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> human extinction and the mere collapse of our civilization How do you imagine human extinction being an outcome? It seems to me that the worst case scenario

> human extinction and the mere collapse of our civilization How do you imagine human extinction being an outcome? It seems to me that the worst case scenario is large loss of population which would decrease greenhouse gas output. There would still be some increase in temperature even once we stop emitting, but wouldn't people in colder climates still survive?

Filligree 4y ago
True human extinction doesn't seem plausible, but in a worst-case scenario we can imagine a > 99% drop in population, roughly to what is sustainable without technology, in a dramatically harsher world. ("Without"? Well, nobody today knows how to build a cast-iron plough.) I don't believe this scenario is likely. For one thing we're not headed for 8C of heating; for another, technological change seems to be coming just in time to head off the very worst outcomes, assuming we struggle hard enough.
- vkou 4y ago
  > assuming we struggle hard enough. We aren't struggling at all, though. We just eased off the accelerator a little. (Assuming that our accounting is correct, and that methane leakage isn't worse than we think. [1]) [1] It's worse than we think.
  - Filligree 4y ago
    True, but... I need to retain some optimism, or I get too depressed to keep on. In this case, my optimism is that solar/wind and batteries will drop enough in price that fossil fuels become economically unfeasible. It seems possible! I just hope it isn't too little, too late.
- skyfaller 4y ago
  We probably aren't headed for 8 degrees of heating, based on what we know today. There are a lot of "out there" scenarios that don't make it into sober, conservative scientific reports from the IPCC, because they recognize how important it is that people take their warnings seriously, and they don't want to mention anything they don't have very clear evidence for already. One of my "favorites" is the "world without clouds" scenario, which for the record, I consider unlikely, but is horrifying to imagine: https://www.quantamagazine.org/cloud-loss-could-add-8-degrees-to-global-warming-20190225/ https://www.quantamagazine.org/cloud-loss-could-add-8-degree... What we're dealing with are "unknown unknowns": what tipping points might exist that we don't know about, that might result in more warming faster than expected based on today's science? We shouldn't take those kind of existential risks.
formerly_proven 4y ago
There's some fairly absurd doomerism going on in the "climate catastrophe tomorrow" camp where climate change will (somehow) turn earth into a barren rock and we're inches away from triggering a self-reinforcing climate resonance cascade of unforeseen consequences. It's of course a very urgent issue, but I think exaggerating it until it becomes a threat to "all life on earth" levels is a) dishonest b) does nothing to convince sceptics that it's a real issue, quite the opposite c) is not really all that actionable (at least not in a good way).
- coldtea 4y ago
  >will (somehow) turn earth into a barren rock Well, hundreds of millios displaced and/or dead would be enough. Doesn't have to "turn earth into a barren rock". And as for "suddenly", many systems tend to have a breaking point, especially systems, like the environment, which have feedback loops that can easily feed into each other and make things worse fast. Collapse is seldom linear or a nice gradual curve.
  - lelanthran 4y ago
    > Well, hundreds of millios displaced and/or dead would be enough. Doesn't have to "turn earth into a barren rock". Actually, yes it does. The OP specified "human extinction". We're arguing that single point. The fact that thousands/millions/billions might displaced isn't being contended.
- seibelj 4y ago
  The temperature and co2 levels have been much higher in the past. The earth has been much more tropical as well as an ice world. Humans can adapt to change quite effectively - we did invent air conditioning, as well as the land of The Netherlands which is reclaimed and existing beneath sea level. What is the greatest tragedy is how much worry and anxiety climate change causes. The earth is not a thinking thing - “Mother Nature” is not a being. The planet will exist and doesn’t care about humans. A century after the last human lives nature will swallow up almost everything we built. Earth exists for humans because we live here and make it so. We will adapt to whatever climate exists.
skyfaller 4y ago
There are a large number of things that could kill everyone, but I think the top threat will always be ourselves. It's very easy to imagine some resource war degenerating into a nuclear war. A few self-induced crises like that on top of the climate crisis would be enough to finish the survivors (who might have made it if the only danger were the environment). Think of the world population's size and global distribution as hedges against disaster: the fewer people who live, in fewer habitable places, the more likely it is that some disaster will affect everyone remaining and leave no one unaffected. We have fewer rolls of the dice, and there may come a day where they're all snake eyes. This why many are excited about the idea of "making humanity an interplanetary species", as I once was until I realized how hard it would be to make a working biosphere anywhere else, given how bad we are at maintaining one that already works. If we don't figure out how to save this biosphere, we won't have enough time to make more.
kpmah 4y ago
Even if it doesn't directly cause extinction, it could do things like destabilise nuclear powers.
thisismyusrname 4y ago
Positive feedback loops causing runaway warming is one way
XorNot 4y ago
Reduce human population by enough and extinction goes back on the agenda long term. There was at least one [1] population bottleneck in the last 70,000 years. Of course I would've thought "aren't you worried your grandchildren will live miserable, dangerous lives struggling to survive" would be a decent argument but I've encountered no Boomer who seems to worry about it as they excitedly tell me about the coming collapse of something or imminent major war in wherever. [1] https://www.businessinsider.com/genetic-bottleneck-almost-killed-humans-2016-3 https://www.businessinsider.com/genetic-bottleneck-almost-ki...
Spooky23 4y ago
People underestimate the suffering humans can endure. Primitive humanity was able to endure reduction to a few hundred mating pairs of humans. Society as it stands is much more fragile, but I’m sure we’re more likely to destroy ourselves from within before climate is a really major factor.

Filligree 4y ago

True human extinction doesn't seem plausible, but in a worst-case scenario we can imagine a > 99% drop in population, roughly to what is sustainable without technology, in a dramatically harsher world. ("Without"? Well, nobody today knows how to build a cast-iron plough.) I don't believe this scenario is likely. For one thing we're not headed for 8C of heating; for another, technological change seems to be coming just in time to head off the very worst outcomes, assuming we struggle hard enough.

vkou 4y ago
> assuming we struggle hard enough. We aren't struggling at all, though. We just eased off the accelerator a little. (Assuming that our accounting is correct, and that methane leakage isn't worse than we think. [1]) [1] It's worse than we think.
- Filligree 4y ago
  True, but... I need to retain some optimism, or I get too depressed to keep on. In this case, my optimism is that solar/wind and batteries will drop enough in price that fossil fuels become economically unfeasible. It seems possible! I just hope it isn't too little, too late.
skyfaller 4y ago
We probably aren't headed for 8 degrees of heating, based on what we know today. There are a lot of "out there" scenarios that don't make it into sober, conservative scientific reports from the IPCC, because they recognize how important it is that people take their warnings seriously, and they don't want to mention anything they don't have very clear evidence for already. One of my "favorites" is the "world without clouds" scenario, which for the record, I consider unlikely, but is horrifying to imagine: https://www.quantamagazine.org/cloud-loss-could-add-8-degrees-to-global-warming-20190225/ https://www.quantamagazine.org/cloud-loss-could-add-8-degree... What we're dealing with are "unknown unknowns": what tipping points might exist that we don't know about, that might result in more warming faster than expected based on today's science? We shouldn't take those kind of existential risks.

formerly_proven 4y ago

There's some fairly absurd doomerism going on in the "climate catastrophe tomorrow" camp where climate change will (somehow) turn earth into a barren rock and we're inches away from triggering a self-reinforcing climate resonance cascade of unforeseen consequences. It's of course a very urgent issue, but I think exaggerating it until it becomes a threat to "all life on earth" levels is a) dishonest b) does nothing to convince sceptics that it's a real issue, quite the opposite c) is not really all that actionable (at least not in a good way).

coldtea 4y ago
>will (somehow) turn earth into a barren rock Well, hundreds of millios displaced and/or dead would be enough. Doesn't have to "turn earth into a barren rock". And as for "suddenly", many systems tend to have a breaking point, especially systems, like the environment, which have feedback loops that can easily feed into each other and make things worse fast. Collapse is seldom linear or a nice gradual curve.
- lelanthran 4y ago
  > Well, hundreds of millios displaced and/or dead would be enough. Doesn't have to "turn earth into a barren rock". Actually, yes it does. The OP specified "human extinction". We're arguing that single point. The fact that thousands/millions/billions might displaced isn't being contended.
seibelj 4y ago
The temperature and co2 levels have been much higher in the past. The earth has been much more tropical as well as an ice world. Humans can adapt to change quite effectively - we did invent air conditioning, as well as the land of The Netherlands which is reclaimed and existing beneath sea level. What is the greatest tragedy is how much worry and anxiety climate change causes. The earth is not a thinking thing - “Mother Nature” is not a being. The planet will exist and doesn’t care about humans. A century after the last human lives nature will swallow up almost everything we built. Earth exists for humans because we live here and make it so. We will adapt to whatever climate exists.

skyfaller 4y ago

There are a large number of things that could kill everyone, but I think the top threat will always be ourselves. It's very easy to imagine some resource war degenerating into a nuclear war. A few self-induced crises like that on top of the climate crisis would be enough to finish the survivors (who might have made it if the only danger were the environment). Think of the world population's size and global distribution as hedges against disaster: the fewer people who live, in fewer habitable places, the more likely it is that some disaster will affect everyone remaining and leave no one unaffected. We have fewer rolls of the dice, and there may come a day where they're all snake eyes. This why many are excited about the idea of "making humanity an interplanetary species", as I once was until I realized how hard it would be to make a working biosphere anywhere else, given how bad we are at maintaining one that already works. If we don't figure out how to save this biosphere, we won't have enough time to make more.

kpmah 4y ago

Even if it doesn't directly cause extinction, it could do things like destabilise nuclear powers.

thisismyusrname 4y ago

Positive feedback loops causing runaway warming is one way

XorNot 4y ago

Reduce human population by enough and extinction goes back on the agenda long term. There was at least one [1] population bottleneck in the last 70,000 years. Of course I would've thought "aren't you worried your grandchildren will live miserable, dangerous lives struggling to survive" would be a decent argument but I've encountered no Boomer who seems to worry about it as they excitedly tell me about the coming collapse of something or imminent major war in wherever. [1] https://www.businessinsider.com/genetic-bottleneck-almost-killed-humans-2016-3 https://www.businessinsider.com/genetic-bottleneck-almost-ki...

Spooky23 4y ago

People underestimate the suffering humans can endure. Primitive humanity was able to endure reduction to a few hundred mating pairs of humans. Society as it stands is much more fragile, but I’m sure we’re more likely to destroy ourselves from within before climate is a really major factor.