Woops...Posted before writing!! Sorry!
As has been said already, CDRs are are photographic medium, and, therefore very susceptible to Heat/Light...As the technology is only a few years old, I don't think that anyone can say with any confidence how long they will last....I use DATs a lot for work, and have some that are over a decade old, but, who knows in the future. I've transferred some of my tape archive to DAT and CDR for ease of playing....But, I've still kept the tapes....!!
Memo to self...Must buy bigger house!
Regards Ralphie