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.
Hi John, thank you for this piece. I know it’s been a long time since you posted this but I wanted to respond to some of your thoughts.
“In my view, solar geoengineering is only likely to be used once warming is quite extreme, roughly exceeding around 4 degrees” - +4C is already endgame and catastrophic in my opinion. Considering that most of the heat is being absorbed by oceans leading to acidification, we’ll already be seeing significant sequestration losses as marine animals are unable to build calcium carbonate shells.
“This suggests that for solar geoengineering to be feasible, all major global powers would have to agree on the weather, a highly chaotic system.”—individual actors may resort to solar geoengineering without worldwide consensus, especially if countries that aren’t suffering from climate change are actively blocking mitigation attempts while still polluting. Understanding the possible ramifications before people begin to experiment through desperation is surely a good thing (e.g. India, China, Saudi Arabia, Brazil).
“We have had about 1 degree of warming thus far and, according to an IMF report, a further 1 degree of warming would be economiclly positive for many regions, especially Canada, Russia and Eastern Europe, and even potentially China (IMF report page 15).”—I think this is sketchy at best. The caveat footer 9 on page 14 should indicate how limited their conclusion is, not counting weather effects, migration, ecological effects, etc.
“Russia is a crucial factor here: global warming seems likely to bring numerous economic benefits for Russia, freeing up the Russian Arctic for exploration and thawing potential farmland.” - the US and Canada have been far more disruptive for climate change global agreements, the Paris agreement was largely stymied by Republican Congress. Permafrost thawing doesn’t free up usable farmland in significant amounts, these are still primarily extremely low viability / low human density forestland in Siberia. In fact, Russia is set to lose out significantly from permafrost thaw.
“Solar geoengineering research has clear risks and, given that we cannot deploy it at least for the next 50 years, there is no need to incur these costs now.”—this argument doesn’t hold weight for AGI research, and I don’t think it should for solar geoengineering. SG is highly neglected and as a fraction of CC research is minimal. The research will take decades to filter through to policy and international agreements, so it is worth starting research (not implementing) well before we are forced to use it.
“This would give us at least 20 years to cover the technical details and a governance framework.”—A lot of the warming is already locked into the ocean. Giving another 30 years before starting to research will likely be too late. I’m not in favour of implementing solar geoengineering now but researching the viability of these measures now seems to be promising, if not for application then for global security to dissuade rogue actors from implementing the measures with false / incomplete information / encourage preventative policy decisions. This requires fundamental technical research to assess the risks.
“This seems to me like enough time, given that: Solar geoengineering is probably technically feasible with adaptations to various different current technologies.”—I’m not sure the current technologies that you are referring to that can be adapted, but the more promising interventions are all much larger scale such as sulfur aerosol injections and have almost no precedent (volcanic eruptions can only tell us so much).
Finally “Another risk of solar geoengineering research is that it will uncover new technologies that could destabilise global civilisation. I discuss weaponisation risks in section 3.2 of my paper. ”—As your paper says, current information on SAI indicates that it will take a highly technically adept state actor decades of spending tens of billions of dollars and will still not be a permanent doomsday device (and will be obvious to other states and easily counteracted). All in all I find it difficult to imagine that SAI research will discover something that is easier and cheaper to generate a doomsday device than already exists in a conventional nuclear weapons stockpile. Additionally this doomsday device would also exterminate the user, whereas nuclear weapons can be directed at other states with no immediate, direct blowback (of course the political and social cost and likely retaliation from affiliated states are the reasons why we haven’t seen this happen yet). So the implication is that the malicious actor would also have to be suicidal. This doomsday device would also take time to work, which would give time to find a counteraction, and if research inadvertently discovers this application the time to find a solution will be the time from that research until the time of implementation.
Adding to this, currently climate change is projected to be a major stressor on international politics which can exacerbate nuclear X-risk, as well as expanding vectors for natural pandemic risks, among others—so this should also be in consideration when considering if SAI may uncover new X-risks as the baseline p(X-risk) for the coming decades is likely to be a curve rather than flat.
In conclusion the injection of CO2 and methane into the atmosphere may already constitute a moral hazard and dangerous weather manipulation method, and I think that we should be researching (not implementing) potential technical geoengineering solutions in order to prevent the expected outcomes of climate change as well as many other potential (part) solutions (As mentioned by others SAI doesn’t reduce CO2 levels and so does nothing for ocean acidification and other related issues). We should evaluate the risks and if (as I expect we will find) them to be too high due to uncertainty, we can use that information to construct international policy around this issue.