I don't like it. It's too long. There's lots of stuff to get done before the end of the world, like running around turning off the lights and fretting about who's going to water the basil seedlings when we're all gone. I haven't got time to pronounce a word this cumbersome.
I have created this word out of frustration that no word exists in medical texts or in common usage for "fear of the end of the world."
There is Kinemortophobia, fear of zombies or the undead, yet this does not apply to all those who harbor fears of pandemics, the collapse of the global economy, etc. There appear to be a few recent halfhearted attempts to call this fear Apocalyptophobia, though it does not seem to have caught on. Because the original word apocalypse derives from the Greek for uncovering or revealing, and because it remains tied to religion in a multitude of ways, I feel dissatisfied with this terminology.
Building off the word phobia and its Greek roots, I decided to use Greek to create the rest: "kósmo" for world and "thánatos" for death. I chose this phrase because death of the world could occur from many different causes. When people begin to feel caught up in the overwhelming fear of the end of the world, it seems to be less about the details (to continue my earlier examples, the spreading disease and its symptoms, or the way that the stock market crashes) and more that life on the planet will end. The fear may focus on the details, but at its foundation and tying together many disparate fears, is the near-existential terror that the world as we know it will end, and we won't be fine.
As far as I can deduce from my limited knowledge of Greek and the Merriam-Webster pronunciation guide, this is how to pronounce the new word: