Trying to predict the future is hazardous, not only because of the conjunction fallacy, but because there are so many factors involved. Even if you're careful to avoid the mistake of thinking that A, B, and C happening are more likely than A and C, it's not easy to estimate what will happen when you've got factors A through Z involved, and complicated chains of relationships like "if D and E, but not F, and G is stronger than expected, then H". Misjudging the likelihood of a factor, or misunderstanding a relationship, or omitting factors or relationships, can make an apparently solid set of predictions completely worthless.

That's not to say that it's impossible, of course. If you restrict yourself to asking what will happen if we push on a physical system, and throw the world's best scientists at the problem for decades with millions of dollars and powerful supercomputers at their disposal, then they can actually model what inputs will cause what outputs with probabilities attached. The existence of anthropogenic global warming is a fact, just as the existence of evolution and atoms is a fact, and it's clear that all else being equal (note 1), basically everyone would prefer for the Earth's climate to be original recipe instead of extra crispy. The problem is, we don't know what the inputs will be, and it's trying to guess what the inputs will be that's especially hazardous. It's a lot harder to model what one Congress will do, let alone many. (Modeling the mind-killer is a headache.)

When faced with this sort of problem, I find it useful to instead think about possible end states, which are typically easier to envision and enumerate, and ask how likely it is we'll end up there, through any path whatsoever. And Stein's Law is usually helpful: "If something cannot go on forever, it will stop."

Anthropogenic global warming can't go on forever, so it'll stop. How will it stop? I can think of several ways - this is a non-exhaustive list:

• We discover a novel feedback loop, Earth's atmosphere becomes like Venus's, and everyone dies. It's pretty clear that this isn't a possibility, we hope, although it should be considered before being rejected (note 2).

• We collectively come to our senses, and do all the right things right now to keep the problem from getting any worse, and to fix as much as physically possible of the damage that's already been done. It's also pretty clear that this will not happen.

• A technological breakthrough substantially solves the problem for us. For example, we solve a bunch of engineering problems, and leapfrog from ITER to cheap and plentiful commercial nuclear fusion in just a couple of decades, without having thrown 100 billion dollars at the problem (as that would be shading into the "come to our senses" scenario). The probability of this one is hard to judge - we get stuck by some problems for a while before eventually solving them - but hope is not really a plan.

• The nasty consequences of global warming keep getting worse and worse, until advanced civilizations are wrecked back into more primitive states, where they're unable to keep dumping carbon into the atmosphere. It looks to me like this one is unlikely too - advanced nations will be able to cope at significant cost. It's just poor nations that are boned.

• We run out of coal (note 3), oil, and natural gas to burn. They're finite, so this is guaranteed to happen - the question is whether it happens before anything else. A more precise question is, when will our rates of production stop increasing - combined with inelastic demand, this will cause significant price increases that force us to consider previously more expensive (or ionizing), but non-carbon-emitting, sources of energy. This is the scenario that I judge as most likely. Unfortunately, it looks like the result will be extra crispy at a minimum.

• Something else - increasing food/water/resource scarcity leads to increasing conflict, and eventually to global thermonuclear war - we know that one is perfectly capable of wrecking technological civilization. Hopefully unlikely (there's that word again).

My conclusion is that because many people are already working on both sides of this issue, this community's time would be better spent elsewhere.

Note 1: The "all else being equal" part is key. The ultimate problem isn't that some people want to seriously modify the Earth's climate in and of itself, or for the lulz, or because they're supervillains. It's because fucking money is at stake, and like Mafia bosses in movies, people want their fucking money and they want it now. This wouldn't even be a problem, except that carbon is an unpriced negative externality.

Note 2: Just as igniting the Earth's atmosphere was considered and rejected before the Trinity test. Note that many popular accounts of how this possibility was considered are completely wrong. The worry was never that a nuclear weapon could ignite a global chemical fire in the atmosphere - it was that it could ignite a global nuclear fire. (Follow Wikipedia's citation.) Fortunately for us, the physics don't work out that way.

Note 3: Fucking coal.