Thoughts about existential risk, history, climate, food security and societal collapse.

How vulnerable are we to the next Carrington Event?

Auroras, space weather and the threat to critical infrastructure

Existential Crunch is a living literature review about societal collapse. When I read new things, which update my views, I’ll also update my posts (1). This post highlights updates I made to three posts. However, before we dive into the changes, I have a little announcement: It’s been six months already since I started this project for real. Since then I have published five posts for the living literature review and two posts about other topics.

November 2023 Updates

Does climate science focus on the right temperature range?

Supply and demand after global catastrophes

End time economics

Is climate the fundamental cause that topples civilizations?

Climate anomalies and societal collapse

This post is part of a living literature review on societal collapse.

What factors allow societies to survive a crisis?

I created a list of researchers in the existential risk field based on the amount of papers they have published. In the following I provide links to their work. This is not meant as a strict evaluation of the value of their contributions to the field, but more as a quick overview of who is working on what.

A quick overview for the field of existential risk studies

The 25 researchers who have published the largest number of academic articles on existential risk

In the last year nuclear winter was a topic I spent a lot of time on. It is one of the potential global catastrophes that motivates me in general and it is directly relevant to my work (Jehn, 2023; Jehn et al., 2023). This makes it kind of obvious that I take nuclear winter seriously.

Science denial and nuclear winter

Almost all researchers use “gap-spotting”, a process that only creates boring research questions

It usually does not happen that I read through a non-fiction book in two days, but I could not put this one down. In the recent months, I noticed that one thing that I have to improve to become a better researcher is to come up with more and better research questions.

A review of “Constructing Research Questions”

Against the dominance of gap-spotting in research

This post is part of a living literature review on societal collapse. You can find an indexed archive here.

Reflecting about the end of our modern civilization requires counterfactual thinking, because fortunately it hasn’t happened yet. But this is not the only way counterfactuals help us understand collapse better. We can also create counterfactuals to reflect about past events.

Why think about what could have been or might become?

Counterfactual catastrophes

The prospect of a famine-free world hinges on improved governance and peace. It is as simple - or as difficult - as that.

Cormac Ó Gráda Sometimes it happens that you are vaguely aware of a person and you know they coined a term and then by some random chance you come across evidence that this person effectively made the world just much worse.

A summary of "Famine: A Short History" by Cormac Ó Gráda

Escaping the Malthusian Trap

This post is part of a living literature review on societal collapse. You can find an indexed archive here.

Many articles highlight famine as a major issue for societal collapse, emphasizing the overall vulnerability of food production and trade. The speed at which such events affect us depends on our food reserves.

How much food is there?

This post is part of a living literature review on societal collapse. You can find an indexed archive here.

Electricity is essential for the functioning of our modern society, as nearly everything we do depends on the electrical grid in some way. While this reliance provides significant comfort and convenience, it also makes us vulnerable if the grid fails. But what happens when the grid stops working?

What happens to a society when the lights go out?

The consequences of large-scale blackouts

This post is part of a living literature review on societal collapse. You can find an indexed archive here.

The first post of this living literature review gave a summary of the field of collapse studies. One thing that post makes clear is that we need better models of societal dynamics.

Exploring the current state of societal dynamics modeling

Simulating the end of the world

This post is part of a living literature review on societal collapse. You can find an indexed archive here.

For this post I aim to essentially create a little repository of catastrophic risk lists, so other people can find those more easily and get an overview of how groups of experts with different backgrounds categorize and evaluate risks.

What could go wrong?

This post is part of a living literature review on societal collapse. You can find an indexed archive here.

When we talk about societal collapse, we usually talk about the factors that led to the collapse of a given civilization. However, you could also turn this around and ask what factors allow civilizations to avoid societal collapse and major crises.

How some societies manage to avoid crisis

Reform or ruin

So, how do you actually write a living literature review? In the more than two years that I have been writing this (time really flies), sometimes I get asked how I go about writing the posts here. With this post, I want to answer this question. While this is focused on a living literature review, I think these notes are probably helpful for everybody who has to do at least some scientific writing or wants to do more of that in the future.

Finding papers, coming up with ideas, writing and publishing

How to write a living literature review

Once again it is time to update the existing posts with new papers I have found. This time the majority of them revolve around how trade and democracy keep our society stable. I also have a little request to my readers: Do you have any paper recommendations for me to read? I have a lot of channels to go hunting for new, interesting papers, but I figured I would be interested in what my readers find relevant.

Understanding trade and democracies better

April 2025 Updates

This post is part of a living literature review on societal collapse. You can find an indexed archive here.

While we generally aim to avoid a collapse, it is crucial to understand the potential recovery time if one occurs. Assessing this is challenging, as it depends on the starting level of complexity, the extent of the loss, and the desired recovery level.

How long until recovery after collapse?

This post is part of a living literature review on societal collapse. You can find an indexed archive here.

Historical evidence shows that human civilizations repeatedly engaged in self-destructive behaviors in the past, especially in terms of resource overuse (1). Today, we could point to climate change, as a clear example of self-destructive behavior.

Anthropocene traps

Understanding famine and its consequences
 

Existential Crunch is a living literature review about societal collapse. When I read new things, which update my views, I’ll also update my posts. This post highlights updates I made to four posts. In addition to those updates, I am also happy to announce that I was invited to the “Prioritäten Podcast” to talk about my work.

Understanding famine and its consequences

January 2024 Updates

This post is part of a living literature review on societal collapse. You can find an indexed archive here.

One explanation for collapse is just bad luck.

The difference between bad luck and bad understanding

Is societal collapse just a random event?

This post is part of a living literature review on societal collapse. You can find an indexed archive here.

The risk of societal collapse is dependent not only on the problems a society faces, but also on the adaptation it makes to counter those problems. These adaptations can increase the resilience of a society and make it less vulnerable to potential hazards.

More perspectives makes for better decisions

Participation, inclusion, democracy, and resilience

This post is part of a living literature review on societal collapse. You can find an indexed archive here.

Past societies often found their end amid a challenging climate. Environmental changes can put considerable strain on a society and there are many cases in history where it was a major contributor to their collapse, especially when the change was sudden.

Are we steering towards a climate catastrophe or a manageable challenge?

The trouble with tipping points

Going forward this blog here will work somewhat differently. I got some funding by Open Phil to start a living literature review on societal collapse (thanks to Matt Clancy for making this happen).  So how is this gonna work? The idea behind this project is to make research on societal collapse more accessible to anyone who’s interested in the topic, by writing it up in a nicely sorted and easy to read way.

Introducing a living literature review on societal collapse

“Man exists. For him, it is not a question of wondering whether his presence in the world is useful, whether life is worth the trouble of being lived. These questions make no sense. It is a matter of knowing whether he wants to live and under what condition.”

Simone de Beauvoir despises fascism. She despises oppressors in general and collaborators in particular.

Exploring the concepts of freedom, oppression, and ethical decision making in a complex world

A Closer Look at Simone de Beauvoir's Ethics of Ambiguity

“

 How do we know there is such a thing as a long-term version of our kind of civilization?

” Adam Frank

 Summary

Given some basic assumptions about how planets and civilizations’ energy use interact, we can create a model that shows that it is likely that most or even all exo-civilizations run into their own version of an Anthropocene.

Things we can learn from exo-civilisations, even if we never meet any

The universal Anthropocene

Diversity is important. Not only inherently, but instrumentally as well. Based on ideas from the book “Why Trust Science?” by science historian Naomi Oreskes this post argues for increased diversity as a chance to produce more reliable knowledge. The main argument is that a more diverse community has more diverse perspectives on any given topic.

You need diverse perspectives to get closer to truth

In diversity lies epistemic strengh

End of an age

Why do civilizations collapse? For some civilizational collapses in the past there is one striking event that leads to a quick end, like environmental damage for the people on the Easter Islands.

The end of the Bronze Age as an example of a sudden collapse of civilization

When we study societal collapse, we typically examine it through the lens of elites. Using the records and remains left by emperors, nobles, and the literate classes who had the most to lose when their world ended. But what if we’ve been asking the wrong question all along? After years of reviewing collapse literature ranging from quantitative databases like Seshat to case studies spanning millennia, certain patterns emerge again and again.

The people's history of collapse

What do you think about when you hear the term revolution? Likely, you think of the French Revolution and things like the Storm of the Bastille, the Guillotine or Louis XVI’s execution. It is on the forefront of our minds, because the French Revolution escalated so quickly and so violently that it left a permanent mark on the world.

Revolution and democracy

The following text presents a condensed summary of "The state of global catastrophic risk research: a bibliometric review" by Jehn et al. (2025), published in Earth System Dynamics. The paper represents the first systematic bibliometric analysis of global catastrophic risk (GCR) and existential risk (ER) literature, examining a large number of documents to map the field's development, identify research clusters, and assess current challenges.

The state of global catastrophic risk research

Structural demographic theory and the United States

Inequality all the way down

This post is part of a living literature review on societal collapse. You can find an indexed archive here.

If we want to learn about human society’s resilience or fragility, it’s helpful to learn from our species’ prior experiences. The trouble is, since collapse is a relatively rare phenomenon, we’re short on data.

How deep into human history can we look and still learn something for today’s civilization?

Lessons from the past for our global civilization

This post is part of a living literature review on societal collapse. You can find an indexed archive here.

Most things you use and particularly the food we consume rely on an intact global supply chain. Without trade, essential resources such as fertilizers would become inaccessible, making food production much harder.

Cascading risks in our global supply chains

Trade collapse

This post is part of a living literature review on societal collapse. You can find an indexed archive here.

Democracies have a stronger incentive to keep their general population content compared to authoritarian regimes, as the political elite’s survival is more directly linked to the general population through elections.

Democracies increase resilience, but are (somewhat) in decline

Democratic Resilience

This post is part of a living literature review on societal collapse. You can find an indexed archive here.

One question that often comes up when discussing global catastrophes and societal collapse is: What is the best place to stay in such a case? This simple question is surprisingly hard to answer, as it depends on a lot of factors.

The best places to weather global catastrophes

Existential risk studies look at events that have the chance of either ending humanity or its potential (for example, by locking us in an eternal pre-industrial state). These kinds of events can vary wildly. Humanity could be wiped out by nuclear war, a pandemic, a supervolcanic eruption and a variety of other causes. Those events need knowledge from all kinds of fields, ranging from geology to medicine.

The importance of creativity for studying the end of the world

We need hot existential risk research

This post is part of a living literature review on societal collapse. You can find an indexed archive here.

This post primarily centers around a comprehensive 2022 case study conducted by Markus Stoffel and colleagues (Stoffel et al., 2022). This information dense paper is notable for its integration of a literature review and the combination of data from diverse sources and historical records.

From temperature drop to political turmoil

Societal consequences of the Little Ice Age

How warm will it get? This question is probably on the mind of every person dealing with the issue of climate change. It is so important because all other consequences of climate change depend on it. The less the earth warms, the better mankind will cope with it. In the following, I will deal with this question and its implications.

Global warming above 2°C

Time to update posts again. I know it is not that long ago since the last update post, but there are just so many interesting things I want to share with you. The first thing observant readers probably have already noticed: Every Substack post now has its own historical image. You can watch all of them by browsing through the archive. I tried to find ones that fit the general vibe of the post and I am quite happy with the result.

July 2025 Updates

I want to try something different with this post here. The post is actually a conference paper for the Stanford Existential Risk Conference in April. I publish it both here and as a preprint to test if I can get more feedback for it this way.

The compounding effects of nuclear winter and overstepped planetary boundaries

Anthropocene under dark skies

This post is part of a living literature review on societal collapse. You can find an indexed archive here.

What would we eat if the sun disappeared tomorrow? Or if our electrical grid collapsed worldwide? This is a topic I am quite interested in, because many of the facets of societal collapse are quite intimately linked to the food system.

How to feed everyone, even in the worst of times

Resilient foods

It has been a while since the last update post. Since then I have come across a lot of interesting papers and also changed some things around this blog here. I now keep both the Substack as well as the archive up to date, so you never have to wonder if you are reading the most recent version of a post. Due to popular demand (one person asked for it) I now also provide a list of all references used in the writing.

Making sure this living literature review is actually alive

December 2024 Updates

This post is part of a living literature review on societal collapse. You can find an indexed archive here.

Imagine a row of dominoes where knocking over one piece triggers a cascade that topples them all. This is systemic risk - when a single failure can bring down an entire system. Now imagine several such cascade failures happening simultaneously at a global scale and making each other worse.

Systemic risk and the polycrisis

Some time ago I came across the potato famine and how it contributed or even caused the revolutions of 1848. I wondered if this is an good example to show how cascading failures lead societal crisis. Starting from a natural event to an agricultural crisis, to an economic crisis, to a financial crisis and finally resulting in a political crisis.