I’d also be keen to see additional work on the climate, agricultural, and famine effects of nuclear war, perhaps ideally by a third team which isn’t connected to either of those teams.
You have probably read the Nature article but they predict 5 billion dead (out of 6.7 billion using 2010 statistics.)
https://www.nature.com/articles/s43016-022-00573-0
People are freaking out over their analysis.
My bad, the first paragraph should have my thesis statement right? That and the remaining paragraphs are the supporting arguments. Good luck. The HTML embedding is not working for links. Their is probably a breakdown somewhere but this site needs a better UI.
My point was abstract threats are not motivating. People are terrified of war. But we have been beaten down and have no political agency. For instance, your comment sucks Optimist. You got the moderator mad. Yeah I hope so. People want this problem solved myself included, but the academics are worried about funding and impact factors.
Threads and the day after were the reason the stockpile was reduced. Diplomats had no impact on it until the public was motivated.
Your perspective is refreshing. I agree that nuclear winter is overblown. Nonetheless achieving the same countervalue strategy is possible without directly attacking cities. The EMP commission reported that up to 90% of the US population would die within a year after an EMP attack with nuclear weapons. The weapons would not create smoke and an EMP would force the country to devote resources to keeping people alive. In other words an EMP attack keeps demand high by not killing anyone but instantly drops the supply which eventually kills almost everyone.
North Korea has created weapons and the missiles to carry them. However, they have not created the technology necessary for a warhead to re-enter the atmosphere and they have not created necessary guidance systems to accurately hit targets. They are also developing a constellation of satellites that in theory could hold nuclear weapons that are detonated when they are above the targeted countries.
I think this asymmetric strategy is likely to be used by the US and Russia too. Even after a successful counterforce first strike enough warheads would survive to achieve countervalue objectives without risking a nuclear winter. In a nuclear war where cities are targeted the initial SLBM EMPs would still kill more people than the direct attacks on cities. So why risk a nuclear winter even if it is a remote possibility?
Effective altruism is about investing my income to do the greatest good. Should I max out my 401k now to give away more money in the future or invest now in a wood gasifier, windmill, biogas generator, solar power system and micro-hydro in order to avoid having to plough after a possible devastating EMP attack?
I agree that nuclear winter is unlikely because an attacker has better options than firestorming cities.
This was a lot to unpack but I agree that it would be extremely difficult for the human race to go extinct. Although 99.9% of all species have gone extinct. It is our enormous numbers and ability to adapt and specialize in different ecological niches using our tools instead of our biology that makes us hard to kill. I keep coming back to this forum because I like to see the academic perspective on nuclear conflict. Although there is still a lot of misinformation on surviving a nuclear war.
In my experience most people avoid thinking about nuclear conflict and it is not something I can bring up in casual conversation. Even the people who identify as preppers fall into nuclear nihilism and say they would want to be cindered in a flash of light rather than go through a nuclear winter.
Most preppers do not build bunkers and besides bunkers are unnecessary. Most preppers have a small amount of extra supplies for a brief interruption of services. They are not planning on bushcrafting to survive or single handedly rebuilding civilization. The research you linked on preppers complains that preppers are often thought as crazies like on the TV show doomsday preppers but still studies that fringe.
Nonetheless, I think most preppers would survive a nuclear war. In fact I believe a family can guarantee their survival in a nuclear war for under $5k. That is cheap insurance against a real risk that can be spread out over several years.
I loved the book, The Knowledge, and have read it a few times. I am jealous if you got the chance to pick the brain of Lewis Dartnell. I agree with his premise that the goal should be to restore civilization as fast as possible if it should collapse. A good primer was needed even if it is missing hydraulics and electronics.
But I think in order to rebuild we first have to show that people can survive something like a nuclear war. A lot of great material on surviving a nuclear war comes from the Cold War era. At the time the governments were afraid that if they instructed people directly on how to survive a nuclear war that they would be signaling to them that they intended to start one. They didn’t want people to think it was inevitable even if statistically it is inevitable. Besides people would cut their funding if they became too afraid. This is how unofficial but official information was created like protect and survive in the UK and Nuclear War Survival Skill in the US.
In Nuclear War Survival Skills they tested their shelters against blast effects and verified a family could build a covered foxhole in 48 hours. Before the nuclear test ban treaty shelters were tested against real nuclear weapons. Most buried structures that can support the weight of earth above them can survive an airburst. We also know the UK did practice nuclear wargames to train officials to make the best possible decisions in the worst possible scenarios. They included members of the BBC in their wargames and unsurprisingly created the dystopian science fiction film Threads which has been called the most realistic depiction of nuclear war.
If a covered foxhole as described on page 123 here a few buckets of food, and electronics wrapped in aluminum foil inside a metal trashcan (to protect against an EMP), can defeat an all out nuclear attack then humanity will survive and rebuild. MAD will be remembered as the greatest waste in the history of the human race of money, time and lost potential.
I am still waiting for an analysis comparing the Brian Toon article on nuclear winter and the Los Alamos nuclear winter paper that predicts much smaller cooling effects.
I will say it again this program needs to be fully funded. But I do wonder if the solution to this is genetic engineering.
Corn and potatoes are well adapted to the areas people live. Both are incredibly calorie dense with a high number of calories per acre. All GMO foods in existence now are further optimized to grow for the present sunlight and UV conditions.
What research has been done on creating GMO foods that are optimized to grow in low levels of sunlight and high levels of UV?
Ideally there would exist a variety of nuclear winter crops that are optimized to grow in those conditions. But there might also be no surviving seeds that are optimized for a normal environment.
It should be possible to breed out or splice in kill switch genes that slowly disables nuclear winter genes after a few harvests. That way the food is optimized to grow every year as the environment changes. Eventually deleting their nuclear winter genes or allowing their post-winter genes to dominate.
What I want to know is with genetic engineering is it possible to preprogram our food to adapt to the changing conditions from the beginning to the end? Can we bake everything into the potato? Is there a limit to how much we can optimize low light level, UV and drought resistant crops?
If agriculture science has no incentive to develop these crops now and it would be impossible to develop them after a nuclear war then should the government step in to fund the science?
I think we need more dystopian movies to get nuclear winter taken as seriously as other existential threats.
https://m.youtube.com/watch?v=uoErk_AIsDU
I would also argue that nuclear winter lead to the late Bronze Age collapse and collapsed civilization again in 536. Maybe we can avoid collapse next time.
Thank you for updating your research. I understand that only a handful of scientists are working on the nuclear winter problem. It seems like this is an area where effective altruism and yourself can make a major difference. I do have a few questions about nuclear winter since you mentioned looking into that subject in greater detail for future publications.
If cities burn without creating a firestorm to lift black carbon into the stratosphere then would a nuclear winter persist for years or would it quickly rain out?
Smoke is the result of incomplete combustion. A firestorm generates enormous temperatures due to the blast furnace effect heating fuels to temperatures between 1,400F and 2,000F. Carbon, like in diamonds, burns at 1,292F to create CO2. A smokeless incinerator is able to burn plastics without releasing black smoke and only release CO2 and water vapor. Do the sources you reference already account for the combustion of pure black carbon in a high temperature firestorm?
A few pyrocumulonimbus clouds have been studied. They appear to be mostly water vapor. If a firestorm releases a large amount of water vapor that condenses into ice as it rises then would the black carbon act as condensation nuclei? Would an ice coating change the color and stop the self-heating and rising necessary to reach the stratosphere? If an ice coated black carbon particle does reach the stratosphere then how does that impact the longevity of a nuclear winter?
If the sources are ambiguous then is this something that smaller scale table top experiments or additional observations can factually determine?
Even if I nailed the macro trends prediction, the Fed lowered interest rates, I cannot predict presidential tweets. Realistically, starting from the bottom you want to invest in low cost index funds.
VCs have a lot of capital to invest and only a few plays can make up for all their losses and then some. Most people cannot beat the market. I could spend all my time trying to squeeze out a few extra percent. However, I still would not know if I am a good investor with smart money or a dumb one who got lucky.
I can compound my investments historically around 10% per year. Including inflation puts the real dollar return at 8% per year. If I want more growth I really need to earn a higher salary. With a tighter job market, from lower interest rates and lower levels of natural unemployment, means switching jobs creates double digit raises. The trend in business is wage compression where people with more experience who continue to work for the same employer are only given inflation wage adjustments but never any real wage growth.
People should invest in index funds since they require no thought and do better than most managed investments. But this also frees up time to change careers and grow your income which is often easier to do, has a better return, and is under their direct control.
The excess income should go into index funds until someone can choose if they want to continue to work.
Index altruism might be a better strategy for most people too. If someone can identify a more altruistic charity that does more good then the efficient market hypothesis should quickly level the playing field. Maybe there is more smart money in investing that becomes dumb money when giving it away?
I have been working on my billionaire VC / EA elevator pitch.
“Money me. Money now. Me a money, needing a lot now.”
What do you think?
The Fed should lower interest rates soon and that will help to create a tighter labor market which will increase wages. The natural rate of unemployment may be a lot lower than previously thought.
Personally, I think this is due to dollarization and how the US exports our inflation to other countries. Our M0 money is often used for currency substitution in countries with a poorly managed central bank. Removing the M0 money supply from the banking system reduces the expected money supply created from fractional reserve banking. The US can and has to keep printing money to satisfy the world demand for dollars.
Nonetheless higher wages will follow after lower interest rates lower unemployment rates. The natural rate of unemployment should be higher but there is a lack of inflation which I believe is from dollarization. A tighter labor market and higher wages will incentivize more research into technology to increase productivity and increase the payoffs from innovations that increase productivity. Why build steam engines if slaves are cheap?
I can see how an extractive economy lowers the cost of labor. High labor costs and excess capital are the prerequisites for investing in labor saving technology.
It is not difficult for a bad government to copy existing technology that is more efficient. I believe the key difference between Africa and Asia is the green revolution of the 60s and 70s. The arguments are outlined here:
As China increased their yields they were able to move labor from subsistence farming into industrial production. Eventually the same revolution will happen in Africa. Inclusive economies are necessary for continued innovation. Applying several hundred years worth of productivity gains into a few decades may even given the illusion that fantastic economic growth is possible without inclusion. We will see if Africa becomes more inclusive as their productivity and growth begin to accelerate. I also feel personally attacked by the spot on long termist description.
*correction
the cost $3340 should be multiplied by 0.003 and 72 years to make a nuclear winter lifetime hedge comparison to malaria. That is $721. This is about 10 years worth of wheat grain. It is still on par with malaria prevention but also looks better if it hedges against multiple existential risks.
The main roadblock to additional funding into alternate foods research is likely the same nuclear fatalism that also cuts into FEMA’s budget. There is some validity to their arguments that this creates more countervalue targets. This is why decentralization, redundancy and resiliency is important. This same set of properties is what motivated the creation of the internet. A mixture of agricultural science, stored foods, alternate foods, fire prevention, arms treaties, and nuclear non-proliferation should all be pursued.
Any advances in those areas, especially agricultural science like dwarf wheat, would still save many lives. Even if there is not a nuclear winter and farming is possible people will not be able to garden as if their lives depended on it. A global year long power outage is expected to kill 90% of the population even with farming as an option. I think of stored food as buying people the time to adapt and survive. It also hedges against multiple existential risk scenarios and allows people to focus on rebuilding what they can before they become generationally trapped into subsistence farming. An electrical engineer turning into a farmer to survive is a waste of talent when they could be working in their specialty. I have read that malaria is considered to be an example of a good effective altruist investment. Their ROI for a single life is $3,340 according to this article: https://www.theatlantic.com/business/archive/2015/06/what-is-the-greatest-good/395768/
Assume that $3,340 is guaranteed to save a life. Stored food is also guaranteed to save a life should the worst happen. Your research shows that the accepted and expected likelihood of a nuclear war is 0.3% per year. Multiplying our good ROI example of $3,340/life by our expected probability 0.3%per year gives us $1002. That is enough to buy 10 years worth of flour for one person and it is more than enough whole wheat to feed multiple people through a nuclear winter (which I think is overblown but cannot prove it yet). This looks like an even better investment when spread out over 70 years. Alternate foods should also be explored and it may be more cost effective but the stored food is guaranteed. I do not understand why someone would be against that. The high costs to save everyone might even incentivize countries to further reduce their stockpiles if the citizens in those countries demand an adequate amount of hedging against their use.
While nuclear winter gets much of the existential risk attention an easy way to reduce that risk is to reduce fallout. This means eliminating high yield groundbursts by removing the outdated hardened targets like silos and cold war government bunkers. The fallout suppresses firefighters and civilians from putting out secondary fires because they would be instructed to remain indoors for weeks or months. Civilian deaths due to fallout would likely escalate the conflict into a full scale exchange. It would also be in an attacker’s best interest to allow civilians to put out fires in order to avoid a nuclear winter.
I appreciate your reply. I feel like I am learning a lot.
Have you ever read, Why Civil Defense Failed? The author argues civil defense failed because people took MAD literally. They believed that any attempts to stop or prevent total annihilation was utterly futile and only made things worse. They did not understand that an effective deterrence might be more effective and cheaper than guaranteeing total destruction. I think we both recognize the possibility MAD does not prevent conflicts but just makes them more deadly.
Civil defense during the cold war was scrapped because people believed it would create an incentive to build more weapons. Civil defense planners were believed to only be creating more targets. Your large scale alternate food production in factories would become targets in their arguments as well as any personnel trained to implement your plans. The author describes how the office of Civil Defense had its budget cut in the 60s even with the recent Cuban missile crisis. Only 7% of Americans made any preparations during the missile crisis because they thought total annihilation meant exactly that. So why bother? Senators believed any civil defense was just a way to prepare Americans for a war that is by definition not winnable or even survivable. I would still be interested to see your research on the nuclear winter effect if FEMA was properly funded and if their personnel were well trained.
Alternate foods are important but preventing firestorms would also stop other mass extinctions and ecological collapse. Being able to farm greatly decrease our chances of going extinct from a nuclear war. The argument can be made that now with nuclear arms treaties in place we should implement the safeguards that were not done during the cold war. This is because unchecked arms growth is less likely and we will forever live with the possibly of nuclear weapons being used.
The Russian dead hand was designed to let their leaders wait and see if an attack was real or a false alarm. They could arm their dead hand knowing that if they were hit that they could still retaliate. This is also true for SLBMs that would retaliate if they confirmed there was an attack against their countries. The submarine second strike ability and their near invincibility to a first strike attack ensures that cooler heads prevail during false alarms. This reduces the likelihood of accidental full scale war. Additionally if the codes are not correct then they would not be launched at countries and would land somewhere in the ocean.
Can the US soybean crop convert into vegetable oil? What about using powdered milk for essential fats?
I plan on reading your book first. I have noticed the assumption in this attack scenario is a surprise nuclear war, however, I think that is unlikely. There would be a period of tension when crisis upgrading and emergency personnel would be on alert. If an attack was expected then natural gas valves would be closed before the attack occurred. Preemptively shutting down utilities would be one way to encourage major cities to evacuate. Only 5% of the country would be subjected to lethal amounts of blast. It is more effective to spread out the population but people may be unwilling to leave unless the can move to areas where utilities are available. Earthquakes do not give the advanced notice while even a surprise attack would have some warning. A buried small metal pipe is highly resistant to blast forces due to its small diameter and the earth arching phenomena and would likely survive directly below the airburst of a 500KT weapon. Natural gas valves near homes would be covered in debris choking off their supply of oxygen.
Painting houses white is another potential crises upgrade that may be encouraged before a conventional war turns nuclear. https://www.youtube.com/watch?v=pGJcwaUWNZg&t=3m30sClosing blinds would also prevent the flash from entering the entire of the homes. In commercial buildings without blinds. The sprinklers do have standing water in them to keep the system pressurized. The flash shown in the video was from 29KT which has a shorter more intense pulse at around 0.3 seconds. A 1 megaton weapon can blow out windows 20 miles away but it is only capable of igniting dry leaves up to 11 miles from the epicenter.
If using intumescent paint becomes the industry standard through inexpensive products then would that stop a global famine?
https://www.youtube.com/watch?v=lVWVP3tKlZc
The flash from a weapon cannot penetrate most substances as it quickly deposits all its energy. What if cities are protected by releasing white smoke when missiles are inbound?
Hiroshima and Nagasaki were largely built from wood, paper with charcoal used for heating and cooking. It was much easier for Japanese cities to firestorm. Conventional weapons were used to firestorm many cities. How did the burning of those cities impact the climate?
Hardtack can be stored for over a century. Salt, sugar and multivitamins never expire. The country is littered with abandoned mines which are at the ideal temperature for long term food storage. I think the costs would be low. A one time expenditure has a long shelf life. It might be more expensive than alternate foods but it can be accumulated over time without triggering food shortages and may help people who are already food insecure under the guise of protecting Americans. Eisenhower argued we needed national highways to win wars. This does not solve the worldwide problem but your arguments are compelling. I just think there is too much uncertainty to give a definitive answer.
Sorry for the delay in my reply but I noticed your response after checking if she posted about risk mitigation.
I read the paper you linked and had previously listened to the 80000 hours podcast in alternative foods. I am for research into alternative foods. I think it is a good plan B and your methods should be tested to narrow down the uncertainty in their efficacy. However, my plan A would be $1,000 in flour baked into hardtack and a few thousand multivitamins or other food stores.
I do not think it is necessary to split hairs between counterforce and countervalue. I would be amazed if our launch on warning and use it or lose it mentality has changed. The assumption should be MAD instead of NUTS.
In her nukemap she uses a 15 and 500 kiloton example. The orange part is the thermal radius where fires are widespread. The grey circle before that is the 5 psi overpressure where most residential buildings are destroyed. However it does not show the 1-2 psi overpressure range where windows and fires are blown out. In smaller yield weapons the flash and blast radii that snuffs the fire out nearly overlap. I think secondary fires are unlikely to start due to modern building codes.
If it were possible for nuke map to MIRV you could see 33 blasts, each with 15 kilotons instead of her one 500 kiloton blast. And
In reality her 500KT example is just one piece of the MIRV attack from the SS-18 which would carry ten 500KT weapons. This would extend the blast radius over the city where the fuel load is highest. It would be immediately apparent that the same total number of kilotons from many lower yield weapons are more effective for total destruction than a single 5MT weapon.
In the firebombing of Dresden a first wave of high explosive blockbusters opened up the interior of the buildings. A second wave of bombers dropped incendiaries to start many fires in a predetermined pattern on top of the exposed interiors. A third wave of fragmentary bombs suppressed firefighters and civilians from extinguishing the fires.
The order of operations to make a firestorm are blast, fire, and the suppression of firefighters. Firestorms are hard to pull off and the allies waited for ideal weather conditions before attacking. The high temperature pyrocumulous cloud lifts the soot into the stratosphere.
In a nuclear MIRV blast the firestorming sequence of events does not occur. The first blast is a high altitude burst which disrupt the power grid reducing the likelihood of secondary electrical fires. Natural gas fires may still be possible.
The flashes start interior fires through transparent windows. Fire suppressing sprinklers in commercial buildings would be triggered to suppress them. Lastly, the blast from a second up to a few minutes later snuffs out any remaining fires. Fires started on the perimeter of cities are unlikely to have a high enough fuel load to firestorm or move before they burnout.
https://m.youtube.com/watch?v=ztJXZjIp8OA
https://m.youtube.com/watch?v=Q0kxCjiIyBA
I understand your analysis shows 50Tg of soot making it into the lower stratosphere from a large number of moving fires. I still think rubble burning in such a manner is unlikely. Although you discount this by giving it a 20% weight. It is hard to tell since it is uncertainties on top of uncertainties.
Your analysis for the number of deaths makes sense. When US designed MAD they wanted enough firepower to assure the destruction of Russia. This was likely done by taking the number of deaths per kiloton and matching their population. Russia has a population of 144 million. Therefore, your 150 million number for US deaths is likely correct because the Russians are now matching the number of US weapons.
I have read everything you have posted so far and your thorough analysis has piqued my morbid curiosity. I feel that I should be playing devil’s advocate.
I think you might be underestimating the number of initial deaths in a nuclear exchange and overestimating the number of deaths from a nuclear winter with your assumptions. You do acknowledge that you assume only one nuclear weapon per city which downplays the importance of MIRVs.
Smaller and more accurate weapons will not reduce the total number of fatalities but kill many more people. Increasing the yield of a weapon by a factor of ten doubles the size of the blast radius. It is more efficient to use many smaller and more accurate warheads with overlapping blast radii to attack a city. Using a death to kilotons calculation based on Hiroshima is likely not a good assumption. More yield means more deaths but with a MIRV smaller yields kill more effectively.
All buildings including above ground reinforced concrete structures are demolished at a 20 psi overpressure. MIRVs are designed to create this overpressure evenly throughout their target areas. By design MIRVs will trap people under rubble. The mechanism that significantly reduces the probability of cities firestorming also kills the people who are trapped. This scenario is ideal for the attacker by maximizing fatalities and minimizing the likelihood of a nuclear winter. The combustible material is buried under rubble where it smolders generating carbon monoxide and asphyxiates the people who are trapped.
In a firestorm the temperature increases by air from the surrounding areas stoking the fire just like in a blast furnace. The hotter the temperature the higher the smoke is lifted into the atmosphere where it is unlikely to rain out. The smoldering fires in a MIRV deprive the fire of oxygen which reduces the risk of firestorming.
In the dark calculus of nuclear war your model shows it may even be ethical to double tap a city with a MIRV that is firestorming. A firefighting MIRV could be over a firestorming city within minutes. The city might burn for several hours before the deleterious climate effects are irreversible. This should give just enough time for nonbelligerent countries to launch in order to protect themselves from a nuclear winter famine. I think this scenario is most likely if India and Pakistan started a nuclear war, annihilated each other, but used only a single warhead per city, generating many firestorms.
If MIRVs are not used then I would reduce your models by at least a factor of two for the amount of smoke generated. Unless your model already accounts for the differences seen in Hiroshima and Nagasaki. Most of the damage and deaths in Hiroshima were due to the firestorm after a single nuclear weapon. Nagasaki did not firestorm due to terrain masking and would not have contributed as much to a nuclear winter.
I believe a counterforce attack will quickly escalate to a countervalue attack. An initial attack would include runways over 7,000 feet long. It is likely that many airports would be targeted to deny nuclear bombers the ability to use them.
A counterforce attack would include groundbursts against missile silos, Cheyenne mountain and Mt Weather. There are many populated areas nearby that will receive lethal levels of fallout from groundbursts on those hard targets. Therefore, I do not see a difference between counterforce and countervalue targets other than counterforce targets being the initial targets of SLBMs.
I think there are ways to reduce these risks assuming we decide to keep nuclear weapons instead of scrapping them altogether. We should prioritize submarines and SLBMs over strategic bombers, hardened ICBM silos, and cold war bunkers. Nuclear submarines are harder to destroy, they operate far away from populated areas, and can quickly hit their targets. This would significantly reduce the number of groundbursts and deaths from fallout. I give nuclear war a 0.1% chance per year since it does not occur once every ten years and likely not once every 100 years. At 1 in 10,000 years we are talking about the entire history of civilization. I put it at 1 in 1000 years because I cannot rule that out and it is still significant enough to look into ways of reducing risk. I see now that I am even more optimistic than the minority report “super predictors” :)
I read their reasoning is that any nuclear weapon will create a firestorm. So the size of the weapon is almost irrelevant. It is true that a smaller weapon created the Hiroshima firestorm. Therefore they argue that even a Pakistan-India conflict would generate enough firestorms and generate enough aerosols to disrupt agriculture and kill billions.
I do not believe modern cities would firestorm as easily as Hiroshima which had mostly wooden structures. Most concrete structures would collapse and smother material inside them extinguishing fires created from the initial flash. To get Tokyo to firestorm a special weapon was created and used under ideal conditions.
https://m.youtube.com/watch?v=uPteVZyF4U0
The Dresden firestorm was also engineered and consisted of two waves of airplanes. The first dropped blockbuster bombs to open up the concrete structures to expose the flammable materials inside. The second wave dropped incendiary bombs to ignite the exposed materials.
However, let’s assume that every nuclear weapon creates a firestorm. Also I will assume the fires cannot be put out due to the fallout dangers after a nuclear attack which suppress firefighting.
I also trust their atmospheric modeling and famine simulations for different levels of soot in the stratosphere which are here:
https://www.nature.com/articles/s43016-022-00573-0
The model focuses on soot, black carbon, which is lifted into the stratosphere with the pyro-cumulonimbus cloud that forms with a firestorm. They argue the black carbon does not rainout but instead absorbs sunlight and is lifted even higher into the stratosphere where it persists for years.
Soot will auto-ignite at the temperatures required to generate firestorms. Above 500C with oxygen present it will turn into carbon dioxide. They also argue that cities have more plastics that generate soot and even that the asphalt will burn. All the plastics are petroleum products which at high enough temperatures and in the presence of oxygen, like in a firestorm will turn into water vapor and carbon dioxide.
I suspect the pyro-cumulonimbus clouds are mostly water vapor and a mixture of other aerosols which are less efficient at absorbing sunlight. There should be enough water vapor that condenses around any black carbon at those altitudes.
A forest fire, like in Australia, that created the pyro-cumulonimbus clouds they reference was created in dry conditions with extremely dry eucalyptus trees. It did not boil lakes, rivers or the standing water left in destroyed urban infrastructure. Cities are relatively wet, fire-sprinklers are everywhere.