They will. However, areas, where almost no one lives today, will be inhabitable instead. There's plenty of barely inhabited space on Earth.

That will be a giant migration crisis, on an unprecedented scale, sure. Maybe even a world war. Nothing good, not in slightest. Something best avoided at all costs.

Yet, the point is, if this won't be avoided - humanity as a whole is still not in danger. We're not going extinct if Earth will warm up. The world will change drastically, many millions will die, ecosystems will be shattered - but H.sapiens aren't going to disappear as a species.

I wouldn't be surprised of most of the western world will wait until the "Areas where more than a billion people live today will become uninhabitable to humans if they warm up" start taking drastic anti-climate-change sacrifices first. If they aren't willing to sacrifice economic growth to mitigate those consequences, then no one will.

Yeah I can totally see that kind of logic coming. But if everyone just waits for someone else to do something, nothing will change. That is the most likely outcome, I think.

But why? Why can't we adapt to those environments using technology? This is what the OP comment is saying.

Because our technology doesn't magically appear out of nowhere. Even the simple DIY "lifehack" you can assemble from $5 worth of RadioShack parts has huge supply chains hidden behind it, staffed by hundreds of thousands of people. On top of that, all those supply chains are full of circular dependencies. A chip needs a fab. A fab needs computers. Computers need chips... and screws. Screws need metal and precision manufacturing machines. Precision manufacturing machines need computers and screws. Metal mining needs computer and screws. Etc.

If the climate situation gets to the point of crashing global supply chains, say goodbye to all modern technology. Whatever's left will degrade quickly, and we'll be back to preindustrial levels, but with no easily accessible dense energy sources to bootstrap another industrial revolution.

This is why I keep saying that the most important goal right now is not to protect the planet, not to protect the human species, but to protect our technological civilization. If it collapses, we'll still be there (albeit in reduced numbers). But our civilization won't recover for millennia.

That's a common trope in Science Fiction. But modern technology is different from the Iron Age. It uses vastly less energy for the same result; its honestly simpler in many regards than what came before.

Sure there are dependencies, and some technologies will collapse and become unachievable for generations. But others are essentially free of dependencies - the germ theory of disease, the staff system, democracy, air travel, bicycles. Easy to bring back or keep, and with tremendous benefits.

I've always been sad that post-apocalyptic scenarios have no bicycles, and no biplanes. They just postulate people being the same as people were in the stone age, maybe with some recycled trash thrown in.

That's a fair observation. In fact, applying modern scientific and engineering knowledge to tech built from ground-up is something I'm interested in[0]. The post-collapse life would be better thanks to all this knowledge (as long as people keep copying books instead of burning them), but I still maintain we'd end up in a pretty dire situation.

Consider that food production is very much dependent and looped with all the existing supply chains. As some say, modern agriculture is essentially pouring petroleum into the ground and harvesting crops that grow from it. Could we use our scientific knowledge to get better results than preindustrial people did with the same tech level? Sure. Will it be enough to feed even 20% of current population, especially given the battered climate? I doubt it. And the way I see it, a lot of our "social technologies" - as well as more "physical" ones - seem to depend on population size and density.

Speaking of science fiction tropes, I read an interesting book once - "The Windup Girl". It featured a post-climate-change world with depleted fossil fuels and collapsed technology, that still sort-of worked thanks to machines being powered by mechanical work (with spring systems for storage and special breeds of animals providing muscle power). I wish more books and movies would go into this territory.

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[0] - not just because it's what we'll need come climatepocalypse, but also because I believe there are many unexplored "low-tech/hi-science" solutions that could let us achieve similar results in many areas of life, while using much less energy, or with much less dependence on existing infrastructure. For instance, I feel that mechanical energy storage (springs) and gliders are underexplored and underapplied, since energy today is too cheap to bother.

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EDIT and a tangent: I am really interested in the possibility of combining gliders with computers and sensors to enable extremely energy-efficient (if not time-efficient) flight. If anyone knows of work being done in this space, I'd love to get some directions or resources about it.

I'm on the same page. The easiest thing to do once the collapse comes will be to give up and die instead of change - and maybe 80% is too conservative an estimate of the number of folks that will take this route.

Farming is more of a 'trickle petroleum into the ground and harvest crops'. Its one of the most efficient of technologies now. With good timing and no-till and ammonia fertilizer, even eroded clay hillsides produce bumper crops. It is a fragile technology tree but much simpler trees could be forged, having a good whack of the same benefits.

RE the 80%, I expect the food shortage pressures to cause immediate wars that would quickly help shed the excess population. I fully expect to die in such a conflict (or be forced to eat a bullet to avoid the pain of starvation).

RE farming and other technology trees, it might be worth it to hedge our bets by trying to develop such simpler tech trees right now. In the worst case, we'd be making life much easier for the survivors. In the best case, maybe we could reapply some of those ideas to further reduce energy waste.

Just come to my place in the country, here in Iowa. That's what all the family are expecting to do. It's our gathering place. Remote from centers of population, food production facilities and stores everywhere, inhospitable enough to discourage refugees (winter), personal firearm ownership the norm. And our family includes doctors, soldiers, farmers and managers. Kind of the perfect mix!

Thanks :). Would love to come and help you fortify. Alas, it'll involve catching a flight from central Europe before shit hits the fan.

All about the timing. Maybe make a dry run before it gets that far, work the kinks out? Honestly, you'd be welcome.

I'd be happy to. Can you send me an e-mail?

Ideas get lost too. The way out of the dark ages was made by monasteries who saved libraries. It still took forever to recover.

Maybe we’ll have a rennasaince. Maybe we won’t; but Paper Books will be critical

Are we going to adapt all the world's flora and fauna to the changed conditions too?

If so it's simply cheaper to entirely fix global warming. If not, what are we planning on eating?

We're already seeing species can't react quickly enough to changing conditions. Flora especially takes time to move. If it's only humanity that is adapting, isn't the point rather moot?

The principle species that can't react quickly enough is Homo Sapiens, sadly. At least lower mammals don't have to deal with denial and demagogues.

Most of the people who live in places that will become uninhabitable, can either not or can barely afford clear water and food. They will not be able to afford hi tech solutions. Since Humanity does not help them now, it is not reasonable to assume that we will help them in the future.

They're not saying that these people will survive, just that the human kind will survive

One immediate reason is our physiological limit (see wet bulb temperature), which is achieved at air temperatures as low as 45 degrees C depending on humidity.

Another is sea level rise. For +14C that's on the order of +30 meters as currently predicted.

And of course such drastic changes don't come alone. Weather patterns will change, food production will be threatened, governments will be destabilized, wars will happen.

We can tech our way out of some of this but who's to say that we will be given enough time and resources. The universe doesn't owe us anything.

Coral reefs and their ecosystem lie at a precise depth - where water clarity, temperature and sea floor cooperate to provide enough sunlight and energy to allow corals to grow. A change in sea temperature of a degree or two, or a rise or fall of a few inches, and existing coral reefs collapse. And it takes centuries for them to regrow.

Many things are like that. And we don't have decades to wait for the Earth to become congenial again, we need to eat every day.