elemental climate concerns - it seems to me like carbon fiber is the best material for varied weather conditions, it doesn't rust like steel does or annodize like aluminium does. It seems like it's the least affected by weather, and claims that it's worse are just part of the typical "it's new so it must be dangerous" kind of stuff that's not true.

theft - it's usually easier to find cheap aluminum or old steel than it is carbon fiber, however, carbon fiber has been around long enough that I've seen cheap full carbon bikes, I was at a bike sale this spring where I saw an older trek for $200. And of course if your parking at work is relatively secure (which it is sometimes), this may not be an issue.

abuse on the part of others - this is the one I don't think anyone has figured out - whether carbon fiber can get damaged easier than steel or aluminum if it's slammed up against other bikes

Every time there's a new frame material, someone is claiming it's fragile and has a limited lifespan, take a look at this thread from 2006 -
http://www.bikejournal.com/thread.asp?ThreadID=%7BDCE81503-8848-4E81-B825-D7833CD9799E%7D&numPost=1

My concern is that I have been told that aluminum frames loose strength at the bonds and have been known to crack after 5-7 years.

Followed up by:
There's a reason why most frame manufacturers only warranty aluminum frames for three years.

Every time a new frame material comes out there are rumors that new is bad and older is good.