Global warming causes extinction? Not exactly.
I've always been fascinated by the Ediacaran fauna, a set of fossils from a nearly alien set of animals that flourished before the current set started to evolve. Some of them are now known to be ancestors of present arthropods and mollusks but others, with five eyes and weird appendages, have left no descendants.

I hadn't kept up with developments in that realm ... now it turns out the Ediacaran period was even stranger than previously thought. New fossil finds since 2003 indicate a geologically brief period before the Ediacara, perhaps 15 million years long, in which the sea was densely and richly populated by large critters that don't fit anywhere in our basic distinctions between animal, fungi, and plant. They seem to have been fixed seafloor dwellers, but (here's the strangest part) they weren't built from cells. Their structure appears to be fully fractal; at all scales from near-atomic to "breadbox size", they are branched, feathery, ferny.

What caused this sudden explosion of new types and species, in an ocean that had been exclusively claimed by one-celled bacteria and algae?

It was the end of an ice age, with melting glaciers.

"Peterson argues further that the primeval ocean would have been bursting with dissolved organic matter freed up by melting glaciers. ... their fractal, modular design allowed them to evolve quickly and grow large quickly, to take advantage of this sudden burst of plenty."

This is from an article [subscription only] in the latest New Scientist mag; needless to say, the same issue is also crammed with the usual Gaia-worshipping panic over melting glaciers causing extinction of species. (I'll give the mag credit for occasionally featuring articles that contradict The One True Goddess; it's too bad they don't actually listen to the other side, though.)
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