No, contrary to what Rello thought (and his idea seemed to be reasonnable), it does not multiply as I was able to go to 0.0 to Harsh condition in 39 years (or perhaps slightly less). The evolution is *very* slow though from Deadly to Harsh, much slower than from Mild to the best for instance, but don't ask me why.
So you have to wait for another 20 years Oleg before having the pleasure to see the transformations of your planet, or you could build ten CI plants.
(My tests have been done with a level 3 CI, so you could speed up the process a bit)