Levels of global catastrophes: from mild to extinction

It is important to make a bridge between existential risks and other possible risks. If we say that existential risks are infinitely more important than other risks, we put them out of scope of policymakers (as they can’t work with infinities). We could reach them if we show x-risks as extreme cases of smaller risks. It could be done for most risks (with AI and accelerator's catastrophes are notable exceptions).

Smaller catastrophes play complex role in estimating probability of x-risks. A chain of smaller catastrophes may result in extinction, but one small catastrophe could postpone bigger risks (but it is not good solution). The following table presents different levels of global catastrophes depending of their size. Numbers are mostly arbitrary and are more like placeholders for future updates. 




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2nd level probably needs more analysis-- I don't think it will look very much like the middle ages because so much will be left from the previous civilization. Even just having a lot of good stainless steel knives isn't nothing, and more generally, there's going to be a lot of refined metal around.

People might well remember crop rotation and sterilizing the drinking water.

Can anyone recommend a serious look at the question of what would remain and what would be likely to get rebuilt fairly quickly?

Yes, middle ages is more about society "style". The main economy may be scavenging, which is very unproductive and prevent to return to manufacturing economy, as scavenging will give high quality objects for hundred of years. As a result, the skills for manufacturing will be lost. Also a lot of weaponry will remain including knifes and guns (and even nukes), which may result in Long War or Somali-style world (I think that these notations are self evident). Such Long War in scavengers world will mean very long process of degradation and population decline, which is rising chances of total extinction. A lot of postapocaliptic fantasy is trying to model such world.

Some information may be here: The Knowledge: How to Rebuild Civilization in the Aftermath of a Cataclysm by Lewis Dartnell

A knife is a tool as well as a weapon.

I think you've got a point about the loss of knowledge if people are scavenging for crucial items.

Population decline strikes me as hard to predict. My casual assumption is drastic decline during the disaster and soon after, followed by gradual increase as people move into abandoned land and grow food.

I also assume that people will be inventing new things to suit their current conditions.

I think you're pessimistic about tech regression.

Assuming survival of some libraries, I think basically any medium-sized functional village (thousands of people, or hundreds with a dash of trade) is adequate to maintain iron age technology. That's valuable enough that any group that survived in a fixed location for more than a couple years could see the value in the investment. (You might not even need the libraries if the right sort of person survived; I suspect I could get a lot of it without that, but it would be a lot less efficient.)

It doesn't take all that much more beyond that to get to some mix of 17th to 19th century tech. Building a useful early 19th-century machine shop is the work of one or two people, full time, for several years. Even in the presence of scavenging, I think such technology is useful enough that it won't take that long to be worth spending time on.

Basically I think anything that's survivable is unlikely to regress to before 17th century tech for a period longer than a few years.

If only one village survive, it will use scavenging of nearby city for decades and during this time it will lost most high educated people.

But lets assume that scavenging economy is no possible, may be this village survive on remote island, which is probable, in case of pandemic.

In this case the main problem will be economy of scale, chemistry and raw materials. Even 19 century economy is based on available coal, iron ore, copper and some other things. Most of them require very specific people, knowledges and instruments to find and produce.

And also they are economically useful only if it is done in the medium size european country.

And finally most ores which were easily available in 19 century are now depleted or not present at all in remote islands. So if a village survive on an island it will not be able to build steampowered ship in next few years to explore surrounding. I also would not overestimate the ability of random people to study new science like geology, using only books, without proper training and control.

Why is runaway global warming at "total extinction"/level 5 and not at the other levels?

Because it is "runaway" )). This means that temperature would rise really high like on Venus. Some scientists think that this is possible because methane and water vapor are also greenhouse gases, and quick release of methane from arctic floor may be the start of this process. See more here: http://arctic-news.blogspot.ru/

Arctic news is generally not credible, using incredibly stupid polynomial fits to observed methane levels at single surface stations to infer absurd and impossible levels in the near future and generally hyping all the positive feedbacks they can find an inkling of in the literature and ignoring every known negative feedback.

As well as the fact that the Earth has been through massive atmosphere excursions in the past from much higher greenhouse condition starting points, like the Paleocene Eocene Thermal maximum or the Permian event, without ever leaving the bounds of long-term homeostasis. The next half milion years stand to be VERY interesting for the biosphere, but this has happened before no matter what scale we push things to.

While I don't agree with everything arctic news say and I see that they overhype some recent small changes in methane concentration, I heard the idea of runaway global warming before. I also think that artificial runaway global warming is possible if nukes will be used to destabilize methane of ocean floor. While answering previous comment I was surprised to find in wiki that if median earth temperature once rise to 47C, than water vapor greenhouse effect will push it until new stable state at 900 C. I still think that we should be more afraid of small probability (I estimate it in 1 per cent) of runaway global warming than of high probability conventional global warming (2-4 C).

The main thing about it is, in my opinion, connected with your notion in the second period in your post that we don't observe past runaway global warming. (Except small scale one like 55 mln. years ago.) One of the reason for that may be observation selection: there is no life on all planets with runaway global warming (Venus).

But more serious consequence of it may be that runaway global warming is long overdue and our atmosphere is in metastable condition where small influence may flip-flop it. I wrote an article about in before "Why anthropic principle stopped to defend us"? https://www.scribd.com/doc/8729933/Why-anthropic-principle-stopped-to-defend-us-Observation-selection-and-fragility-of-our-environment (It needs to be rewritten).

Points taken. Still, the PETM was as recent as 50 million years ago, when the sun was on the order of 99.5% as bright as it is now and the base state from which the temperature and atmospheric carbon rose (as quickly as we have measurements able to say - as in, it took less than 15k years and they cant be more specific than that and there's evidence that at least some places warmed ifaster) was one in which there were fewer eroding mountain belts to suck up carbon and more subduction zones to produce it and a geological equilibrium CO2 concentration on the order of 3-4x that of today with an average global temperature of about 8 C warmer than today, before the pulse even happened. I find it unlikely the solar and geochemical situation has changed considerably over that ultimately not terribly long timeframe,

I have read somewhere that the main difference is that now we have 10 times more accumulated methane in the form of methane hydrates on ocean floor and permafrost. Methane is strong green house gas, like 100 times stronger than CO2. But as it lives only 6 years in atmosphere, the main difference would be not its amount, but the speed which which it could be realised from permafrost. This depends of speed of CO2 accumulation (which is now very high, while the total level is still low). The last thought is mine conclusion from what I read.

Geochemical situation also changed as we had several ice ages which are very good for methane hydrates accumulation and also because geography of Arctic ocean changed.

Anyway, I think that we runaway global warming may be easily prevented by artificial nuclear winter or some cloud seeding, if situation will be urgent. But AI situation is more complex.

Could you point me to an article that specifies that this would actually race temperatures to Venus levels?

This wiki article have many links: https://en.wikipedia.org/wiki/Runaway_climate_change But I would like to clarify my position: I am not a climatologist and can't independently evaluate these claims on math level, but I understand their logic and think that while runaway climate change is low probability event, we should do more to prevent it. The interesting point is similarity between two communities. The community of people who think that self-improving AI is possible and is x-risk and community of people who think that runaway warming is possible and is x-risks. The most interesting thing is that both communities choose to ignore each other. But the mechanism of risk (positive feedback) and timeframe (2030) is almost the same.

That article says:

Global warming of that magnitude would make most of the planet uninhabitable by humans.

That would be really bad but it's not the same as total extinction.

timeframe (2030)

I don't think that's the timeframe of the LW community as shown by our census.

timeframe (2030)

I checked the timeframe in Arctic-news.com. They said that things will become serious after 2030, but extinction will happen around 2060. It is shown on last graph in http://arctic-news.blogspot.ru/p/the-mechanism.html As I remember the LW census, it put AI on 2060? Could you remind me exact data?

As I remember the LW census, it put AI on 2060? Could you remind me exact data?

(in the form mean + stdev (1st quartile, 2nd quartile, 3rd quartile) [n = number responding]))
From 2013:
Singularity year: 1.67E +11 + 4.089E+12 (2060, 2090, 2150) [n = 1195]
From 2014:
Singularity: 2143.44 + 356.643 (2060, 2090, 2150) [1177]

I fail to see the difference. Of course, if we take into account possible space colonies it will not be extinction... Also the article speaks about "which refers specifically to climate changes that cause a planetary body's water to boil off". I don't think it is survivable.

Also runaway global warming is (relatively) easy to prevent by the means of geo-engineering.

Most of the planet being uninhabitable means that there are still part of it that are habitable.

May be it will be highest mountains after 7000 meters, which will turn from - 50 to +30 C. Wiki said that threshold for water runway warming is 47 C (at 10 per cent high solar luminosity) and if it reached, the temperature will reach 900 C in new stable state. https://en.wikipedia.org/wiki/Future_of_the_Earth#Loss_of_oceans It means that very hot earth where small highlands will still be habitable - is still in unstable condition and could have much higher global warming.