So this thread could be philosophical, but I'm actually asking about the game. :)

Corporations raise productivity, but at an environmental cost that we (in the real world) currently don't know if it will kill the human race, or if we can develop and deploy technology to save us. The consensus seems to be that people will most likely be displaced or die in the millions, and the cost to offset our last 100 years of industrialisation will be in the trillions.

Sea levels will change, deserts will grow, farmlands will be wiped out (we ourselves are wiping out forests), weather will become even more extreme...

In Humankind, the developers have the option to explore both scenarios I mentioned, but will they?

It's doubtful that they will explore this with any depth in the base game, but might expand on it later on in a DLC. However you cant simply look at corporations as purely destructive to the environment, thats simply not what they are. Corporations and companies, especially in a society that promotes free enterprise, can do litterally anything. From develpoing the latest in recycling technologies to expanding startegic resource exploitation, regardless of whether they exist these things will happen but with a government in charge instead of a corportaion or company. But I also think such things were touched on in Civ 6, with mixed fanfare. While consequesnces to industrialization were shown in an extreme sense (having coal units causes global warming at an alarming rate) and certain technologies simply held above all others as a savior (solar power and wind power having 0 drawbacks besides space to build).

 In the end its a modern topic thats very devisive (mostly within the United States) with little besides game mechanics to punish you for developing. But they do have natural disasters, just local ones specific to your cities and how you handle things with them. An example was given during a live stream where someone asked if there will be natural disasters and the answer was yes to a point, but they are presented as a consequence to specific choices you make with that city when an event pops up. Such as a city developing around a series a rivers having the chance for flooding causing damage, you can spend money building dams to avoid this threat or you can ignore it for whatever reason you choose.

In the end you might get what you're aiming for, but it will be for roleplay rather than hard mechanics that punish or reward everyone on the map. 

Ok then just ignore everything I wrote I guess. End of the day heavy mechanics for climate change takes a ton of resources to develop and those resources are currently better off being used to flesh out the rest of the game.