The article is well cited with external references if you're interested in validating the claims made.

FWiW I've been in geophysical exploration, mapping, and modeling since the 1980s and have no issue with the IPCC's reports on AGW. (I'm also responsible for posting this submission after reading the paper linked).

From your linked medium article:

  By 2050 total human population will likely be under 2 billion.

  Humans, along with most other animals, will go extinct before the end of this century.

  These impacts are locked in and cannot be averted. 
are all things I don't agree with.

How can you validate (ie prove) these claims?

NB: Climate aside, the current "birthrate crisis" that the natalists scream about will see a flattening of population growth by 2050 .. that leaves ~ 8 billion to vanish to reach the 2 billion asserted.

The statement directly following your lifted intro quotes is

> Everything in this article is supporting information for this conclusion.

So,

> How can you validate (ie prove) these claims?

By reading the rest of the article and its references.

As you probably know, not many things in this realm can be proven with 100% certainty.

Which falsifies

  These impacts are locked in and cannot be averted. 
trivially.

It's not as outlandish as you're attempting to paint it as, considering the author is assuming that capital interests remain in control when making such a claim.

And under that assumption, it's a bit crazy to think anything but depopulation will happen. Everything points to it being in their playbook; the blatant mishandling of COVID (which is far from over) by the uniparty being one of many glaring examples.

I agree depopulation will happen by simple resource limitations but I do not think it is any part of a playbook. Hanlons razer : Never attribute to malice that which is adequately explained by stupidity.

Many wish there was at least malice because then there is a narrative, the reality is probably much more muddled and messy.