That's the nasty thing. It doesn't "finally collapse".
The world just eats the climate costs and keeps going.
There's no global catastrophe. No single moment when the magnitude of your folly is revealed to you a blinding flash. Just a slow trickle of "2% worse". A loss of what could have been.
Whether there will be a global catastrophe or not, it is unknown yet and unpredictable.
There are many mechanisms of positive feedback that can accelerate global warming instead of just reaching an equilibrium at a higher average temperature than now.
If some of those mechanisms of positive feedback would be triggered, a global catastrophe would be possible, due to the excessive speed of the climate change, which does not give enough time for the biosphere to adapt to it.
Instead of hoping that we will be lucky, it would have been much better to avoid such risks and prevent further increases in CO2 concentration and average temperature.
I am old enough to have seen a dramatic change in climate from the time when I was a child, when the seasons were still exactly as they had been described for centuries and millennia at that location in Europe, to the present time, when winters are no colder than autumns were before and I have never used again my winter clothes and boots for about 15 years.
I find such a radical change during my lifetime quite scary and I see no evidence for claims that "the world will keep going". The truth is that nobody knows whether this will be true and hoping that this will happen without doing anything to guarantee such an outcome is reckless.
There is not enough "positive feedback" going around in the system to do anything of the sort.
Plenty of feedback mechanisms were proposed, investigated, and found lacking. It's a "makes climate change 10% worse than it would otherwise have been" kind of thing, not a "makes climate change 1000% worse than it would otherwise have been" kind of thing.
Making the temperature rise 10% worse doesn't mean the GDP impact won't be 1000% worse.
There's only so much worse things can get before the fundamentals of civilization aren't there any more. 3 meals a day from anarchy.
The world got hit with WW2 and moved on. It takes a lot to destroy "the fundamentals of civilization" on a global level. Climate change is woefully insufficient.
The problem is that we will not move on from WW3, and famine, water depletion, resource exhaustion etc. are all existential problems for individual countries that will cause conflicts between previously peaceful nations. At some point the nations in conflict will have alliances and nuclear weapons, and people will use them when the choice is between that or starving to death by the millions. I would be somewhat more optimistic about humanity's ability to weather worsening circumstances if we didn't develop the human extinction button in all of our grand technological wisdom.
Climate change is not the great equalizer people want it to be.
Nuclear superpowers are among the least likely countries to actually collapse from climate damage.
US isn't Syria, and it's Syria that's at risk.
First world countries like France can absorb a +30% spike to food prices. Countries where the same food price spike would come with a major death toll don't have the tools to kick off WW3.
Pakistan and North Korea have nuclear weapons. What makes you think that other countries won't develop them when push comes to shove? Right now the status quo is such that smaller countries find violating international sanctions on nuclear weapon development to be disadvantageous (no immediate benefit from having them; expensive to have them; economic punishment for having them). The calculus on the status quo changes considerably when famine or other ecological disasters are threatening to wipe out half your population. Is the US going to invade all potential nuclear weapons developers like it did with Iran? Do you have complete confidence that will always work and never escalate towards anything larger?
You know it. The country that was probably the closest to "developing nuclear weapons" is currently in the process of being bombed to shit for it.
Not the only reason, no. But their nuclear ambitions certainly did contribute to their current predicament.
Nuclear weapons take time, expertize, resources and sustained political will to develop and deploy. If you have all of that, you might be able to put all of that towards climate adaptation instead. Or: go for the nukes and bet hard that you aren't going to get bombed to shit for it. Worked out for NK, but doesn't seem to have worked for Iran.
I think the level of tolerance US has for marginally stable autocracies with nuclear weapons has receded permanently.
Not to mention that merely having a nuclear bomb doesn't automatically allow one to cause WW3. Nuclear weapons were used in a world war already, and that didn't even destroy a single country - let alone the world. It takes a lot of nukes, and a lot of delivery mechanisms, to actually move the needle on the matter of human civilization existing.
> Is the US going to invade all potential nuclear weapons developers like it did with Iran?
Invade? No. Bomb? Probably. Same if for India if e.g. Sri Lanka decides it wants nuclear weapons.
Global warming will unfortunately disproportionately hit poor, equatorial countries. (Also, starving countries can’t afford a nuclear programme. There is no breakout risk in Sudan.)
> US isn't Syria, and it's Syria that's at risk. First world countries like France can absorb a +30% spike to food prices
And you think a second, much larger Syrian refugee migration will have 0 impact on France?
Nothing happens in a vacuum. Everything and everyone is connected.
WW2 hit the higher layers of abstraction. You could still grow food plants in those countries during and after the war, but the governance structures were bombed. Climate change is the opposite. If you can't grow food, you're fucked.