It argues Toon 2008 has overestimated the soot ejected into the stratosphere following a nuclear war by something like a factor of 191[1] (= 1.5*2*2*(1 + 2)/2*(2 + 3)/2*(4 + 13)/2).
I think a geometric mean would be more appropriate, so (48*468)^0.5 = 150. But I disagree with a number of the inputs.
They also assume 4,400 warheads from the US and Russia alone, significantly higher than current arsenals.
Current US + Russia arsenals are around 11,000 warheads, but current deployed arsenals are only about 3000. With Putin pulling out of New START, many nuclear weapons that are not currently deployed could become so. Also, in an all-out nuclear war, currently nondeployed nuclear weapons could be used (with some delay). Furthermore, even if only two thirds as many nuclear weapons are used, the amount of soot would not scale down linearly because of hitting higher average combustible loading areas.
I agree that targeting would likely not maximize burned material, and I consider that in my Monte Carlo analysis.
While it is true that most city centers have a higher percentage steel and concrete than Hiroshima, at least in the US, suburbs are still built of wood, and that is the majority of overall building mass. So I don’t think the overall flammability is that much different. There is also been the counteracting factor of much more building area per person, and taller average buildings in cities. Of course steel buildings can still burn, as shown by 9/11.
The linear burn area scaling is a good point. Do you have data for the 400 kT average? I think if you have multiple detonations in the vicinity, then you could have burn area outside the burn area that one would calculate for independent detonations. This could be due to combined thermal radiation from multiple fireballs, but also the thermal radiation from multiple surrounding firestorms so it creates one big firestorm. Also, because assuming a linear burn area means small/less dense cities would be targeted, correcting the linear burn area downward by a factor of 2-3 would not decrease the soot production by a factor of 2-3.
The large area covered by the Australian bushfires and the low amount of soot reaching the stratosphere calls this into question.
There is a fundamental difference between a moving front fire (conflagration) like a bushfire and a firestorm where it all burns at once. If you have a moving front, the plume is relatively narrow, so it gets heavily diluted and does not rise very high (also true for a oil well fire). Whereas if you have a large area burning at once, it gets much less diluted and will likely go into the upper troposphere. Then solar lofting typically takes it to the stratosphere. Nagasaki was a moving front fire, and I do give significant probability mass to moving front fires instead of firestorms in my analysis.
So overall I got a median of about 30 Tg to the stratosphere (Fig. 6) for a full-scale nuclear war, similar to Luísa’s. I could see some small downward adjustment based on the linear burn area assumption, but significantly smaller than Bean’s adjustment for that factor.
Added 20 September: though the blasted area goes with the 2⁄3 exponent of the yield because energy is dissipated in the shock wave, the area above the threshold thermal radiation for starting fires would be linear if the atmosphere were transparent. In reality, there is some atmospheric absorption, but it would be close to linear. So I no longer think there should be a significant downward adjustment from my model.
>Current US + Russia arsenals are around 11,000 warheads, but current deployed arsenals are only about 3000. With Putin pulling out of New START, many nuclear weapons that are not currently deployed could become so.
Possibly the single most important goal of the deployed warheads is to stop the other side from deploying their warheads, both deployed and non-deployed. Holding to deployed only is probably a reasonable assumption given that some of the deployed will not make it, and most of the non-deployed definitely won’t. And this was written a year before Putin pulled out of New START. I have doubts that they’ll be able to actually deploy all that many more without spending a lot of money that they frankly don’t have.
>Do you have data for the 400 kT average? I think if you have multiple detonations in the vicinity, then you could have burn area outside the burn area that one would calculate for independent detonations. This could be due to combined thermal radiation from multiple fireballs, but also the thermal radiation from multiple surrounding firestorms so it creates one big firestorm.
400 kT is basically my guess looking at a list of strategic warheads, and it might well be lower. As for scaling, that’s going to be really complicated, but superlinear scaling seems unlikely.
>While it is true that most city centers have a higher percentage steel and concrete than Hiroshima, at least in the US, suburbs are still built of wood, and that is the majority of overall building mass. So I don’t think the overall flammability is that much different.
Yeah, but it’s clearly more fire-resistant than Japanese buildings in the 40s. They burned really well compared to everywhere else that firebombing was tried. US suburbs may have a lot of building mass in aggregate, but it’s also really spread out and generally doesn’t contain that much which is likely to draw nuclear attack. And a lot of the outside material is reasonably flame-resistant in a way I’m pretty sure Hiroshima wasn’t.
>There is a fundamental difference between a moving front fire (conflagration) like a bushfire and a firestorm where it all burns at once.
Yeah, sorry, I’ve heard enough crying wolf on this (Sagan on Kuwait being the most prominent) that I don’t buy it, at least not until I see good validation of the models in question on real-world events. Which is notably lacking from all of these papers. So I’ll take the best analog, and go from there. Also, note that your cite there is from 1990, when computers were bad and Kuwait hadn’t happened yet. Also note that the doommonger’s best attempt to puzzle stratospheric soot out of atmospheric data from WWII didn’t really show more than a brief gap at most.
US suburbs may have a lot of building mass in aggregate, but it’s also really spread out and generally doesn’t contain that much which is likely to draw nuclear attack.
There are only 55 metropolitan areas in the US with greater than 1 million population. Furthermore, the mostly steel/concrete city centers are generally not very large, so even with a nuclear weapon targeted at the city center, it would burn a significant amount of suburbs. So with 1500 nuclear weapons countervalue even spread across NATO, a lot of the area hit would be suburbs.
Yeah, sorry, I’ve heard enough crying wolf on this (Sagan on Kuwait being the most prominent) that I don’t buy it, at least not until I see good validation of the models in question on real-world events. Which is notably lacking from all of these papers. So I’ll take the best analog, and go from there. Also, note that your cite there is from 1990, when computers were bad and Kuwait hadn’t happened yet.
“As Toon, Turco, et al. (2007) explained, for fires with a diameter exceeding the atmospheric scale height (about 8 km), pyro-convection would directly inject soot into the lower stratosphere.” Another way of getting at this is looking at the maximum height of buoyant plumes. It scales with the thermal power raised to the one quarter exponent. The Kuwait oil fires were between 90 MW and 2 GW. Whereas firestorms could be ~three orders of magnitude more powerful than the biggest Kuwait oil fire. So that implies much higher lofting. Furthermore, volcanoes are very high thermal power, and they regularly reach the stratosphere directly.
Also note that the doommonger’s best attempt to puzzle stratospheric soot out of atmospheric data from WWII didn’t really show more than a brief gap at most.
I don’t see this as a significant update, because the expected signal was small compared to the noise.
Furthermore, the mostly steel/concrete city centers are generally not very large, so even with a nuclear weapon targeted at the city center, it would burn a significant amount of suburbs. So with 1500 nuclear weapons countervalue even spread across NATO, a lot of the area hit would be suburbs.
First, remind me why we’re looking at 1500 countervalue weapons? Do we really expect them to just ignore the ICBM silos? Second, note that there’s a difference between “a lot of the area hit would be suburbs” and “a lot of the suburbs would be hit”. The US has a vast amount of suburbs, and the areas damaged by nuclear weapons would be surprisingly small.
“As Toon, Turco, et al. (2007) explained,
Let me repeat. I am not interested in anything Turco, Toon et al have to say. They butchered the stuff I can check badly. As such, I do not think it is good reasoning to believe them on the stuff I can’t. The errors outlined in the OP are not the sort of thing you can make in good faith. They are the sort of thing you’d do if you were trying to keep your soot number up in the face of falling arsenals.
Re firestorms more broadly, I don’t see any reason to assume those would routinely form. It’s been a while since I looked into this, but those are harder to generate than you might think when that’s the goal, and I don’t think it’s likely to be a goal of any modern targeting plan. The only sophisticated model I’ve seen is the one by the Los Alamos team, which got about 70% of the soot production that Robock et al did, and only 12% of that reached the stratosphere. That’s where my money is.
First, remind me why we’re looking at 1500 countervalue weapons? Do we really expect them to just ignore the ICBM silos?
My understanding is that the warning systems are generally designed such that the ICBMs could launch before the attacking warheads reach the silos. I do have significant probability on counterforce scenarios, but I can’t rule out counter value scenarios, so I think it’s an important question to estimate what would happen in these counter value scenarios.
Possibly the single most important goal of the deployed warheads is to stop the other side from deploying their warheads, both deployed and non-deployed. Holding to deployed only is probably a reasonable assumption given that some of the deployed will not make it, and most of the non-deployed definitely won’t.
I would think the non-deployed warheads could just be stored deep underground so they would nearly all survive.
Second, note that there’s a difference between “a lot of the area hit would be suburbs” and “a lot of the suburbs would be hit”. The US has a vast amount of suburbs, and the areas damaged by nuclear weapons would be surprisingly small.
Other people have probably done more rigorous analyses now, but my rough estimate in 2015 was that 1500 nukes to the US would destroy nearly all the suburb area of 100,000+ population metro areas. If they were spread over NATO, of course it would be a lower percentage, but I would estimate still the majority of wood in suburbs would be hit.
Let me repeat. I am not interested in anything Turco, Toon et al have to say. They butchered the stuff I can check badly. As such, I do not think it is good reasoning to believe them on the stuff I can’t. The errors outlined in the OP are not the sort of thing you can make in good faith. They are the sort of thing you’d do if you were trying to keep your soot number up in the face of falling arsenals.
I think we should try to evaluate this argument on its merits. If there is a fire 8 km wide, I would argue that it is intuitive that it could rise ~16 km to the stratosphere. It turns out it’s a little more complicated than this, because it depends on the potential temperature. The potential temperature is the temperature of a parcel of air would have to be at sea level in order to become neutrally buoyant at the particular altitude. A typical value for the potential temperature at the tropopause is about 100°C. Because combustion temperatures are more like 1000°C, if you don’t have dilution, it would rise high in the stratosphere. And if the fire is very wide, there is not that much dilution. In reality, there is significant dilution, but another fire model generally found the smoke going to the upper troposphere (the Lawrence Livermore National Lab study).
Re firestorms more broadly, I don’t see any reason to assume those would routinely form.
Some argue that Hiroshima was exceptional that it did firestorm, and some argue that Nagasaki was exceptional that it did not, but I just went with around 50⁄50 for my model.
It’s been a while since I looked into this, but those are harder to generate than you might think when that’s the goal, and I don’t think it’s likely to be a goal of any modern targeting plan. The only sophisticated model I’ve seen is the one by the Los Alamos team, which got about 70% of the soot production that Robock et al did, and only 12% of that reached the stratosphere.
As noted above, the Livermore model does generally support Robock’s estimates of lofting of particles. However, the Livermore model did have a shorter particle lifetime in the stratosphere (~4 years vs 8-15 for Robock), partly because the Livermore particles were not mostly soot (black carbon). So I think this is a potentially important possibility. However, inclusion of the non-soot smoke may actually make the sunlight reduction greater than Robock’s estimate (for the same amount burned).
My understanding is that the warning systems are generally designed such that the ICBMs could launch before the attacking warheads reach the silos. I do have significant probability on counterforce scenarios, but I can’t rule out counter value scenarios, so I think it’s an important question to estimate what would happen in these counter value scenarios.
Even leaving aside the ICBMs, “countervalue” was one of McNamara’s weird theories, and definitely wouldn’t be implemented as a pure thing. If nothing else, a lot of those warheads are going after military targets, not cities.
Other people have probably done more rigorous analyses now, but my rough estimate in 2015 was that 1500 nukes to the US would destroy nearly all the suburb area of 100,000+ population metro areas.
Maybe if they were targeted specifically with that goal in mind, but again, that seems unlikely, particularly with modern guidance systems. You’ll do better for yourself shooting at specific things rather than asking “how many civilians can we kill”? A lot of those will be far away from cities, or will have overlap with something else nearby that is reasonably hard and also needs to die.
In reality, there is significant dilution, but another fire model generally found the smoke going to the upper troposphere (the Lawrence Livermore National Lab study).
I might be misreading it, but that paper seems to bury a lot of the same assumptions that I’m objecting to. They assume a firestorm will form as part of the basis of how the fire is modeled, and then explicitly take the 5 Tg of stratospheric soot per 100 fires number and use that as the basis for further modeling. For other fuel loadings, the amount of soot in the stratosphere is linear with fuel loading, which is really hard to take seriously in the face of the “wildfires are different” assertion. Sure, they accurately note that there are a lot of assumptions in the usual Turco/Toon/Robock model and talk a good game about trying to deal with all four parts of the problem, then go and smuggle in the same assumptions. Points for halving the smoke duration, I guess.
Edit:
I would think the non-deployed warheads could just be stored deep underground so they would nearly all survive.
Deep bunkers like that are expensive and rare, and even if the bunker itself survived, ground bursts are messy and would likely leave it inaccessible. Also, there’s the problem of delivering the warheads to the target in an environment where a lot of infrastructure is gone. Missile warheads are only of use as a source of raw materials, and while you might be able to get gravity bombs to bombers, you wouldn’t get many, and probably couldn’t fly all that many sorties anyway. It’s a rounding error, and I’m probably being generous in using that to cancel out the loss of deployed warheads. (Why do we keep them, then, you ask? Good question. Some of it is in case we need to up deployed warheads quickly. A lot is that various politicians don’t want to be seen as soft on defense.)
Deep bunkers like that are expensive and rare, and even if the bunker itself survived, ground bursts are messy and would likely leave it inaccessible.
There are thousands of underground mines in the US (14000 active mines, but many are surface mines), and I think it would only require 1 or a few to store thousands of nuclear weapons. Maybe the weapons would be spread out over many mines. It would not be feasible to make thousands of mines inaccessible.
Missile warheads are only of use as a source of raw materials, and while you might be able to get gravity bombs to bombers, you wouldn’t get many, and probably couldn’t fly all that many sorties anyway.
Are you saying that missile warheads could not be quickly configured to be used as a gravity bomb? I’m not claiming that most of the non-deployed nuclear weapons could be used in a few days, but I would think it would be feasible in a few months (it would only take a few surviving bombers if the warheads could be used as gravity bombs).
OK, remember that we’re dealing with nuclear weapons, which inspire governments to levels of paranoia you maybe see when dealing with crypto. Dropping a dozen nukes down a mine somewhere is not going to happen without a lot of paperwork and armed guards and a bunch of security systems. And those costs don’t really scale with number of warheads. Sure, if you were trying to disperse the stockpile during a period of rising tension, you could take a few infantry companies and say “hang the paperwork”. But that requires thinking about the weapons in a very different way from how they actually do, and frankly they wouldn’t be all that useful even if you did do that, because of the other problems with this plan.
Are you saying that missile warheads could not be quickly configured to be used as a gravity bomb?
Yes, I am. The first commandment of nuclear weapons design since 1960 or so has been “it must not go off by accident”. So a modern missile warhead has an accelerometer which will not arm it unless it is pretty sure it has been fired by the relevant type of missile. And trying to bypass it is probably a no-go. The design standard is that one of the national labs couldn’t set a US warhead off without the codes, so I doubt you can easily bypass that.
it would only take a few surviving bombers if the warheads could be used as gravity bombs
A modern bomber is a very complex machine, and the US hasn’t set ours up to keep working out of what could survive a nuclear exchange. (This is possible, but would require mobile servicing facilities and drills, which we do not have.) Not to mention that they can’t make a round-trip unrefueled from CONUS to any plausible enemy, and the odds of having forward tankers left are slim to none.
I might be misreading it, but that paper seems to bury a lot of the same assumptions that I’m objecting to. They assume a firestorm will form as part of the basis of how the fire is modeled, and then explicitly take the 5 Tg of stratospheric soot per 100 fires number and use that as the basis for further modeling.
For reference, here is what they say about their fire modelling:
The goal of the fire simulations in this work is to better characterize the spatial and temporal distribution of smoke from a mass urban fire resulting from a 15 kt nuclear detonation. Therefore, our modeling is informed by the Hiroshima firestorm, and the Hamburg firestorm, due to its rough similarity to the Hiroshima firestorm in size and duration. The assumption that all 100 detonations cause fires, and that these fires are more like the Hiroshima firestorm than Nagasaki, is a worst-case scenario. The studies of Penner et al. (1986) and Toon et al. (2007) also use fire parameters based on these historical cases (Hiroshima and Hamburg), so our fire parameters have the additional benefit of being similar to these previous studies. To produce simulations of fires similar to Hiroshima and Hamburg, it is assumed that the terrain is flat (i.e., topography does not provide shielding of thermal radiation) and there is uniform fuel loading over the area where thermal radiation is sufficient to ignite standard construction materials, such as wood. The WRF model source code is modified to allow for specification of surface fluxes of heat, water vapor and smoke (or black carbon), requiring quantification of these three fluxes, as well as the fire shape, size and duration.
The Hiroshima firestorm burned an area of about 11 to 13 km2 in 4 to 9 h, taking 20 to 30 min to develop into a firestorm (Glasstone, 1962; Rodden et al., 1965). The Hamburg firestorm burned a comparable 12 km2 in about 6 h (Carrier et al., 1985). Therefore, we specify a circular area with a 2 km radius (12.57 km2) for our fires. Each fire has a 30 min ramp-up period as surface fluxes increase linearly from zero, followed by a 4 h fire duration where surface fluxes are constant. The 4 h duration is chosen because it is the shortest time estimate for the fire in Hiroshima, and releasing a given mass of emissions and burning a given fuel amount over the shorter time period will result in higher smoke concentrations and heat fluxes, thus providing a worst-case estimate.
I very much agree that a larger area burning all at once will loft soot higher on expectation than a thinner moving flame front, because the hot gasses at the center of the burning mass essentially have nowhere to diffuse but up. That specific argument isn’t really a matter of crying wolf, it was just very silly for people to claim that oil well fires could have such big effects in the first place.
That said, this it doesn’t really matter in terms of the estimates here because the soot loft estimate is based on the Los Alamos model, which is also where I’d place my bet for accuracy. Also, the initial Los Alamos model was based on Atlanta’s suburbs which means their outputs are highly relevant for burning in U.S. cities, and cover some of Dave’s objections as well.
I think a geometric mean would be more appropriate, so (48*468)^0.5 = 150. But I disagree with a number of the inputs.
Current US + Russia arsenals are around 11,000 warheads, but current deployed arsenals are only about 3000. With Putin pulling out of New START, many nuclear weapons that are not currently deployed could become so. Also, in an all-out nuclear war, currently nondeployed nuclear weapons could be used (with some delay). Furthermore, even if only two thirds as many nuclear weapons are used, the amount of soot would not scale down linearly because of hitting higher average combustible loading areas.
I agree that targeting would likely not maximize burned material, and I consider that in my Monte Carlo analysis.
While it is true that most city centers have a higher percentage steel and concrete than Hiroshima, at least in the US, suburbs are still built of wood, and that is the majority of overall building mass. So I don’t think the overall flammability is that much different. There is also been the counteracting factor of much more building area per person, and taller average buildings in cities. Of course steel buildings can still burn, as shown by 9/11.
The linear burn area scaling is a good point. Do you have data for the 400 kT average? I think if you have multiple detonations in the vicinity, then you could have burn area outside the burn area that one would calculate for independent detonations. This could be due to combined thermal radiation from multiple fireballs, but also the thermal radiation from multiple surrounding firestorms so it creates one big firestorm. Also, because assuming a linear burn area means small/less dense cities would be targeted, correcting the linear burn area downward by a factor of 2-3 would not decrease the soot production by a factor of 2-3.
There is a fundamental difference between a moving front fire (conflagration) like a bushfire and a firestorm where it all burns at once. If you have a moving front, the plume is relatively narrow, so it gets heavily diluted and does not rise very high (also true for a oil well fire). Whereas if you have a large area burning at once, it gets much less diluted and will likely go into the upper troposphere. Then solar lofting typically takes it to the stratosphere. Nagasaki was a moving front fire, and I do give significant probability mass to moving front fires instead of firestorms in my analysis.
So overall I got a median of about 30 Tg to the stratosphere (Fig. 6) for a full-scale nuclear war, similar to Luísa’s. I could see some small downward adjustment based on the linear burn area assumption, but significantly smaller than Bean’s adjustment for that factor.
Added 20 September: though the blasted area goes with the 2⁄3 exponent of the yield because energy is dissipated in the shock wave, the area above the threshold thermal radiation for starting fires would be linear if the atmosphere were transparent. In reality, there is some atmospheric absorption, but it would be close to linear. So I no longer think there should be a significant downward adjustment from my model.
>Current US + Russia arsenals are around 11,000 warheads, but current deployed arsenals are only about 3000. With Putin pulling out of New START, many nuclear weapons that are not currently deployed could become so.
Possibly the single most important goal of the deployed warheads is to stop the other side from deploying their warheads, both deployed and non-deployed. Holding to deployed only is probably a reasonable assumption given that some of the deployed will not make it, and most of the non-deployed definitely won’t. And this was written a year before Putin pulled out of New START. I have doubts that they’ll be able to actually deploy all that many more without spending a lot of money that they frankly don’t have.
>Do you have data for the 400 kT average? I think if you have multiple detonations in the vicinity, then you could have burn area outside the burn area that one would calculate for independent detonations. This could be due to combined thermal radiation from multiple fireballs, but also the thermal radiation from multiple surrounding firestorms so it creates one big firestorm.
400 kT is basically my guess looking at a list of strategic warheads, and it might well be lower. As for scaling, that’s going to be really complicated, but superlinear scaling seems unlikely.
>While it is true that most city centers have a higher percentage steel and concrete than Hiroshima, at least in the US, suburbs are still built of wood, and that is the majority of overall building mass. So I don’t think the overall flammability is that much different.
Yeah, but it’s clearly more fire-resistant than Japanese buildings in the 40s. They burned really well compared to everywhere else that firebombing was tried. US suburbs may have a lot of building mass in aggregate, but it’s also really spread out and generally doesn’t contain that much which is likely to draw nuclear attack. And a lot of the outside material is reasonably flame-resistant in a way I’m pretty sure Hiroshima wasn’t.
>There is a fundamental difference between a moving front fire (conflagration) like a bushfire and a firestorm where it all burns at once.
Yeah, sorry, I’ve heard enough crying wolf on this (Sagan on Kuwait being the most prominent) that I don’t buy it, at least not until I see good validation of the models in question on real-world events. Which is notably lacking from all of these papers. So I’ll take the best analog, and go from there. Also, note that your cite there is from 1990, when computers were bad and Kuwait hadn’t happened yet. Also note that the doommonger’s best attempt to puzzle stratospheric soot out of atmospheric data from WWII didn’t really show more than a brief gap at most.
There are only 55 metropolitan areas in the US with greater than 1 million population. Furthermore, the mostly steel/concrete city centers are generally not very large, so even with a nuclear weapon targeted at the city center, it would burn a significant amount of suburbs. So with 1500 nuclear weapons countervalue even spread across NATO, a lot of the area hit would be suburbs.
“As Toon, Turco, et al. (2007) explained, for fires with a diameter exceeding the atmospheric scale height (about 8 km), pyro-convection would directly inject soot into the lower stratosphere.” Another way of getting at this is looking at the maximum height of buoyant plumes. It scales with the thermal power raised to the one quarter exponent. The Kuwait oil fires were between 90 MW and 2 GW. Whereas firestorms could be ~three orders of magnitude more powerful than the biggest Kuwait oil fire. So that implies much higher lofting. Furthermore, volcanoes are very high thermal power, and they regularly reach the stratosphere directly.
I don’t see this as a significant update, because the expected signal was small compared to the noise.
First, remind me why we’re looking at 1500 countervalue weapons? Do we really expect them to just ignore the ICBM silos? Second, note that there’s a difference between “a lot of the area hit would be suburbs” and “a lot of the suburbs would be hit”. The US has a vast amount of suburbs, and the areas damaged by nuclear weapons would be surprisingly small.
Let me repeat. I am not interested in anything Turco, Toon et al have to say. They butchered the stuff I can check badly. As such, I do not think it is good reasoning to believe them on the stuff I can’t. The errors outlined in the OP are not the sort of thing you can make in good faith. They are the sort of thing you’d do if you were trying to keep your soot number up in the face of falling arsenals.
Re firestorms more broadly, I don’t see any reason to assume those would routinely form. It’s been a while since I looked into this, but those are harder to generate than you might think when that’s the goal, and I don’t think it’s likely to be a goal of any modern targeting plan. The only sophisticated model I’ve seen is the one by the Los Alamos team, which got about 70% of the soot production that Robock et al did, and only 12% of that reached the stratosphere. That’s where my money is.
My understanding is that the warning systems are generally designed such that the ICBMs could launch before the attacking warheads reach the silos. I do have significant probability on counterforce scenarios, but I can’t rule out counter value scenarios, so I think it’s an important question to estimate what would happen in these counter value scenarios.
I would think the non-deployed warheads could just be stored deep underground so they would nearly all survive.
Other people have probably done more rigorous analyses now, but my rough estimate in 2015 was that 1500 nukes to the US would destroy nearly all the suburb area of 100,000+ population metro areas. If they were spread over NATO, of course it would be a lower percentage, but I would estimate still the majority of wood in suburbs would be hit.
I think we should try to evaluate this argument on its merits. If there is a fire 8 km wide, I would argue that it is intuitive that it could rise ~16 km to the stratosphere. It turns out it’s a little more complicated than this, because it depends on the potential temperature. The potential temperature is the temperature of a parcel of air would have to be at sea level in order to become neutrally buoyant at the particular altitude. A typical value for the potential temperature at the tropopause is about 100°C. Because combustion temperatures are more like 1000°C, if you don’t have dilution, it would rise high in the stratosphere. And if the fire is very wide, there is not that much dilution. In reality, there is significant dilution, but another fire model generally found the smoke going to the upper troposphere (the Lawrence Livermore National Lab study).
Some argue that Hiroshima was exceptional that it did firestorm, and some argue that Nagasaki was exceptional that it did not, but I just went with around 50⁄50 for my model.
As noted above, the Livermore model does generally support Robock’s estimates of lofting of particles. However, the Livermore model did have a shorter particle lifetime in the stratosphere (~4 years vs 8-15 for Robock), partly because the Livermore particles were not mostly soot (black carbon). So I think this is a potentially important possibility. However, inclusion of the non-soot smoke may actually make the sunlight reduction greater than Robock’s estimate (for the same amount burned).
Even leaving aside the ICBMs, “countervalue” was one of McNamara’s weird theories, and definitely wouldn’t be implemented as a pure thing. If nothing else, a lot of those warheads are going after military targets, not cities.
Maybe if they were targeted specifically with that goal in mind, but again, that seems unlikely, particularly with modern guidance systems. You’ll do better for yourself shooting at specific things rather than asking “how many civilians can we kill”? A lot of those will be far away from cities, or will have overlap with something else nearby that is reasonably hard and also needs to die.
I might be misreading it, but that paper seems to bury a lot of the same assumptions that I’m objecting to. They assume a firestorm will form as part of the basis of how the fire is modeled, and then explicitly take the 5 Tg of stratospheric soot per 100 fires number and use that as the basis for further modeling. For other fuel loadings, the amount of soot in the stratosphere is linear with fuel loading, which is really hard to take seriously in the face of the “wildfires are different” assertion. Sure, they accurately note that there are a lot of assumptions in the usual Turco/Toon/Robock model and talk a good game about trying to deal with all four parts of the problem, then go and smuggle in the same assumptions. Points for halving the smoke duration, I guess.
Edit:
Deep bunkers like that are expensive and rare, and even if the bunker itself survived, ground bursts are messy and would likely leave it inaccessible. Also, there’s the problem of delivering the warheads to the target in an environment where a lot of infrastructure is gone. Missile warheads are only of use as a source of raw materials, and while you might be able to get gravity bombs to bombers, you wouldn’t get many, and probably couldn’t fly all that many sorties anyway. It’s a rounding error, and I’m probably being generous in using that to cancel out the loss of deployed warheads. (Why do we keep them, then, you ask? Good question. Some of it is in case we need to up deployed warheads quickly. A lot is that various politicians don’t want to be seen as soft on defense.)
There are thousands of underground mines in the US (14000 active mines, but many are surface mines), and I think it would only require 1 or a few to store thousands of nuclear weapons. Maybe the weapons would be spread out over many mines. It would not be feasible to make thousands of mines inaccessible.
Are you saying that missile warheads could not be quickly configured to be used as a gravity bomb? I’m not claiming that most of the non-deployed nuclear weapons could be used in a few days, but I would think it would be feasible in a few months (it would only take a few surviving bombers if the warheads could be used as gravity bombs).
OK, remember that we’re dealing with nuclear weapons, which inspire governments to levels of paranoia you maybe see when dealing with crypto. Dropping a dozen nukes down a mine somewhere is not going to happen without a lot of paperwork and armed guards and a bunch of security systems. And those costs don’t really scale with number of warheads. Sure, if you were trying to disperse the stockpile during a period of rising tension, you could take a few infantry companies and say “hang the paperwork”. But that requires thinking about the weapons in a very different way from how they actually do, and frankly they wouldn’t be all that useful even if you did do that, because of the other problems with this plan.
Yes, I am. The first commandment of nuclear weapons design since 1960 or so has been “it must not go off by accident”. So a modern missile warhead has an accelerometer which will not arm it unless it is pretty sure it has been fired by the relevant type of missile. And trying to bypass it is probably a no-go. The design standard is that one of the national labs couldn’t set a US warhead off without the codes, so I doubt you can easily bypass that.
A modern bomber is a very complex machine, and the US hasn’t set ours up to keep working out of what could survive a nuclear exchange. (This is possible, but would require mobile servicing facilities and drills, which we do not have.) Not to mention that they can’t make a round-trip unrefueled from CONUS to any plausible enemy, and the odds of having forward tankers left are slim to none.
Thanks for the engagement, David and Bean!
For reference, here is what they say about their fire modelling:
I very much agree that a larger area burning all at once will loft soot higher on expectation than a thinner moving flame front, because the hot gasses at the center of the burning mass essentially have nowhere to diffuse but up. That specific argument isn’t really a matter of crying wolf, it was just very silly for people to claim that oil well fires could have such big effects in the first place.
That said, this it doesn’t really matter in terms of the estimates here because the soot loft estimate is based on the Los Alamos model, which is also where I’d place my bet for accuracy. Also, the initial Los Alamos model was based on Atlanta’s suburbs which means their outputs are highly relevant for burning in U.S. cities, and cover some of Dave’s objections as well.