Nuclear Winter Projection Probably Flawed, But Valuable Prepper Lessons Still Present

An interesting new study predicts that a limited nuclear exchange between warring powers would result in a ‘nuclear winter’ scenario.

The study says this would create global famine, cooling, drought and massive increases in UV radiation (due to damage to the ozone layer), lasting some 20 years, and with between hundreds of millions and billions of people dying (the total population on the planet is about 7 billion).

The full study is available here, and there’s a more easily read paraphrase/summary of it here.

This scenario is based on a hypothetical possible war between India and Pakistan, and assumes each side fires 50 nuclear warheads at the other side (ie 100 total), and each of a moderate 15 kiloton yield.

On the face of it, this sounds apocalyptic.  On the other hand, we have major concerns about the underlying assumptions of this computer model, and our email to the study’s authors requesting clarification, which they quickly opened and read, has gone unanswered.  Just like the old computer adage ‘GIGO’ (Garbage In, Garbage Out), if the model’s assumptions are wrong, then its conclusions are also flawed.

It is interesting to look at the study and see where the assumptions may be invalid, and also to draw some lessons for preppers from its projections, whether valid or not.  Although we don’t believe a ‘limited’ 100 warhead exchange would have the apocalyptic results forecast, other events might bring about these effects and so it is helpful to understand what to expect and prepare for in such a case.

The study is based on what would happen if 5 Tg (Teragrams, the same as 5 million metric tons) of ‘black carbon‘ (a fancy way of saying smoke soot) was released into the atmosphere, and suggests this is a likely result from the detonation of 100 15 kiloton nuclear bombs.

We can’t comment on the validity of the model’s projections for the impact of 5 Tg of BC into the atmosphere, and will assume that the model is correct about this – although note that most climatological models are somewhat controversial as the ongoing debate over global warming indicates.  But we do have concerns about the suggestion that 100 typical nuclear explosions, such as might occur in a limited nuclear exchange between warring powers, would have this effect.  Let’s have a look at what we see to be flaws in the model’s underlying assumptions.

The Problems With This Study’s Underlying Assumptions

The first reason for doubting this is that in total 100 15 kiloton explosions would seem to total to about the same as a single 1.5 megaton explosion (there are reasons for and against suggesting that 100 15 kiloton explosions create either more or less effect than one single 1.5 megaton explosion).  Let’s put that in context, to appreciate how ‘trivial’ (on a global scale!) that actually is.

During the days of above ground nuclear testing by both Russia and the US, nuclear explosions of much greater than 1.5 megatons in magnitude were regularly detonated, with the largest ever nuclear explosion, the Russian Tsar Bomba, being estimated at between 50 – 58 megatons in destructive power.  Yes, this one single explosion was almost 40 times greater than the amount this study says would be sufficient to create a 20 year ‘nuclear winter’, but created almost no measurable impact on local, regional, or global climate at all.

So clearly there is more to consider than just the size of the explosions.  There are several other factors built-in to the study assumptions which the authors have not clarified.  Some are described in some of the supporting studies they are relying upon, others are not clear to us and regrettably the authors have chosen not to reply to our queries.

The first thing to appreciate is there is a huge difference between an air burst and a ground burst nuclear explosion.  A ground burst throws up a lot more material into the atmosphere than an airburst.  Most nuclear weapons are designed to be detonated as air burst rather than ground burst devices, because an air burst has a greater blast effect, destroying more buildings for a greater distance than a ground burst.

Ground bursts are only used to destroy ‘hardened’ targets such as missile silos.

We don’t know what the model assumes about air vs ground bursts.

There are two assumptions that are detailed, however.  The first is that all explosions occur over built up areas, meaning there is a lot of combustible material (ie buildings) within the blast radius, making for much larger fires and smoke and black carbon release.

The second assumption is that none of the explosions overlap with the locations of any of the other explosions, meaning that each explosion is assumed to have a complete fresh supply of material to destroy and set fire to.

In other words, these two assumptions create a maximum ‘worst case’ scenario to build upon.

How likely are these two assumptions?  We rate them as unlikely rather than likely.  Nuclear targets tend to first be military installations, secondarily industrial, and only as a very distant lowest priority do we see population concentrations targeted.  Of course, often the industrial and sometimes even the military targets overlap with population clusters, but equally, many times they do not.  Strategic military bases are not in the centers of large cities, they are in outlying areas, and tend to be sprawling over hundreds of acres with a low concentration of buildings and little combustible material.

Furthermore, it is standard military doctrine to have multiple warheads targeting each priority target so as to ensure that if one of the warheads is intercepted, or fails, or goes off target, the backup warheads will still destroy the target.  Alternatively, if attacking a large population concentration, it is still likely that multiple warheads would be set to have overlapping regions of destruction rather than being evenly spaced out such as happens when you use a cookie cutter to cut cookies out of a sheet of dough.  The problem with the cookie cutter model is that it leaves parts of the city unharmed entirely, and other parts with only moderate degrees of harm.  When designing an attack to create maximum harm, it is more common to have overlapping explosions.

Seven Possible Problems with the Study’s Assumptions

So, we see at least seven problems with the study’s underlying assumptions :

1.  No nuclear tests, including some up to 40 times the magnitude of this complete 100 warhead scenario, have resulted in any significant climate change at all.

2.  We suspect the model assumes the ‘worst case scenario’ for air vs ground bursts, a scenario which is unlikely to be reflected by actual ‘best practice’ military doctrine.

3.  We do not believe that all of the 100 explosions would be over high density population centers.  Many – maybe even most – would be over lower density militarily or industrially significant areas with much lower BC release as a result.

4.  We do not agree with the model assumption that there would be no overlap in blast effects and that each and every one of the 100 explosions would occur over high density buildings that had not yet been partially or even completely destroyed by preceding blasts.

5.  There might also be some significance in the study’s choice of India and Pakistan as a location.  These two countries are closer to the equator than most other potential future nuclear battlegrounds, meaning that there will likely be more efficient and rapid transportation of the BC from the northern hemisphere to the southern hemisphere than if the nuclear explosions occurred further away from the equator.  In other words, this is another aspect of the study that might overstate the global implications of a nuclear exchange.

6.  If we are to accept the opinion that current industrial activity is causing global warming and adverse climate effects (and we’re not saying we do!), the depressed effect on the global levels of industrial activity caused by the predicted enormous famine and associated probable social and economic collapse will result in the reduction of other manmade carbon emissions and may therefore provide some counter-balancing relief from the effects of the BC release and accelerate the earth’s recovery.  There is no sign of this being factored into the study model.

7.  It appears their model assumed that all the BC was shot up into the atmosphere in a concentrated area of either 50 or 100 nautical miles in radius.  This is unlikely to be the case – India in particular is an enormous country with many different potential targets for nuclear attack, meaning a more realistic model should have a series of much more diffuse and smaller BC sources.  We also suspect that the model anticipates all 100 explosions occurring more or less simultaneously, whereas in reality, there is likely to be some spread of time during which they occur – possibly only minutes, maybe hours or days.  We don’t know what impacts this would have on the model, but we guess it may slightly soften the outcomes.

Is 5 Million Tons of Black Carbon a Lot?

One more thing.  The study is talking about the release of 5 Tg of black carbon, or 5 million tonnes.  How does that compare to current annual black carbon emissions?

We did some research and found wildly varying figures – for example, on this page almost next to each other are two contradictory claims, one suggesting about 7.5 million tonnes a year are released from all sources at present, and the other claim saying that forest fires alone release between 40 – 250 million tonnes a year.

According to this page, forest fires represent about 40% of total black carbon emissions, so if forest fires contribute 40 – 250 million tons a year, that would suggest in total between 100 and 625 million tonnes are released each year.

The significant part of the 5 million ton release from the nuclear war is that most of it is propelled up very high into the atmosphere and stays there for some time, whereas much of the ‘normal’ black carbon doesn’t go so high and more quickly falls back to earth.

But, at the same time, we have to note that if total black carbon emissions each year are as much as 100 times more than the amount released by this hypothetical nuclear war, is 5 million tons actually a significant amount to consider?  The study also does not put this size release into any sort of contextual perspective.

Prepper Implications of the Study’s Projected Outcomes

So, we think we can confidently state that this hypothetical 100 nuclear bomb scenario is unlikely to release 5 Tg of black carbon, and therefore, a nuclear winter scenario is unlikely from this.

But, maybe a larger scale conflict between major nuclear powers could indeed cause the 5 Tg release, and even a more limited black carbon release will still cause some modification to the global climate.  We also asked the study authors if the effects were linearly proportional – ie a 2.5 Tg release having half the impact of their modelled 5 Tg release, but, yet again, they didn’t reply.

So, while we are dismissive of the study’s basis and assumptions, there are still some valid lessons to be learned for preppers if we simply ask ourselves ‘what if some type of event caused a massive climate change?’.

1.  We often think about the impacts of a nuclear exchange as being one that is an attack on American soil.  It is easy to understand how nuclear explosions close to us would have some direct effects, but harder to realize that nuclear weapons going off on the other side of the world can still impact on us here.  Clearly, the risk is more global than we might first think.  A war between two far away countries can still upset the climate, globally.  From this perspective, the studied model provides more cause for concern than relief, and should encourage us to realize why it is such a bad thing, for, eg, Iran to be allowed to continue down its steady path to becoming a nuclear power.

2.  A probable outcome will be less solar energy for our solar cells.  Although UV levels will rise, these are not efficiently used by solar cells (which are most sensitive to red light, ie the part of white light that is red).  So we should allow for this loss of solar energy and increase our solar arrays accordingly.

3.  The cooling effect and shortened growing season means that we should consider locations that currently have sufficient growing season as to still remain productive with a 10 – 40 day reduction in season length.

4.  Substantial increases in UV radiation levels mean preference should be given to growing UV-resistant crops.

5.  While temperature changes don’t directly threaten our society or its industrial base, the loss of food production does and will threaten much/most of society, particularly when famine starts to cause the death of substantial percentages of the population.  In addition to slower acting famine, there is reason to fear that as the black carbon falls from the sky, there will be a fast and massive rise in respiratory diseases and deaths.

6.  The effects of famine will likely be of greatest impact in third world countries.  Hopefully, in the US, urgent attempts at creating hothouses, hydroponics, and other ‘high tech’ solutions, and simply changing our food habits to waste less and eat less, and buying in more food from other countries (assuming it is still for sale) will cushion the impacts on US society.  If we reduced our food intact to a more appropriate level and if we cut down on waste, we’d instantly halve our food requirements, and if we shifted our food production to most effective yielding crops, we’d probably bring about a doubling in net food production.

7.  It seems we should plan for less rain and – in areas currently short of water – more drought.  Ensure your location has sufficient water access, even in adverse conditions that – worst case scenario – may see rivers dwindle in size and creeks dry up entirely.  Rainwater collection systems will become less effective, and underground water table levels will drop due to reduced rates of replenishment (and possibly accelerated rates of offtake due to increased reliance on wells).

8.  This scenario shows an immediate impact on crop production (depending of course on what time of year the nuclear exchange occurs) and lasting effects extending 25 years or more.  On the other hand, if there are massive population losses in the first few years, it might be possible that the smaller sized population could more quickly balance the reduced agricultural capabilities and allow for a faster return to an industrialized self-sustaining society.

9.  The model shows that global temperatures drop over a five-year period.  This means that maybe the result is less a sudden apocalyptic transition and more a gradual deterioration in weather.

10.  The  climate change effects seem generally more extreme, the further away from the equator you go, and less extreme closer to the equator.  Perhaps this argues in favor of establishing a retreat in a southern rather than northern part of the US.

11.  Damage to crop DNA from increased UV levels will be passed from generation to generation, probably getting worse each time.  It is prudent to have sufficient stocks of seed to enable you to used undamaged seed to restart your crops several times during the period of increased UV.

12.  Air-borne fine particulate black carbon is harmful to health.  It will be beneficial to have filtration systems in your retreats to filter out the particulate matter before air is circulated within the retreat.  HEPA type filters will address this need, and if you get washable ones, that will extend their life (which will probably be much shorter than anticipated due to the much greater concentration of black carbon in the air).  If you’re going outside, you might want to use a respirator to give you protection while outdoors too.

13.  Although also impacted, the southern hemisphere seems to not be as severely affected as the northern hemisphere.  Because this type of climate based calamity would take some days/weeks/months/years to fully develop, it would give you time to fly to your choice of southern locations and set up your retreat there.

Summary

Although this study suggests an apocalyptic outcome of a relatively minor nuclear war, we disagree.  We think that the study may possibly overstate the direct results of a 100 warhead nuclear exchange, and we further feel that the western world – and in particular the United States – may be able to adapt its food sourcing and consumption fast enough to minimize the widespread famine and death projected in the study.

On the other hand, the increase in harmful particulate matter in the air is something that you do need to be able to respond to.

Depending on the importance you attach to this type of sudden climate change risk, you may want to factor it in to your choice of retreat location (ie issues such as water sufficiency, growing season length, and perhaps more generally, closer to the south than the north of the country).