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I don't think it embeds properly because it is part of a Science image player. I will try to fix it.

  1. The paper makes the general statements quoted but in the text body clarifies that the evaluation has limitations in scope, omitting:

a) Tipping element cascades

So far, research on cascading behavior has primarily leveraged conceptual modeling rather than process and scenario-based approaches, limiting the applicability of these results for investigating the third question of what the cumulative impacts of transitions by multiple tipping elements might be.

b) Several tipping elements that are warming-dependent

We omit potential carbon fluxes or radiative forcing impacts from other candidate tipping elements (boreal forests, stratocumulus cloud decks, tropical monsoons, AMOC, and Greenland/Antarctic ice sheets ) given higher uncertainty surrounding their potential impacts upon carbon cycling and planetary radiative balance under different warming scenarios. One or more of these tipping elements could add net contributions to warming, however current levels of scientific knowledge and confidence are insufficient to formulate assumptions that aren't largely arbitrary. As stratocumulus cloud deck evaporation remains a novel and uncertain hypothesis, we also omit this mechanism. We assume die-off of tropical coral reefs produces no global climate feedbacks.

c) Several tipping elements that are warming-independent

Our review does not cover the full range of Earth system components that have been proposed to be candidate tipping elements over the last few decades. A number of other systems have been described as potential tipping elements, such as disruptions to the El Niño Southern Oscillation, loss of Antarctic sea ice, changes to snow cover in the Northern Hemisphere, and future shifts in ocean temperatures and oxygen levels, but are not expected to exhibit tipping behavior in response to warming (Ranasinghe et al., 2021).

As such I find this a little untrustworthy as the abstract implies a much higher confidence than is presented through the paper, but they did state it in the text.

  1. I agree with what Sanjay said, there is fairly good agreement between the Armstrong McKay and Wang papers. One difference is the Amazon dieback is considered to be much more likely in the latter paper.

Armstrong projections

Wang projections

The paper broadly conforms to my previously held views on the tipping points discussed, but I would assign more risk to ice melt and AMOC slowdown as these projections don't include new research on grounding line movement that increase sea level rise projections by up to 200% and evolving understanding of crevasse contribution to melting.

Verbalising the distinctions between 1 - 5 was something I was struggling with, so thanks for putting it so concisely and comprehensively. I agree with all the points you have made and the clarification at the end, which is what I was trying to say in a jumbled up way.

My impression on tipping point sensitivity was based on specific events happening significantly ahead of projections from modelling. I will have a read through the linked paper suggesting tipping points aren't as bad as thought and comment on your linked post from March if necessary, but otherwise will update based on that.

I also agree that while the expected temperature trajectory is moderating (as well as the risk of higher trajectories), we may be underestimating the "political climate sensitivity" which is a function of the risks you provided in Figure 4 rather than warming, and which appear to be getting worse. I also don't think great power conflict is significantly exacerbated by these indirect effects until much higher warming but Israel / Arab world and Pakistan / India are a couple of conflicts I think could be worsened and would still be of global concern, despite not being between Great Powers.

I haven't done a deep dive on it but my reading has leant towards political instability being very sensitive to increases in risks, risks which are plausible at temperatures expected in the next 30 years. That being said, the frequent example of the Syria drought-conflict could be the wrong narrative in favour of unsustainable agricultural policies. So I think I need to investigate more.

Thanks for the discussion!

I found myself strongly aligned with the opinions expressed in this podcast. I strongly agree with Johannes’ opinion on personal emissions reduction, pro-nuclear, funding in high growth, large population countries, governmental advocacy and almost everything else said. So the following isn’t meant to be a broad critique.

I was confused about a small section that had several layered points that I didn’t really agree with after a whole podcast of opinions that aligned with mine. The comments around the idea that indirect effects of climate change leading to higher conflict are predicated on severe climate impacts. From the podcast:

"And then there is a, from my perspective, really plausible critique of [the report], which is saying that we’re having a lot of indirect unforeseeable effects and generally a situation of decreasing political stability feedback loops.

The thing I would say there, though, is that all of that kind of requires pretty severe climate impacts still. So, the fact that the climate picture overall has been getting so much better makes all of those things less likely, and we should be honest about that.”

• Indirect effects kick in at much lower temperature thresholds

I guess it largely depends on what is meant by “pretty severe” but the following sentiment about the climate picture getting better had me thinking that what was meant was a world of >4 °C or another future world that is considered unlikely even in business-as-usual scenarios. I have always pictured severe climate impacts (in the sense of significant pressure on governments and populations) at much lower, even on a +2 °C pathway.

• The climate picture overall has been getting worse

In terms of government responses to climate change, public perception, scientific understanding there have been many positive events in the last 10 years but nowhere near the requirement to avoid significant harm. The picture on climate effects at different temperatures appears to be getting worse, such as Thwaites, ocean circulation slowdown and extreme temperature anomalies all of which are way outside of predictions for this temperature. We have also made slow progress on understanding and incorporating feedback loops in models and planning. So with effects being worse at different temperatures the expected instability is also worse.

I may just be misunderstanding what was meant as there are a few plausible interpretations, but those are my thoughts from what I understood. As said slightly earlier:

“Increasing conflict is kind of the reason mostly to prioritise climate from a longtermist perspective.”

So I think it’s an important point.

Hi John, thanks for the reply, I wasn't expecting one after this long but I am pleased about the thoroughness and thought you put into it.

  1. Yes, I think it's likely to be catastrophic (not extinction risk). If your assertion that it is only likely to be used when warming is 4C+, your whole argument is moot because that is already past the point of no return. From the base that 4C+ is an unacceptable situation, you would immediately be making the case that SG should be funded and accelerated by your own following argument - that currently policy and research are preventing it from being available until well after it is a viable temporary mitigation strategy (if it on balance positive).

  2. In the framing of the desperation-triggered, unilateral application of SG this would not be in the context of "statecraft". If millions are facing water shortages and famines in India they may have bigger concerns than their relations with allies, and equally could criticise them for not contributing to climate change solutions that are disproportionately affecting them. Scapegoating a unilateral SG actor for adverse weather is possible but they could also point to climate change for those effects and say they are trying to combat them, which no one else is doing. This very much gets into the mire of propaganda and spin and I don't think that a direct consequential chain of "public gets angry, state representing that public puts pressure on SG-using state, SG-using state acquiesces" is bulletproof as an argument. Saudi Arabia has such significant political and economic power that they can support terrorism with the West calling them allies. I think these things are far from obvious. I am not so concerned with unilateralism not for the state "peer pressure" reason you give but because it would be a significant financial burden for any one state. I also see it as a potential risk while you appear to discount it heavily, and use this to support 1b) which then kicks the ball down the road for 50 years.

This bet seems severely against your interests so I will treat it as rhetorical - your payout will only be accessible in 30 years and on those time scales inflation, life expectancy, technological change, X-risks and remembering the bet are all not in your favour. Whereas I have the potential to cash out at any time before that deadline. I don't particularly think that it's likely but I would still have taken that bet because of the conditions - 30 years is a long time.

  1. We are, depending on estimates, a decent way off having AGI, so by your argument there is no point doing AGI safety research now because we don't need it now, if there are any risks / costs associated. I think the same arguments in support of that work in this context, time required and complexity of the issue prompt early investment (and that early-stage research is neglected currently). This isn't about the neglect but the timeline - any research is going to incur costs now and pay off later. AGI safety has clear risks in potentially downplaying the risks of AGI and achieving a Dunning-Kruger effect for the entire human race, accelerating development of an inherently uncontrollable technology. It's a case of balancing the costs with the advantages of starting earlier.

  2. Over 90% of warming since the 1970s has been absorbed by the oceans, this conversation will only be of relevance if we are following higher RCP trajectories where it may be warranted to use controversial techniques, but there is a huge thermal sink that will work to bring the atmosphere back into equilibrium even using SG. This undermines the wait and see approach because it would be valuable to prepare in advance of the requirements.

  3. I didn't realise that this was referenced - if other people have investigated then that's fair enough. I didn't think there was any precedent for creating and dispersing particulate matter into the atmosphere and to keep them there, considering weather and localisation and other challenges. We are not able to replicate a volcanic eruption in terms of getting material airborne was my point, so the relevance of global cooling via volcanism isn't ironclad, direct evidence that SAI would work in the same way, as I expect it would depend on the distribution method and location (altitude etc.). If people who have looked into this see this as feasible with current tech then they will likely have more info than me.

  4. The counterfactual of not implementing SAI isn't a flat line for X-risk, in the absence of mitigating effects the risk of existential events increases over time as a result of the indirect effects of climate change unmitigated by SAI (other things being equal). This would somewhat discount the increasing X-risk of SAI.

  5. On rereading I may be misinterpreting, I thought that you were using moral hazard in the standard economic sense but you may be defining it just after as per previous papers as plan B undermining plan A. I agree in that case that my use of the term doesn't make sense, but I'm more familiar with it's use as increasing exposure to risk because the actor doesn't bear the full consequence of that risk, a sort of generalised externality. In that case CO2 emission is a moral hazard because the systemic risk isn't borne just by that actor, which incentivises overproduction.

Again, thanks for the response, I enjoyed the article and your reply has helped me understand the sources of disagreement a bit better. Some of them seem to be purely opinion-based or miscommunication. I also agreed with a lot of your points, although some not for the same reasons that you have given. I would still like to see small scale research on this topic being done and didn't see that much wrong with doing it. I will have to read more about the moral hazard argument sources you mentioned because they should be more convincing than those I have encountered previously.

Cloud formation was the biggest unknown feedback loop and efforts to model them more accurately has led to the increase in range. The effects only start at unprecedented levels of warming which is why observational data may not fit.


I have tried to lay out in the section on probability, above, that most X-risks are a subset of C-risks as they collapse usually has to happen before an existential event. Most X-risks in their moderate form, such as a nuclear winter lasting a few years, moderate climate change, or a global pandemic seem much more likely to pose a C-risk than an X-risk.

Thanks for the comment! I am aware about the GCRI and GCRs but I don't see the term getting used much and (in both cases) seem to get conflated with X-risks, but I haven't addressed this at all in the piece so I will add an edit.

Thanks for catching the typo. I've been trying to embed the images but it hasn't been working, so I'm contacting support for help.

The analogy I was making was that socially held values are liable to change and (usually) improve over time, and any specific value might not disqualify a future civilisation from being counted as valuable by us today, but at some point in the future there may be sufficient drift to make that claim. This may happen gradually and piecemeal as in the ship of Theseus. The full thought experiment also mentions restoration of rotting parts and asks whether these are also the ship of Theseus, similar to a Renaissance period.

This doesn't seem to be the context in which you were dropping the link, seeing as they all have top-level summary numbers that feed into your boundaries and point 1 doesn't say anything about 2m/year being a lower bound, seeing as you are using it as the upper bound. I would like to see these other estimates of climate mortality as they aren't referenced or seem to feed into point 1.

On a meta-level I think disconnecting sources with the context with which you are referencing them is very unfriendly to the reader as they have to wade through your links to find what you are saying where, but apparently these aren't even sources for adding evidence to your claims. So I am further befuddled by your inclusion of incidental contextualising literature when you haven't included references to substantiate your claims. I also think your edit comes across as quite uncharitable to readers (and self-defeating) if you don't think you can change people's minds.

I think when considering your estimates for 1. it is important to consider the boundaries given by those sources and to contextualise them.

The WHO is only looking at disease burden but even there they are expecting 250k to 2050 (not even looking to 2100) and they estimate that CC will exacerbate malnutrition by 3% of current values - this seems extremely conservative. They don't seem to include the range increases for most other insect-transmitted diseases, just malaria, even within the extremely limited subset of causes they consider.

Impactlab's "big data approach" - they don't give their assumptions, parameters, or considerations - I think this should largely be discounted as a result. It seems to be based on historic and within-trend correlation data, not accounting for risk of any higher-level causes of mortality such as international conflicts, political destabilisation, famine, ecological collapse, climate migration, infrastructure damage etc. that will have an impact and I am guessing aren't accounted for in their correlational databank.

Danny Bressler is only looking at extrapolating inter-personal conflicts. It doesn't include famines, pandemics, increased disease burden, ecosystem collapse, great nation conflicts, etc. etc. etc. that are very likely to be much, much worse than the trends considered in his model. As such his 74 million estimate should be considered an extremely conservative lower bound to the estimated value. He is also showing a significant upwards trend per-year, so the burden should be considered to exacerbate over time.

Overall this seems to cast doubt on 1, 4 and 5. For 2. I have also critiqued John Halstead's work in a previous post, and the Ozy Brennan post is refuting CC as an extinction risk, not as a global catastrophic risk as you use it. He is saying nothing about the chances of >10% likelihood of >10% population decrease. These combined should cause pause for thought when making statement 7.

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