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Comment by Daishiman | Hacker News Reader

Sure, but necessarily, any informed person understands that it is by the largest existential risk of humanity.

No. Informed people realize that there is no possibility that climate change will lead to human extinction (except possibly by some indirect means, such as leading to a war in which bioweapons are used, but then, drastic action to curtail climate change could also lead to war...).

Saying "existential risk" again and again does not make it true. Hearing it again and again does not make a rational person believe it.

>No. Informed people realize that there is no possibility that climate change will lead to human extinction

Avoiding human extinction from climate change is very easy but with this attitude you're not doing a good job at avoiding that fate. Right now I don't have much faith that humanity won't try to burn every single last drop of oil or chunk of coal. Although it should be very difficult to reach insane targets like 9°C warming it is definitively possible with enough ignorance and dedication and as humanity has shown we have an unlimited supply of these two qualities.

How would a 9°C warming cause human extinction? There is plenty of currently cold land that would benefit from warming temperatures for farming and humans are massively adaptable in that we live in large populations in pretty much every climate. Even if things continue the way they are, it'll happen over such a long time that time that the rate of change won't be a real issue either.

I'm all for zero carbon emissions but the ridiculous "everyone is going to die due to climate change" is pure FUD.

A 9 degree difference will wipe out almost all phytoplankton biomass responsible for generating most of the oxygen in our planet. You will see a raise in multiple meters of sea level, causing mass migrations involving over 20% of the world population, will make most of the planet uninhabitable, and will reduce the oxygen levels of the oceans to the point that they will be mostly anoxic.

That is an extinction level event greater than the Permian mass extinction.

So what specifically in your list do you think will cause humans to go extinct?

Phytoplankton are also responsible for 50-80% of atmospheric oxygen, so in the parent poster's scenario I think the loss of a breathable atmosphere is the most likely nail in our species' coffin.

Probably won't happen, probably not a great idea to push things to see how far we can let things go before it's catastrophic, though.

I don't need to speculate on this. There is never anything "specific" as any one of these things individually and all things combined are a death sentence.

With a 9 degree temperature increase a large amount of the planet simply becomes uninhabitable during the summer, period.

You just said it yourself. It's irrelevant whether the mechanism of action is direct or indirect. Collapse of the ecosystems that sustain us will accelerate processes that dramatically increase the likelihood of catastrophic events.

The semantic game of whether it's "human extinction" or "the end of organized large-scale human civilization" is stupid and grasping at straws.

> It's irrelevant whether the mechanism of action is direct or indirect.

If you take that view, then practically everything is an "existential threat". Wars have been triggered by soccer games...

As for whether "existential threat" means "human extinction" - well what else would "existential" refer to other than human existence?

Again, if you broaden this, then practically anything could be an "existential threat" - to democracy, say. And it's pretty clear that the people screaming "existential threat" intend for people to take it as meaning human existinction - the naive people at least.

> no possibility that climate change will lead to human extinction

low, but existing, possibility*

> Saying "existential risk" again and again does not make it true.

Existential risk includes more than extinction, it could also mean society collapses and takes 100 years to recover to current level, or 1000, or 10,000, or _never_ recovers. Maybe some societies collapse but others just turn into deserts. Maybe there is a recovery, but we'll never have the global trade networks of today, maybe we'll never send a man to Mars. It might mean 90% of the population is lost.

I've said nothing about the probability of any of that, but it goes up the slower we act.

Collapse of civilization (human society with huge amount of specialization) with the simultaneous ecological collapse can IMHO lead to human extinction. Civilization gives us science and technology, which allows us to be, in theory, less dependent on nature. Conversely, if the civilization fails, we will have to rely much more on nature. If the nature undergoes mass extinction event when we strongly need to rely on it, we can easily get screwed. We can probably (as species) somewhat manage to handle one of these events, but not both at the same time.

just because you don't want to accept it doesn't make it not real

Is it? Others that come immediately to mind:

1. Intentional or accidental development of a biological weapon that would wipe out the human race.

2. Asteroid strike sufficient for same.

3. Nuclear war, same.

4. Takeover and eventual decimation by AI of some form.

5. Reproductive failure (think falling sperm counts).

6. Failure to thrive, as a species.

OK, now assign probability scores to those 6 and to climate change.

None of those are as directly relevant as climate change. None.

downerending@ events would affect just about every human in a very large way. Climate change will only affect a subset of the human population in a noticeable way as a mild inconvenience [0].

[0]: https://climate.nasa.gov/evidence/

Ok, but just because it isn't the most dangerous thing that could happen doesn't mean you can just ignore it. You shouldn't stop brushing your teeth just because you could be hit by a bus tomorrow.

I by no means think we should ignore the issue. But I disagree with OP that climate change is obviously a massively more important risk than all of the others.

I also think that a stance approaching religious fervor is entirely inappropriate for this sort of policy discussion.

(As a wild guess, I think some combination of #4 and #6 is our biggest risk for extinction over the next 10,000 years.)

Lots of people don't believe it's a problem or even claim it will be a benefit and no amount of evidence will convince them otherwise.

I don't understand this sentiment. After years of stagnation at around 911 million tons of CO2 Germany managed to reduce carbon emissions by 40 million tons in 2019 alone. The only thing that changed was a spike in the price of EU CO2 certificates which resulted in less electricity being produced from coal. It's absurd that this incredible progress is held back by the fear of losing 20k coal jobs when the reality is that those 20k coal jobs prevented the creation of hundreds of thousands in the renewable energy sector.

Even if you think the whole thing is a scam you see that having a grand mission to invest in modern technology is an incredibly effective jobs program just like sending people to the moon. Nobody has gone to the moon again but we still benefit from all the research from that era.

After years of stagnation at around 911 million tons of CO2 Germany managed to reduce carbon emissions by 40 million tons in 2019 alone.

Meanwhile, France has consistently had around half the per-capita CO2 emissions as Germany due to not giving in to the fearmongering over nuclear power.

It's absurd that this incredible progress is held back by the fear of losing 20k coal jobs when the reality is that those 20k coal jobs prevented the creation of hundreds of thousands in the renewable energy sector.

It's true that preserving jobs is a terrible justification for keeping coal around. But similarly "it takes a lot more green jobs to produce the same amount of energy" is not good; it is bad. We should switch to cleaner energy despite that, not because of it.

I'm reminded of Kubrick's quote about the atom bomb[0]: "People react primarily to direct experience and not to abstractions; it is very rare to find anyone who can become emotionally involved with an abstraction. The longer the bomb is around without anything happening, the better the job that people do in psychologically denying its existence. It has become as abstract as the fact that we are all going to die someday, which we usually do an excellent job of denying."

A disturbing corollary: the same challenge of processing an abstraction exists amongst most non-experts who accept AGW (and I'm among them). Hence symbolic gestures (banning straws), conflation with other sacred-cow political issues (corporate capitalism), belief in looming extinction (unlikely; the threat is to civilization, not homo sapiens), all generally filtered through a "purity" moral matrix (to put it in Haidt-ian terms).

As the complex reality becomes filtered through moralizing and politicizing, the other side digs in their heels for predictable tribalist and game-theoretic reasons. It's a truly wicked problem.

[0]: https://www.newyorker.com/magazine/1966/11/12/how-about-a-li...

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