I do not see those billions dying peacefully, do you?
You call me a doom and gloom guy… I disagree, I am looking at the data I see and pointing out its implications.

Large sections of the Earth WILL become uninhabitable- where will those people go? How many wars will it lead to? There WILL be global food shortages, how many will die, and how many wars will THAT lead to.

There WILL be a refugee crises several orders of magnitude greater than we have ever seen… and what we have seen has led to a shift towards fascism. When the trickle of refugees becomes a tsunami how do you expect global politics to go?

These are things that are, for the most part, inevitable. I am NOT making up some doom and gloom scenario. I am looking at the situation and noting it is impossible to come up with a realistic scenario where we manage to avoid theses crises.

By 2100, the global population will be a shockingly small fraction of its current level. The majority of that reduction will be the result of very large scale dying- from famine, war, flooding, and heat. It will be a brutally ugly process. And even the well off and wealthy countries will see suffering they have not experienced so far.

Humanity will be greatly diminished and building back up will be much harder the second time around.

But of course it will be probably decades before a working fusion reactor is in service.

I have no idea when it will be available for commercial power production… but even if we had a blueprint for a Fusion power plant, just look at how long it takes to build a nuclear power plant…
What I can say is that the first working Fusion power plant will NOT be using the NIF method.

I interviewed at NIF to be shot director in 2008-ish, and that facility is HUGE… and they can only do a few shots a day- if even that…

I think the successful fusion reactor will be a hybrid of a few techniques. There are multiple commercial efforts working on this, I have no idea if they will be successful, but I am happy fusion power has reached the point where people are gambling that they can make it work… I was even contacted by one such venture out of the blue and offered a job (I told them I did not have the experience with monster laser systems they needed, and offered to advise for free where I could, which I did a couple of times).

I think there are promising approaches, but even the most promising have many years of research and development to get to the point where they are viable.

In short, fusion may help us get power without having to use fossil fuels… at some point well in the future, but it will not save us.

I’m willing to bet humanity will survive as a species regardless of the damage caused by climate change–it too, has survived much worse in the past.

What I fear is that the progress and gains we’ve made since the Enlightenment will be severely rolled back. This will include advances in science, technology, political and intellectual freedom and cultural progress. The world of the future will not just be threatened by climate, it will also suffer from overpopulation, resource shortages, massive migrations, disease and political and economic conflict that will be aggravated by the turmoil and disruption caused by climate change, pollution and sea-level rise.

Most of the past major crises and disruptions you allude to in your post occurred in a world which was essentially underpopulated and where vast amounts of natural resources remained untouched. This will not be the case in the late 21st century. We’re going into this crisis already severely crippled. And we now have a new demon to contend with, nuclear war.

Automobiles became common long before horse-drawn vehicles vanished. What if the horses disappeared and there was no internal combustion to take their place? Whale oil was replaced by petroleum well before the whales ran out. Consider what might have happened if the last whale was killed and there had been no oil in the ground.
The funny part is we kept on hunting whales, almost to extinction, long after it was clear we no longer needed them–simply because it was profitable. Their flesh was still useful as fertilizer, animal feed and gourmet delicacies.

There will be no Marshall Plan or oil shale or fracking for our children. And there will be no hydrogen fusion or space program either. Those activities require huge investment in resources. The only thing in our history we have to compare with this is the fall of the Roman Empire, and that was not an eco-catastrophe, it was simply a failure of the administrative infrastructure. In other words, the managers and capitalists and state bureaucrats simply lost control of the house of cards they had built to live in, soooo comfortably. We lost a thousand years of progress that time, in spite of living in a world filled with easily recoverable resources.

Next time, there won’t be any cheap, plentiful, easily accessible sources of energy lying around to rebuild civilization, we will have pissed it all away driving our two-ton SUVs down to the corner 7-11 to buy a pack of smokes. Climate change was just one of those “unanticipated consequences”.

Now as all you doom and gloom guys point out, it will be too late to stop the effects of Climate Change in the coming decades. All the political and social upheaval rising sea levels and desertification will cause is probably already baked in (no pun intended). RL believes civilization will collapse as a result. But consider this: civilization as it had previously existed essentially collapsed during WWII. But even in that era of global madness there were parts of the world that were unaffected. I believe there will be parts of the planet that will survive Climate Change and civilization will endure. And if we can eventually turn back the effects of Climate Change in a century or so humanity will once again thrive.

But the economic power of the fossil fuel industry, plus the political power of the major oil producers would move heaven and earth to keep it from happening. The guys in the white lab coats may find a solution to this problem, but the guys in the gray flannel suits are making too much money off the problem. They will do whatever it takes to stop fixing it.

Remember carcinogens in cigarettes? Remember how they tried to deny AGW in the first place? Remember pesticides, lead poisoning, the ozone hole? These guys don’t give a shit about you, Rob. They don’t give a shit about anybody.

Now if you can bribe the oil companies and the Saudis and Russians into running the fusion program…maybe. But first you’re going to have to convince them they’ll make a lot more money out of fusion than out of fossil.