Fear isn't our most rational feeling; the amygdala is an inherently inscrutable bit of brain. Tyler Cowen makes a good point about how the irrationality of fear manifests itself with global warming:
I believe, for instance, that ocean acidification will, in the long run, be the most dangerous consequence of carbon emissions. (And by saying that I don't mean to downgrade the other worries.)
I am aware that this belief isn't necessarily justified. It is shared by some scientists as a speculation, and it could turn out to be true, but it is hardly well-grounded as our major worry even though it does seem to be a real worry.
Still, for whatever reason, I cannot help but believe it, or at least believe it with some excess degree of credence.
I've also got a deep dread of ocean acidification, in large part because the name sounds so terrible. The underlying chemistry, though, is rather simple: the seas absorb carbon dioxide, which dissolves into carbonic acid, which will gradually drop the pH of water and kill all the plankton. When I read stories about the mysterious death of blue whales, my first thought is what have we done, we are destroying everything.
There are many aspects of global warming that should provoke fear - rising sea levels, more intense hurricanes, altered natural habitats, etc. - but I'm sticking with ocean acidification. And how the does rational part of my brain respond? It calmly tells me that the blue whales were probably killed by ships, and that not all scientists have nightmares about carbonic acid. It also informs me that, despite all the fancy theoretical models, we might not yet know the worst symptoms of a warmer earth. In essence, humans are running a huge climate experiment with too many unknown variables and invisible feedback loops.
Perhaps what you are describing, at its essence, is the fear of the unknown.
Me, I'm afraid of the basement, it's creepy down there, especially in the dark.
Reminds me of the old SimEarth game:
terraforming at its best--the unintended consequences of fooling around with intricate feedback loops--send in a few ice meteors to cool things off!!