Florian U. Jehn
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florianjehn.fediscience.org.ap.brid.gy
Florian U. Jehn
@florianjehn.fediscience.org.ap.brid.gy
4 followers 1 following 35 posts
Aggressively agreeable | currently exploring the overlap of #ExistentialRisk, #FoodSecurity, #NuclearWinter and #Collapse | also quite interested in […]

🌉 bridged from https://fediscience.org/@florianjehn on the fediverse by https://fed.brid.gy/
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florianjehn.fediscience.org.ap.brid.gy
Next round of updates for my #LivingLiteratureReview. This means I go back to the old posts and add new papers I found, to make sure that everything stays as up to date as possible. Posts which got updated this time:
* Mapping out collapse research ( […]

[Original post on fediscience.org]
Baguettes spread out on a table. These symbolize the bread rations in France in WW1.
December 17, 2025 at 9:12 AM
florianjehn.fediscience.org.ap.brid.gy
For #globalwarming it seems that we are on a pathway to be clearly above 1.5°C and arguably also clearly above 2°C. In my new post I summarize research that highlights why this is the case and also how much of these higher temperatures ranges we really have […]

[Original post on fediscience.org]
A orange tinted, old picture from an old house near a river. There are snow capped mountains in the background.
November 30, 2025 at 4:32 PM
florianjehn.fediscience.org.ap.brid.gy
Remember the beautiful auroras last year? These occur when solar particles interact with Earth's magnetic field. When #earth is hit by large amounts of these particles, this is called a #geomagneticstorm. Geomagnetic storms can induce currents into the […]

[Original post on fediscience.org]
A dark and small alley with houses high up on both sides. In the middle of the picture is a street lamp which is hit by sun light from the side and casts an interesting shadow on one of the buildings.
October 29, 2025 at 10:45 AM
florianjehn.fediscience.org.ap.brid.gy
New post on my blog. I summarized Peter Turchin's book "End Times: Elites, Counter-Elites, and the Path of Political Disintegration". The post gives an overview of how #structuraldemographictheory works and how this explains the present political and social […]

[Original post on fediscience.org]
A large, dark blue curtain halfway hiding a large, somewhat modern looking iron gate. An out of focus person is standing at the edge of the curtain.
October 1, 2025 at 11:38 AM
florianjehn.fediscience.org.ap.brid.gy
(2/4) Even when two catastrophes cause similar global yield losses, their effects on trade are dramatically different.

Abrupt sunlight reduction (#nuclearwar, #supervolcano) concentrates damage in high-latitude major exporters → severe trade disruption […]

[Original post on fediscience.org]
Global map showing the distribution of relative food import losses for abrupt sunlight reduction scenarios and global catastrophic infrastructure loss. Northern Hemisphere countries in nuclear war scenario loose most.
September 30, 2025 at 10:26 AM
florianjehn.fediscience.org.ap.brid.gy
(1/4) We modeled how global food trade would collapse after catastrophic events like nuclear war or infrastructure loss. It matters enormously where damage occurs, not just how much. Especially, in nuclear winter many countries would loose the majority of […]

[Original post on fediscience.org]
A three panel figure showing the distribution of wheat trading communities now, after a nuclear war and after a loss of industrial production. The impacts of the nuclear war are considerably larger with many countries having to switch their trade community.
September 30, 2025 at 10:23 AM
florianjehn.fediscience.org.ap.brid.gy
New preprint: "The Largest Crop Production Shocks: Magnitude, Causes and Frequency"

Large #cropfailures happen regularly around the world, threatening #foodsecurity. We analyzed sixty years of global crop production data and found that every country has […]

[Original post on fediscience.org]
World map that shows the largest crop production shocks. These range from around -10 % in countries like China and up to -80% in some parts of Africa. The dataset is from 1961-2023.
September 4, 2025 at 5:37 PM
florianjehn.fediscience.org.ap.brid.gy
#climatechange, #nuclearwinter, and #stratosphericaerosolinjection are all human-made interventions in the climate system. They share the potential to be massively disruptive to the habitability of this planet. Usually, we see them as separate catastrophes […]

[Original post on fediscience.org]
Abandoned trenches in the desert.
September 3, 2025 at 9:05 AM
florianjehn.fediscience.org.ap.brid.gy
New theory on how #societalcollapse works just dropped. In his book "Goliath’s Curse: The History and Future of Societal Collapse”, @lukekemp describes how human societies repeatedly fall into the same trap: when resources become easily controlled and people […]

[Original post on fediscience.org]
A worn out path vanishing into the distance. Two large elephant statues are left and right of it. In the distance you can see some mountains with a large complex at the base of them.
August 6, 2025 at 7:54 AM
florianjehn.fediscience.org.ap.brid.gy
Have been doing some nature photography for the last two years or so. Was thinking about sharing a few here. Starting with one of my favorites. This very cute little #mouse.

#nature #photography
A mouse hiding in leaves. Some small plants sprouting around it.
July 24, 2025 at 3:38 PM
florianjehn.fediscience.org.ap.brid.gy
New paper is out: The State of Global Catastrophic Risk Research: A Bibliometric Review.

I am quite happy with this one. I think the paper gives a nice overview of what people in the global catastrophic risk community think about and what their research […]

[Original post on fediscience.org]
Visual abstract of the paper: 1) Collecting all GCR/ER papers from OpenAlex. 2) Connect them based on their reference list 3) Cluster them by similarity 4) Overview of the results
July 22, 2025 at 10:21 AM
florianjehn.fediscience.org.ap.brid.gy
Can really recommend to go hiking along the #rhine
View on the Rhine river from the hills above. In the distance you see small ships and a castle in the middle of the river.
July 21, 2025 at 10:34 AM
florianjehn.fediscience.org.ap.brid.gy
Time for updates on my blog again. However, not only the articles, but also the infrastructure. Thanks to @rogue_scholar now every post has a DOI and can be cited. Also, to make things look nicer, every post now has its on fitting picture at the start.

When […]

[Original post on fediscience.org]
An old, large, iron bridge stretching in the distance over a very wide river. Lots of small boats in the foreground.
July 16, 2025 at 8:14 AM
florianjehn.fediscience.org.ap.brid.gy
To prepare you need to know what you might face. This is true for an individual, as well as a society. To make it a bit easier to figure this out on a societal level, I aggregated a number of sources that try to assess what challenges humanity might face […]

[Original post on fediscience.org]
A once beautiful, but not destroyed little church in France. Around it you can see a simple graveyard and some small houses in the background.
June 19, 2025 at 6:45 AM
florianjehn.fediscience.org.ap.brid.gy
Preventing a #crisis is better than solving one after it happens. The challenge lies in recognizing signs early and knowing how to intervene. The latest entry in my living literature review explores three key questions: How can we detect crises before they […]

[Original post on fediscience.org]
The ruins of the Roman Forum. Léon, Auguste. (1921). Italie, Rome, Forum Romain [Photograph]. Public Domain (CC-0). Inventory number: A25515S.
May 21, 2025 at 8:22 AM
florianjehn.fediscience.org.ap.brid.gy
Time for another update in my living literature review about societal collapse: https://existentialcrunch.substack.com/p/april-2025-updates This time I mainly updated the posts #trade and democratic resilience (but there are more updates as well). One of my […]

[Original post on fediscience.org]
Very old picture of the harbor in Constantinople. The picture is taken from up high and you can see the houses around the harbor and the large sailing ships anchoring there. Reference for the picture: Passet, Stéphane. (1912). Constantinople (actuelle Istanbul), Turquie: La Corne d'Or prise de la tour de Galata vers le port de commerce [Photograph]. Public Domain (CC-0). Inventory number: A1125.
April 16, 2025 at 11:50 AM
florianjehn.fediscience.org.ap.brid.gy
In the research around #societalcollapse, once you get to the 18th century, revolutions start to pop up as a topic. To better understand the ideas and concepts important for revolutions, I read and summarized Hannah Arendt's "On #revolution". In this she […]

[Original post on fediscience.org]
Picture of a historic looking building made of white stone and a large cupola. Passet, Stéphane. (1914). Paris VIe arr., France L'Institut de France depuis le pont des Arts [Photograph]. Public Domain (CC-0). Inventory number: A7488.
March 19, 2025 at 10:12 AM
florianjehn.fediscience.org.ap.brid.gy
#systemicrisk and #Polycrisis are terms that are used more and more, especially in discussions around #climatechange. However, at least to me, they sometimes feel a bit vague and hard to pin down. So, I sat down, read a bunch of papers, and tried to create a […]

[Original post on fediscience.org]
An empty conference room with old and majestic furniture design. More information about the origin of the picture: Passet, Stéphane. (1929, August 18). La Haye, Pays-Bas Binnenhof, la salle de la Conférence de la Paix [Photograph]. Public Domain (CC-0). Inventory number: A61808.
February 19, 2025 at 11:11 AM
florianjehn.fediscience.org.ap.brid.gy
During my research around #societalcollapse, one thing that comes up again and is economic #inequality. It seems that there is something about it that makes societies inherently less stable and less able to tackle challenges ahead. To explore this more, I […]

[Original post on fediscience.org]
A view on the port in Algier. Photo cred: "Alger , Algérie Vue panoramique du port" by Jules Gervais-Courtellemont (1909-1911). Source: Musée Départemental Albert-Kahn. CC-00- Public Domain.
January 15, 2025 at 10:17 AM
florianjehn.fediscience.org.ap.brid.gy
In the last few days the news focused a lot on the fact that #2024 was the first year where we went above #1.5°C. This made me want to highlight a paper again where I was the main author in 2022. In this paper we looked at what temperatures the #ipcc reports […]

[Original post on fediscience.org]
Scientific figure which shows for each assessment report since 1990 how it focused on temperatures in the range between 0.5°C and 10 °C. The figure shows that the first four reports had a similar focus, with lots of research on higher temperatures, but that this trend shifted with the last two reports and is now mostly focused on 1.5°C and 2°C.
January 14, 2025 at 10:07 AM
florianjehn.fediscience.org.ap.brid.gy
Happy to share our new #preprint—the first-ever #SystematicReview on global catastrophic risk. 🌍

We explores the growing field of #globalcatastrophicrisk and #existentialrisk, which focus on global threats like #nuclearwar. This bibliometric analysis shows […]

[Original post on fediscience.org]
A visual summary of the preprint, which highlights how the methods were done and what the main findings are. It contains the same information as the abstract of the preprint.
December 4, 2024 at 7:45 AM