Because it’s objectively unsustainable?

I don't think we know that. Indeed, what we're currently doing as a species to the environment is unsustainable. But it's not clear to me how it's the capitalism that's the unsustainable part. My understanding is that capitalism is a system which allows us, as a society, to produce things very efficiently, and to distribute resources. It hasn't failed in that role, has it?

I don’t really get what it even means to be “pro capitalist” at this point.

I believe that, for example, if I wanted to open a bookshop, I should be able to. Or that if I wanted to rent a couple of 3D printers and sell widgets, that I should be able to. Or if I wanted to hire some dude on fiverr to write some music to my screenplay, I should be able to. This is capitalism. Do you disagree? This is what confuses me, and why I asked the question-- on my side of the fence, I don't really understand what it means to be anti-capitalist. Hence why I asked.

We know, for a fact, that capitalism will lead to disaster if we keep doing what we’re doing. Do you disagree with that? Or do you not care?

Well no need to be rude! Of course I care! And yes, we're headed towards disaster in terms of the environment. But I don't understand, like I said above, how capitalism is causing it and how not-capitalism would solve it. We have 7 billion people on the planet and they all need to be fed. Capitalism is the most efficient system we know of to create and allocate resources. Should we... move to a less efficient system? Wouldn't that be worse for the environment? How does that solve anything? This is my confusion.

What is your general plan for what we should do when we can see that something we currently do and rely on will have to stop in the near future? Not that we will have to choose to stop it, but that it will stop because of something being depleted or no longer possible.

This is an interesting question! I'm parsing it to mean "how can the current problems be solved within a capitalist system?". It's a good question, and I don't have a 100% guaranteed answer. But I don't see that any capitalism alternative has a good answer either, so still I don't see how capitalism is the "bad guy".

In any case, my answer is this: A side effect of all of capitalist driven efficient production is that the environment is harmed. Here, I think the governing bodies have failed in their roles: their role is to define what "capital" means and rules of ownership. They haven't done that for environmental concerns, which is why capitalism isn't taking it into account properly. My desired solution is that the government could define a "total amount of carbon emissions" that would be allowed by the country as a whole, and then distribute transferrable carbon credits on the open market. This turns "rights to emit carbon" into a form of capital, and capitalism will do what it do and optimize for it.

In essence, I believe that governments have done a bad job of using the tool of capitalism to solve the problem of pollution.

If you imagine that we’re trying to find the best long-term system for humanity, and that the possible solutions exist on a curve on an X/Y plane, and we want to find the lowest point on the function, capitalism is very clearly a local minima

Great analogy! But.... have we seen a lower minimum? What's the rationale behind that system? That's my question