Termination shock analysis

[H simmens]

Can someone provide a reference to an authoritative paper or article that analyzes the risk of termination shock. 

Thanks

Herb

Herb Simmens
Author of A Climate Vocabulary of the Future

“A SciencePoem and an Inspiration.” Kim Stanley Robinson
@herbsimmens
HerbSimmens.com

[Robert Chris]

Herb

All anyone needs to know about termination shock is that it only arises in very specific circumstances that are very unlikely to arise.  Two conditions both have to apply.

First, the risk of termination increases with the amount of warming suppressed by SAI.  That is why recourse to SAI must not reduce commitment to decarbonise.

Second, the risk of termination shock, however great the suppressed warming, only arises if there is a sudden cessation of the SRM.  In this event the suppressed warming would emerge over a couple of decades.

In effect, termination shock requires many decades of at scale SRM accompanied by weak or negative decarbonisation, and for its deployment to be abruptly stopped.

Clearly, these conditions are plausible.  But they can't arise for many decades to come, and we'd have to assume that those then in power would be ignorant and/or stupid enough to allow the termaination shock to happen.

If we claim that they might be that ignorant and/or stupid and as a result we do not deploy SRM at scale in circumstances where our successors have been equally as ignorant and/or stupid not to aggressively decarbonise, the warming will get them before the termination shock does.

Not doing SRM is an example of the 'dangerous precedent', once described as obliging one not to do what you know to be right, for fear that your successors might be too timid to do likewise.

In sum, not doing SRM for fear of termination shock is a lose/lose choice.  We'd have to be as ignorant and/or stupid as we would be assuming our successors will be.

Termination shock is ike moral hazard, everyone writes a lot about them and they're raised as big issues and obstacles.  They're both theoretical possibilities that are extremely unlikely to arise in practice simply because they are both anchored in a cynical view about human wisdom.  We are not ignorant and/or stupid, and despite all our mistakes and follies, most of the time we get things more or less right.

Is that authoritative enough for you?  😆

Regards

RobertC

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From: healthy-planet-...@googlegroups.com <healthy-planet-...@googlegroups.com> on behalf of H simmens <hsim...@gmail.com>
Sent: 27 October 2025 15:44
To: healthy-planet-action-coalition <healthy-planet-...@googlegroups.com>
Subject: [HPAC] Termination shock analysis

 

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[H simmens]

Hi Robert,

Your narrative is persuasive enough but it is inherently not authoritative enough. 

I’m engaged in a dialogue with a well known Climate author who is knowledgeable yet adamantly against SRM. I want to be able to send him /her an article - preferably peer reviewed- by someone who is recognized as an expert. 

Herb 

Herb Simmens
Author of A Climate Vocabulary of the Future

“A SciencePoem and an Inspiration.” Kim Stanley Robinson
@herbsimmens
HerbSimmens.com

On Oct 27, 2025, at 12:10 PM, Robert Chris <robert...@gmail.com> wrote:

[Robert Chris]

Here's the first one (attachments not in same order as my comments). 

Malm is VERY anti-SAI.  But his argument perfectly illustrates the points I was making.  Here a brief extract:

Imagine it is the year 2130 and the operation has been going on for a century. In the meantime, fossil fuel combustion has not ceased.

He assumes that we'd get to 2130 untroubled by the unmitigated warming up until then.  A typical one-sided argument that presumes there's no risk associated with the no-SRM status quo.

He also completely ignores the possibility, even the likelihood, that alternatives to SO2 might be found, that deployment strategies might be developed, that decarbonisation might be delivered, and so on.

He also has no idea how much the suppressed warming might be in 2130.  My model tells me that in the scenario he posits it would be about 1C by then, depending upon the deployment strategy adopted.  The unmitigated warming would be almost 3C by then.

He then says:

If, come 2130, emissions have not only been reduced to zero, but carbon dioxide removal has also cleaned the atmosphere of the historical accumulation and returned the co2 concentration to, say, 350 ppm, termination would not set off any roasting. If the net sum – behind the frail engineered glass door – is rather a doubling or quadrupling of that concentration, the result could be exceedingly cataclysmic. It follows that inasmuch as geoengineering exerts an effective temptation upon capitalist society to keep business-as-usual in place, the risk of a severe termination shock rises. (emphasis in original)

But in the first scenario he posits here, there would be no need for any SRM, and in the second, we'd be so totally fucked without the SRM, that it beggars belief that he could argue that not having it would be a wise response to our predicament.

The rest is a Marxist anti-capitalist rant.  Just because Malm is an Assoociate Professor in 'Human Geography', doesn't make him an authority on climate science.

The next is David Keith examining concerns about SAI, including termination shock.  He does his usual calm and rational analysis, trying hard not to overstae his case.

Next up is Holly Buck.  Here's an extract from her paper:

Risks and harms: the stopgap poses several types of direct  risks, including ozone depletion34, cirrus cloud interactions35, suppression of the hydrological cycle36, effects of increased diffuse sunlight37 and termination shock in the case of poor implementation38. The severity of these risks is highly uncertain and represents a clear research priority. Indirect risks are hard to quantify; many of them inhere in the details of the chosen stratospheric aerosol deployment scheme and how it is implemented39. Risk assessment must also take into account the counterfactual climate change scenario.

She's making clear that the risks are recognised, that they require further research, but there is nothing inherently certain about the harms the SAI might cause to enable a safe conclusion that there are no cicustances in which it would b better to do it than not.

Another extract from Keith being interviewed:

David Keith: I personally do not see [temination shock] as a risk in the same categories as others. So first of all, it’s certainly true that we will discover new surprises and new bad outcomes. And that may cause people to change how much they’re doing or to transition from one kind of solar geoengineering to another. But I think the risk of very sudden turn off of large-scale solar geoengineering is pretty low because of individual country level selfinterest. Even countries that initially opposed deployment of solar geoengineering have a very strong self interest in maintaining the ability to start it once deployed because of the risks of sudden termination. And sudden termination effectively requires unanimity, global unanimity among countries of significant scale, in shutting it off. And I think that’s a very unlikely outcome.

Parson writes:

Other studies suggest that risks of termination shock (Parker & Irvine, 2018; Rabitz, 2019) and geopolitical conflict (Heyen et al., 2019) may be overstated or mitigable.

Those authorities can easily be referred to; Parker & Irvine attached here.

Then there's me.  I've also attached a note I wrote this time last year.  Not published nor peer reviewed. 

And I leave the best til last.  here's the Andy Parker/Pete Irvine contribution referred to by others.

I have more!

Regards

Robert

---

From: Robert Chris <robert...@gmail.com>
Sent: 27 October 2025 16:48
To: H simmens <hsim...@gmail.com>
Subject: Re: [HPAC] Termination shock analysis

 

Let me see what I've got in my archive.

Regards

Robert

---

From: H simmens <hsim...@gmail.com>
Sent: 27 October 2025 16:28
To: Chris Robert <robert...@gmail.com>
Cc: healthy-planet-action-coalition <healthy-planet-...@googlegroups.com>
Subject: Re: [HPAC] Termination shock analysis

 

[John Nissen]

Hi Herb,

Robert Chris is absolutely correct on the physics and my confidence arises from the original paper by Caldeira and Matthews on the subject and the irrefutable logic. Most importantly there is not a jump in temperature but a jump in the rate of temperature rise since climate forcing has just jumped up.

Those who are scared of SRM will grasp any straws to argue that it's too risky. Perhaps there should be a well-funded campaign to rehabilitate SRM and counter decades of bad publicity, even continued in the latest New Scientist.  If Rob T idea of an albedo accord materialises, rehabilitation should be part of its remit.

Cheers John 

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[Ye Tao]

Hi Robert C,

Could you please explain your thinking on mechanisms and pathways for decarbonization within the current economic super-organism (Hagens's term)?  I personally see no dynamical mechanisms given the economic rebound effect, and with the elimination of a desirable temperature/extreme climate negative feedback on economic growth.  Yet, full decarbonization, with sustained global manufacturing flux intensity, a reduction of non-renewable material flux, and rewilding (to enable slow deployment of NBSs) are prerequisites for avoiding termination shock on multi-century timescales.

Please be quantitative where possible:)  Example: 30g CO2e per kwh when sourcing PV electricity, excluding storage.

Thanks,

Ye

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[Robert Chris]

Hi Ye

Easy!  We're fucked!  Well, probably not me; fortunately I'm not going to be around long enough to feel the heat.

I see no credible path to significant decarbonisation on any timescale that implies keeping GSAT at or close to 1.5^oC and keeping any overshoot to anywhere close to anything I'd consider to be 'safe'.  It's impossible to quantify what being 'safe' means because it's a function of the area under the overshoot curve not just its maximum height.  My gut feel is that we entered overshoot territory when we went past 1^oC of warming.  My metric for this is ^oCyears arrived at by summing the annual height of the overshoot over its duration.  I use this to compare alternative scenarios but I don't have a benchmark for what's acceptable.  It requires setting the threshold temperature above which everything is overshoot.  That's a subjective exercise.

Moreover, I see no credible path to the deployment of any form of SRM at the scale and timing necessary to keep the ^oCyears low enough to make me feel comfortable about my grandchildren's future.

The situation is much as it has been since international negotiations started in the late 1980s.  We have always had, and still have, the means to avert a climate induced catastrophe - what I call COCAWKI - the Collapse Of Civilisation As We Know It - but we continue show no signs of having the communal wit to deploy them effectively.  COP30 is just another dagger to the heart.

You asked me to quantify my response.  I'm always asking people to do that!  I can do that to illustrate the mountain we now have to climb and also to illustrate the rate at which the mountain is getting higher.  The numbers are BIG.  Hence my opening remark.  But not to illustrate a plausible avoidance of catastrophe given 'the current economic super-organism'.

Your remark about not being able to avoid termination shock 'on multi-century timescales' I regard as of academic interest only.  First, as I say above, I don't think that SRM will ever be scaled sufficiently to make termination shock an issue, doubly so because I don't see decarbonisation becoming sufficiently entrenched for there to be that much warming suppressed by whatever SRM may be done.

The most likely endgame here is that the human population catastrophically declines to 1 or maybe 2 billion within the next century, or maybe a little longer.  The consequential effects of that will be drastically to reduce emissions. The survivors will, by definition, have learned how to adapt to the changed situation, and slowly slowly there'll be a regeneration and something amazing will emerge over the coming centuries.  The West had a Dark Ages that ended little more than 1000 years ago.  There's no supreme law that says we're not about to enter another.

Happy days!  Thanks for asking.  You've really cheered me up.

Joking apart, looking at humanity's predicament from a systems perspective, I suspect that there's a certain inevitability about the forthcoming COCAWKI.  Complex adaptive systems, which is what humanity is an example of, routinely self-destruct.  I see no reason for us to be exempt from this.  There are plenty of signs of it in progress of which COP30 and Trump's Ukraine/Russia 'peace' deal are just today's examples.  The list is long. 

Human systems collapse because power becomes increasingly concentrated in fewer hands.  This has the double effect of them making poorer decisions because of the lack of diversity in the decisionmaking process, and making the consequences of their bad decisions more disastrous because they have wider reach (technical term for this elite  is 'global controller').  The collapse is a response to what is referred to in the literature as 'an accident waiting to happen'.  You can't be sure what will trigger it, but as the elite become more focussed on conserving their wealth, power and status, the resilience of the systems is eroded.  When the accident happens, the system lacks the capacity to absorb the shocks or adapt to the new situation.  The collapse then takes on the nature of a catharsis, clearing out the deadwood and creating space for a renewal and regeneration.   In my more positive moments focussing on a flourishing future for humanity, I say 'Climate change - bring it on!'  The reason to be positive despite it all, is that the human spirit is indefatigable.  There have always been enough people with the motivation to pick themselves up, dust themselves down, and start all over again.

Regards

Robert

---

From: Ye Tao <t...@meer.org>
Sent: Sunday, November 23, 2025 13:13
To: Robert Chris <robert...@gmail.com>
Cc: H simmens <hsim...@gmail.com>; healthy-planet-action-coalition <healthy-planet-...@googlegroups.com>

[Robert Chris]

Literally as I pressed Send on the message below, I received a link to a 2018 book by John Dryzek.  He shone a light for me in my early struggles with all things environmental.  I have just flipped thought he book in less than 2 minutes.  I think this might be a valuable read.

Regards

Robert

---

From: Ye Tao <t...@meer.org>
Sent: 23 November 2025 13:13
To: Robert Chris <robert...@gmail.com>
Cc: H simmens <hsim...@gmail.com>; healthy-planet-action-coalition <healthy-planet-...@googlegroups.com>

[Ron Baiman]

https://academic.oup.com/oocc/article/4/1/kgae008/7706251  

Sent from my iPhone

On Oct 27, 2025, at 11:29 AM, H simmens <hsim...@gmail.com> wrote:

Hi Robert,

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[Ye Tao]

Hi Robert C,

Given your prediction of inevitable collapse and a rather optimistic projection that " there'll be a regeneration and something amazing will emerge over the coming centuries.‘, shouldn't then the focus of us engineering-minded visionaries also include

1) Schemes to attract and gather subsets of humans with behavioral and moral genotypes/phenotypes compatible with that "amazing" future.  Well, HPAC is a good example, but forgive my being blunt, our average age is no spring chicken...  Where are the young people and how do we get to them?

2) Develop scalable low-tech and social organization to enable such pockets of humans to thrive within a 5C warmer world. 

3) Develop defense mechanisms to prevent take over by descendents of the billionaire class currently building high-tech bunkers. (e.g. site selection away from bunker locations.  and Intrinsically mobile systems.)

Perhaps there would be no need for deliberate engineering than simply watching nature do its magic through evolutionary forces.   After all, multicellular organisms evolved from unicellular ones under resource constraints.  This time, the same forces on the macroscale should also select for groups that have strong pro-social tendencies.  The question is whether there will remain enough number of small groups to survive the filter due to statistical noise, when the total number of groups, "N", is small.

Ye

[Tom Goreau]

 

Indigenous people on isolated high tropical islands who have managed to maintain their subsistence traditions are likely to survive systemic collapse of “civilization”. There aren’t many left, but they will continue in peaceful isolation, like the North Sentinelese.

 

With luck, new civilizations might emerge centuries after the thieves, liars, killers, and greedheads destroy this one. It’s happened several times before.

 

My Taino Arawak ancestors, who came to the Caribbean thousands of years ago in canoes crammed with Amazonian food crops, are generally thought to have been totally exterminated by European genocide. But our culture is still intact in all Caribbean rural settings, here for example a man living in a tree house on my home island, Jamaica, which survived the strongest hurricane ever to hit land:

 

https://www.youtube.com/watch?v=rBst9p6QDkw   (long, hope you appreciate our language).

 

We are all survivors, will rebuild, and can live on the land without AI and all other non-essentials as the Earth is over-run by opportunistic weeds and parasites.

 

https://www.globalcoral.org/jamaica-cleans-up-damage-from-worst-hurricane-on-record/

 

Earth history shows coral reefs will re-evolve a few million years after we kill these ones:

 

https://www.globalcoral.org/coral-history/

 

 

 

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[Ye Tao]

Thank Tom, for the tree house video.  I see that an intrinsic ability to yield to shocks (single pole foundation) and the dampening effect of surrounding branches most likely contributed to its survival. 

It is shockingly sad that the global South continues to switch over to ugly, high-emission, expensive, and deadly cinder blocks + corrugated iron sheets construction style.  Here in Freetown, concrete bricks are regarded as high-status.   We are working on ecological and PET-based replacements that look better, are cooler, flood resistant, and non-lethal in case of hurricanes and landslides.  

Best,

Ye

[John Nissen]

Hi Robert,

You say "We're fucked!".  But you seem to have dismissed SRM; I am surprised at you.  We are indeed f'ed without SRM, specifically SAI.

Moreover we are probably f'ed without SAI rapidly deployed to start refreezing the Arctic, because of the five tipping points there, already activated.

And, I agree, we are f'ed without reducing CO2e to below 380 ppm, to guard against abrupt termination of SAI (and/or other cooling interventions) and allow it/them to be phased out gradually. But this is a long-term consideration.

BTW, I have chosen 380 ppm CO2e because it was about the value in 1980 when some tipping points were triggered.  And to achieve 380 ppm CO2e this century we need at least 60 GtCO2 removal per year for a number of decades as well as CO2 emissions reduction and the suppression of emissions of short-lived GHGs.

Going back to SAI, we need some moral leadership to get SAI going.  The IPCC is misusing its power: they are defending the status quo while the planet accelerates away from late Holocene norms.  Billionaires are misusing their power which could do immense good if used properly.

Listen to the Reith Lecture, if you didn't hear it this morning.  The world is in a mess.  We urgently need moral leadership from people with power who value the future of humanity.  But it might only take a small group of determined people to make a transformation.  This is what history teaches us.  The transformation needed is not social, but the acceptance of technical intervention both as an emergency measure and for the future flourishing of humanity and the biosphere. 

Cheers, John

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[Rocio Herbert]

Thanks Tom, for the tree house video.   I can imagine many trees with treehouses.  That is how a few would survive and keep the species going.

Ye, once a 'people' are touched by westerners, they cannot unsee what they have seen.   They compare and choose as we all do.  In the global South (where I come from), a house made of wood is worthless because it burns.  The only houses with value are the ones made of cinder block.  The concept of new ecological replacements is very new.  I trust they will choose those new materials when they realize the benefits, economically and ecollogically.   Better get those materials to increase the value of their homes ...  then you may see uptake :)

Great conversation.   

Rocío Herbert

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[Robert Chris]

Hi John

I know all that science stuff!  That's easy.  The problem is the politics stuff.  That's a systemic problem.  I stress 'systemic' because it's not about the odd bad actor here or there, or the odd lack of vision or absence of leadership.  It's about a global economic and geopolitical system that has emerged over the last two or three centuries.  For all the wondrous achievements it can take pride in, the gradual accumulation of its internal weaknesses is now coming home to roost.

As COP30 proved yet once again, there is no appetite to stop the gravy train that is enriching the elites that travel on it.  Globalisation has created huge benefits but also huge inequities.  Those inequities are increasingly destabilising.

I don't see any credible mechanism whereby an intervention in the global climate system, such as SAI, is going to be enabled in an essentially anarchic world order where moral rectitude has become increasingly understood in terms of individual rather than collective norms. 

I see even less scope for that in the Arctic with such a large part of it controlled by Putin's Russia, and both Russia and China seeing the Arctic more in terms of its extractive potential than its climate role.

All that said, it's important that we keep plugging away.  Something good might happen.  I bought 4 tickets in tonight's Euromillions lottery, there's a £135 million prize.  I think it more likely I'll win that than we'll get SAI to climatically significant before it's too late.

I stress 'climatically significant'.  I think it quite likely that there'll be some SAI but I very much doubt that it will be allowed to scale at the rate we'd think is necessary.  Moreover, I personally would be very concerned if it was not accompanied by aggressive decarbonisation.  The combination of lots of SAI and lots of CO2 emissions, is a recipe for an even more spectacular calamity than the one that would happen if we just let the emissions do their thing without the SAI, albeit that it may be a little delayed.

It might come down to a choice between losing 80%-90% of the human population and losing all of it.

Sorry, I'm feeling very grumpy.

Regards

Robert

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From: John Nissen <johnnis...@gmail.com>
Sent: Tuesday, November 25, 2025 15:34
To: Robert Chris <robert...@gmail.com>
Cc: Ye Tao <t...@meer.org>; H simmens <hsim...@gmail.com>; healthy-planet-action-coalition <healthy-planet-...@googlegroups.com>; Planetary Restoration <planetary-...@googlegroups.com>

[Robert Chris]

Hi John

I should have mentioned that I couldn't agree with you more about this morning's Reith lecture.  It may have been that that put me in an even more grumpy mood.

This guy is good.  I'm really looking forward to the next two lectures, not least because he said it was all going to end on a positive note.

For those of you not familiar with the Reith Lectures, it's an annual series of three lectures broadcast on BBC Radio 4 in memory of Lord Reith, the first Director General of the BBC.  They always attarct high calibre thinkers.  It's an hour well spent.  Try it.

Regards

Robert

---

From: Robert Chris <robert...@gmail.com>
Sent: Tuesday, November 25, 2025 19:20
To: John Nissen <johnnis...@gmail.com>