"What do you think it's going to be like when about a billion people have to migrate inland due to sea level rise?"
Considering that even the worst-case doom-crying scenarios issued by the IPCC predict a sea level increase of the order of 1 meter over the period of a century (i.e., ~1 cm per year), your (and Hollywood's) suggestion of rioting mobs fleeing the tsunami-like rising ocean is just not based in reality.
The fact that this is news to you is a clue that perhaps you know less about this subject than you think you do.
Hint: that means I won.
You claimed that the ecosystem "didn't survive" the Chicxulub event because there were different organisms afterward. I pointed out that by that "definition" the ecosystem has never "survived", because it has been in a state of constant change since day one.
Rather than responding to this, you just got nasty.
I repeat: I win. Sorry.
The question is, what do those changes mean for individual organisms? Because that's what you and I are.
Changes to the climate and ecosystem are like changes to velocity. Whether the change is good or bad for people depends on the magnitude and direction.
I do think that your focus on who is "winning" an imaginary Internet slap fight is detracting from your understanding.
"Ecosystem" is not shorthand for "life exists on Earth somewhere." An ecosystem is a particular state of the dependencies between life forms.
The ecosystem that existed before the big asteroid strike was thoroughly and rapidly destroyed; a new ecosystem developed afterward. That's fine from a general "life finds a way" perspective, but it sucked for the sauropods, who went extinct.
EDIT: if you want a sense of why the indirect effects of anthropogenic climate change might be bad, look at the social unrest reacting to a couple million people migrating out of Syria. What do you think it's going to be like when about a billion people have to migrate inland due to sea level rise?