# How many “years without a summer” can society survive?

In 1815 Mount Tambora erupted throwing so much dust into the atmosphere that the year became known as "the year without a summer". *There were a few other mitigating factors but Tambora is thought to be the main culprit.

From Wikipedia

"This climate anomaly has been blamed for the severity of typhus epidemics in southeast Europe and the eastern Mediterranean between 1816 and 1819.The climate changes disrupted the Indian monsoons, caused three failed harvests and famine contributing to the spread of a new strain of cholera originating in Bengal in 1816. Many livestock died in New England during the winter of 1816–1817. Cool temperatures and heavy rains resulted in failed harvests in Britain and Ireland. Families in Wales travelled long distances as refugees, begging for food. Famine was prevalent in north and southwest Ireland, following the failure of wheat, oat, and potato harvests. The crisis was severe in Germany, where food prices rose sharply and demonstrations in front of grain markets and bakeries, followed by riots, arson, and looting, took place in many European cities. It was the worst famine of the 19th century"

In 1883 Kratotoa erupted and is known as the deadliest volcanic eruption in modern times. It threw so much sulphur and dust into the air that it caused temperatures to drop worldwide for ~5 years. At least 36 000 people died.

In the year following the 1883 Krakatoa eruption, average Northern Hemisphere summer temperatures fell by as much as 1.2 °C (2.2 °F). Weather patterns continued to be chaotic for years, and temperatures did not return to normal until 1888

and

The Krakatoa eruption injected an unusually large amount of sulfur dioxide (SO2) gas high into the stratosphere, which was subsequently transported by high-level winds all over the planet. This led to a global increase in sulfuric acid (H2SO4) concentration in high-level cirrus clouds. The resulting increase in cloud reflectivity (or albedo) would reflect more incoming light from the sun than usual, and cool the entire planet until the suspended sulfur fell to the ground as acid precipitation.

These are global cooling events but are not as extreme as nuclear winters or as if Yellowstone super volcano had erupted. There is no radioactive fallout, actually thinking about it there are probably trace amounts in the ejected tephra. This sort of chaotic event would not create a snowball earth scenario. I'm trying to avoid that.

In my story, I have a similar setup where several various factors intermingle and create a period of time with large to excessive amounts of dust in the atmosphere leading to cooler summers, colder winters and severe food shortages. People die, regimes fall, chaos ensues. But then the dust clears and life can resume.

I'm not aiming for long-term ice ages or anything as 'fixed' as that. I'm aiming for an extended period of chaotic weather (only a slight 1-2 degree average temperature difference) that will affect the stability of human food production that would further influence mankind's societies in the short-term.

Now for the question. Just how long can a society survive in such conditions? I have a minimum range of 5 - 10 years from Krakatoa and Tambora but society didn't fail in the real world. Yes, people died and moved around as refugees looking for food but I haven't found any mention of nation states breaking down. How much longer could such an event have lasted so that it could be the direct cause of a state breaking down. What is the maximum range; decades up to 50 years?

A sub question to help focus any answers. Would the ensuing climate chaos have to have a more severe effect over a shorter time period or can I just extend the duration of the climate chaos to decades to cause society failure? I have a feeling if the climate changes are just extended, surviving humanity will adapt and find new crops and contingencies to make do with.

Note: I haven't focused on the industrial level pre-disaster as I haven't figured that out yet. Several centuries after the event and my society in question is approaching or is already in the Renaissance. If this is the second enlightenment or the first I haven't decided yet. It all really depends on how intense the colder famine period was. Answers can take this into consideration.

Note: I do realise that the political situation will play a part in if the state fails or not. But I'm trying to figure out how long a state/society could theoretically survive with a damaged food production system before bringing political factors into play (which will help me narrow down the time period even more).

• Comments are not for extended discussion; this conversation has been moved to chat. – Monica Cellio Apr 14 '17 at 22:58
• This looks a lot like Westeros with Volcanoes. – T. Sar Apr 5 '18 at 11:17
• @T.Sar, that is a valid point. I suppose in most GoT long seasons, they have time to prepare and stockpile etc. Obviously I have no idea how long people will be able to survive the long night, with all the burning and pillaging that has taken place. – EveryBitHelps Apr 5 '18 at 11:27

That is highly dependent on how bad it comes.

The Deccan Traps lasted 30 000 years and were together with the meteorite impact (which very likely also did trigger the traps) responsible for the mass extinction at the end of the Cretaceous period.

100 years ago such an event would very, very likely eradicate humanity. Now we would be able to continue even under an ash cloud with nuclear energy, but most of the human population will die an ugly death with a complete breakdown of society (riots, anarchy).

Another supervolcano incident, the Toba eruption, lasted only 6 years, but nearly wiped us from earth because it caused a severe genetic bottleneck, reducing humanity to approximately 1000 persons.

Essentially storages are only a short term solution (half a year at max). Humans have fat storage which enables us for weeks/months to continue working, but once this storage is empty, we need on average 300g fat or 500g carbohydrates and approx. 1 g protein per kg each day not to starve. That's a lot. While previous societies had fewer people they also had more diseases/war and less productivity, so I do not think the timeframe will be very different. So expect that society breaks down 1/2 - 1 year after the incident because people will be reduced to survival level or below.

• The bottleneck theory no longer holds credence. en.wikipedia.org/wiki/… – JohnWDailey Apr 14 '17 at 3:47
• @JohnWDailey The wikipedia article does not refute the bottleneck theory. Essentially the archaeologists claimed that they have found evidence that the local population in India survived. If you read the paper you see that at location 3 215 artifacts were found pre-Toba 77 ka and in the very same ash layer over a timespan of 3000 years later (!) at 74 ka only 108 artifacts (almost a half) were found. – Thorsten S. Apr 14 '17 at 13:37
• Even worse, the cited papers for the presence of Neanderthals and Homo floresiensis are contradictory. The first paper "Environmental Impact of the 73 ka Toba Super-eruption in South Asia" confirms massive ecological changes and the second one "New Evidence Shows Populations Survived the Toba Super-eruption 74,000 Years ago" is not even found in Google Scholar. At best you can say there are hotly debated points in the bottleneck theory, but "no longer holds credence" is incorrect. – Thorsten S. Apr 14 '17 at 13:50
• Lake Malawi would like to have a word with you. – JohnWDailey Apr 14 '17 at 17:19
• Agreed - this is a matter of degrees. Were there a major cooling incident: sunspots, or obscuring dust in the atmosphere, society would be affected. The question is - to what degree? The elimination of human society is unlikely. But, it is quite likely that a crop failing event that spans more than one or two years will cause a substantial number of premature human deaths from lack of food. – tj1000 Jun 26 '17 at 17:41

According to the german Wikipedia article the little ice age needed around 50 years with a growing population and crop failures to be a partial cause of the thirty year's war. And then only one year with a high population, drought, hail, hard winter and no money to spark the events of 1789.

But if you look the other way around at the french in the 17th century or the prussians in the 18th you have very "stable" societies.

I think a "stable" society may survive several generations of hardships as long as the population believes in it's nation / leadership / emperor / common goal / blood sacrifice ...

• Welcome to WorldBuilding! If you have a moment please take the tour and visit the help center to learn more about the site. Have fun! – Secespitus Jun 26 '17 at 17:29
• Please do provide links. Even if it's in German, not English, that's at least something. – a CVn Jun 27 '17 at 8:31

To look at the global situation, there is an example of a report here. Basically, the world production of basic cereals is about 2500 million tonnes a year, roughly balanced by consumption, with stocks of c. 600 million tonnes.

So - if a volcano completely wiped out farming, the answer is 'About 3 months'. The world does not carry a lot of food stocks. you might worry about this. You might add a month for food people had stored locally, and in supply chains, but with 'just in time' policies, that doesn't help much.

But.. from the same source, you'll note that over a third of grain production goes to animal feed. A large chunk of this could be diverted to human use without much problem; this gives the system a buffer. So as long as we didn't have complete harvest failure, we could cope with significant reductions. And it's fair to say that with the knowledge that a volcanic eruption had caused a temporary climate shift, farmers could adapt far more quickly nowadays than in, say, 1815.

The big problem could be market reaction. With prices being bid through the roof and normal exporting countries imposing export bans, local or regional famines could easily develop even when storehouses elsewhere were full. These can quickly escalate into revolution and war, as we saw in the 'Arab spring', mainly studied in the context of global warming, but also applicable for volcano induced cooling.

Conclusion: We could survive given sensible adaptation and international cooperation. So we would probably see some major wars and famines, then.

• There's another factor involved: internal farming with greenhouses and hydroponics. It isn't used as much as it could be because it's comparatively more expensive than normal farming and unnecessary, but it can be expanded fairly rapidly if resources were put into it: as a stopgap, use plastic sheeting and poles and build directly over existing fields. Obviously developed countries would have the advantage here, but it's an advantage no one had in 1815. – Keith Morrison Apr 7 '18 at 19:33

There is a perfect example in a very good book: The Bible. In there you will find a story about a guy who advised to store food to be not only enough for 7 years for the country storing it, but also in surplus to be sold outside.

So this points you to two things: The famine would need to be long enough to deplete the country's storage and large enough to affect the worldwide market. If only one condition would be fulfilled you would get some unrest, maybe a few uprisings. But without any outside force it's very unlikely the society would change.
And the outside force I have in mind: German agent Lenin working to change the government for the actual profit of Russia to withdraw from war.

• I was going to add a comment about 7 good years and 7 lean but didn't know if people would appreciate the religious humour. +1 – EveryBitHelps Apr 13 '17 at 13:43
• If this was wikipedia, your claim "a very good book" would bear a [quotation needed] ;-) – Burki Apr 13 '17 at 14:02
• A "very good book" about catastrophes and humanity middle finger to dying. :) – SZCZERZO KŁY Apr 13 '17 at 14:05
• @Burki I believe you mean Citation needed ;) – Alex Robinson Apr 13 '17 at 16:35
• @Burki it is at least very popular. #1 best selling IIRC – Asher Apr 13 '17 at 16:37