SO2 can take more than 100 days if H2S or some other source of "odd hydrogen" (HOx - OH or OH2 - based on google!) is not available.  

This is from the abstract: "It is found that the chemical lifetime for the volcanic SO2 would be greater than 100 days for a large portion of the cloud if HOSO2 does not regenerate odd hydrogen during conversion to sulfate and if heterogeneous losses of SO2 are not competitive. However, observations of sulfate particle formation and SO2 imply a chemical lifetime of 30–40 days, which is consistent with HOSO2 conversion regenerating odd hydrogen."

A prominent geoengineering expert at the session (not Doug) told me privately (after I had asked this question) that the time it would take to create aerosols would depend on the location of the injection - which I take to be a proxy for other factors - perhaps linked to the presence of "odd hydrogen". 

BTW -  Support for applied science testing near-term global climate cooling methods is the subject of the Open Letter: https://docs.google.com/document/d/1ShSdXTOe50SVf1L0ZwI5imBhbSG1IItn/edit?usp=sharing&ouid=116465941111195452408&rtpof=true&sd=true  (this Jan 3 version is a cleaner copy than the Jan 5 version - linked to in the poster - that is now undergoing a bit of further editing)  that I was promoting at the AGU2025 via this poster: https://drive.google.com/file/d/1hvklktEZSciny9JnuMaU4Jn6_2pRN8w6/view?usp=sharing

Best,
Ron

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